摘要:

248 TRORPE: THE INTERDEPENDENCE OF THE PHYSICAL AND XXX1.- The Ch,ernicu I Interdependence of the Physical and Cderia in the Analysis of Butter- fat. By THOMAS EDWARD THORPE, C.B., F.R.S. IN July, 1901, a Departmental Committee was appointed, at the instance of the Board of Agriculture, to inquire and report as to what regulations, if any, might with advantage be made for determining what deficiency in any of the normal constituents of butter should raise a presumption that the butter was not genuine. To assist the Committee in arriving at a conclusion on this matter, it became necessary to obtain at first hand the values of various analytical constants of specimens of butter of known origin, and produced from milk given under varying conditions. Observation has shown that the chemical nature of butter-fat is dependent t o a certain extent on the climatic influences to which the cows are exposed, on the nature and amount of the food supplied, and on the breed, period of lactation, and idiosyncrasy of the individual cow.In order to give such weight as was practicable to the effect of these factors, the samples of butter were obtained from carefully selected districts, and often from cows set apart for the purpose of the inquiry ; whilst particulars of the breed, diet, stabling, and period of lactation were supplied with the samples in nearly all cases. For example, to illustrate the effects of more rigorous climatic conditions than obtain in the United Kingdom generally, farms and dairies in Caithness, Sutherland, the Orkneys, Shetlands, and the Hebrides were laid under contribution ; whilst a series of samples from Hollesley Bay, Suffolk, served to exemplify the influence of exposure of the cattle to the winds of the North Sea.From the arrangements made for the collection and transmission of the butter, it is believed that all the samples can be relied on as authentic. The analyses were made at the Government Laboratory. Altogether about 430 samples were received ; of these, for special reasons, 73 samples were only examined as regards water, salt, curd, and amount of fat, with which data we are not here concerned. The analytical figures obtained for the remainder, 357 in all, included, besides the foregoing particulars, determinations of the Reichert- Wollny number of the fat, its relative density and saponification value, and the Zeiss reading at 45'.I n nearly all cases, the proportions of soluble and insoluble fatty acids were also determined, together with the mean molecular weight of the insoluble acids. Details concerning the origin of the samples are published in theCHEMICAL CRITERIA IN THE ANALYSIS OF BUTTER-FAT. 249 Minutes of Evidence to the Report of the Committee (Cd. 1750, Appendix xxix, 505-58s). As relatively few systematic observations appear to have been made on authentic samples of British and Irish made butter having the representative character of those now dealt with, it may be useful to put on record a summary of the results obtained. The object of the present 'communication is to indicate the general relations between the analytically-important chemical and physical constants of butter-fat as disclosed by a study of the average values of these constants determined on a number of samples sufficiently large to ensure with reasonable certainty n fairly close approximation to the true values.Before attempting to make use of the observations with a view to general deductions, it is desirable to obtain some idea of the magnitude of the error to which the several determinations are liable. Taking first the Reichert-Wollny experiments, the results were obtained by working strictly under the conditions agreed upon by myself and a Committee representing the Council of the Society of Public Analysts, who in 1900 examined the matter in conjunction with analysts of the Goverment Laboratory in connection with the question of butter-fat in margarine (see Abstr., 1901, ii, 77).I n a large number of duplicate experiments the mean difference obtained between two determinations of the Reichert-Wollny number on the same sample of butter-fat was 0.20. So far, therefore, as what may be called fortuitous errors are concerned, the average values may be taken as known to within about k0.1 unit where the value is obtained from a fairly large number of samples, and probably to within +_O-2 unit where the number is relatively small. The relative densities of the fats were generally taken in a pycnometer of bottle form, adjusted to contain 50 grams of water a t 37.8'. . Duplicate weighings of the same fat with such a pycnometer rarely differ by more than 0-005 gram, corresponding with one unit in the fourth decimal place when expressed as specific gravity.I n a few cases a bottle of only half the above capacity was used ; the error here might be twice as great as with the larger pycnometer, or two units in the fourth decimal place. Consequently the average values may, as regards the variable errors of experiment, be looked upon as accurate to within & 0.0001. A small constant erroi- might conceivably arise thus : after the fat in the bottle has been brought to the desired temperature of 37.8' a little time is required to complete the filling and to insert the stopper. During this time, the temperature is falling, and the effect of this would be to slightlyincrease the weight of fat which the bottle would contain.The same tendency would, however, be found during250 THORPE: THE INTERDEPENDENCE OF THE PHYSICAL AND the adjustment of the instrument with water, and the actual error would therefore be only that arising from the difference of these effects. The average difference shown by duplicate determibations of the saponificatibn value of butter-fat, deduced from a large number of experiments made by several operators, was found to be 0.065, expressed as percentage of potassium hydroxide. This corresponds to about 0.7 of a unit when calculated into ‘‘ saponification-equivalents.’’ Sub- stantially the same difference was found in the case of the molecular weight determinations. The values may, therefore, be regarded as subject to an experimental error of about k0.4 of a unit.I n all cases the acid and alkali used were carefully standardised, and it is not thought that any appreciable error is to be attributed to this part of the experimental work. As regards the refractometer indications, it may be noted that there are two or three possible sources of inaccuracy in using the Zeiss butyro-refractometer. (1) Since the instrument is graduated into divisions representing whole units, the fractions of a unit have to be estimated by the eye. (2) The line of shadow is often not very sharply defined where i t cuts the scale of the instrument. (3) The temperature may fluctuate slightly during the course of the experi- ment. Probably a single observation might be liable t o a maximum error of & 0.4 unit, and the mean of a number of experiments‘ such as are used in the curves given below may be relied upon as accurate within about k 0 .2 of a unit. For the soluble and insoluble acids, the method adopted was sub- stantially the modification of Hehner’s process recommended by the American Association of Official Agricultural Chemists. The saponi- fication of the fat, however, was effected in silver flasks instead of in glass. For the soluble acids, the mean difference between duplicate analyses in a large number of cases was found to be 0.12 per cent., and for the insoluble acids 0.15 per cent. So far as manipulative error is concerned the average values given in the table may therefore be taken as accurate to within about f 0.06 and f 0.08 per cent. in the two cases respectively. The averages of the analytical data from which the curves given below are constructed are given on p.254. I n obtaining these figures -taking, for example, the first line-all the Reichert-Wollny values lying between 22-00 and 22.99 have been taken from the experimental results and averaged, giving the number 22.5. The corresponding values of the specific gravity, sapouification-equivalent, and Zeiss number were also abstracted and averaged, giving the figures shown in the table. For the next line, the Reichert-Wollny values lying between 23.0 and 23-99 were taken; and 80 on for the others. It wouId be small, and sensibly constant.CHEMICAL CRITERIA IN THE ANALYSIS OF BUTTER-FAT. 251252 THORPE: THE INTERDEPENDENCE OF THE PHYSICAL AND 0 0 I - c1CHEMICAL CRITERIA IN THE ANALYSIS OF BUTTER-FAT.253 Li VOL. LXXXV. S254 THORPE: THE INTERDEPENDEKCE OF THE PHYSICAL AND Specific gravity at 37.8" 37.2. I Saponifica- tion equivalent. No. of samples' Reichert- Wollny number. 22.5 23'5 24'5 25.5 26 5 27'5 28'8 29 -5 30.5 51 '3 32'6 450. Per cent. on fat. _____ 0'91C1 0'9104 0-9108 0.9110 0'9113 0.9114 0'9118 0'9120 0'9123 0'9125 0,9130 ~. 7 17 15 27 37 51 78 56 41 18 255.4 253'4 251.3 251.1 248.9 247'4 245'7 244'0 242 -4 241.5 241.2 _ _ I In- soluble acids. Per cent. on fat. I---- 42.0 I 4'3 90.1 41'5 1 4.5 89.7 41.5 4.7 ' 89.4 41'3 41'0 40.6 40'1 40.1 39.9 39 .7 39 '4 4 .8 4'9 5.2 5.4 5.6 5.8 5.7 6'0 89'3 88.9 88.7 88'4 88.3 87'9 87-9 87 -7 Mean molecular weight of insoluble acids. - 266.9 265-5 865.0 264'2 261'9 261.7 260-9 259% 260.1 258.0 257'8 * Calculated as butyric acid.Two or three samples, the data for which would fall beyond the extremities of the curves given, have been omitted on account of the number of observations being insufficient to afford trustworthy average values. As regards the probable errors of the observations, it may be remarked that any constant error pertaining to a process will not, when the results are presented in the form of curves, affect the shape of the curve; i t will only alter its position relative to the axes. Such errors are those which, for example, might arise from the thermo- meter of a Zeiss instrument having altered since the refractometer was standardised, or from the retention in the distilling-flask of a small constant quantity of volatile acids in determining the Reichert- Wollny figure.On the other hand, errors of manipulation and observation, the incidence of which is sometimes on one side of the truth, sometimes on the other, will, in accordance with statistical principles, be largely nullified by taking the averages of a sufficiently large number of experiments. Curves plotted, therefore, from the mean results of many observations should show with some degree of accuracy the general tendency of the relations between the several constants, and illustrate their interdependence. It will be seen that, in a general sense, the relative density of butter-fat increases as the Reichert-Wollny number is augmented. This would, of course, folIow from the well-known fact that the glycerides of low molecular weight have a greater density than the glycerides of the higher fatty acids which occur in butter.Very approximately, the increase is A few comments may be made on these curves.CHEMICAL CRITERIA IN THE ANALYSIS OF BUTTER-FAT. 255 directly proportional to the increase in the Reichert-Wolhy values, as is shown by the curve approaching more or less closely to a straight line, Speaking broadly, the variations of the saponification numbers are in inverse relation to those of the Reichert-Wollny values and the relative densities; but they show, as from the nature of the case might be expected, some notable departures from proportionality in the amount of variation. The aberrations aro most marked towards the extremities of the curve. Here the observations are fewar in number than those from which the middle of the curve is constructed, but it is not likely that any presumable experimental error would account for the variations shown.When it is considered that the saponification-equivalents of the glycerides of the volatile fatty acids range from 100.6 for tributyrin to 212-6 for trilaurin,* whilst those of the glycerides of the non-volatile acids vary between 240.7 for trimyristin and 296.6 for tristearin, it will be obvious that even small variations in the relative proportions of the glycerides may affect rather considerably the mean saponification-equivalont of the whole fat. Somewhat similar remarks apply to the Zeiss numbers These generally decrease in magnitude as the Reichert-Wollny values in- crease, but the rate of diminution is not regular, and this points, like the variations of the saponification-equivalent, to changes in the proportions of the individual acids which, in butter-fat, constitute the ‘‘ volatile ” and ‘‘ non-volatile ” groups respectively.The curve showing the mean molecular weights of the insoluble acids is of some interest, from the physiological problem whichit suggests. From it we infer that, as the acids of low molecular weight increase in amount, the mean molecular weight of the remaining acids decreasep, and, broadly speaking, decreases proportionally. This may indicate one of several things. Remembering that the molecular weights of the insoluble acids which are believed to occur in butter are as follows : lauric (200),? myristic (228), palmitic (256), oleic (282), stearic (284),f and that the mean molecular weights dealt with in the table decrease from 266.9 to 257.8, it will be seen that this decrease may be due to one of the following causes.In the first place, i t may be due to a diminished proportion of oleic acid. Or, the oleic acid remaining the same, the decreased molecular weight may be due to a displacement of palmitic acid by myristic and lauric acids, one or both ; or, possibly, of myristic by lauric acid. Finally, if the oleic acid increases, this can * Or to 184.7 for tricaprin. t Lauric acid is said to be slightly soluble in water and appreciably volatile when $ Apparently stearic acid exists in butter to a small extent only. If this is so, it distilled with steam.may be neglected in the present connection. s 2256 ANALYSIS OF BUTTER-FAT. only be compensated for, and the decreased mean molecular weight explained, by a n increase in the amount of lauric acid, with a simul- taneous decrease in the myr istic and palmitic acids. The physiological question which presents itself is whether the metabolic changes which, in the bovine organism, result in the production of an increased proportion of the lower saturated fatty acids, bring about this produc- tion a t the expense of the oleic acid. Judging from the values obtained for the iodine-absorption of a number of the specimens, it would seem that, speaking generally, a low proportion of volatile acids in butter-fat is associated with a high percentage of oleic acid, and vice ves-sd.The figures are as follows : Mean molecular Reichert- weight of Wollny Iodine - Oleic Insolnlde in so 1 uble number. value. I - acid. acids. aceicls. (1) Average of 20 samples 24.2 40.0 44.4 per cent. 89% per cent. 264'6 (2) 30 ,, 30'8 32.4 36.0 ,, 88-1 ,, 259.8 I n the first series, the oleic avid cor~stitutes 4'3.6 per cent. of the insoluble acids; in the second series, 40.9 per cent. This decrease in the proportion of oleic acid would diminish the mean molecular weight of the insoluble acids from 264.6 to 261.5. The actual figure obtained for the molecular weight in the second series being 259.S, it would appear that the decrease is l;irgely, but not eutirely, brought about by the diminution in the proportion of oleic acid. Since the whole of the decrease is not accounted for by the oleiu acid, it follows t h a t the mean molecular weight of the insoluble saturated acids is lower in the second series than in the first. I n fact the values, calculated from the foregoing table, are 247.4 and 244.4 respectively. It should be mentioned that the iodine-values were determined after the fats had been kept some time, and they are not given as repre- senting precisely the values for the fresh fat. It is well known t h a t the oxidation changes which may take place during the keeping of butter-fat tend to affect the iodine number. Neverthelesp, since the two groups cover practically the same dates and were kept side by side until examined, it may be assumed that, on the whole, they would be about equally affected, and the relative values of the averages would remain substantially unchanged. THE GOVERNMENT LABORATORY, LONDON.

ISSN:0368-1645    

DOI:10.1039/CT9048500248

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

REFRACTOMETRIC EXAMIKATION OF OILS AND FATS. 257 XXXI1.-A Simple Thermostat for Use in Connection with the Refruetometi-ic Examination of Oils and Fats. By THOMAS EDWARD THORPE, C.B., F.R.S. IN the Government Laboratory, as in other laboratories where large numbers of commercial oils and fats, and especially butter, are required to be examined, the Zeiss butjro-refractometer has proved to be of great service. As is well known, it is generally necessary in using the instrument t o allow a current of water of conytant temperature to flow through the apparatus for some little time before making the readings, and it mas with the view oE rapidly and easily obtaining this current that the little contrivance seen in the accompanying figure was devised in substitution for the special heating arrangement supplied with the instrument, which was found to be homewhat cumbrous and uncertain in action.The temperature employed in the refractometric examination of butter-fat is 45’, and it must be understood, therefore, that the details of the arrangement as described have been adjusted in order that the circulating water shall give this temperature as indicated by the thermometer attached to the refractometer. It is, however, possible, by a slight rearrangement of the details, to obtain a considerable range of constant temperatures. The principle of the thermostat and the method of working it will be obvious from the figure. The apparatus consists essentially of a vessel for generating steam or other appropriate vapour, containing a coil through which the current of water flows and is heated before it passes through the refractometer or other instrument, the position of which is shown in the drawing a t Z, by which the observations at a given constant temperature are to be made. I n the figure (p.258), A represents a metallic cylindrical vessel 5 cm. in diameter and 5 cm. deep, containing approximately 100 C.C. of water, &c., for generating steam, &c. B, a conical steam-chamber, in which the coil, C, is suspended and heated by the steam from A. C, a coil of copper or ‘‘ compo,” tubing, from 25 cm. to 30 cm. long, and having an internal diameter of about 3 mm. The current of water passing through the coil is heated before entering the instru- ment, Z . D, a reflex condenser, preferably of glass, held in position by a tubulure, d, provided with a sliding or screw cap to prevent loss of the liquid in A.E, an arrangement for maintaining a constant head of water at the The diameter of cover is 10 cm.258 REFRACTOMETRIC EXAMINATION OF OILS AXD FATS. point of entrance t o the coil, so as to reduce variations in the tempera- ture of Z, due to fluctuations in the pressure of the current of water. It consists of an outer metal tube, through which a narrow central tube rises, and serves as an overflow when the water in the outer tube has reached the level of its upper orifice. I C s F, a stout glass tube, acting as a gauge or ‘( tell-tale,” to indicate whether or not the overflow and the current of water through the instrument, Z, are running properly.a, a thick-walled caoutchouc tubing (for example, pressure-tubing), to minimise loss of heat during the passage OF water from the coil to the instrument, Z.ACTION OF NITROGEN SULPHIDE ON ORGANIC SUBSTANCES. 259 H, a screw clamp, for regulating the rate of flow of water through the coil and through the instrument, Z. The final adjustment of the desired temperature may be made by means of the screw clamp, K, a caoutchouc tubing, carrying away waste water from the instru- ment, Z, and terminating in the gauge, F, where the rate of the current can be observed. L, Bunsen burner with cone. M, a metallic cylinder for protecting Bunsen flame From draughts, and to reduce loss of heat due to radiation from walls of the steam generator. At the foot is a semicircular opening, m, €or the admission of the gas tube. This little apparatus has been in use for some years in the Govern- ment Idaborittory, and has been found t o answer its purpose sufficiently well. Only a few minutes are needed to bring it into action, and, under ordinary working conditions, i t is readily possible to secure a steady current of water, not varying more than 0.1' or so in tempera- ture throughout the day. THE GOVERNMENT LABORATORY, LONDON.

ISSN:0368-1645    

DOI:10.1039/CT9048500257

出版商:RSC    

年代:1904

数据来源: RSC

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ACTION OF NITROGEN SULPHIDE ON ORGANIC SUBSTANCES. 259 XXXII1.-The Actiozz of Nitrogen Subhide o n Oryccnic Substances. P a ~ t I. By FRANCIS ERNEST FRANCIS and OLIVER CHARLES MINTY DAVIS. AN investigation of the action of nitrogen sulphide on organic sub- stances has been undertaken in the hope that it may throw some light on the constitution of this substance, Nitrogen sulphide is formed together with other products when ammonia acts on a solution of sulphur dichloride in carbon disulphide or benzene. According to the investigations of Fordos and G6lis (Compt. rend., 1850, 31, 702), tbis substance has the empirical formula N8. The molecular weight, which was first given by Schenck as N,S4, was determined by tbe cryoscopic method in naphthalene, and this was confirmed by Muthmann (Bey., 1896, 29, 340), who obtained the same result with the ebullioscopic method in carbon disulphide.By employing the latter method, with benzene as solvent, we have also found the same molecular complexity. The sulphide is best prepared by passing ammonia into a 10--15 per cent. solution of sulphur dichloride in benzene. When the ordinary chloride is employed, the yield is much smaller. A rapid260 FRANCIS AND DAVIS: THE ACTION OF NITROGEN current of the dry gas is passed into the solution until red fumes appear, the flask in which the operation is being conducted is then cooled, and on maintaining the current for a short time the reaction is completed. After filtering off the ammonium chloride formed, the solution, on evaporation, deposits long, orange-red prisms of nitrogen sulphide.This is a beautifully crystalline substance, and may be readily puritid by recrystallisation from either boiling benzene, tolu- ene, or carbon disulphide ; our specimens always showed a perfectly con- stant decomposition point a t 1 8 5 O , although Muthmann gives 17S0, and earlier determinations mere even lower, these results being probably owing to contamination with free sulphur. The properties of nitrogen sulphide have been fully described, but it may be of interest to state that Prof. Muthmann informed us that it was unwise to keep more than a few grams of the subslance in one vessel, since it is apt to explode spontaneously with considerable violence. Although dealing with moderately large quantities, we have never observed this change, and are inclined to believe that t h e sulphideis rather more stable than is usually supposed.The first group of organic substances investigated were the aromatic aldehydes. With benzaldehyde, a violent reactiari takes place near the boiling point of this liquid ; sulphur dioxide and water are evolved, and considerable amounts of triphenylcyanidine (cyaphenin), are formed. The reaction proceeds more slowly at lower temperatures, and at 100" was complete in about 30 hours. I n each caqe, the main product is cyaphenin, and a much smaller quantity of a less fusible, crystalline substance, which was only isolated with difficulty. This product appears to be upp-triphenylglyoxaline or lophin, C3N2H(CGH5)3 ; it is probably formed by the reduction of cyaphenin by sulphur di- oxide; this view of its formation is strengthened by the fact that small quantities of ammonium sulphate were detected among the products of the reaction.This interesting reaction does not seem to be depend- ent on the intermediate formation of benzonitrile, since nitrogen sulphide does not yield cyaphenin when treated with this substance. Benzylidenenniline, in a similar way, yields cyaphenin, and we are a t present investigating the other products of this reaction. With p-tolu- aldehyde and nitrogen sulphide, the action is very similar, and the corresponding tritolylcyanidine is easily obtained. G. Glock (Bey., 1888, 21, 2652) described the preparation of a polymerised toluonitrile, which he considered was probably kyan- tolin," and there is no doubt that the substance he obtained is identical with our preparation, which, judging from the method of its formation, is very probably tritolylcyanidine, C3N3(C,H,*CH3)3. With anisaldehyde and nitrogen sulphide, the action proceeds rather (33% (C,H,) 3,SULPHIDR ON ORGANIC SUBSTANCES.PART 1. 261 more rapidly at 100' than in previous cases, and the main product is a white, crystalline powder which is still under investigation. W e only found it possible to isolate very small quantities of what appeared to be tri-p-methoxyphenylcyanidine, C3N3(C,H,*O~CH,),. Like cya- phenin, this substance, a1 though only slightly soluble in boiling alcohol, is readily recrystallised from hot benzene ; it dissolves in concentrated sulphuric acid to a deep yellow solution, and is precipitated unchanged on the addition of water.Similarly, i t has been found by one of US that salicylonitrile, on heating, readily polymerises in to a yellow, crys- talline compound with a high melting point, this product being also soluble without decomposition in concentrated sulphuric acid giving a yellow solution. From its great stability, it is not decomposed at 350°, and from the fact that its molecular weight was found to be approxi- mately three times that of salicylonitrile, it appears probable tbat this substance is tri-o-hydroxyphenylcyanidine, C3N3(C,H4*OH),. Want of material prevented 11s from obtaining the corresponding tri-p-hgdr- oxyphenylcyanidine from the foregoing trimethyl ether and comparing its reactions with those of the o-derivative.The constitution of these cyanidines or 1 : 3 : 5-triazine compounds may in all probability be represented by the formula Ph they are very stable Substances having high melting points, and they are not decomposed by aqueous or alcoholic potassium hydroxide. The cyanidine ring is broken by reducing agents, as when the tripheiiyl derivative yields lophin, U6H5'g *N H>C-C6H,. C6H,*C-N The complete decom- position into ammonia and benzoic acid can, however, only be effected by more powerful reducing agents, such as hqdriodic acid a t 220'. We are at present pursuing the investigation of the interaction of nitrogen sul phide and aldehydes, and propose trying similar reactions with other groups of organic substances. EXPERIMENTAL. 1. Action of Nitrogem Sulphide on BenxaZdehyde.Two grams of nitrogen sulphide were dissolved in a small quantity of benzene and treated with 10 grams of benzaldehyde; no reaction took place on boiling for 8 hours. On distilling off the benzene and262 FRANCIS AND DAVIS: THE ACTION OF NITROGEN heating with a free flame, the reaction became violent near the boiling point of the aldehyde, sulphur dioxide, water, and the 0XC66S of aldehyde distilled off, and the solid residue, after repeated crystal- lisation from benzene, gave about 1-3 grams of triphenylcyanidine. The following results were obtained on analysis : C=81.52; He5.18; N=13.61, C,N,(C,H,), requires C = 81.55 ; H = 4.85 ; N = 1359 per cent. The melting point was 230°, the numbers given for triphenylcyanidine by different authors being between 231' and 233O.An attempt was made to follow quantitatively the course of the reaction, but without any very definite result. One gram of nitrogen sulphide was treated with a large excess of benzaldehyde, the operation being carried out in absence of air, and the sulphur dioxide liberated passed into a standard iodine solution. It wits found that, approxi- mately, 0.2 gram of sulphur was liberated as sulphur dioxide, and, after distilling off the unchanged aldehyde, nearly 0.1 2 gram wasobtained from various crystallisations, the amount unaccounted for being 0.37 gram. The experiment could only, of course, be regarded as an approximation, but in attempting to account for the loss in sulphur, we were led to detect, among the residues, ammonium sulphate (in another experiment, carried out under similar conditions, t h i s amounted to nearly 1 gram, whichwas equivalent to 0.24 gramof sulphur) and a substance muchmore soluble in absolute alcohol, and less so in benzene than triphenylcyanidine.The isolation of the latter substance in the pure state was extremely difficult, and, judging from the analysis given later, the compound we eventually obtained was not quite pure. The reaction between the aldehyde and nitrogen sulphide was tben carried out on a larger scale, and the excess of aldehyde removed by distillation in steam; the aqueous solution in the distilling flask contained ammonium sulphate and a very small quantity of a substance containing nitrogen, but not sulphur; this was extracted by means of ether, recrystailised from benzene, and found t o melt at 128'.The amount obtained was in- sufficient for a n analysis. The residual solid, insoiuble in water, was dried and treated several times with boiling alcohol; from the filtrate, small quantities of t r i phenylcyanidine crystallised on cooling, and on adding water it was found that the substance which separated had a much higher melting point. On repeating this process many times, a white, feathery, crystalline mass was eventually obtained, only slightly soluble in benzene, but much more so in alcohol, from which it crystallises in characteristic tufts. From its appearance, we thought it might be lophin, although its melting point was 265--267', whereas that substance is stated t o melt at 275'. The following data were obtained on analysis :SULPHIDE ON ORGANIC SUBSTANCES. PART I.263 C= 85.63 ; H = 5.66 ; N = 9.87. (C6H5)2C3N2H requires C = 85.13 ; H = 5.40 ; N = 9.46 per cent. Laurent and Brunner (Anncden, 1869,151,135) state that lophin gives a hydrochloride melting a t 1 5 5 O , which is soluble in alcohol but insoluble in water. I n order t o confirm our view that we were actually dealing with this substance, the small amount a t our disposal was converted into the hydrochloride, which decomposed a t 157-159', and was soluble in alcohol but insoluble in water. In all probability then, the substance was impure lophin, formed, possibly, by the reduction of triphenylcyanidine by sulphur dioxide, this view of its formation being strengthened by the presence of ammonium sulphate in the products of the reaction.We were unable to obtain a better yield of this substance, and as many experiments gave only 0.7 gram of this product, its further investigation was consequently abandoned. The reaction between the aldehyde and nitrogen sulphide was then carried out in an inert atmosphere at loo", and although the velocity of the reaction was thereby greatly reduced-the time required for 6 grams of nitrogen sulphide to react being about 30 hours-yet the products were very similar. The yield of triphenylcyanidine was slightly increased, the amount of free sulphur was not quite so large, and the lophin was formed in about the same proportion as in previous cases. When benzylideneaniline was employed in place of benz- aldehyde, the reaction takes place much less energetically, and the products contained triphenylcyanidine and a large amount of an oil which we are at present investigating. 2.Action of Nitrogen XzcZphide on p-Toluuldehyde. On warming together p-tolualdehyde and nitrogen sulphide, a reac- tion takes place very similar to that described with benzaldehyde; the solution darkens on heating, sulphur dioxide is slowly evolved, and a crystalline substance separates, which, after washing with ether and recrystallising from boiling benzene, melts sharply a t 278'; i t is slightly soluble in boiling alcohol and cr gstallises from hot benzene in long needles. The following results were obtained on analysis: C = 82.32 ; H = 6.20, C,N3(C6H,*CH,), requires C = S2.05 ; H = 5.98 per cent.This substance appears t o be identical with a polymeride of toluo- nitrile, termed by Gustav Glock '' kyantolin " and described as crys- tallising in long needles melting above 260'.264 CROSSLEY : AROMATIC COMPOUNDS OBTAINED 3. Actioit of Nitvogen Xulphide on Anisccldeh9de. Five grams of nitrogen sulphide were heated for 20 hours with 12 grams of anisaldehyde i n nn inert atmosphere. The solid mass obtained at the end of t h a t time was extracted with boiling alcohol t o remove any unchanged aldehyde, and then extracted with boiling benzene. The insoluble matter constituted by far the larger bulk (about 5.6 grams) ; i t was a white, crystal!ine powder, partially soluble in water, and at present it, is still under investigation. The soluble matter consisted chiefly of sulphur, together with a very small quantity of a substance crystallising from benzene in white leaflets, and best separated from t h e sulphur by solution in acetone or con- centrated sulphuric acid. This compound melts sharply at 2 1 7 O , and is but slightly soluble in alcohol. On analysis, it gave the following result : N = 10.70. C,N,(C6H,*OoCH,), requires N = 10.52 per cent. It appears to be tri-p-cuethoxycyanidine, which is soluble in concen- trated sulphuric acid forming a deep yellow solution and is precipitated unchanged on the addition of water. As previously mentioned, tri-o- hydroxycyanidine is a yellow, crystalline substance alvo soluble in sulphuric acid t o a yellow solution. UNIVERSITY COLLEGE, BRISTOL.

ISSN:0368-1645    

DOI:10.1039/CT9048500259

出版商:RSC    

年代:1904

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264 CROSSLEY : AROMATIC COMPOUNDS OBTAINED XXXlV.-AYomatic Cornpounds obtained from the Hyd?*oaromatic Series. P u r t I. The Action of Bromine 012 3 : 5-Dichloro-1 : I - d i ~ i ~ e t h y l - A ~ : ~ - d i - h y d ~ o benzene. By ARTHUR WILLIAM CROSSLEY. MANY instances have been recorded of the conversion of hydro- aromatic into aromatic substances under the influence of such reagents as bromine or nitric acid. For example, 1-keto-3-methyl-A2-tetra- hydrobenzene (I) readily absorbs two atoms of bromine to form an unstable product (11) which loses two molecules of hydrogen bromide yielding m-cresol (111) (Knoevenagel, Ber., 1893, 26, 1951) : 111.FROM THE HYDROAROMATIC SERIES. PART I. 265 and with nitric acid, 1 : 3-dimethyldihydrobenzene gives mono-, di-, and tri-nitroxylenes (Wallach, AnmaZen, 1890, 258, 31 9).* This direct converbion of hydroaromatic into aromatic substances has often been of fundamental importance as a method for determining the constitution of a hydroaromatic compound when, by its trans- formation into a n aromatic derivative of known constitution, the relative positions of its substituting groups have been ascertained.B u t the method is not always valid, for instances are known in which an alkyl group wanders during the conversion (Baeyer and Villiger, Ber., 1898, 31, 2068). Recently it has been shown that 3 : 5-dichloro-A2 : 4-dihydrobenzene under the influence of excess of phosphorus pentachloride or bromine is converted into m-dichlorobenzene (Trans., 1903, 83, 495) and that 3 : 5-dichloro-1 : l-dimethyl-A2' *-dihydrobenzene, when acted on with excess of phosphorus pentachloride, is converted into 3 : 5-dichloro- o-xylene (Trans., 1902, 81, 1536) : also when phosphorus pentabromide acts on dimetbyldihydroresorcin brominated o-xylenols are produced (Trans., 1903, 83, 11 6).I n the two latter cases, the reaction is complicated by the fact that, as the original substance contains the gem-dimethyl group, the migration of one of these methyl groups becomes an essential step in the production of the aromatic compound. As a quantity of 3 :5-dichloro-o-xylene waswanted for another research, and as the action of bromine on dichlorodihydrobenzene had resulted in the formation of m-dichlorobenzene as the main, if not the sole product, it was thought advisable to try the action of bromine on 3 : 5-dichloro-1 : 1-dimethyl-A' : *-dihydrobenzene (Trans., 1902, 81, S27).From the desired point of view, the reaction is disappointing, inasmuch as only a very small quantity of 3 : 5-dichloro-o-xylene is formed, but it has agorded an interesting example of the passage from hydroaromatic to aromatic substances, and a s i t is, on account of the symmetry of the molecnle, one of the simplest cases in which the wandering of an slkyl group can take place, it has been worked out, so as to gain an insight into the course of such reactions. Moreover, as the dimethyldihgdroresorcin, which forms the starting point of the investigation, is readily obtained from aliphatic substances (ethyl * The following are references to a number of typical examples of reactions in- volving the conversion of hydroaromatic into aromatic substances : Schweitzer, J.pr. Chem., 1841, 24, 257; Wallach, Annalen, 1877, 187, 159; Baeyer, Ber., 1892, 25, 1037; Knoevenagel, Ber., 1894, 27, 2347; Einhorn and Willstatter, Alznnlen, 1894, 280, 85 ; Zelinsky, Bcr., 1895, 28, 782, and 1901, 34, 2803 ; Baeyer and Villiger, Ber., 1898, 31, 1401, 2067 ; Klages, B e y . , 1899, 32, 1516 ; Crossley and Le Sueur, Trans., 1902, 81, 831, 1533, and 1903, 83, 116 ; Crossley and Haas, Trans., 1903, 83, 495.266 CROSSLEY : AROMATIC COMPOUNDS OBTAINED malonate and mesityl oxide, Trans., 1899, '75, 772), the subject becomes of interest as helping to connect together the aliphatic and aromatic series. The main products of an aromatic nature obtained when bromine acts on dichlorodimethyldihydrobenzene are the two theoretically possible dichlorobromo-o-xylenes containing the chlorine atoms in the 3:5-position, and no substance has been encountered in which an alkyl group has wandered into any but an ortho-position, The reaction is largely influenced by the condition of experiment, entirely different results being obtained according as to whether one or two molecules of bromine are employed.When dichlorodimethyldihydrobenzene, dissolved in a small amount of chloroform, is treated with bromine, so long as this reagent is used up a quantity is absorbed corresponding almost exactly with two moleciilar proportions, and during the later stages of the reaction volumes of hydrogen bromide are evolved, The product consists mainly of a viscid, syrupy liquid, which, on distillation, or preferably when left in a vacuum over potassium hydroxide, gives 3 : 5-dichZo?-o-4- homo-o-xglene (see page 2 7 5 ) ; and to R smaller extent of a beautifully crystalline solid having the formula C,H,Cl,Br,.This substance is evidently a dichlorot~.ibrornodimethyZtetl.alZydrobenzene, but the exact position of the halogen atoms cannot be readily ascertained. It has been shown (Trans., 1902, 81, 823) that when 1 : 1-dimethyl- Aa:4-dihydrobenzene is treated with bromine or hydrogen bromide, only one molecule of either reagent is absorbed, in the latter case giving rise t o 5-bromo-1 : 1 -dimethyl-A3-tetrahydrobenzene, and presumably, therefore, the first action of bromine on dichloro- dimethyldihydrobenzene mould consist in the direct addition of two atoms of bromine in a similar way, giving rise to a dichlocl.odibromo- dimethyltetrahydrobenzene (V), having the following constitution : Notwithstanding the fact that the product contains a double linking, the net result of the second phase of the reaction is the replacement of hydrogen by bromine in this compound.It is a well-known fact that substances containing two double link- ings in the position indicated in formula IV, *C:C*C:C*, do add on bromine at the terminal carbon atoms with the formation of a new double bond between the central carbon atoms, *C.C:C*C*, and that this new bond often does not perform the ordinarily accepted func-FROM THE HYDROAROMATIC SERIES. PART r, 267 tiom of an unsaturated linking by taking up a further molecule of bromine t o give a saturated substance.Such appears to be the case with the compound under discussion, for in order t o obtain a deriva- tive having the formula CSH,Cl9Br3 from the unsaturated compound (V), one hydrogen must be replaced by bromine. I n discussing the position of this bromine atom, it must be borno in mind that dich lorotribromodimet hyl te trahydro benzene, C8H,C1,13r,, on heating, loses two molecules of hydrogen bromide giving a dichloro- bromo-o-xylene, CMe<g:$Eg:>CBr, the constitution of which has been definitely ascertained by synthesis (see page 277). It would appear from this fact, that the bromine atom must become attached to the carbon atom between the two chlorine atoms, and this is ex- plained by supposing that either substitution takes place, or more probably that bromine is first added on at the double linking, giving an unstable substance having the formula TI, which immediately loses hydrogen bromide.This loss may take place in several ways : CMe, CMe, CMe, H,C/\C HBr H,C/'\CHBr HC/\CHBr BrClCl h32l ClC()CClBr CH Br \/ B ~ C I ~ ICClBr \/ CBr CHBr VI. VII. VIII. giving rise to substances with a double linking in different positions; but, as will be seen from the context, only two of these possibilities need be considered, namely, those involving the configura- tions VII and VIII, and from which the production of the above dichlorobromoxylene can be readily accounted for in the manner indicated by the following formule : C"H3 y 3 3 C-CH,I-Hj , .C-CH, , . i H HC/\CHjBr; -...--. -+ HC"+H + , . 1 . iB&*CI , . ICCl ClJ()CCl . . . -_ -. CBr . \/ UBi? VI.268 CROSSLEY : AROMATIC COMPOUNDS OBTAINED NOW when dichlorotribromodimethyltetrahpdrobenzene is oxidised with potassium permanganate, the sole products are bromoform and dimethylmalonic acid (thus definitely proving the presence of the gem-dimethyl group), the yield of the latter substance being 71 per cent. of that theoretically obtainable. It has been observed during the oxidation of many hydroaromatic substances containing halogen, that although they may be originally broken down a t a double linking, the oxidation does not become completed until all those carbon atoms to which halogen atoms are attached in the original substance are either eliminated from the oxidation product or form part of a terminal carboxyl group; in other words, an acid obtained as an oxidation product is always free from halogen.For example, 5-bromo-1 : l-di- mebhyLh3-tetrahydrobenzene (Trans., 1902, 81, 824) gives on oxidation &3-dimethylglutaric acid and not bromodimethyladipic acid : Bearing this in mind, the formula which would best represent dichloro- tribromodimethyltetrahydrobenzene would be VIII, for from a sub- stance with formula VII dimethylsuccinic acid should result ; but un- fortunately the latter structure cannot be altogether excluded on these grounds. The first product of the action of one molecule of bromine on dichloro- dimethyldihydrobenzene is, for the foregoing reasons, supposed t o have the following constitution : CMe2<CH,.(IH Br-cC1>CH. CCIBr This dichlorodi- bromodimethyltetrahydrobenzene is a liquid which cannot be purified, as on distillation either in air or in a vacuum i t decomposes, evolving hydrogen bromide. In order t o obtain some clue as to its constitu- tion, the raw material in aqueous suspension was oxidised with potassium permanganate, when it became necessary to heat the mixture to the temperature of boiling water. The main product was dimethylmalonic acid, no trace of dimethylsuccinic acid being obtained, but the latter acid was produced in small quantities by carrying out the oxidation in cold acetone solution. Prom a comparison of the formulze of dichlorodibromo- and dichloro- tribromodimethyltetrahydrobenzene, VII, it mould appear that the substances represented by the formulix VII, should give the same oxidation products, but the reactions are not strictly comparable on account of the greater stability of the latterFROM THE HYDROAROMATIC SERIES. PART I.269 substance, which is not oxidised by potassium permanganate in the cold. This greater stability may be due simply to the presence of an additional halogen atom, or it may possibly point to the double linking being in a different position. On referring to the oxidation of dichlorodimethyldihydrobenzene, CH-CCl CMe,<CH~CCl>CIH, with potassium permanganate (Trans., 1902,81, '5 S29), i t is seen that, when carried out a t looo, a mixture of dimethyl- malonic and dimethylsuccinic acids is obtained, whereas if allowed to take place in the coId only the latter acid is formed, This proves fairly conclusively that if as-dimethylsuccinic 'acid can result as an oxidation product, the amount obtainable may be considerably lessened by carrying out the oxidation at a high temperature, since as-dimethyl- succinic acid is further oxidised to dimethylmalonic acid in similar cases when heat is employed.If, therefore, dichlorotribromodimethyltetrahydrobenzene be repre- sented by formula VII, it might be expected that some trace of as- dimethylsuccinic acid would have been obtained, which, however, was not the case; so that formula VIII seems the more probable, although this point is not quite definitely established. When dichlorotribromodimethyltetrahydrobenzene is heated with ordinary concentrated nitric acid, a somewhat unexpected reaction takes place, resulting in the formation of 3 : 5-dicldoro-4 : 6-dibrorno-0- xyZene, CH2*C<~~!!&~~>CB~, a substance which has also been synthetically prepared by the direct bromination of pure 3 : 5-dichloro- o-xylene.I t s production in the above case is accounted for by sup- posing that, under the influence of heat, dichlorotribromodimeCuhy1- tetrahydrobenzene first loses two molecules of hydrogen bromide forming 3 : 5-dichloro-4-bromo-o-xylene, which is then further bromin- ated by the bromine liberated from the interaction of the concentrated nitric acid and hydrogen bromide. As already mentioned, the product of the action of one molecule of bromine on dichlorodimethyldihydrobenzene is supposed to be dichlorodibromod imet h yl t e trahydrobenzene, C M e 2 < ~ ~ ~ < ~ ~ ~ > C H but owing to the instability of this substance there does not seem to be any method of proving this supposition.As, however, it gives as-dimethylsuccinic acid on oxidation, it must contain the grouping CMe,<& c. When heated, it evolves hydrogen bromide and gives as the two main products, 3 : 5-dichloro-o-xylene and 3 : 5-dichloro-6- bromo-o-qlene, MeC<CBrzCCI CMe *CC1yCH, VOL. LXXXV. T270 CROSSLEY : AROMATIC COMPOUNDS OBTAINED The production of the former compound is readily explained by the loss of two molecules of hydrogen bromide : p 3 7% $ 3 3 3 C-CH,H'; C-CH, C . . . . -+ HWWH -+ HCfNC*CH, :H; H C / \ C ~ ~ j Brj . . . . . . . , . . . . I . . ClC!' iCCl \/ C H &ClC 2 .. . . . . , \/ ICCl CICiJ V' U H LCl CH but at the present time no reasonable explanation can be offered for the formation of 3 : 5-dichIoro-6-bromo-o-xylene, as in the case of the isomeric substance obtained by heating dichlorotribromodimethyl- tetrahydrobenzene. The reaction, which is more involved, is by no means quantitative, only 17-20 grams of the dichlorobromoxylene being obtained from the product of the action of bromine on 50 grams of dichlorodimethyldihydrobenzene. There can, however, be no doubt about the constitution of this substance, for in the first place it is shown t o be a derivative of 3 : 5-dichloro-o-xylene, because on treat- ment with bromine it is quantitatively converted into 3 : 5-dichloro- 4 : 6-dibromo-o-xylene (IX), identical with the substance produced by the direct bromination of pure 3 : 5-dichloro-o-xylone ; and, further, 5 9 3 3 C 7% C C' B~C/%CH~ B~C/\C-CH, -~ N02*C(NC*CH3 UH +- ClC'I b l UlC(>C Cl C*NO, \/ C l d b c 1 \/ CrBr IX.X. when treated with fuming nitric acid, i t yields 3 : 5-dichloro-4 : 6- dinitro-o-xylene (X), identical with the compound obtained by the direct nitration of pure 3 : 5-dichloro-o-xylene. The only additional point t o be decided is the position of the bromine atom, which is proved to be attached to the carbon atom 6 in the following manner. There are but two pxsible forms of dichlorobromo-o-xylenes con- taining the chlorine atoms in the 3 : 5-position, and both these possibilities, have been encountered in the course of this investigation.The best method for deciding between these seemed to consist in synthesis, and 4-o-xylidene (XI) was used as the starting point. This base, the con- stitution of which has been definitely established by the work ofFROM THE HYDROAROMATIC SERIES. PART I. 271 Jacobson (Ber., 1884, 1’7, 159), when successively acetylated and treated with chlorine in glacial acetic acid solution, yields a dichloro- rrcetoxylidide, in which the chlorine atoms occupy the ortho-positions relatively to the amino-group. The corresponding dichloro-base, XU, QH3 QH3 C C Q*3 C HC/\C.CH, H C ~ ~ C H , HC(’\C*CH, -+ ClClI lCCl \/ HCll ICH -+- ClCI lCCl C*NH2 CBr C*NH, XI. XII. XIII. when diazotised in presence of cuprous bromide and hydrogen bromide, yields 3 : 5-dichloro-4-bromo-o-xylene (XIII), melting at 1 OOO, and possessing all the characteristic properties and reactions of the compound obtained by the action of heat on dichlorotribromodi- methyltetrahydrobenzene, thus proving that the substance obtained by heating dichlorodibromodimethyltetrahydrobenzene has the con- stitution of 3 : 5-dichloro-6-bromo-o-xylene.Both dichlorobromo xylenes give, on further bromination, one and the same dichloro- dibromo-o-xylene, but in their behaviour towards nitric acid they differ markedly. When occupying position 4, the bromine atom is stable towards this reagent, but in position 6 it is readily re- placed by a nitro-group. Thus, 3 : 5-dichloro-4-bromo-o-xylene gives, with fuming nitric acid, 3 : 5-dichloro-4-bromo-6-nitro-o-xylene (XIV), and, on oxidation with dilute nitric acid under pressure, is converted into 3 : 5-dichloro-4-bromo-o-phthalic acid (XV) : \/ \/ p 3 C p 3 C QO2H C N02*C/b*CH3 f- H C / ” ~ C H , HC/\\C.CO,H ClCIl lCCl -+ ClCII Jcc1 \/ C‘Br \/ c1cI1 ‘CCl \/ CBr whereas 3 : 5-dichloro-6-bromo-o-xylene gives, under similar conditions, respectively.3 : 5-dichloro-4 : 6-dinitro-o-xylene (XVI) and 3 : 5-dichloro- 6-nitrotoluic acid (XVII).CBr XIV. xv. 7% C 7% C p 3 C272 CROSSLEY : AROMATIC COMPOUNDS OBTAIXED E X P E R I M E N T A L. Intevaclion of 3 : 5- Dichlom-1 : l-dimethyl-A 4. dihydrobenxene wit14 Two ~k!oZeczcles of Bromine. One hundred grams of freshly prepared dichlorodimethyldihydro- benzene (1 mol.) (Trans., 1908, 81, 826) were dissolved in 100 grams of dry chloroform, and 190 grams of bromine (2 mols.) added as rapidly as the comparative violence of the earlier stages of the reaction permitted.A t first, the bromine was rapidly absorbed without the evolution of much hydrogen bromide, but subsequently, torrents of the gas were given off, and a quantity of a solid substance separated. The chloroform was then evaporated on the water-bath as quickly as possible", and the whole when left became semi-solid. It was filtered at the pump (Filtrate = A) and the solid residue (50 grams) purified by erystallisation from alcohol. 0.1388 gave 0.1176 CO, and 0.0368 H,O. 0.1442 ,, 0.1220 CO, ,, 0.0360 H,O. C = 23.07 ; H = 2-77, 0.1034 ,, 0.2112 Ag haloids and 0.1340 Ag. C1= 17-00 ; Br = 57.65. C,H,CI,Br, requires C = 23.07 ; H = 2.16 ; C1= 17.07 ; Br = 57-69 per cent.The high results obtained for the hydrogen are doubtless due to the fact that at its melting point this substance rapidly evolves hydrogen bromide, a small amount of which might find its way into the calcium chloride tube. 3 ; 5-Dichloro-2 ; 4 ; 5-tribromo-1 ; 1 -dillzeI7~~L-A5-leh.n1~y~robenxent, C=23-10; H=2*94. is readily soluble in the cold in chloroform, benzene, or acetone, an6 in light petroleum or alcohol on warming; it crystallises from the latter solvent in stout, prismatic needles melt- ing with evolution of gas at 1 1 8 O . Action of Heat om Dic~109.otribromodimethyZ- tetrahydrobenzene.-The action of heat on this compound was investigated in the apparatus given in the accompanying sketch, when i t was found that the reaction is almost a quan- titative one corresponding with the loas of two molecules of hydrogen bromide.A weighed quantity of the substance was placed in the tube, A , which was heated at 120-125c in a sulphuric * If the heating on the water-bath is continued for long, decomposition takes place, thus causing a considerable decrease in the Rmount of solid product.FROM TRE HYDROAROMATIC SERIBS. PART 1. 273 acid bath and through which a slow current of dry air was drawn, thus causing the evolved hydrogen bromide to pass into the aqueous solution of silver nitrate contained in the flask, B. When no more gas was given off from the molten substance, the contents of B were filtered, dried, and weighed. 0.5138 gave 0.4466 AgBr. CSH9C12Br3, when losing 2HBr, requires HBr = 38.91 per cent.The residue in A solidified on cooling, and was proved by the follow- ing facts to be identical with the 3 : 5-dichloro-4-bromo-o-xglene described on p. 275 ; it crystallised from alcohol in masses of felt-like needles melting a t 99-looo. HBr = 37.45. 0.1148 gave 0.2140 Ag haloids. C,H7C12Br requires Ag haloids = 187.0. Halogen = 59.46 per cent. Moreover, on treatment with bromine in the presence of iron, it gave 3 : 5-dichloro-4 : 6-dibromo-o-xylene melting at 233O (see page 284), and fuming nitric acid converted it into 3 : 5-dichloro-4-bromo- 6-nitro-o-xylene melting at 176" (see page 275). Halogen = 59.26. Action of flitric Acid O ~ L DichZo~oti.ibromocli~nethyZtetrffi?~ydrobenxene. Five grams of the tetrahydrobenzene derivative and 40 C.C.of nitric acid (sp. gr. 1-42) were placed in a flask with a ground-glass stopper attached to a condenser. No reaction took place in the cold, so the mixture was heated on a water-bath, when the solution soon became coloured and quantities of nitrous fumes and bromine were evolved. The solid was quickly converted into an oil, which gradually resolidified in flakes. After heating for ten minutes, the contents of the flask were poured into water, filtered, spread on porous plate, and the residue (2.5 grams) crystallised from ethyl acetate. The needles so obtained melted at 2 3 3 O , and the melting point was not altered on mixing with the 3 : 5-dichloro-4 : 6-dibromo-o-xylene described on page 284; and that these two substances are identical is conclusively proved by the following analytical figures : 0.1566 gave 0-1670 CO, and 0.0268 H,O.0*2006 ,, 0*4012 Aghaloidsand0.2617 Ag. C1= 21.65; Br =47*94. C,H6CI,Br2 requires C = 28.83; H = 1.80; C1= 21-32; Br = 48.05 percent. The ethyl acetate mother liquors contained a small quantity of a more fusible solid ; this substance and the small oily residue obtained on evaporating the aqueous filtrate from the raw material were not further investigated. Oxidcbtion of Dic~~lorotriliromodinaethyltetra?~ydrobcnxcne.--Twentg C-29.08; H- 1.89.274 CROSSLEY : AROMATIC COMPOUNDS OBTAINED grams of the substance were suspended in 500 C.C. of water and heated on the water-bath in a flask attached to a reverse condenser, and 60 grams of finely powdered potassium permanganate added in small portions at a time.After heating for ten hours, practically all the permanganate had been used up and the whole was dis- tilled in steam, when a small amount of bromoform passed over. The residue was filtered from manganese dioxide, the filtrate evapor- ated to a small bulk, acidified, and extracted ten times with ether. The ethereal solution, on evaporation, left a residue weighing 4.5 grams, whereas the amount calculated for the production of dimethylmalonic acid is 6.3 grams. This residue rapidly solidified and melted at 187-188' ; after one crystallisation from water, it melted a t 190Owith evolution of gas. 0,1412 gave 0.2346 CO, and 0-0778 H,O. C,H,O, requires C = 45.45 ; H = 6.06 per cent. In order to prove more completely the identity of this substance with dimethylmalonic acid, the remainder was heated in a distillation flask, when carbon dioxide was evolved, and a colourless liquid with the unmistakable odour of isobutyric acid passed over, a portion of the liquid was converted into the silver snit.C = 45-31 ; H= 6.12. 0.1412 gave 0.0'788 Ag. After tinding that dichlorodibromodimethyltetrahydrobenzene gave dimethylsuccinic acid on oxidation with potassium permanganate in acetone solution (see page 253), the oxidation of dichlorotri- bromodimethyltetrahydrobenzene was repeated, using boiling acetone as solvent, the reaction being carried out as described on pago 283. The crude oxidation product melted at 189-190" with evolution of gas and formation of isobutyric acid, and therefore consisted of dimethy lmalonic acid, no trace of dimethylsuccinic acid being obtained.Examination of the Filtrate A (see page 272).-On distilling this liquid either in air or in a vacuum, a violent evolution of hydrogen bromide took place, and the main fraction (260-270' under 764 mm.) solidified completely on cooling t o a waxy substance melting at 85-90'. Considerable difficulty was experienced in purifying this material, and it was only after repeated crystallisation from absolute alcohol that a substance melting at 9s-99' was obtained. A better method for the isolation of this substance in a pure condi- tion consists in allowing the liquid A t o remain in a vacuum over caustic potash, when it gradually solidifies to a semi-solid cake, the mother liquor being again placed in a vacuum, when more solid Ag = 55.80.C,H,O,Ag requires Ag = 55.38 per cent.FROM THE HYDROAROMATIC SERIES. PART I, 276 separated. By repeating this prxess, 65 grams of a crystalline com- pound were obtained melting a t 95-97', and which, after recrystal- lisation from alcohol, melted sharply at 100'. 0.1884 gave 0.2594 CO, and 0.0470 H,O. 0.1053 C = 37.55 ; H = 2-77'. ,, 0.2004 Ag haloids and 0.1364 Ag. C1= 27.27; Br = 31.82. C,H@I,Br requires C = 37.79; H = 2.75; C1= 27.95; Br = 31.49 per cent. 3 : 5-Dichloro-4-b~*omo-o-xyZene, CH3-C<g$H3):Eg>CBr, is readily soluble in the cold in light petroleum (b. p. 80-100°), chloroform, benzene, ether, or acetone, and in glacial acetic acid or alcohol on warming. It crystallises from alcohal in long, felt-like needles (com- pare the properties of 4 : 5-dichloro-6-bromo-o-xylene, Clam and Kron- weg, J.pr. Chem., 1891, [ii], 43, 259), which, on pressing, form a waxy material melting at looo and resolidifying at 98'. It distils without decomposition at 170-175' under 30 mm., and at 265-270" under the ordinary pressure, and is volatile in steam. Action of Bromine on 3 : 5-Dichloro-4-bromo-o-xyZene.-The substance was dissolved in a small quantity of chloroform, and bromine added in presence of iron filings. On warming, substitution readily took place, and the resulting solid crystallised from ethyl acetate in glistening needles melting at 233-233*5O, the melting point remaining unaltered when the substance was mixed with pure 3 : 5-dichloro-4 : 6-dibromo-o- xylene (see page 284), thus proving the identity of these two substances.The yield is quantitative. Action of iVitric Acid on 3 : 5-DichZoro-.l-brorno-o-xylenc.--Three grams of dichlorobromoxylene were added to 40 C.C. of fuming nitric acid and warmed on the water-bath, when the solid gradually dissolved. The heating was continued for 20 minutes, when the mixture was poured into water, and the separated solid (2.6 grams) crystallised from alcohol. The crystals melted at 175-1776", and were thought to be identical with the 3 : 5-dichloro-4 : 6-dinitro-o- xylene (m. p. 175-176'), described on page 284, but a mixture of the two substances melted at 154-155') thus proving that its com- ponents were dissimilar. After a further crystallisation of the above material, the nitrogen was determined. 0.2589 gave 10.2 C.C.moist nitrogen at 23' and 772 mm. N = 4.52. C,H,O,NCI,Br requires N = 4-68 per cent. 3 : 5-DichZoro-4-b~omo-6-nitro-o-~~Ze~e, CH;C~C(CH3)'CC1~CBr, C(N0,)-CCl is readily soluble in the cold in chloroform, benzene, acetone, ethyl acetate, or ether, and crystallises from dilute acetic acid or alcohol in faintly yellow, glistening needles melting at 1'75.5-176592 76 CROSSLEY : AROMATIC COMPOUNDS OBTAINED Oxidation of 3 : 5- Dichloro.4 bromo-o-qZene.-Eight grams of the di- chlorobromoxylene were heated in quantities of two grams at a time, with 15 C.C. of nitric acid (sp. gr. 1*15), in sealed tubes for 7 hours at 180-200'. The contents of *the tubes, which were entirely liquid, were evaporeted in vc~cuo, when 9 grams OF a white solid, giving a marked fluorescein reaction, were obtained.On testing the solubilities, it was found that this substance would crystallise from xylene, and the whole was therefore boiled with this solvent, when it slowly dissolved, but on cooling only 0.9 gram separated (see page 277). The mother liquors were evaporated, and the solid residue purified by crys- tallisation from a mixture of benzene and light petroleum. 0.1592 gave 0.1880 CO, and 0.0084 H,O. 0.1042 ,, C = 32.20 ; H = 0.58. C,H03CI,Br requires C = 32.43 ; H = 0.34 ; C1= 23.98 ; O-oc 0-1667Ag haloids and 0,1134 A.g. C1= 23.50; Br = 27.63. Br = 27.02 per cent. is readily soluble in the cold in benzene, chloroform, acetone, and ethyl acetate, soluble with difficulty in alcohol and light petroleum, and crystallises from a mixture of benzene and light petroleum in radiating clusters of stumpy needles melting at 170-171'.It can be sublimed unchanged in feathery needles and gives a most marked fluorescein reaction. Its method of preparation from the correspond- ing acid by boiling with xylene is somewhat unusual, but presumably the temperatare of boiliDg xylene is sufficiently high to cause the formation of anhydride, and a t the same time supplies a ready means for separating the acid from the nitrogenous substgnce (see p. 277), which is also produced in small quantity during the oxidation. I n a second preparation, the anhydride mas produced by heating the crude oxidation product with acetyl chloride, 65c. The solid so obtained was found t o contain nitrogen, but on submitting it to a process of sublimation, the nitrogenous substance was decomposed, whilst the sublimate, after crystallisation, melted at 169-170' and consisted of pure 3 : 5-dichloro-4-bromo-o-phthalic anhydride.The anhydride is not acted on by cold water, but dissolves slowly in the boiling solvent, and on evaporating the solution the corre- sponding acid remains; this substance is readily soluble in the cold in water, alcohol, and acetone, but dissolves readily in boiling chloroform or benzene ; it crystallises from water saturated with hydrogen chloride in small, flattened needles melting a t 169-170" with previous diminution in bulk and partial sublimation. Unless purified in this way through the anhydride, the acid meits much lower (156-162Oj with vigorous evolution of gas.FROM THE HYDROAROMATIC SERIES.PART I. 277 A portion of the pure acid was converted into the silver salt, which 0.2000 gave 0.0817 Ag. C,HO,CI,BrAg, requires Ag = 40.91 per cent. The c~nil was obtained by dissolving the anhydride in benzene and adding the calculated amount of aniline, when a precipitate was at once formed, which was filtered and dried. When heated, it melts at 120-125' with evolution of gas, then resolidifies, and, finally, again melts at 180-195", ai; which temperature it was maintained until no no more gas mas evolved. The solid thus obtained readily dissolved in cold benzene or chloroform, but was not readily soluble in alcohol even on boiling; i t crystallised from acetone or ethyl acetate in masses of glistening, silken needles melting at 200-200*5°. 0.2638 gave 8.6 C.C.moist nitrogen at 1 4 O and 762 mm. C,,H,0,NC12Br requires N = 3-77' per cent. It mas mentioned on page 276 that on crystallising the crude oxid- ation product from xylene, only 0.9 gram of solid separated, which, on examination, was found to contain nitrogen. is a white, caseous precipitate. Ag- 40.85. N = 3.84. 0,1990 gave 8.6 C.C. moist nitrogen at 1 8 O and 768 mm. C,H,O,NCl, requires N = 5 *OO per cent. This subs tance is in all probability 3 : 5-dic?iZoro-4-nitro-~-~?~t~zaZ~c ncid, as in a halogen determination the proportion of silver in the total silver haloids showed conclusively that the substance could not contain any bromine. The acid is very readily soluble in the cold in water, alcohol, ethyl acetate, and acetone, almost insoluble in chloro- form and benzene on boiling, and crystallises from xylene in clusters of fiattened needles melting at 165O mith a brisk evolution of gas.N = 5 9 5 . Synthesis of 3 : 5-Dic~loro-4-bromo-o-xyZ~~~. The 4-o-xylidine used in these experiments melted sharply at 49', and gave an acetyl derivative crystallising from dilute alcohol in long, glistening needles melting a t 99O (compare Jacobson, Ber., 1884, 17, 161). The acetoxylidide, in quantities of 5 grams, was dissolved in 10 C.C. of glacial acetic acid, the whole cooled in ice, and dry chlorine passed in until the gain in weight corresponded with the substitution of two hydrogen atoms by chlorine. A crust of white, nodular crystals then slowly separated, which was drained from excess of acetic acid and placed in water.At first, the substance became semi-liquid, part dissolving, and then the whole mass resolidified, the solid being278 CROSSLEY : AROMATIC COMPOUNDS OBTAINED purified by crjstallising from dilute alcohol until the melting point of the glistening scales which separated was about 185'. The yield is small, being 15--20 per cent. of the theoretical. No attempt was made to isolate a pure acetyl derivative, and the substance melting at about 185' was directly hydrolysed by boiling for 3-4 hours with concentrated hydrochloric acid ; the solid product was suspended in dilute caustic potash and distilled in steam, when an oil passed over which soon solidified. The crude material melted for the most part a t 503, but did not become clear until 9 5 O , and was found to consist of two substances which could be easily separated by means of their different solubilities in alcohol.The whole was dissolved in the smallest possible quantity of hot absolute alcohol, when on cooling a few long, needle-shaped crystals separated, me1 ting a t 170'. The filtrate from these crystals (which were not further investigated) was diluted with water, when glistening needles eeparated, which melted for the most part at 43-45', but did not become quite clear until 85'. After repeating the above process of purification, a substance was obtained melting sharply at 44-5O, and in this the chlorine was determined. 0.1028 gave 0.1560 AgCI. 3 : 5-Dicl~Zoro-4-o-x~Edine, CHs*C<CII c(cH3):CC1>C*NH2, ccl is extremely soluble in the cold in light petroleum (b. p.40-60°), chloroform, acetone, benzene, or ether, and crystallises from dilute alcohol in long, glistening, silken needles melting at 44.5'. I n order t o replace the aminogroup by bromine, the base was sus- pended in hydrobromic acid (sp. gr. 1*45), in which it is not at all readily soluble, a solution of freshly prepared ciiprous bromide in hydrobromic acid added, and slightly inore than the calculated quantity of sodium nitrite dissolved in the smallest possible amount of water dropped into the mixture, which was heated on the water-bath t o x temperature of 60-70'. After one hour, the whole was distilled in steam, when a solid passed over which melted a t 95-97', and proved t o be identical in every respect with the dichlorobromoxylene described on page 275.It crystallised from absolute alcohol in long, glistening, felt-like needles me1 ting at 1 O', which, on pressing together, assume a waxy consistency. When brominated in the presence of iron filings, it gave a dichlorodibromoxylene crystallising from ethyl acetate in glistening, silken needles melting at 233', a melting point which remained unaltered on mixing with the 3 : 5-dichloro-4 : 6-dibromo-o- xylene described on page 284. Fuming nitric acid slowly dissolves the substance on warming, and on pouring the solution into water a solid separated which crystallised from alcohol in pale yellow, glistening C1= 37.54. C,HSNCI, requires C1= 37.37 per cent.FROM THE HYDROAROMATIC SERIES. PART I. 279 needles melting at 175-176", and giving the same melting point when mixed with the dichlorobromonitroxylene described on page 275.Intercdon of 3 : 5 -DichZoro-l : 1 -dimethyl-A2 4-dihyds.obenxene with One Molecule of Bromine. Dichlorodimethyldihydrobenzene (1 molecule) was dissolved in three times its weight of dry chloroform and dry bromine (1 molecule) gradually added, the whole being cooled in ice. The bromine is readily absorbed, hardly any hydrogen bromide being evolved, and a sharp end point is noticed when one molecule of bromine has been used up. On evaporating the chloroform, a light yellow liquid remained, which, as it showed no signs of solidification even after a long time, was distilled, when torrents of hydrogen bromide were evolved, and a clear yellow, refractive liquid, boiling between 200" and 270°, passed over.On submitting the liquid to careful and repeated fractional distillation, two main fractions were obtained, boiling at 220-230° and 240-250°. All the intermediate fractions slowly deposited crystals which were found to be identical with the 3 : 5-dichloro-6-bromo-o-xylene contained in-the fraction 240-250' (see page 280). The Iirmiion 220-230' contttined 3 : 5-Dichloro-o-zylene (Trans., 1902, 81, 1534). This liquid was again fractionated, and a portion, boiling at 226*, was found to solidify on cooling and melted at 3-4'. When treated with bromine in presence of iron filinp, it gave 3 : 5-dichloro-4 : 6-dibromo- o-xylene melting at 233' (see page 284), and on nitration gave 3 : 5-dichloro-4 : 6-dinitro-o-xylene melting a t 175' (see page 284).As a further proof of the presence of 3 : 5-dichloro-o-xylene, some of the liquid was oxidised with dilute nitric acid under pressure (compare Trans., 1902, 81, 1536). On opening the tube, it was found to contain a quantity of long, silken needles floating in a liquid; these were filtered (Filtrate =A), purified by crystallisation from dilute acetic acid, and the chlorine determined. 0.1088 gave 0.1544 AgCI. C1= 35.10. C,H,O,Cl, requires C1= 34.63 per cent. The acid was also titrated against N/lO sodium hydroxide with the 0,4350 required 21.94 C.C. N/lO solution = 0.0877 NaOH. following result. C,H,O,CI2 requires 0.0849 NaOH.280 CROSSLEY : AROMATIC COMPOttNbS OBTAINED This substance, which is evidently a dicldorotoluic acid, readily dissolves in the cold in potassium hydroxide, alcohol, acetone, ethyl acetate, or benzene, and is not readily soluble even on boiling in light petroleum or water; it crystallises from dilute acetic acid in long, glistening needles melting at 184-185°.The production of this dichlorotoluic acid was never observed during the preparation of 3 : 5-dichloro-o-phthalic acid (Trans., ibid.). This may be accounted for by the facts that in the above oxidation rather less nitric acid was used than formerly, and that the sealed tube was not heated for so many hours. It is intended to repeat the oxidation of S : Ldichloro-o-xylem in the hope of obtaining the above dichlorotoluic acid, and definitely proving its constitution. The filtrate A (see above) was evaporated in vucuo, when a white solid remained which gave a very marked fluorescein reaction. The anhydride prepared from it by treatment with acetyl chloride crystallised from light !petroleum in radiating clusters of glistening needles molting at 89", the melting point remaining unaltered on mixing the compound with the anhydride of 3 : 5-dichloro-o-phthalic acid, with which the substance is evidently identical.The fiuction 240-250°, which solidified completely (17-20 grams from 50 grams of dichlorodimethyldihydrobenzene), was spread on porous plate and purified by crystallisation from ethyl alcohol. 0.1546 gave 09161 CO, and O*OdOS H,O. C = 38.12 ; H = 3.93. 0.1040 gave 0.1954 Ag haloids and 0.1334 Ag. C1= 28.23 ; Br = 31.38. 0,H7CI,Br requires C= 37.79; H = 2-75 ; C1= 27.95; Br = 31-49 per cent.C(CH )'CCl 3 : 5-L)~chZoro-6-bron~o-o-x~Zene, CH3*C<CB,~'Cc,>CH, is readily soluble in the cold in benzene, acetone, light petroleum, or ethyl acetate, crystallises from ethyl or methyl alcohol in long, slender, glistening needles melting at 42O, and can be distilled in air without undergoing any decomposition. It does not decoloriae a chloroform solution of bromine, but in the presence of iron filings substitution takes place readily. The solid product crystallised from ethyl acetate in long, glistening needles melting at 233O, and was identical with the 3 : 5-dichloro-4 : 6-dibromo-o-xylene described on page 284. Action of Nitric Acid on 3 : 5-Dichlo~o-6- b~~o.rlzo-o-xybne.-Two grams of the substance were gradually added to 10 C.C.of fuming nitric acid, when it readily dissolved, and the solution became warm. The whole was heated on the water-bath for 20 minutes, poured into water, the separated solid filtered, and crystallised from alcohol, It separated in pale yellow, four-sided plates melting a t 174-175", and proved to be in every way identical with the 3 : 5-dichloro-4 : 6-dinitro-o-xylene described on page 281.FROM THE HYDROAROMATIC SERIES. PART I. 281 0.2356 gave 20.0 C.C. moist nitrogen at 19' and 760 mm. N = 10.20. C8HG0,N,Cl, requires N = 10.56 per cent. Oxidation of 3 : 5-DichZoro-6-b~orno-o-xylene.-The substance mas oxid- ised by heating it in quantities of 2 grams at a time with 15 C.C. of dilute nitric acid (sp. gr. 1.15) for 6 hours at 180-1909 The con- tents of the tube, consisting of white, needle-shaped crystals suspended in a greenish-brown liquid, were filtered (filtrate A), the solid treated with potassium hydroxide, in which a slight amount was insoluble, filtered, reprecipitated with sulphuric acid, and purified by crystallisa- tion from water.0.2042 gave 9-8 C.C. moist nitrogen a t 32' and 770 rnm. N=5*51. C,H50,NC1, requires N = 5.6 per cent. The acid was then titrated against N/lO sodium hydroxide. 003952 required 16.2 C.C. NjlO solution =; 0.0648 NaOH. C8H,0,NC12 requires 0,0632 NaOH. 3 : 5-Dic~Zoro-6-nit~otoluic acid is readily soluble in the cold in aqueous potassium hydroxide, alcohol, acetone, and ethyl acetate, less SO in benzene or chloroform, and crystallises from water in feathery needles melting at 187-189°.The filtrate A (see above) yielded on evaporation a solid which gave the fluorescein reaction in a marked degree, but the amount was too small for complete investigation. As the light yellow liquid (see page 279) obtained by the action of one molecule of bromine on dichlorodimethyldihydrobenzene and pre- suma bl y d i d Zorodibromo&imeth yltetrahgdrobanxene cannot be distilled even in a vacuum without decomposition, it was submitted to oxida- tion with potassium permanganate in order to obtain some evidence as to its constitution. For this purpose, 50 grams of the substance were suspended in 700 C.C. of water, 90 grams of finely-powdered potassium permanganate gradually added, and the whole heated on the water-bath in a flask attached to a reflux condenser.At first, the oxidation is vigorous, and some bromine is liberated, but i t soon becomes much lees active, and the permanganate is very slowly decolori$ed, in the above case requir- ing 10 hours, The contents of the flask were then filtered, when some oil passed through with the filtrate (=A), which was extracted with ether (extract = B). The residual manganese dioxide was then sus- pended in water and distilled in steam, when an oil passed over with the aqueous distillate, and this was extracted with ether (extract A. The filtrate was evaporated to a small bulk, acidified, and re- = C).282 CROSSLEY : AROMATIC COMPOUNDS OBTAINED peatedly extracted with ether, when 3.5 grams of a solid having a marked odour of fatty acids were obtained. On crystallisation from water, a slab of crystals separated, which melted at 190-1 91' with brisk evolution of gas, and consisted of dimethylmalonic acid, for on distillation, isobutyric acid was obtained boiling a t 153-155'.A por- tion of this acid was converted into the silver salt. 0-1888 gave 0.1046 Ag. Ag=55*40. C,H,O,Ag requires Ag L= 55.38 per cent. The mother liquors from the dimethylmalonic acid were evaporated t o dryness and distilled, when a further quantity of isobutyric acid was obtained, and at a much higher temperature 0.3 gram of a liquid passed over which a t once solidified. This solid was insoluble in cold water but dissolved on boiling, and after saturating the solution with bjdrogen chloride, needle-shaped crystals separated, melting a t 164' with evolution of gas.These crystals gave the fluorescein reaction in a marked degree and evidently consisted of 3 : 5-dicbloro- o-phthalic acid, for on heating with acetyl chloride they were con- verted into an anhydride which crystallised from light petroleum in glistening, flattened needles melting at 89'; this melting point Was not altered on mixing the substance with pure 3 : 6-dichloro-o-phthalic anhydride (compare Trans., 1908, 81, 1536). B. This extract, which weighed 9 grams, slowly deposited crystals. These were filtered and crystallised from alcohol, when the compound separated in stout needles, which melted with evolution of gas at 118' and were proved by the following facts to be identical with the dichlorotri bromodime t h yl te trah ydro benzene described on page 2 7 2.C,H,CI2Br, requires halogen = 74.75 per cent. 0.2184 gave 0,4472 Ag haloids. Halogen = 74-81. This substance, when warmed with concentrated nitric acid, yielded 3 : 5-dichloro-4 : 6-dibromo-o-xylene melting a t 233" (see page 273). The liquid from which the above crystals had separated was distilled in air, when hydrogen bromide was evolved and two fractions were obtained boiling a t 220-230' and 240--%50°. The first of these fractions contained 3 : 5-dichloro-o-xylene, and the latter, on cooling, solidified almost completely t o a solid which melted at 42', and was identical with the 3 : 5-dichloro-6-bromo-o-xylene mentioned on page 280. C. The oil deposited a small quantity of solid, readily soluble in the ordinary organic solvents with the exception of light petroleum and alcohol ; from these solutions, the compound separated in fern-like aggregates of flattened needles melting a t 143-144'. The crystals, which contained halogen, did not decolorise a chloroform solution ofFROM THE HYDROAROMATIC SERIES.PART I. 283 bromine, and were readily oxidieed by potassium permanganate on warming, but the amount was too small for a determination of their constitution. The results of this oxidation, although appearing somewhat com- plicated, are easily explained. The temperature to which the mixture is heated evidently causes the partial decomposition of the original substance into hydrogen bromide, 3 : 5-dichloro-o-xylene, and 3 : 5- dichloro-6-bromo-o-xylene, from the second of which, on further oxidation, there results 3 : 5-dichloro-o-phthalic acid.Moreover, the liberated hydrogen bromide would, in contact with potassium per- manganate, evolve bromine, which would act on some of the original material to give dichlorotri bromodimethyltetrahydrobenzene. The oxidation was then repeated, using acetone as solvent instead of water. Fifty grams of crude dichlorodibromodiwethyltetrahjdrobenzene (page 279) were dissolved in a mixture of 500 C.C. pure acetone and 100 C.C. of water, and 110 grams of finely-powdered potassium permanganate gradually added. The first stages of the Oxidation were accompanied by a considerable evolution oE heat, so much so that the mixture was cooled in ice-water, and later, when the oxidation became less vigorous, it was allowed to take place at the ordinary atmospheric temperature.When the permanganate had been used up, the product was filtered and the acetone evaporated, when 6 grams of an oil eeparated which was not further examined. After removing the oil by filtration, the filtrate was evnporated to a small bulk, acidified with sulphuric acid, extracted ten times with ether, and the ether evaporated, wheq a residue weighing 9 grams was obtained, which slowly solidified. The solid melted for the most part at 120-125°, but did not become clear until 150°, when a gas was evolved. This is the manner in which a mixture of dimethylmalonic and as-dimethylsuccinic acids behaves on heating in a capillary tube as already observed ('t'rane., 1902, 81, 829). The solid was therefore heated a t 180' in a distillation flask until no more gas was given off, during which time a liquid distilled over which proved t o be isobutyric acid.The liquid residue in t h e distillation flask was insoluble in cold water, but dissolved on boiling, and after saturating the solution with hydrogen chloride, needle-shaped crystals separated melting at 1 40 - 14 1 O. 0.1178 gave 0.2128 CO, and 0.0746 H,O. C=49*26; H=7*03. C,H1,O, requires C = 49-31 ; H = 6.85 per cent. The identity of this substance with as-dimethylsuccinic acid was further proved by the preparation from it of an anilic acid, which284 CROSST,EY: AROMATIC COMPOUNDS OBTAINED crystallised from methyl alcohol in flattened, nacreous needles melting at 186-187'. Incidentally, i t was observed that as-dimethylsuccinic acid gives a particularly brilliant fluorescein reaction.D e&vcctives of 3 : 5 - D ich E or0 -o-xy Zen c. The following derivatives were prepared from pure 3 : 5-dichloro-o- xylene (Trans., 1902, 81, 1533) for the purpose OF comparison with substances encountered in the course of this investigation. On adding 3 : 5-dichloro-o-xylene t o a mixture of fuming nitric and Concentrated sulphuric acids, much heat is evolved, and a solid separates almost at once. The whole was heated on the water-bath for ten minutes, poured into a large volume of water, filtered, and after purifying the residue by crystallisation from alcohol, the nitrogen was determined. 0.2550 gave 22.8 C.C. moist nitrogen at 20' and i 7 2 mm. N = 10.39. C8H,O,N2CI2 requires N = 1Oe56 per cent.3 : 5-Dichloro-4 : 6-dinitro-o-xylene is readily soluble in the cold in chloroform, acetone, ether, benzene, or ethyl acetate, and crystallises from dilute acetic acid or alcohol in faintly yellow, glistening, four- sided crystals melting at 175-176'. 3 : 5 -DiChh0-4 : 6-dib~omo-o-xyZene, CH,*C<CBr--CC1>CBr, C(CH,):CCI This substance is readily obtained by brominating 3 : 5-dichloro-o- xylene in presence of a small quantity of iron filings. It is soluble in the cold i n benzene and chloroform, sparingly so in alcohol, even on boil- ing, and crystallises from light petroleum (b. p. SO-loo'), acetone, or ethyl acetate in slender, glistening needles melting at 233-233-5'. It sublimes in stout needles without decomposition. C1=81.65; 0.1039 gave 0.2088 mixed haloids and 0.1362 Ag.Br = 48.1 2. C,H,CI,Br, requires Cl = 31.32 ; Br = 48 05 per cent. The mother liquors from the crystallisation of this derivative con- tained a substance of much lower melting point (100-118°), which from its appearance and properties must have consisted for the mostFROM THE HYDROAROMATIC SERIES. PART I. 285 part of 3 : 5-dichloro-4-bromo-o-xylene, but although repeatedly crystal- lised, i t was not found possible to isolate a substance of constant melting point. The action of one molecule of bromine on 3 : 5-dichloro-o-xylene was also investigated, because Claus (J. pr. Chem., [ii], 42, 125) attempted to prepare a dichlorobromoxylene by the action of one molecule of bromine on dichloro-m-xylene, but found that under these conditions one half of the substance was converted into the dichlorodibromoxylene, whilst the residue remained unchanged.When 3 ; 5-dichloro-o-xylene is treated with one molecule of bromine in presence of iron filings, a very small amount of unaltered material is recovered, and on submitting the solid obtained t o fractional crystal- lisation from alcohol, it was found to consist principally of 3 : 5-dichloro- 4-bromo-o-xylene, melting at 100' (see page 275). Some dichloro- dibromoxylene (m. p. 233') is also produced, from which it is almost impossible to separate t h e dichlorobromoxylene in a pore condition, Undoubtedly the latter substance is most easily obtained pure by the elimination of hydrogen bromide from dichlorotribromodimethpltetra- hydrobenzene (see page 274). This acid may be prepared by heating the above dichlorodibromc- xylene in quantities of two grams a t a time with 15 C.C. of dilute nitric acid (sp. gr. 1.15) in sealed tubes a t a temperature of 230-240' for six hours. Experiment showed that this strength of nitric acid had l i t t k or no action on the dichlorodibromoxylene at a temperature of 190-200°, even after heating for 7 hours ; with more concentrated nitric acid, considerable quantities of acids containing nitrogen were produced, and these were difficult t o remove from the desired phthalic acid. The semi-solid contents of the tubes were filtered and the residue extracted two or three times with boiling water, in which solveut any unchanged dichlorodibromoxylene is quite insoluble. On cooling the filtrate, the phthalic acid separated, and was purified by further crys- tallisation from water. 0.1622 gave 0.1444 CO, and 0.0126 H,O. C,H,O,Cl,Br, requires C = 24.42 ; H = 0.51 per cent. 3 : 5-Dichlo~o-4 : 6-dibro~no-o-p~thaEic acid is readiIy soluble in the cold in alcohol, acetone, and ethyl acetate, insoluble even on boiling in light petroleum or chloroform, and crystallises from water in small, C = 24.27 ; H = 0.86, VOL. LXXXV. U286 BARGER : A lClICROSCOPICAL METHOD OF shining scales, which, on heating, sinter and partially sublime, and finally melt a t 240-241O with evolution of gas. It gives a very marked fluorescein reaction, and, when heated between two watch glasses, sublimes in feathery needles, which were found to consist of the anhydride. The mhydride was prepared by heating the acid with excess of acetyl chloride for one hour, evaporating the solvent, and crystallking the residue from acetic anhydride. 0.2016 gave 0.1930 CO, and OmO014 H,O. 0.1032 ,, 0.1834 mixed haloids and 0.1198 Ag. C1= 19.40 ; Br = 42.67 C = 26.10 ; H = 0.00. Er = 42.21. C,0,ClzBr2 requires C = 25-60 ; H = 0.00 ; C1= 18.93 ; per cent. The anhydride readily dissolves in the cold in benzene and ethyl acetate, and is sparingly soluble, even on boiling, in water, alcohol, or light petroleum ; it crystallises from acetic anhydride in stout, prismatic needles melting at 248-250°, and sublimes unchanged. When dis- solved in benzene and treated with aniline, a white solid separates, which crystallises from alcohol in glistening, flattened needles melting with decomposition at 266-26’7’. This substance may be the anilic acid, although i t was found to contain more than the calculated amount of nitrogen (Found, N = 3.6 and 4.0. Calculated 3 per cent.). The author’s thanks are due to the Research Fund Committee of the Chemical Society for a grant, which has in part defrayed t h e cost of this investigation. CHEMICAL LABORATORY, ST. THOMAS’S HOSPITAL.

ISSN:0368-1645    

DOI:10.1039/CT9048500264

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

286 BARGER : A lClICROSCOPICAL METHOD OF XXXV.-A Microscopical culur ,Nethod oj’ Weights. Deter rnijiing Mole- By GEORGE BARGER, Scholar of King’s College, Cambridge. THIS research, a preliminary account o€ which has been given in the Proceedings (1903, 19, 121), originated in Professor Errera’s labora- tory at Brussels, where experiments were being carried out on the hereditary adapOation of fungi to strong salt solutions. The fungi were grown in hanging drops of the solutions; each drop was sus- pended from the lower surface of a coverslip, which was separated from the slide by a cardboard frame, the chamber thus produced beingDETERMINING MOLECULAR WEIGHTS. 287 moistened from time to time with distilled water. The experiments generally lasted a few weeks, and it was noticed that the drops of the salt solutions invariably increased in size. This phenomenon was explained by Prof, Errera in the folloming manner.As the vapour pressure of the salt solutions was less than t h a t of pure water at the same temperature, and as the drop was confined in a closed space, moistened by pure water, a condensation of vapour took place on the drop. Prof. Errera then asked me to study the effect quantitatively, and for this suggestion and for the kindly interest he has taken in the work I wish to express my hearty thanks. My earliest experiments were made either with small flasks or with small crystallising dishes, which could be completely closed by ground glass plates, but as the results mere only of a qualitative character, I finally determined to study the behaviour of the drops in a capillary tube, so that their change in thickness could be measured under the microscope.Description of the Method. A solution of known strength of the substance, the molecular weight of which is unknown, is compared with standard solutions of a sub- stance of known molecular weight, a series of drops taken alternately from the two solutions; being introduced into a capillary tube (length 6-43 cm.; bore 1-5 mm.). After the drops have been measured, the tube is put aside for some time varying from a few minutes to a day, and then another measure- ment is taken. If there is a decided difference in the vapour pressure of the two solutions employed, one series of drops will be found to have increased, while those alternating with them have decreased.I n that case we can decide whether the solution experimented with con- tains more or less molecules than the standard solution, and so arrive a t two limits for the unknown molecular weight. The theory of the determination is very simple. Each drop is placed between two others of a different solution, and can evaporate on either side into a small, closed air-chamber. This chamber is soon saturated with vapour, which can condense freely on the drops. If the vapour pressures of the two solutions are equal, the evaporation will equal the condensation, and there will be no change in volume of the drops. If, on the other hand, the vapour pressures are unequal, there will be a gradient of vapour pressure in the air spaces ; some drops will therefore be in contact with an atmosphere the vapour pressure of which is greater than their own.Condensation mill take place on these drops and they will increase. The others, alternating with them, will have a vapour pressure greater than that of the adjoining u 2288 BARGER: A MICROSCOPICAL METHOD OF air spaces; these drops will evaporate and thus decrease. Hence there is a distillation from the drops of the one series to those of the other series, although all are at the same temperature. By measurement, we can tell which drops increase, and hence ascer- tain which solution has the smaller vapour pressure. If the solvent is identical in both cases, and if the solutes are non-volatile, the solution with the smaller vapour pressure will have the greater concentration of molecules and vice versd, and t h u s the determination of the molecultw weight is rendered possible.Prepamtion qt Solutions. The supply of the substance, the molecular weight of which is to be determined may be very limited, but good results have been obtained with as little as 30 milligrams. The substance is weighed out i n a minute stoppered bottle or cylinder. A known volume of the solvent is then added from a pipette, for instance, a one C.C. pipette graduated in hundredths. It is generally easier to add enough of the solvent to dissolve the substance completely and then weigh the solution. To obtain the voliime of the solution, we must know its density, but as the solution is generally dilute, we may, without great error, take its density as being equal to that of the pure solvent.The density of the solvent is easily estimated by a hydrometer. It is best to express the concentration of the solution thus prepared by volume, and not by weight, as it ia easier to make up the other (standard) solutions by volume. The choice of the standard substance is determined by the following circumstances : 1. I n the first place, it should neither be associated nor dissociated under the conditions of the experiment, that is to say, it should actually have the molecular weight deduced from its formula. 2. Secondly, the standard substance must neither combine with the solvent, nor with the other solute (for a certain amount of mixing of the two solutions is inevitable). 3. Thirdly, both the standard and the unknown substance should be very much less volatile than the solvent employed.4. Fourthly, if the unknown substance is colourless, i t is useful to employ a coloured substance as standard, for then one can always see a t a glance to which solution a given drop belongs, and to what extent mixing has taken place. Benzil and azobenzene are two good substances for work with organic liquids. They can be easily obtained pure, are freely soluble in most solvents, have normal molecular weights, and give coloured solutions.DETERMINING MOLECULAR WEIGHTS. 289 With water, I have most frequently used cane sugar and boric acid. The latter substance bas the advantage of not being attacked by moulds, so that its solutions can easily be kept unchanged; its electrolytic dissociation is so slight as to be negligible. Tbe standard solutions are conveniently made up in 10 C.C.graduated stoppered measuring cylinders. It is then easy to obtain a solution of any desired intermediate strength by mixing two others, Sometimes i t may be desirable to dilute a solution of known strength very slightly with the pure solvent. I n t h a t case, t o the known volume of the solution the calculated quantity of the solvent from a one C.C. pipette graduated in hundredths can be added, this procedure being much more accurate than taking the difference between the two readings of the measuring cylinder. With regard to choice of solvent, the method allows considerable latitude. The solvent need have neither a constant melting point nor a constant boiling point.Therefore, its purity is not a n essential condition. Ether saturated with water, wet acetone (b. p. 66-7-65') alcohol with 10 per cent. water, acetic acid with 20 per cent. water, can all be used successfully. Boiling point determinations with acetone and pyridine, for instance, require specially purified samples of these substawes, whereas by the microscopic method an approximate value of the molecular weight can easily be found in a short time. The best proof that a solvent of con- stant boiling point is not required is given by the experiments with light petroleum (b. p. 50-60'; see below). Although the solvent need not be pure, it is obviously essential that a11 the solutions for one determination should be made up from the same sample. Very volatile solvents cannot be used, for with them it is impossible to fill tubes with any degree of accuracy.I have performed a few experiments with ether and obtained satisfactory results, but cannot recommend this solvent on account of the dificulty of manipulation. With a little care, carbon disulphide may be employed. If, on the other hand, the solvent is not sufficiently volatile, the experiment takes too long. Xylene is one of the least volatile solvents which can conveniently be used. The cupillcry tubes are best prepared by drawing out soft glass tubing of 8'' bore into capillaries of 1-2 feet long, which should be cut into smaller pieces, having a smooth, regular edge, in order that the tube may be closed tightly with the finger while i t is being filled. The internal diameter of the capillaries should be between 1 and 2 mm., preferably about 1.5 mm.The influence of the bore will be discussed later. Thefilling of the tubes requires a little practice, but when this has been obtained i t can be done quite rapidly. The tube is taken between290 BAROER: A MICROSCOPICAL METHOD OF the middle finger and thumb, and its upper end, which should be rounded, is closed with the index finger. The other end is then dipped below the surfacte of ono of the two solutions (which in the following experi- ments is always the standard one). By lifting the index finger very slightly, enough liquid is admitted into the tube to make a column of about 5 mm. long. The index finger is again pressed against the tube, so as t o close it, and the tube is then held in a slanting position, with the open end uppermost. By again diminishing the pressure of the finger on the closed end, some air is allowed to escape, and the column of liquid slides down the tube, Its progress is regulated by the amount of slant given to the tube.When the column has travelled about 3 mm., it is stopped by closing the tube again with the finger. The tube is now once more held vertically, and its open end is made to touch the surface of the second solution, while the upper end is still closed by the index finger. This time only a minute drop enters, for the capillary forces are soon balanced by the increase in the pressure of the air inside the tube. The tube is then again held in a slanting position, and the small drop allowed to slide down a short distance, and so on.Most organic solvents wet the glass and slide down the tube with ease, but with water, especially in narrow tubes, the drop descends very slowly or not at all. This difficulty can be overcome by previously wetting the tube with the first solution to be employed. The drops can also be sucked into the tube by heating the free end and then closing it with the finger. The air, on cooling, contracts, and the drop is forced in. For the sake of uniformity, I always use tubes with 7 drops; when sealed, the tubes have the following appearance (natural size) : FIG. 1. A is the end which has been dipped in the various solutions. B is the end which is closed by the finger. I n the diagram, the drops are numbered in the order in which they have entered the tube, and the drops of the standard solution are shaded black. The first aud last drops are about 5 mm.long, and are riot measured, for they generally decrease by evaporationDETERMINING MOLECULAR WEIGHTS. 29 1 into the air-spaces a t A and B. They are also the ones most liable to become heated while sealing the tube ; for this reason, they are made rather large, in order that their concentration may not so easily be changed by evaporation. The drops 2, 4, and 6 contrin the substance the molecular weight of which is being determined. To ensure a rapid interchange of vapour with small differences of concentration, the drops should be close together-say 2 or 3 milli- metres apart-but they must not be too close, or they will mix.The thickness of the drops 2-6 is limited by the size of the micrometer scale. Thicker drops can be measured with a lower objective, but then the measurements are, of course, less accurate. With a little practice, drops of the right thickness can easily be obtained. Water gives some difficulty on account of its high surface t’ension. If too much liquid has been sucked up, the excess can always be removed by means of filter paper. With some heavy liquids in wide tubes, the capillary rise is not great enough, in which case the end of the tube is dipped well under the surface of the liquid, and the pressure of the finger on the other end is slightly diminished until the right quantity of liquid has entered. The same procedure is sometimes necessary with very volatile solvents, the vapour of which may expand by the warmth of the hand, and so tend to drive out drops which have already entered.When all the drops are in the tube, they are allowed t o slide down until the last drop is about 1 cm. distant from the end 8, and then this end is sealed carefully in the lower part of a small Bunsen flame, and withdrawn immediately. With volatile solvents (acetone, car- bon disulphide, &.), i t is advisable t o let the last drop get more than 1 cm. from the end A before sealing, but there is an objection t o letting the drops slide so far down the tube, as will be seen later. Tubes with volatile liquids are best closed by means of soft paraffin wax, a t least at the end A . A plug of the wax is introduced, and then, by gently warming the end of the tube, it is melted, so as to become air-tight on solidification.The end B may be closed by ordinary sealing, or by warming it and letting i t suck up a little melted wax while cooling. The wax constitutes a slight source of error, because i t attracts some of the solvent from the terminal drops, especially if the experiment lasts a long time. As these end drops are, however, especially long, no great change in their concentration need be feared. Instead of paraffin wax, fusible metal may be used, pre- ferably d’Arcet’s alloy with mercury, which melt,s at 45’. The difficulty here is in getting the alloy i i t o the ends of the tube, owing to the negative capillarity of metals. It can perhaps best be accom- plished by means of another thinner capillary, which is dipped into the melted alloy, and then, with some of the metal adhering, it is used to plug up the larger tube.292 BARGER : A MICROSCOPICAL METHOD OF After the tubes have been Blled, the drops are measured.For ease in handling and for purposes of identification, they are fixed to a microscope slide (3" by I.") by means of thick Canada balsam. Each slide is numbered and can take a t least half a dozen tubes. The slides are placed in a glass Petri dish about 3.$" square, and enough water is placed in the dish to cover the tubes, so that the drops are always a t the same temperature, and do r,ot move owing to the expansion of the air between them. Under the microscope, the drops and scale present the following appearance : FIG. 2. \ A sharp image is obtained if the microscope is focussed to the level of the centre of the tube.The menisci then become exceedingly distinct, and the distance between them (which is the minimum thickness of the drop) can be measured. The Petri dish is moved till one of the menisci almost coincides with the zero of the scale ; a drop of water between the stage and the dish allows the latter to be moved small distances without jerking. The exact coincidence of the meniscus with the zero is obtained by moving the eye-piece (with the scale in it) trans- versely in the tube OF the microscope, in which it has a little play. As we are only concerned with the direction of the change in the drops, not with its magnitude, the scale need not be standardised. The distance between the menisci can now be read off to tenths of a scale division. As the micrometer has 50 divisions, 5 numbers below 500 are obtained for each tube.I use a 2" objective (Leitz, No. 3) ; with a lower one, larger drops can be measured on the scale, but the accuracy is correspondingly decreased. With higher objectives, the drops have to be inconveniently small, and the focussing also becomes difficult. The eye-piece should be a strong one, in order to magnify the scale as much us possible. I use a Leitz No. 4 eye-piece ; a Zeiss micrometer disc is placed on its diaphragm. With a No. 3 objective, the magnification is about 65 diameters, so t h a t a scale division is equivalent to 17 p , and an accuracy of 3 p is easily obtained.DETERMINING MOLECULAR WEIGHTS. 29 3 The time during which the tubes have to be kept before a definite ieault is obtained varies greatly with the nature of the solvent,, the difference in concentration of the solutions, &c.The changes in the various drops of the same tube are by no means I egular. Sometimes all the drops increase if the difference in concen- tration between them is small. The reason for this is that in filling the tube some of the solution adheres to its walls. This solution forms a dew of minute, convex drops, whereas the large drops, which are measured, have a concave surface. Now, other things being equal, the vapour pressure of a convex surface is greater than that of a con- cave one (Lehmnnn : Molecularphysik, vol. ii, p. 151). Hence the general tendency of the drops is to increase, and this l i m i t s the sensitiveness of the method. If the difference in concentration between the two solutions employed is not very small, the drops of one solution increase much more than those of the other solution, and often, if the tube be kept long enough, the drops which increase least will afterwards decrease.This initial increase of all drops and subsequent decrease of some is illustrated by the following tube : azobenzene (0.19 mol.) and ethyl behzoate (0.20 mol.) in benzene : Time. Readings in tenths of scale divisions. 12.15 p.m. ............ 331 264 289 279 215 2.15 p.m. ........... 325 272 292 297 214 5.30 p.m. ............ 321 289 286 310 210 As already mentioned, solvents with very high boiling points cannot be used, because the change in the drops occurs too slowly.Theoretically, there is no good reason why tubes should not be kept for an indefinitely long time, so that even the smallest difference of vapour pressure might be demonstmted. I n practice, I find, however, t h a t when the difference between the two solutions is small, or when the solvent is insufficiently volatile, the changes in the drops are irregular. l h e possibility of keeping tubes a t temperatures other than the ordin- ary naturally suggests itself in this connection. I hoped by this means to apply the method to all high boiling solvents, but my experiments SO far have not been successful. The difficulty arises from the necessity of cooling the tubes again before measuring, By cooling, the air spaces between the drops become super-saturated, and the solvent is condensed on the walls of the tube, which, being on the outside, are coldest.Hence, generally, all the drops are smaller than before they were heated. If the tubes have not been heated too much and if they have been r i294 BARGER : A MICROSCOPICAL METHOD OF cooled slowly (for instance, immersed in a large water-bath), good results may nevertheless be obtained. I have kept tubes with water or with acetic acid a t n temperature of 37O, and in this way the change in the drops is more rapid than a t the ordinary temperature. The temperature of the determination can therefore be varied within certain limits ; possibly this may be of use in studying the change of molecular weight with the temperature, for example, of substances which undergo association.Consideration OJ the Probcdle Errors. The effect of the various manipulations on the accuracy of the method will now be considered. Solutions can be prepared, the con- centration of which is accurately known. The only difficulty arises when the supply of the substance is very limited. Through frequent use, the concentration of a solution may gradually undergo a change, for while a tube is being filled, the bottle containing the solution is left open. If the solvent is volatile, it may evaporate ; if hygroscopic, it may attract water from the air ; in the first case, the vapour pressure of the solution will always be lowered ; in the second case, it will only be lowered with low boiling solvents (acetone, alcohol). If accuracy is desired, it is advisable, after an approximate value has been found, to repeat the last steps in the determination with freshly prepared solutions.The error due to increased concentration of the solution can be over- come by weighing the residue left on evaporating a small quantity of the solution. This is most easily done with volatile solvents, where i t is at the same time of most importance. For the ordinary determinations in this paper, no such special precautions were taken, and the same standard solutions generally served for all t,he work with a given solvent. The principal object was to find a short and easy method of wide application, not necessarily a very accurate one. Each drop remains for a moment a t the end of the tube before it slides down and is placed between the drops of the other liquid.During this short time, it is exposed to the same influences as the solutions in an open bottle. It may evaporate and absorb moisture ; i t presents a relatively large surface to the air, and so may change its vapour pressure. The time of exposure is, however, very short, and may be made approximately equal for the drops of both solutions. The two errors will then balance each other, as we are only concerned with the difference between the two solutions. Some experiments were performed to study this source of error, The errors produced in filling the capillaries are as follows.DETERMIK ING MOLECULAR WEIGHTS. 295 choosing acetone as solvent, because i t is b0t.h volatile and hygro- scopic. Normal tube, both series of drops composed OF b e n d in acetone, 0.10 mole.," and all exposed for 2-3 seconds, 3.21 p.m............. 347 310 346 283 491 3.37 p.m. ............ 351 312 345 290 490 4.3 p.m. ............ 357 318 342 298 492 A similar tube, but with the 2nd, 4th, and 6th drops exposed for 10 seconds (the 1st and 7 t h drops were not measured). - - + + 3 3.21 p.m. ............ 349 401 366 330 388 3.37 p.m. ........... 353 400 371 331 391 4.3 p.m. ............ 367 392 382 326 396 It will be seen t h a t whereas the first tube gives no clear result (theoretically, the drops ought not t o change at all), the second tube shows that those drops which mere exposed for 10 seconds have become distinctly more concentrated tban the others. To get a n idea of the amount of concentration, two different solutions of benzil in acetone (strengths 0.09 and 0.10 iuole.) were next used, 1.Normal tube, 0.10 benzil as standard (that is, drops 1, 3, 5, 7). 11.59 a.m. ............ 422 509 491 414 478 - - 4- + - 12.09 p.m. ............ 420 510 488 416 476 12.57 p.m. ............ 416 520 478 421 471 2. A similar tube with drops of 0.09 mole. exposed for 5 seconds. 1.6 p.m. ............ 346 592 331 394 328 1.16 p.m. ............ 346 396 331 400 324 1.65 p.m. ............ 342 402 330 412 336 - - -t + - 3. Same as above, but drops of 0.09 mole, exposed for 10 seconds. 11.59 a.m. ............ 251 236 246 217 241 - - + + - 12.10p.m. ............ 250 240 250 220 246 12.57 p.m. ............ 251 250 248 222 250 * Throughout this paper the term " mole." signifies a concentration of one gram- molecule per litre.296 BARGER: A MICROSCOPICAL METHOD OF 4.Same as before, but drops of 0.09 mole. exposed for 15 seconds. 1.6 p.m. ............ 249 341 222 269 165 1.16 p.m. ............ 253 341 224 269 176 1.55 p . ~ . ........... 258 349 225 275 193 From these experiments, it would appear that by an exposure of a quarter of a minute a change of sometbing like 10 per cent. is produced in the concentration of an acetone drop, for only the last tube of the series does not clearly indicate which solution is the stronger. As this time is far in excess of the ordinary differences which occur in filling a tube, the error can only be a slight one. At the same time, i t may be one of the reasons for the occasional irregular behaviour of drops in the tube.Sometimes (when the difference between the two solutions is small) there is no regular alternation of increase and decrease, so that no conclusion can be drawn. In that case, the experiment must be re peat ed. We now come t o the chief interference with the concentration of the drops, namely, their mixing with one another. Each drop, as i t slides down the tube, leaves a portion of itself behind on the walls. This is shown (in a dry tube) by the decrease of the first drop. The succeeding ones travel over a part wbich has already been wetted, so they retain their original thickness. As each drop is composed of a different solution from its predecessor, it becomes to some extent mixed with the other solution. That this is so can be easily shown by alternately using a colourless and a coloured solution.For instance, with a potassium permanganate solution and pure water all the drops become pink or red, and the only diflerence between them is in the intensity of their colour. By making the drops slide up and down the tube a number of times, the mixing becomes more complete, and the difference i n their colour disappears. At first sight, this might seem t o be a fatal objection to the method, but such, however, is not the case. The mixing which takes place lessens the difference in concentration between the two series of chops. It cannot, however, obliterate this diEerence, still less prodace a differ- ence in the opposite direction, and the method is only concerned with the direction of the difference, not with its absolute magnitude.To return to the permanganate solution and water : the drops which were originally composed of pure water will become dilute permanganate solutions ; they can never be more concentrated than the other original permanganate drops. Even if an infinite amount of water were added to one drop of permanganate, the resulting mixture would never be pure water, A difference must, therefore, always remain, and it must remain onDETERMINING MOT,ECULAR WEIGHTS. 29 7 the same side as between the original solutions employed; if we can observe any regular changes in the drops, we shall be able to conclude which solution has the greater vapour pressure. Although the mixing of the drops does not impair the reliability of the method, it makes i t less sensitive.The rate of change depends on the difference between the concentration of the drops, and this difference is decreased by mixing. The mixing should therefore be reduced to a minimum, and it may be useful to consider what conditions will tend to make it so. Firstly, the amount of liquid which adheres t o the walls of the tube varies with the nature of the solution, and seems to depend on its viscosity as well as on its surface tension. Secondly, the amount of mixing depends on the diameter of the tube. Suppose this diameter to be 2r and the average thick- ness of the film OF liquid which adheres t o the walls of the tubes to be 6 (depending on the nature of the liquid), then, if the drop travel along the tube for a distance I, it will have lost 2 d Z (supposing 6 to be small compared with T).If the average thickness of the drop be d, its volume will be m2d. '" and The proportional loss will be- - - 2rrr6l rr2d - r d ' this will approximately represent the amount of mixing. I n order to reduce this to a minimum, I should be small, d and r should be large ; 8 is presumably a constant For a given liquid. 1. Z should be small ; this means that the drops should slide along as short a piece of the tube as possible. The distances of each drop from the end of the tube by which it was admitted should be a minimum; the drops must, therefore, be close together, yet not so close that they come into contact and mix. The end drop must be near t.he entrance of the tube, yet not too close lest it becomes heated when the tube is sealed.2. The thickness of the drop should be the greatest which can still be measured on the micrometer scale (except in the case of the first and last drops). 3. The tube shobld be fairly wide, yet sufficiently narrow to allow of the formation of stable drops by surface tension. It is easy t o show that the above general conditions are correct by comparing the behaviour of a coloured and a colourIess solution in tubes of widely different bore. Iodine in chloroform and pure chlcroform were used for this purpose. The extent of the mixing is indicated by the difference in shade of the two solutions after they have been made to slide up and down the tube a number of times. The difference between the drops sooner becomes imperceptible in the narrow capillary than in the wide one, In the same way, the influence of I and of d can be shown.298 BARGER : A MICROSCOPICAL METHOD OF There is yet another reason why the drops should be close together ; their proximity favours the rapid interchange of vapour.This may be inferred from the experiments of Stefan (Sitxungsber. Wiener Akad., 1873, 68, 385) on the rate of evaporation in vertical capillaries, The rate is inversely proportional to the distance of the liquid surface in the tube to the mouth of the tube, and a similar law probably applies to the drops. T t may be asked whether the thin film of liquid which adheres to the walls of the tube does not constitute a permanent means of communica- tion between neighbouring drops. I n practice, no such interchange was ever detected (unless the drops actually touch each other).This is probably because the thin layer of liquid sticking to the side of the tube soon breaks up into a number of convex drops, which tend to disappear (as the vapour tension of a convex surface is greater than that of a comave one). Oily liquids which wet the glass with difficulty (ethyleno dibromide, aniline) do not leave a uniform film adhering to the walls of the tubes, but a few relatively large drops, which makes it less convenient to work with these liquids. I n most cases, the simplest plan is to seal i t by holding the end in the lower part of a Bunsen flame. The flame should be steady and the tube should be removed from it as soon as it is completely sealed. The drops nearest the flame are liable to become slightly heated by this process, but the heating only lasts a very short time, so that no appreciable effect can be observed.With liquids such a s ether and carbon disulphide and with chloroform (which seems to attack the glass), I prefer to close the tube with melted paraffin wax. I n these cases, the heating effect is negligible, but a different error is introduced, because the parafin wax attracts the organic solvent from the end drop and so gradually concentrates the latter. The end drop is, however, very large, in order that its concentration should only change slowly, whereas with volatile solvents, the change in the measured drops takes place very quickly, before the error due to the paraffin has time to make itself felt. The large size of the end drop is, of course, also useful in counteracting the error due to heating.Occasionally the tube may turn out to be imperfectly closed; this is at once detected when the tube is measured under water by the movement of the drops and the entrance of the water. I n that case, another tube had better be prepared. I n handling the tubes, they must not be jerked or dropped, for this produces sudden and irregular changes in the drops. If the tube is inconveniently long, i t must not be scratched with a file, but a piece can be drawn off in a Bunsen flame. The last error to be considered is the change i n the Ehape of the The next possible source of error is in the closing of the tube.DETERMINING MOLECULAR WEIGHTS. 299 drops. The method presupposes that any change in the least diameter (that is, the distance measured) is accompanied by a corresponding change in the volume of the drop.Hence the curvature of the meniscus must remain the same. This is invariably the case with nearly all organic solvents, but occasionally with water and some less volatile liquids t h e curvature changes, especially on one side of the drop and if the tube is not quite clean, I t does not necessarily follow t h a t the apparent change in the drops is in opposite direction to the real one, but they may become quite out of proportion. Tbis change in the curvature of the meniscus is of rare occurrence and need only be considered with a few solvents ; it can, moreover, be readily detected. Attempted Improvements and Applications of the Xethod.As mas said in a previous section, the method only depends on knowing the. direction of change in the drops (whether increase or decrease), not the amount of this change. Theoretically, if all the conditions were known, i t should be possible to calculate the amount of this change, or, conversely, calculate at once from any observed change the difference in molecular concentration between the drops. It should, moreover, be possible to find the concentration of the unknown solution by interpolation, knowing its behaviour t o two known solutions. A good deal of time was spent in experimenting in this direction, with scarcely any result. The chief aim was to know the influence o€ the difference in concentration of the drops o c their rate of change, the other conditions being kept constant.To eliminate the variations in the diameter, pieces of ther- mometer tubing of uniform bore were used. The drops were placed at approximately equal distances from one another. All the solutions contained the same solute, and differed only in strength. The tem- perature was kept constant, and a special method of filling the tubes with capillary syringes was used in order to prevent mixing. The tubes were closed with wax. Another attempt to study the change in the drops quantitatively was to use capillary tubes of about 6-10 uim. long, which were slightly constricted in the middle, so that they would, at t h i s point, retain by capillarity a measured drop of a solution. These tubes were put horizontally into a Petri dish filld with distille 1 water without being sealed.I n this way, mixing was excluded, as in the previous plan. These experiments did not even show a constant rate of change when all the known conditions were constsnt. The only300 BARGER: A MICROSCOPICAL METHOD OF general statements which can be made about this rate of change in the drops is that i t increases with the temperature, with the difference in concentration and with the proximity of the drops, and that the influence of the diameter of the tube is doubtful. There are a few special problems which might perhaps be solved by the present method, such as the ionisation of salts in mixtures of an ionising with a non-ionising solvent. Similarly, the method may be used in studying association in mixtures of associative and a non- associative solvent (for example, alcohol and benzene). Some prelimin- ary experiments on this are given at the end of the paper. So far, I have mainly devoted myself to showing that the new method is reliable, widely applicable, and sufficiently accurate t o be of r e d practical use in organic chemistry.Results. The value of a new quantitative method can only be proved by the results obtained with it ; a large number of determinations with various solvents have therefore been made. I n the experimental records, I have not only mentioned in each case the strength of the two standard solutions-the one hypertonic, the other hypotonic to the unknown solution-but the actual changes which were observed in the drops are also given. In this way, the personal factor has been eliminated.I n order to illustrate the degree of sensitiveness, and by way of showing the accuracy obtainable in the micrometer readings, some measurements are first given with different urea solutions in 90 per cent. alcohol. I. Odd drops 0.095 nzole. ; even drops 0.10 mole. Concentration 0.095 0.10 Apr. 7,11 a.m. 312 340 12a.m. 312 340 1 p.m. 312 342 2p.m. 311 344 3p.m. 310 345 4p.m. 308 316 5p.m. 306 346 6p.m. 304 348 Apr. S, 10 a.m. 372 342 0.095 384 378 376 372 372 370 367 366 363 0.10 0.095 76 376 82 369 86 368 92 362 96 360 100 358 102 35s 105 356 114 356 0.10 0.095 0.10 0.095 448 417 361 128 448 413 360 126 449 413 361 126 449 413 361 125 451 413 362 126 450 412 362 128 450 410 360 126 450 408 361 130 452 402 368 149DETERMINING MOLECULAR WEIGHTS.301 11. Odd drops 0.10 mole. ; even, drops 0.095 mole. Concentration Apr. 7, 11 a.m. 12 a.m. 1 p.m. 2 p.m. 3 p.m. 4 p.m. 5 p.m. 6 p.m. Apr. 8,lO a.m. 0.10 233 235 235 335 233 232 230 230 206 0.095 255 253 252 250 250 250 248 247 232 0.10 0.095 0.10 0,095 189 240 248 256 190 236 248 256 194 236 250 257 195 234 250 258 197 232 250 260 199 232 251 261 201 231 252 262 202 230 252 262 202 228 256 268 0.10 0.095 0.10 240 270 262 239 267 261 239 268 261 239 265 263 240 264 265 240 262 266 240 261 264 240 261 265 242 262 285 111. Odd drops 0.24 mole. ; even drops 0.25 mole. Concentration 0.24 0.25 0.24 0.25 0.24 0.25 0.24 0.25 0.24 Apr. 3 , l p.m. 73 360 364 347 384 367 345 371 379 2.30p.m. 75 367 356 342 382 368 341 372 372 4 p.m. 75 372 353 350 380 369 340 374 372 5.30 p.m.73 375 351 354 377 367 336 373 365 Apr. 4, 10 a.m. 77 373 345 361 385 370 333 378 364 Apr. 6, 10 a.m. 36 344 325 358 408 354 342 382 372 The changes in the drops of the foregoing three tubes are very slight, yet they are so regular as t o show the great accuracy of the measure- ments. The tables illustrate a further point : the drops on the right hand side, that is, those which have travelled furthest up the tube and have the greatest chance of becoming mixed, show, generally, a smaller rate of change than the other drops on the left. For this reason, I have confined myself to five measured drops. The first and the last drop in each tube, as seen in the preceding tables, do not be- have in a regular manner. Therefore, the five above-mentioned drops were enclosed between two large ones which were not measured.To economise space, in all further cases the change in the drops is alone recorded, not their actual measurement. For tshe same reason, the changes f o r those standard solutions which were most nearly isotonic with the unknown solution are alone given. By way of example, other concentrations of the standard solution have been included in the case of the first two determinations (glucose and manriitol in water). With these exceptions, therefore, only those tubes have been included which have the slowest rate of change. All the other tubes gave results more quickly on account of the greater difference between the two solutions contained in them. VOL. LXXXV, x302 -97 +71 -79 +71 -18 +25 -31 +30 BARQER: A MICROSCOPICAL METHOD OF +548 +130 Water.Glucose, 25.02 grams per litre (0.139 mole.). + 230 + 26 +6 + 21 + 3 +8 + 18 -1 - 3 - 41 - 3 - 75 In the above and all subsequent tables of measurements, the first column gives tbe concentration of the standard solution, the second that of the time from the beginning of the experiment (where several times are given with one concentration, these times all apply to the same tube). The next column gives the changes observed during that time in five drops. The figures denote tenths of a micrometer scale division. As has already been said in the descrip- tion of the method, the first, third, and fifth of these drops contain the substance the molecular weight of which is being determined (glucose in this case).The other two are composed of the standard solution, and in addition the whole series of five are enclosed between two large drops of the standard solution which are riot measured. I n the last column is shown the change between the aggregate thickness of the three gluccse drops and that of the two cane sugar drops (in a period of about 20 hours). These figures show at once that the glucose solution is somewhere between 0.13 and 0.14 mole. They also show that the rate of change in the drops is greatly influenced by the difference between their concentrations. Assuming the molecular weight of cane sugar to be 342, we have 25-02 25.02 0.13' 0 14 and- Mean 186; C,H,,O, requires 180. now for glucose M between 7 M between 179-192.DJSTEHMINING MOLECULAB WEIGHTS.Mannitol, 15.69 grams per litre (0.0862 mole.). Cane sugar 0.064 mole. 24 hours + 5 - 7 + 4 - 7 + 10 j, ,, 0.072 ,, 24 ,, + 4 - 4 + 3 - 2 + 3 3s 9 , 0.080 9 , 24 0 - 1 0 + 1 + 1 48 ,, + 2 -1 + 1 + 3 0 9 9 7 s 0-08s ,, 24 ,, - 2 +5 - 1 + 3 - 4 48 1, - 1 + 3 -1 + 4 -1 9 , $ 7 0.096 ,, 24 1, - 2 4-12 - 7 + 4 -5 ?f ,> 48 ,, + 7 -5 + 5 -5 +10 303 + 33 + 16 -1-1 + 1 - 15 - 30 The mannitol solution is practically isotonic with the cane sugar of 0.080 mole. 15-69 M = -___ - 196 ; C6H,0, requires 182. 0.08- Munnitol, 11-41 grams per litre (0.063 mole.). Cane sugar 0.056 mole. 8 hours + I + I + I + 3 - 2 24 , Y - 2 +4 - 3 + 6 - 6 9 , Y, 0-060 1 ) 8 9 1 + 1 -1 + 2 + 2 r 2 24 ,, 0 -1 + I - 1 + 2 Molecular weight of mannitol= 190-204, mean 197 ; C6HI4O, requires 182.Boric Acid us Stundurd. Cane suga~, 95.76 grams per litre (Oo2S mole.). Boric acid 0.30 mole. 22 hours 0 - 13 +12 -15 +12 ,Y 9 , 0.29 9, 17 Y, -5 +14 - 4 +8 +1 Molecular weight of cane sugar= 319-331, mean 325 ; C,,H,,O,, requires 342. In the foregoing and following calculations, no allowance has been made for the electrolytic dissociation of borio acid, but if ionisation is considered, then the result for cane sugar approaches more nearly t o the theoretical value. Urea, 12.00 grams per litre (0.20 mole,). Boric acid 0.195 mole. 15 hours + 9 -5 + 7 - 11 + 34 ,, ,, 0.20 ,, 21 y , -1 + 7 - 1 + 5 3-1 Molecular weight of urea = 60-61 -5 ; CH,ON:, requires 60. x 2304 BARGER : A MICROSCOPICAJ, METHOD OF Z'artavic Acid, 30.00 grams per litre (0.20 mole.). Boric acid 0.19 mole.21 hours + 3 - 1 + 8 - 2 +5 ), ,, 0.20 ,, 21 ,, +4 + 4 + 3 +4 + I 0 45 :, + 4 +13 + 9 + 6 + I 9 (othertube) 0.20 ), 96 ,, +10 + 8 + 8 - 2 - 1 Molecular weight = 143-157 ; C4H606 requires 150. 0.21 ,, 21 ,) - 6 +19 - 3 + 3 0 Succinic Acid, 18-29 grams per litre (0,155 mole.). Boric acid 0.15 mole. 23 hours + 4 - 4 +10 - 15 - 18 ,, ,, 0.16 ), 24 ,, + 2 +17 -1 +12 +1 Molecular weight = 114-122 ; C,H604 requires 118. Mcccnnitol, 29.12 grams per litre (0.16 mole.). Boric acid 0.165 mole. 22 hours +10 - 7 + 9 - 10 +11 Molecular weight = 166-171 ; C,H,,06 requires 182. 9, 0.17 ,? 18 9 , - 5 + 8 - 2 -4 0 Catechol, 15.95 grams per litre (0.145 mole.). Boric acid 0.13 mole. 15 lioul*.i + 22 - 9 + 18 - 5 0 > ¶ 0.14 ,, 23 ,, -20 +19 - 3 +30 -10 Molecular weight = 114-123 ; CGH,O, requires 110.Glucose, 28.8 grams per litre (0.16 mole.). Boric acid 0.17 mole. 18 hours +14 -40 +33 -27 +38 9 , 0.175 ,, 21 ), -1 + 3 - 2 +1 -5 Molecular weight = 165-170 ; C6€I1206 requires 180. The following two determinations show electrolytic dissociation : Potassium Nitrate, 10.1 grams per litre (0.10 mole.). Boric acid 0.19 mole. 21 hours + 11 - 18 + 8 + I + ? i (van't Hoff's coefficient) = 1-92. 7, 0.195 ,, 21 ,, -1 + I 1 -31 0 0 Sodium Chloride, 5-85 grams per litre (0.10 mole.). Boric acid 0.17 mole, 21 hours + l o - 3 +10 - 10 +18 9 , 0-175 ,, 24 ,, + 1 + I -5 0 0 ,, 0.18 ,, 45 ,, 0 +13 +1 +18 - 3 Tttkii:g the salt to be isotonic with 0.175 mole., i- 1.75.DETERMINING MOLECULAR WEIGHTS. 305 Tryptophan. For a specimen of this substance, I have to thank Dr.F. G. Hopkins of Cambridge (J, Physiol., 1903, 29, 451). Boric acid 0.075 mole. 1 day +19 - 1 +10 -1 +4 Cane sugar 0,085 ,, 2 days + 3 +19 + I +10 -11 Two C.C. of the solution left, on evaporation, 0-0368 gram of tryptophan. M= -- = 230 ; CllH1202N, requires 204. 0.002 x 0.08 A l c o h o I . The experiments were performed either with commercial '' absolute " alcohol (99.5 per cent.), or with 90 per cent. methylated spirits. a-Naphthol ccs Standard; 99.5 per cent. Alcohol. Axobenxene, 30.94 grams per litre (0.17 mole.). a-Naphthol 0.16 mole. 100 mins. +13 - 13 +20 - 11 ?) 0.18 ,, 125 ,, -26 +21 -30 +32 Molecular weight = 172-193 ; C,,H,oO, requires 182. Phemyl Salicylate, 38.52 grams per litre (0.18 mole.), a-Naphthol 0.17 mole. 50 mins.+1 - 3 + 4 - 3 9 , 0'19 , I 90 Y $ -17 +14 - 2 +5 Molecular weight = 203-227 ; Cl,H,,O, requires 214. Salicylic Acid, 24-84 grams per litre (0.18 mole.). a-Naphthol 0.17 mole. 45 mins. +5 - 3 +5 - 1 ? I 0.19 ,, 90 9 , -10 + l o -12 +12 Molecular weight = 131-146 ; C,H,O, requires 138. Benxoic Acid, 21.96 grams per litre (0-18 mole.). a-Naphthol 0.17 mole. 30 mine. + 3 - 1 + 2 - 1 99 0.19 ,, 90 ,) - 7 +4 - 7 +1 Molecular weight = 115-129 ; C7H,0, requires 122. Catechol, 19.80 grams per litre (0.18 mole.). a-Naphthol 0.17 mole. 45 mins. + 5 -4 + 3 -3 9 9 0.19 ,, 80 ,, - 3 +5 0 + 9 Molecular weight = 104-116 ; C6H60, requires 110. + 15 - 18 +1 -8 + 2 - 14 +4 -1 + 4 - 3306 BARGER : A MICROSCOPICAL METHOD OF Resorcinol, 19.80 grams per litre (0.18 mole.). a-Naphthol 0.17 mole.80 mins. + 11 - 9 + 11 - 3 1 , 0.19 ,, 80 ,, -10 +23 -22 +16 Molecular weight = 104-116 ; C,H,O, requires 110. Quinol, 19.80 grams per litre (0.18 mole.). a-Naphthol 0.17 mole. 45 mins. + 4 - 3 + I 1 - 5 , 9 0.19 ,, 80 ,, - 2 + 7 -1 + 6 Molecular weight = 104-116 ; C,H,O, requires 110. CinnEcmic Acid, 26.64 grams per litre (0.18 mole.). a-Naphthol 0.17 mole. 30 mins. 0 - 5 +13 - 9 1 , 0.19 ,, 30 ,, - 2 - 3 - 5 - 2 15 hours -24 +40 -32 + 3 7 Molecular weight = 140-157 ; C,H80, requires 148. Acetanilide, 24.30 grams per litre (0.18 mole.). a-Naphthol 0.17 mole. 90 mins. + 4 0 + 8 - 4 9 3 0.19 ,, 110 ,, - 8 +20 - 1 7 +31 Molecular weight = 128-143 ; C,H,ON requires 135. + 6 0 + 6 0 + 3 - s - 30 +5 - 19 Biphenylamine, 30.42 grams per litre (0.18 mole.). a-Naphthol 0.17 mole.60 mins. + 11 - 7 + 13 - 9 +8 Y , 0.19 ,, 125 ,, 0 + 7 - 7 + 6 +1 Molecular weight = 160-178 ; C,,H,,N requires 169. The error in the preceding ten determinations in no case exceeds 5 per cent., but a greater deviation from the theoretical value was found with t h e following substances : hippuric acid, diphenyl, dinitro- benzene, and urea. These all gave values which were more than 10 per cent. too high as compared with a-naphthol in absolute alcohol. I t was repeatedly found that the molecular weight of urea was too high as compared with other substances. Urea is therefore not a good standard. This is further illustrated by the first of the following three determinations, all of which were carried out in 90 per cent. of methylated spirit.DETERMlNING MOLECULAR WEIGHTS.307 Urea aa Xtandard; 90 per cent. Alcohol. Phenyl Xalicylate, 38.52 grams per litre (0-18 mole.), Urea 0.18 mole, 20 hours 0 - 6 +12 -10 + l 8 9 , 0.19 9 ) 2 9 ) - 2 1-2 0 0 - 3 9 9 0'20 Y, 2 9 9 - 2 + 6 -1 +5 - 7 The change with 0.19 mole. is not very decisive. The phenyl sali- cylate solution gives values between 0.18 and 0.20 mole. (probably between 0.18 and 0.19). Molecular weight = 193-214 ; Cl,HloO, requires 213. Taking the values 0.18 and 0.20, we get : Phenyl Xalicylate as S t a n d a r d ; 90 per cent. Alcohol. Axobenxene, 29.12 grams per litre (0.16 mole.). Phenyl salicylate 0.15 mole, 130 mins. + 8 - 3 + 21 + 2 + 5 Molecular weight of azobenzene = 182-194 ; C,,H,,N, requires 182. $ 9 0.16 ), 90 ,, -13 +23 -13 + 7 -27 Benxil, 23.10 grams per litre (0.11 mole.).Phenyl salicylate 0.1 15 mole. 70 mins. + 20 - 19 + 18 - 40 - 1 I Y 0.12 $, 120 ,, - 6 +7 --lo + 6 - 5 Molecular weight of benzil = 193-201 ; C,,H,,O, requires 210. A c e t o n e . The acetone used for a,ll the experiments contained water and boiled between 56.7' and 6 5 O . Various substances were used as standard. With Phenyl Salicylate as Xtccndard. Salicylic Acid, 27.40 grams per litre. Phenyl salicylate 0.18 mole. 35 mins. + 12 - 10 + 15 - 26 + 31 Molecular weight = 124-131, mean 127 ; C7H,0, requires 138. 9 , 0.19 ,, 20 ,, - 7 + 7 -10 +12 -1 Picric Acid, 45-80 grams per litre. Phenyl salicylate 0.20 mole. 11 mins. + 11 - 7 + 8 - 11 + 17 Molecular weight = 217-229, mean 223 ; C,H,07N, requires 239. 7, 0.21 ,, 48 ,, - 3 0 - 6 +5 -14308 EARGER: A MICROSCOPICAL METHOD OF Bend, 42.00 grams per litre.Phenyl salicylate 0.20 mole. 22 mins. + 54 - 76 + 93 - 71 + 75 7, 0.21 ,, 15 ,, - 8 +71 - 6 7 +SS - 4 7 Molecular weight = 200-210, mean 205 ; C,,H,,O, requires 210. Phenol, 18.8 grams per litre. Phenyl salicylate 0.17 mole. 40 mins. + 6 0 + 6 - 2 + 6 Molecular weight = 103-111, mean 107 ; C,H,O requires 94. 9 , 0.18 ,, 30 ,, - 8 +24 -32 +29 - 1 4 With Salicylic Acid as Standard. Phenol, 18% grams per litre. Salicylic acid 0.16 mole. 20 mins. + 48 - 12 + 3 - 2 + 1 L Molecular weight = 111-119, mean 115 ; C,H,O requires 94. ,9 0.17 9 , 20 9 , -21 +75 -48 +27 - 2 1 The two values for phenol are a good deal too high. This is because the vapour pressure of phenol is not, negligible at the ordinary temperature. To further illustrate this point, I made some determina- tions with aniline as standard.Although two substances having approximately the same boiling point need not have nearly the same vapour pressure at the ordinary temperature, yet the boiling point gives a general indication as to the volatility of the substance. With Aniline as Standard. Phenol, 18.8 grams per litre. Aniline 0.19 mole. 80 mins. +22 - 3 + 16 - 19 0 97 0.20 9 , 120 9 1 - 4 +14 + 1 +5 - 1 4 Molecular weight = 94-99, mean 97 ; C,H,O requires 94. Nitrobenzene, 24.6 grams per litre. Aniline 0.19 mole. 25 mins. + 2 - 5 +16 -15 + 2 9 , 0.20 ,9 25 9, - 1 3 +1 - 1 3 +17 -21 Molecular weight = 11 7-1 23, mean 120 ; C,H,O,N requires 123.DETERMINING MOLECULAR WEIGHTS.309 Ethyl Benxoate, 30.00 grams per litre. Aniline 0.19 mole, 50 mins. +30 - 2 + 7 - 11 + 10 9 ) 0.20 ,, 20 ,? - 5 0 - 5 + 2 -5 Molecular weight = 143-150, mean 146 ; C,H,,O, requires 150. The last three determinations give good results. The boiling points of phenol, nitrobenzene, and ethyl benzoate are close to that of aniline. With the same standard, the molecular weight of a con- siderably less volatile substance is found to be too low. PhenyE Scclicylate, 38.52 grams per litre (0.18 mole.). Aniline 0.21 mole. 60 mins. 0 -30 +70 -92 +175 9 9 0.22 3) - - 6 + 1 2 - 7 + 2 -11 Molecular weight = 175 -182, mean 178 ; C,,H,,O, reqiiires 214. In the same way: the molecular weights of salicylic acid and of catechol are found to be more than 10 per cent.too low when these substances are compared with aniline. Conversely, for camphor and phenetole, which are more volatile, values are found which are a good deal too high. As a last example of a determination in acetone solution, 1 give that of a new substance kindly given me by Dr. Ruhemann (Trans., 1903, 84, 1133). L>imethoxybis~tocouma~an. Owing to the small quantity available (0.04 gram) the process was slightly modified. The strength of the solution of the substance was determined after it had been rendered isotonic with a solution OF benzil. 1.0415 grams of the solution left a residue of 0.0315 gram of the substance. The density of the acetone was 0.794; hence the volume of this solution was 1.312 C.C. and the solution contained 24.01 grams per litre. With benzil, 0.0775 mole.23 mins. + 9 - 7 4- 31 - 19 + 19 The following readings were obtained : 9 ) o'080 9 ) 30 9 ) 0 + 4 0 + 4 - 3 ,, 0-0825 ,, i 3 ,, - 4 +13 - 3 + 7 - 8 The solution of the new substance was therefore between 0.0775 and 0.080 mole. Taking 0.0775 as the value, we get M = - 24*01 = 309. C,,H,,O, requires 326. 0-0775310 BARGER : A MICROSCOPICAL METHOD OF A c e t i c A c i d . Glacial acetic acid was used, with b e n d as standard substlance. Acetanilide, 18.90 grams per litre (0.14 mole.), Benzil 0.135 mole. 23 hours +45 -68 +95 - 105 +160 9 , 0.145 1 ) 23 9 , -10 +36 -20 +12 -89 Molecular weight = 130 -1 38, mean 134 ; C,H,ON requires 135. Z’riphemylmethane, 34.16 grams per litre (0.14 mole.). Benzil 0.135 mole. 45 hours 0 - 9 + 2 -3 +5 9 9 0.145 19 21 ,? -58 +30 -30 +29 -31 Molecular weight = 236-253, mean 245 ; C,,H,, requires 244.Picric Acid, 27.48 grams per litre (0.12 mole.). Benzil 0.115 mole. 19 hours + l o - 4 +23 - 6 + 7 9 , 0.12 9 , 19 5, -16 +21 -31 +37 -10 Molecular weight = 229-239, mean 234 ; C,H,07N, requires 229. Diphenyl, 21.56 grams per litre (0.14 mole.). Benzil 0.10 mole. 17 hours + LO - 4 +23 - 6 +7 9 , 0.11 19 21 9 , -16 +21 -31 +37 -10 Molecular weight = 196-216, mean 206 ; C,,H,, requires 154. The last of these determinations was repeated, but the same high value was found, this inaccuracy differing markedly from the exact results obtained in the three preceding examples. namely, 80 per cent. acetic acid, 20 per cent. water : The following is an example of a determination in a mixed solvent Acetanilide, 29.83 grams per litre.Urea 0.20 mole. 17 hours + 6 + I +12 - 3 +5 Molecular weight = 143-147, mean 145 ; C,H,ON requires 135. 99 0.208 ?, 17 5, - 4 +24 - 6 +8 -1 Remxene. In all the experiments except the last, azobenzene was used as standard substance ; in this case, it was benzil.DETERMINING MOLECULAR WEIGHTS. 31 1 Bend, 42.00 grams per litre (0.20 mole.). Azobenzene 0.19 mole. 4 hours + 4 - 9 - 2 - 6 +7 Molecular weight = 200- 221 ; C,,H,,O, requires 210. f , 0.21 ,, 30mins. -13 +5 - 8 + I 1 - 3 Diphenyl, 30.80 grams per litre (0.20 mole.). Azobenzene 0.19 mole. 100 mins. + 7 - 2 +5 + 3 + 10 ?, 0.20 ,, 18 hours -32 +I1 -20 - 2 -13 Molecular weight = 154-162, mean 15s ; C,,H,, requires 154. TripAenyEmethane, 48.80 grams per litre (0.20 mole.).Azobenzene 0.20 mole. 30 mins. +4 - 10 0 0 + 3 9 , 0.215 ,, 3 hours - 2 + 9 -8 + 4 - 2 Molecular weight = 227-244, mean 235 ; C,,H,, requires 244. Diphenylamine, 33.80 grams per litre (0.20 mole.). Azobenzene 0.19 mole. 100 mins. + 3 0 +4 + 1 + 4 (With 0.20 mole., no definite result could be obtained.) Molecular weight = 161-177 ; C,,H,,N requires 169. 2s 0.21 ), 100 ,, -1 + 6 -4 + 3 0 a-Nitronaphthulene, 34.60 grams per litre (0.20 mole.). Azobenzene 0.18 mole. 75 mins. + 9 - 7 +1 - 3 +1 (With 0.19 mole., no definite result could be obtained.) Molecular weight = 173-192, mean 183 ; C,,H70,N requires 173. 9 , 0.20 ,, 5 hours -10 - 2 -13 +8 -12 m-Dinitrobenxene, 32-26 grams per litre (0.1 92 mole.). Azobenzene 0.18 mole. 75 mins. + 7 0 - 2 - 4 + 6 Molecular weight = 170-179, mean 175 ; C,H,O,N, requires 168.?t 0.19 ,, 2 hours + 1 0 -21 + 3 - 4 Ethyl Benzoate, 30.00 grams per litre (0.20 mole.). Azobenzene 0.18 mole. 70 mins. + 16 0 +5 - 2 + 7 J 9 0.19 ,? 5 hours 0 +25 - 3 +31 - 5 Molecular weight = 158-167, mean 162 ; CgH,,O, requires 150. accordingly gives a higher molecular weight. Ethyl benzoate is slightly volatile; phenetole is still more so, and31 2 BARGER : A MICROSCOPICAL METHOD OF Phenetole, 23.42 grams per litre (0*192 mole.). Azobenzene 0.16mole. 40 mins. 4 1 2 -1 + 5 + l + 1 2 9 , 0.17 ,, 150 ,, - 9 +16 -1 +40 -14 Molecular weight = 138-146, mean 142 ; C,H,,O requires 122. Triphenylguanidine, 28.70 grams per litre (0.1 0 mole.). Azobenzene 0.09 mole. 65 mins. +53 - 2 + 8 - 8 + l ? 9 0.10 ,, 130 ,, - 7 + 9 -1 + 6 - 3 Molecular weight = 287-319, mean 303 ; Cl,H17N, requires 287.The following acids show association in benzene solution : Benzoic Acid, 24.40 grams per litre (0.20 mole.). Azobenzene 0.10 mole. 85 mins. + 6 - 3 + 3 -1 + 2 ? 9 0-11 ,, 70 ,, 0 + 6 -4 +1 0 Molecular weight = 222-244, mean 233 ; C7H,0, requires 122. Cirmamic Acid, 29.60 grams per litre (0.20 mole.). Azobenzene 0.17 mole. 45 mins. -31 +27 -22 +20 - 2 7 The change in the drops is a large one in a small time. The molecular weight is considerably above 174 ; C,H,O, requires 148. Axobenxene, 20.02 grams per litre (0.11 mole.). Benzil 0.10 mole. 4 hours +12 -44 +18 + S +17 99 0.12 9 , 4 9 ) -15 +13 + 2 +22 -1 Molecular weight of azobenzene = 167-200 ; C,,H,,N, requires 182. C h l o r o f o r m .With chloroform, there was often some difficulty in sealing the tubes; the glass was attacked, and did not fall together very easily. Hence paraffin wax was always used to close the capillaries. Phenyl Salicykate m Standwd. Bend, 42.00 grams per litre (0.20 mole.). Phenyl salicylate 0.19 mole. 2 hours + 16 - 19 + 30 - 23 + 52 Molecular weight = 200-220 ; C7HIo0, requires 210. 9 9 0.21 ,, 2 ,, -11 + 4 - 8 +4 - 2DETERMINING MOLECULAR WEIGHTS. 313 m-Dinitrobensene, 33.60 grams per litre (0.20 mole.). Phenyl salicylate 0.21 mole. 2 hours + 19 - 6 + 3 - 6 Molecular weight = 153-160 ; C,H,0,N2 requires 16s. 7, 0.22 ,) 3 77 - 4 + 3 - 7 +18 Benxi2 as Xtandurd. T'ripAenyZmethar~z, 24.40 grams per litre (0.1 0 mole.). Benzil 0.095 mole. 2 hours +19 - 6 + 3 - 6 9 9 0.105 ), 3 ), - 4 + 3 - 7 +I8 Molecular weight = 232-256 ; ClgH1, requires 244.Diphenyl, 15.40 grams per litre (0.10 mole.). Benzil 0.095 mole, 1 hour +4 - 8 +1 - 6 7 , 0.105 ,) 1 ), - 6 + 2 - 4 + 4 Molecular weight = 146-162 ; C12H1, requires 154. Diphenyllamine, 16-90 grams per litre (0.10 mole,). Benzil 0-09 mole. 10 mins. + 7 + 1 + 7 3 . 2 ,, 0.095 ,) 2 hours -5 + 3 - 1 + 3 Molecular weight = 178-188 ; C,,H,,N requires 169. m-Dinitrobensene, 16.80 grams per litre (0.10 mole.). Benzil 0.09 mole. 2 hours +31 - 2 2 +I6 0 9 , 0.095 ,) 3 ,) - 2 +14 - 3 +11 Molecular weight = 177-187 ; C6H404N, requires 168. Phenyl Salicylate, 21.40 grams per litre (0.10 mole.). Benzil 0.09 mole. 40 mins. + 3 - 2 + 6 - 3 7, 0.095 ,, 2 hours - 8 + 5 - 1 + 6 Molecular weight = 225-238 ; Cl,HloO, requires 214.a-Nityonaphthalene, 17.30 grams per litre (0.10 mole.). Benzil 0.09 mole. 90 mins. + 15 - 1 +3 0 ) I 0.10 ), - - 1 2 + 9 - 5 + 6 8 , 0.095 ,, (gave no distinct result) Molecular weight = 173-192 ; Cl,H70,N requires 173. + 14 - 21 + 14 - 21 + 2 -1 + 7 - 3 + 37 - 1 f 8 - 5 + 6 -7314 BARGER: A MICROSCOPICAL METHOD OF Cafleins (anhydrous, dried at llO"), 19.4 grams per litre (0.10 mole.). B e n d 0.10 mole. 3 hours +10 - 9 +4 - 6 +10 Molecular weight = 185-194 ; C8H100,N4 requires 194. 3 , 0.105 ,, 1 hour - S + 4 - 2 + 6 - 7 Cafeine (with water of crystallisation), 21.2 grams per litre (0.10 mole.). Benzil 0.105 mole. 2 hours + 6 - 4 +2S -12 +28 Molecular weigbt = 193-202 ; C8H,,0,N4,H,0 requires 21 2, 73 0.11 9 9 2 9 ) - 3 +4 - 1 + 2 - 1 Cocaine (crystalline, dried at 11O0), 30.3 grams per litre (0*10 mole.).Benzil 0.105 mole. 50 mins. + 2 -22 +13 - 17 +17 y, 0.11 9, - - 6 + 9 - - 6 + 5 - 1 0 Molecular weight = 275-289 ; C17H,,0,N requires 303. Pipekine (air-dried crystals), 28.5 grams per litre (0.10 mole.). B e n d 0.105 mole. 45 mins. + 14 - S + 16 - 2 + 2 1 ) 0*11 ) 9 loo J 9 - 2 +10 - 5 +4 - 4 Molecular weight = 259 -27 1 ; C17Hl,0,N requires 285. Quinine (precipitated, dried at 120°), 32.4 grams per litre (0.10 mole.). 7, 0495 9 9 2 hours -24 +27 -SO +30 -22 Benzil 0.09 mole. 50 mins. +5 - 3 + 6 - 5 +20 Molecular weight = 341-360 ; C,oH,,O,N, requires 324. Phen ylbenxp Zmethylethy laiiznzonizcna Iodide. For a specimen of this salt, I am indebted to Mi. H. 0. Jones (Trans., 1903, 83, 1419).Two determinations were made. I. Ib-iphenylmethane as Standurd. 0,0487 gram of the iodide was dissolved in 2 C.C. of chloroform, Afterwards 2.358 grams of the solution left 0.0370 gram of salt, This gives a concentration of 37 1'502 = 23.6 grams per litre. Mean concentration = 23.9 grams per litre. this being equivalent to 24.35 grams per litre. dried at 70". Density of chloroform = 1.502. 2.358DETERMINING MOLECULAR WEIGHTS. 315 Triphenylmethane 0.07 mole, 30 mins. f 22 - 11 + 20 - 22 + 42 ,, 0.075 ), 70 ,, +4 + 4 + 2 +5 + 9 9 , 0.08 ,, 30 ,, - 5 +4 - 3 + 3 - 3 23.9 0.075 Taking the concentration to be 0.075 mole. : M = - = 319. II. Axobenxene as Standard. 0.2008 gram of salt in S C.C. - 25.1 grams per litre. Azobenzene 0.07 mole.35 mins. +15 - 10 +4 0 + 3 9 , 0.075 7, 23 ,9 - 3 + 2 - 1 0 - 5 Mean = 0.725 mole. 25-1 0-0725 M = - = 346 ; C,,H,,NI requires 353. a-Phenylbe~~~lmethy~aZZ~Zanzmoni~m Iodide.-This salt, for a sample of which I am indebted to Mr. H. 0. Jones, is of special interest because Wedekind, its discoverer, has recently found that by the ebullioscopic method its molecular weight is one-third of the normal value (Zeit. physikal. Chem., 1903, 46, 235). Tripheny Emethane as Standard. 0.2771 gram of salt in 4-70 C.C. =59-0 grams per litre (0.162 mole. theoretically). Triphenylmethane 0.17 mole. - -16 +13 - S + 9 - 6 ,? 0.15 ,, 70 min. -1 + 9 - 3 + 3 - 4 This was within a few hours of making up the iodide solution. The Next molecular weight of the salt is greater than the normal value.morning, the determination was continued : Triphenylmethane 0.15 mole. 20 mins. + 6 - 1 + 3 - 2 + 5 7 9 0.17 ,, 15 ?, - 1 +4 -1 +5 - 5 99 0.155 ,, 1 hour + l o - 4 + 3 -5 +15 Taking the numbers 0.155 and 0.1 7 (intermediate concentrations giving uncertain results), i t was found that the values for the molecular weight ranged between 335 and 381 (mean 358); CI7H,,NI re- quires 365. 0.5450 gram of salt in 7.60 C.C. of chloroform 171.71 grams per litre (0.196 mole.). A second determination was made.316 BARGER: A MICROSCOPICAL METHOD OF Within 2 hours of making up this solution : Triphenylmethane 0.150 mole. - + 8 -2 +14 -28 +26 ?? 0.165 ,, 35 mins. - 23 + 20 - 23 + 9 - 12 Molecular weight = 435-478, mean 457. The salt is therefore associated, as in the previous determination.The new solution (71.71 grams per litre) was now directly compared with the old one (59.0 grams per litre), which had been made some days previously. The old solution its standard 7 mins. - 8 + 9 - 5 + 10 - 11 The new solution contains, therefore, less molecules. Two days later this had changed : The old solution as standard 95 mins. + 10 - 5 + 5 - 6 + 34 The molecular weight in the new solution had diminished. The following numbers were obtained : Triphenylmethane 0.21 mole. 7 mins. -8 0 -2 + 7 - 2 Molecular weight between 301 and 341, mean 321. ,> 0.238 ,, 15 ,, +18 -1 + 2 - 1 +21 The effect of heat was next tried. The second iodide solution was divided into two parts, one of which was kept overnight a t the ordinary temperature, the other at 37", both in tightly stoppered bottles in the dark.The determinations were made on the following day, the solution which had not been heated being taken as standard : 30mins. +22 -16 +17 - 9 +15 The molecular concentration of the solution has been, therefore, considerably increased by heating. This explains the fall in the molecular weight observed by Wedekind in employing the ebullio- scopic method. Citybon D i s u Z p h i d e . Triphenylmethane was used as standard. The other substances were used in solutions of 0.20 mole. Axobenxene, 36.4 grams per litre. Standard 0.19 mole. 15 mins. +13 -14 +14 -17 + 6 I 9 0.20 9, 100 ,, -26 -2 -3s + 5 - 2 Molecular weight = 182 - 192, mean 187 ; C,,H,,N, requires 182.DETEHM I NING MOLECULAR WEIGHTS. 317 Dipheriyl, 30.8 grams per litre.Standard 0.20 mole. 35 mins. + 3 + 1 +4 0 + 8 J ) 0.21 ,, 45 ? > - 7 + 3 -12 0 -31 3Tolecular weight = 147-154, mean 150; C,2K,, requires 154. PhenyE Sdicytate, 42.8 grams per litre. Standard 0.18 mole. 50 mins. + 2 - 7 -4 -8 +1 ?, 0.19 ) ) - -15 -11 -19 + 6 - 3 0 3Xolecular weight = 22.5- 238, mean 232 ; C,,H,,O, requires 214. a-Nitronnpkthalene, 34.6 grams per litre. Standard 0.18 mole. --- + 6 - 1 0 +4 4-10 7 7 0.19 ,? 15 mins. -18 - 3 -20 +'i -16 JIolecnlar weight = 172 - 192, mean 182 ; C,,H70,N requires 173. Etl~yl Benzoate, 30.0 grams per litre. Standard 0.19 mole. 25 mins. + 2 - 7 0 - 1 2 + 2 $ 9 0.20 9 9 35 ;, - 1 4 +17 - 6 -1 - 7 Molecular weight = 150-15S, mean 154 ; C,H,,O, requires 150. Phenetole, 24.4 grams per litre.Standard 0.18 mole. 15 mins. + 9 - 3 + 6 -1 + 3 Y9 0.19 , I 35 9 , -16 +1 -1 +17 0 Molecular weight = 128-136, mean 132 ; C8H,,0 requires 122. The behaviour of the last two substances is interesting, since ethyl benzoate is very slightly volatile, and phenetole rather more so. I n benzene, for instance, solutions of 0.20 mole. behave as if they were respectively between 0.18 and 0.19 mole. and between 0.16 and 0.17 mole. Carbon disulphide is much more volatile than benzene, so ethyl benzoate and phenetolo approach more nearly to the theoretical values. As the latter substance is the more volatile of the two, it gives a greater difference from the theory than the former. Benxoic Acid, 24.4 grams per litre. Standard 0.10 mole. 30 mins. +45 -77 +60 -40 + 3 7 >? 0.11 ? ? - -8 + 9 -4 + a 0 Molecular weight = 222-244, mean 233 ; C7H,0, requires 122.VOL. LXXXV. Y318 BAHQEH : A MICROSCOPICAL METHOD OF PjLunoZ, 18-4 grams per litre. Standard 0.10 mole. - + 5 $1 + 5 ;1 + 4 ,, 0.11 ,, 12 mins. . - 1 + 5 - 1 + 1 - 2 Molecular weight = 167-184, mean 180 ; C,H,O requires 94. It will be seen that, while ethyl benzoate and phenetole give normal values, the substances with which they are closely connected, namely, benzoic acid and phenol, have almost double the normal molecular weight. This association was to be expected in a non- hydroxylic solvent like carbon disulphide. When the hydrogen of the hydroxyl is replaced by ethyl, t h e association disappears. Sulphur. disulphidc gave the following numbers : The determination of the molecular weight of sulphur in carbon Triphenylmethane, 0.14 mole.14 mins. + 4 - 8 + 6 - 20 + 5 9 9 0.15 ,, 35 ,, - 1 +18 (3 + 5 - 2 After these results had been obtained, the strengths of the standard solutions were checked. Of the solution called 0.15 mole., 5 C.C. left on evaporation 0.2030 gram of triphenylmethxne. I t s concentration had, therefore, changed during the determination to 0.166 mole., and t h e other solution, obtained from it by dilution, mas in reality 0.155 mole. The mean =0*160 mole. may be taken to represent the strzngth of the sulphur solution. Of this, 1-10 C.C. left on evaporation 09738 gram of sulphur, t h a t is, 43.4 grams per litre. 1.00 C.C. left on evaporation 0*0132 grams of sulphur, that is, 43.2 grams per litre. Mean, 43.3 grams per litre.Molecular weight of sulphur = 270 = 8, - S,. This is i n close agreement with t h e value previously obtained by E. Beckmann (Zeit. physikal. Chem., 1890, 5, 8) who finds as a n average S, - 266. L i g h t Petrolszcm. 0.160 gram-molecules = 43.3. A fraction boiling between 60' and 60' was obtained from ordinary light petroleum by distilling once with a Young's still-head. All the substances were tried at a concentration of 0.10 mole., on account of the sparing solubility of certain of them, Azobenzene was used as standard in all cases.DETERMINING MOLECULAR WEIGHTS. 319 Triphenylmethane, 24.4 grams per litre. Azobenzene 0.10 mole. 40 mins. +5 -- 1 +1 - 6 + 3 3, 0.10s ,, 35 ,, +1 + 9 + I + I 1 - 6 Molecular weight = 226-244, mean 3.35 ; C,,H,, requires 244.Diphenyl, 15.4 grams per litre. Azobenzene 0.09 mole. 14 mins. + 8 + 1 +4 0 + 5 9 9 0.10 ,, 150 ,, -10 +14 --21 +30 + 3 Molecular weight = 154-169, mean 162 ; Cl2Hl0 requires 154. Diphentjlamiize, 16.9 grams per litre. hzuberixerie 0.01, mole. 100 mins. + fz - 15 +5g - 29 +36 ,9 0.10 ), 40 ,, - 1 + 7 - 8 +26 + 6 Molecular weight = 169-186, mean 178 ; C,,H,,N requires 169. Phenyl Salicylate, 21.4 grams per litre. Azobenzene 0 10 mole. 40 mins. + 5 - 1 -I- 1 - 6 + 3 7, + 1 3-10 4-4 +10 0 0.108 ;, - Molecular weight = 198-214, mean 206 ; Cl,HloO, requires 214. The above non-volatile substances give quite satisfactory values for their molecular weight, but this is not tho case with the following substances, the vapour pressure of which at the ordinary temperature is not negligible.Ca?iaphos., 15.2 grams: per litre. Azobenzene 0.07 mole. 15 mins. + 6 - 14 + 7 - 10 + b $ 9 0.0s ,, 85 ,, -11 +31 -18 + 3 7 - 6 Molecular weight = 190-217, meail 203 ; C,,Hl60 requires 152. Naphthalene, 12.8 grams per litre. Azobenzene 0.07 mole. 15 mins. + 6 - 1 + 9 -4 + 2 9 9 0.08 ,, 130 ,, -11 +48 -59 +47 - 3 Molecular weight = 160-183, mean 171 ; C,,H, requires 128. Phenetole, 12.2 grams per litre. Azobenzene 0.07mole. 15 mins. + 3 - 5 +1 0 0 > Y 0.08 ,, 85 ,, - 9 +58 -4-7 +30 - 1 3 i\dolecular weight = 152-174, uiean 163 ; C,H,,O requires 122. Y 2320 BARGE13 : A MICROSCOPICAL METHOD OF Ethyl Benzoate, 15.0 grams per litre. Azobenzene 0.08 mole, 85 mins. + 29 0 +20 0 + 3 0 0.09 f ) - -1 + l o - 4 + 2 0 -2 Molecular weight = 167-187, mean 177 ; C,H,,O, recluires 150. 7 9 As might have been expected, ethyl benzoate gives a result most nearly approaching to the real value, because it is the least volatile of this series. As petroleum is a non-hydroxylic solvent, phenols, acids, &c., are associated in it, and give high values for their molecular weights.This is shown by the following examples : Z'hymol, 15.0 grams per litre. Azobenzene 0.07 mole. 30 mins. +4 - 6 +1 - 10 - 3 99 0.08 ,, 35 ), - 1 + 1 2 - 1 3 +30 - 1 b ; Molecular weight = 188-214, mean 201 ; Cl,H1,O requires 150. Triclilorophenol, 19 5' grams per litre. Acobenzene 0.0'7 mole. 35 mins. +15 + 2 +25 + 3 +20 73 0.08 ,, 35 ,, - 1 +$) - 3 + 2 j - 3 Molecular weight = 246-281, mean 263 ; G6H3OC1, requires 197. P y r i d i r t e .The pyridine, which was a commercial specimen containing a little water, boiled at 115-118'. Benzil and azobenzene were used as standard substances. Of the other substances, eolutions of 0.20 mole. were prepared. Diphenylantine, 33.8 grams per litre. Benzil 0.19 mole. 90 mins. + 4 0 +1 0 tl ,, 0.20 ,, 5 hours - i + $ 1 - 1 + I - 3 Xolecular weight = 169-178 ; mean 174 ; C,,H,,N requires 169. Cinnaniic Acid, 29.6 grams per litre. Benzil 0.19 mole. 17 hours +2(3 -28 + 2 6 -10 +31 ,, 0020 ,, 95 mins. - I i - 2 - 11 -1-20 -8 Molecular weight = 148- 166, mean 152 ; C,H,O, reqcires 148.D ETEliM LNING MOLECULAR WEIGHTS 331 Salicylic Acid, 27.6 grams per litre. Benzil 0.19 mole. 7 hours + S - 1 +4 - 20 +30 9 , 0.21 Y , 7 9 ) - 3 +8 + 1 + 5 + 1 Molecular weight = 131-145, mean 138 ; C,H,O, requires 138.Triphenylmethane, 48.8 grams per litre. Benzil 0.18 mole. 20 hours +28 - 13 + 1 2 - 6 +22 99 0.19 ) ? 2 3 , -10 + S S - 2 6 + 3 4 -25 hlolecular weight = 257-271, mean 264 ; C,,H,, requires 244. Axobe~zzene, 36.4 grams per litre. Benzil 0.18 mole. 30 hours +16 -21 +10 - 19 +15 > ? 0.19 99 16 1, - 2 0 +38 --127 -1-130 - 1 3 Molecular weight = 192-202, mean 197 ; C,,HloN, requires 182. Acetanilide, 2700 grams per litre. B e n d 0.18 mole. 5 hours + 3 - 7 + B -5 + 3 7 ) 0.19 99 16 ) ? -21 + 9 - 9 +17 0 Molecular weight = 142-150, mean 146 ; C,H,ON requires 155. a-*;i'troiz~~)htiia~e7~e, 34.6 grams per litre. Benzil 0.18 mole. 5 hours + Y - 6 + 2 - 9 + 7 ?, 0.19 9 9 2 3 9 - 3 + 2 -8 + 5 -4 Molecular weight = 182-19.3, mean 187 ; C,,H70,N requires 173.a-h-aplhthol, 28.8 grams per litre. B e n d 0.21 mole. 22 houra. + IG -28 +39 -22 + 17 9 9 0.22 ?, 5 ? 7 -4 +8 -4 +5 0 Molecular weight = 131-136, mean 131 ; Cl0H,O requires 144. Judging from the comparatively small errors in the values for cinnarnic and salicylic acids and for a-naphthol, the association in pyridine does not seem very marked, which is in accordance with the results obtained by Ross Innes (Ti*anF., 1901,79, 261). Abnormal results were obtained for the following : n~-dinitrobenzene, phenyl salicylate, diphenyl (more than 10 per cent, too high), picric acid, succinic acid, thiocarbanilide (more than 10 per cent. too low). With azobenzene as standard, the error for nt-dinitrobenzsae and for diphenyl was 6-10 per cent.322 RARCER: A MICROSCOPICAL METHOD OF Ether.The ether was previously saturated with water to avoid the effect of atmospheric moisture. The tubes were sealed with paraffin wax. D i p h q l , 30.8 gram per iitre (0.20 mole.). Benzil 0.18 mole. 4 mins. + 8 - 3 +1 - 2 0 Y, 0.22 9 9 5 9 9 0 +5 + 1 4-13 - 3 Molecular weight of diphenyl = 140-171 ; CI2H,, requires 154. Quinol, 22.0 grams per litre (0.20 mole.). Benzil 0.18 mole. 4 mins. + 5 - 3 + 2 - 3 +36 Y ¶ 0.22 ,, 4 9 9 -10 + l - 3 +5 -4 Molecular weight of quinol = 100-1 22 ; C,H,O, requires 110. X y l s n e . Triphemyhethane, 51.24 grams per litre (0.21 mole.). Benzil 0.17 mole. 55 mins. +15 - 6 +1 - 3 +1 ,, 0-223 ,, - -34 +12 - 9 +10 -4 Molecular weight of triphenylmethane = 230-301, mem, 265 ; C19H16 requires 244.A s s o c i a t i o n i n Mixtuyes of a n A s s o c i a t i v e a n d u N o n - ch s s o c i a t i v e. S o I z e n t. As the microscopic method is particularly suited for work with mixed solvents, it seems desirable to study with its help the problems of association. The results of some preliminary experiments are here communicated, and although no special attention was paid to accuracy, the values show the general nature of the association in mixtures. The object in view was to determine the molecular weight of acids, phenols, kc., in mixtures of varying composition of two solvents, the boiling points of which are not very remote, and in one of which the substance has a normal molecular weight, whereas it is associated in the other. Such pairs of solvents are: ether and carbon disulphide, methyl alcohol and chloroform, ethyl alcohol and benzene, &c. Determinations were carried out with the second and third pairs. using cinnamic and benzoic acids 1 espectively as solutes. I n both cases, the concentrationDETERMINING MOL ECULA K WEIGHTS. 323 was 0.20 mole., the standard substance was benzil, and the tempera- ture mas 16'. Mixtures were made containing the two solvents in known propor- tion by volume, and with each mixture the cinnamic (or benzoic) acid solution was prepared, together with the necessary benzil solutions. Benzoic acid in crystallisable benzene and absolute ethyl alcohol ; 24.4 grams per litre. 50 per cent. benzil 0.204 mole. 5 minc. + 4 - 2 + 1 - 1 + 7 1 - 8 -1 - 5 + 3 - 4 1 '75pcrcent. ., 0.19 ., : ! l 1 o u i s + 5 - 1 1 + 6 - 8 +1\ benzene { ,, 0-312 ,, 30 ., benzene { ,, 0.195 ., 1 .) - 2 + R - 2 + 3 - 9 i 57.5percent.J ,, 0 19 ), - + l S -1 + 9 + 2 4-81 benzene ), 0.202 ,, 4 ,, -39 +41 - Z + 9 - 3 1 9 2 p r r c e n t . ,, 0.175 ,, 1 ., + 8 -18 + 3 -14 4-S) benzene { ., 0.185 ,, 18 ,, - 2 3 4 3 1 -11 I-53 -30) 95 per cent. J ,. 0.16 ), 3 , 7 +1 - 5 0 - 3 + l \ benzene I 7 , 0.1s ,, 1 ,, +I + 3 - 1 +4 - 5 1 95 per cent. I ,. 0.1:; ,, _- f 9 f S + 7 f 4 f l l benzene I ., O - l i ,, - + 3 + 1 0 - 5 + - l . i -5) 1 0 0 p e r c e n t . J ,) 0.095 ,, 1 ,, + 2 -1 +-g +; +:) beiizeiie I ,, 0'112 ,, 2 ,, - 1 - - P mean = 0'208 31. m. -117 menn=0*192 31. w. =I27 mean=0'196 91. 7V. =124 mean = 0'18 AT. W. =136 mean = 0.17 hI. w. =141 mean = 0.135 M. W . = l S l mean = 0.102 AT. w. =237 -4rnong the results given in an earlier section of this paper there Pcrmnlnge of benzene or chloroform. will be found for the molecular weight of benzoic acid in pure benzene 233, and in alcohol 122, both i n concentrations of 0.20 mole,324 METHOD OF DETERMINING MOLECULAR WELUHTS. TI. Cinnamic acid ; 29 -6 grams per litre ; methyl alcohol and chloroform not specially purified. SO per cent. chloroform { ), 0.20 ,, 12 ), 90 percent. j ., 0'175 ,, 40 ,, chloroform ( ,) 0.185 ) ) 55 ,, chloroform { :: :':: 90 ), 100 per cent./ ,) 0.119 ,, 1 hour chloroform ,, 0.125 ,, 15 mins. bcnzilO*lQ mole. 50 mills. 94 per cent. 9 , 8 3 9 - 7 +I - 3 +1 - 2 + 5 4-1 - 3 + 1 2 - 3 4-2 - 2 + 3 - 2 + 4 - 5 +13 0 +20 +3] 1-7 + I + 5 -4 + 6 1 -10 Sr; - 1 3 + 9 - 2 5 J mean = 0-195 31. W. =1,52 inem = 0'18 If. W. =161 mwn=0'155 mean = 0.122 If. TIT. =245 nr. TV. 191 The molecular weight of cinizamic acid in 100 per cent. methyl alcohol has not been determined, but in ethyl alcohol i t was found t o be 148. The values for benzoic acid may be slightly vitiated by its relatively considerable vapour pressure at the ordinary temperature. With the molecular weights as ordinates and t.he percentage of benzene or chloro- form as abscissae, two curves have been plotted which clearly show that a small proportion of alcohol is sufficient t o do away with the associa- tion. Should this observation prove to be general, it may be of con- siderable practical importance in those cases where one.is restricted to associative solvents because the substance is not sufficiently soluhle in the others. A small percentage of a non-associative solvent would not materially affect the solubility, yet i t mould reduce the molecular weight to its normal value. THE WELLCOME PHYSIOLOGICAL R,ESEAP.CII LABORATORIEB, HERNE HILL, S.E.

ISSN:0368-1645    

DOI:10.1039/CT9048500286

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

STUDIES IN THE CAMPHANE SERIES. PART XIII. 325 XXXVL-Studies in the Camphane Series. Part X I I I . Action of Niti*ogen Peroxide on 1 - Nitmcamphene By MARTIN ONSLOW FORSTER and FRANCES MARY GORE MICKLETHWAIT. IN connection with the study of isonitrosocamphor, it seemed probable t h a t a n examination of structural isomerides would furnish useful information, and we have therefore attempted to prepare a substance of this class from 1-nitrocamphene, the compound obtained by the action of silver nitrate on 1-bromo-1-nitrocamphane dissolved in alcohol (Forster, Trans., 1901, 79, 644). The behaviour of 1-hydroxycamphene toward:, bromine, which converts it into P-bromocamphor (Trans., 1902, 81, 264), renders it probable that the constitution of 1-nitrocamphene is expressed by the formula CH,.YH-CK, UH-C(CH,) C*NO, I ;PHJzl , I I and the fact that this compound readily yields additive derivatives with bromine, hydrogen bromide, and hydrogen iodide led us to hope that nitrogen peroxide would give rise t o tue nitrosate, from which on hydrolysis, followed by elimination of nitrous acid, an isonitrosocamphor having the constitution CH2*YH-CH2 1 yCHJ21 H ON : c' -C(C H 3) CO should be formed. On submitting 1 -nitrocamphene to the action of nitrogen peroxide, we obtained a compound having the composition C10H1506NS, and therefore containing the elements of N,O, in addition to thoEe of the original material. The substance, however, although empirically the nitrosate of 1-nitrocamphene, is not a genuine member of this class, because alcoholic ammonia and piperidine, instead of transforming it into a nitrolamine and a piperidide respectively, convert it into a substance, Cl0HI4O4N2, identical with the product arising from the limited action of alcoholic potash.Moreover, the high melting point VOL. LXXXV. Z326 PORSTER AND MICELETHWAIT : and sparing solubility of this nitrosate suggest a bimolecular character, but we have no evidence that it belongs to the class of dioxime peroxides. Furthermore, the treatment to which it has been subjected has failed to provide us with the structural isomeride of isonitrosocamphor . Circumst,ances having compelled us to interrupt the investigation, and costliness in time and material prezluding the likelihood of its being resumed, me confine ourselves to recording the changes which have been observed, without speculating on the constitution of the substances obtained.Action of Nitrogern Pwoxide on 1 -iVitvocarnphene. The nitrocamphene required for the investigation was prepared by the method alraady described (Trans., 1901,79,646), and on repeating this process 20 or 30 times it was found that when alcoholic silver nitrate acts on 1-bromo-1-nitrocamphane, a certain amount of the silver salt leaves the solution in combination with nitrocamphene. After evaporating off the grester portion of the alcoholic filtrate from the silver bromide, the liquid yielded colourless crystals when left for several hours, This product, when suspended i n boiling water, gave a solution of silver nitrate from which highly purified nitro- camphene was obtained by distillation in steam.The circumstances controlling the formation of the substance, however, could not be determined; it was isolated on several occasions, but in more frequent cases the crystalline deposit consisted of the compound of silver nitrate with silver bromide. The nitrogen peroxide mas prepared by heating dry lead nitrate, and was passed into solutions containing 10 grams of nitrocamphene in 60 C.C. of chloroform. The liquid gradually became pale brown, and a rise of temperature occurred ; when a considerable amount; of gaa had been absorbed, the colour became greenish-brown, and at 50° lustrous crystals appeared, and increased rapidly. The passage of the gas was then interrupted, and, after an interval of 12 hours, the intensely green, or bluish-green liquid was filtered.The conditions of this experiment have been considerably varied from time to time with the object of improving the yield, but although the operation has been repedted more than 50 times, we have not succeeded in obtaining the nitrosate in quantities exceeding 24 per cent. The crude substance is usually stained with blue, which is retained with some psrsistence. By recrystallisation from boiling alcohol, 100 C.C. of which are required by 1 gram, the substance is obtained in lustrous, snow-white, flattened needles which melt and completely decompose at 21'7''. The greatest difficulty has been experienced inSTUDIES IN THE CAMPHANE SERIES. PART XlII. 327 obtaining concordant results in the combustion of this compound, owing to the readiness with which nitrous gases are eliminated on heating ; whilst the determinations of nitrogen have served to distin- guish between the nitrosate and the nitrosite, we cannot claim t o have established conclusively the empirical formula CloHI,O,N, in preference to C*OH28O12~6.0.2262 gave 0.3670 CO, and 0.1222 H,O. 0.2043 N = 15-69. 0.1803 ,, 23.4 C.C. y y at 18' ,, 782 mm. N=15*58. C,,H,,O,N, requires C = 43.95 ; H = 5.50 ; N = 15.38 per cent. C,oH,,012N6 ,, C = 44.1 1 ; H = 5.01 ; N = 15.44 ,) CloH150,N, ,, C = 46.69 ; H = 5.84 ; N = 16.34 ,? C = 44.25 ; H = 6-05. 0.2003 ,, 0,3280 CO, ,, 0*1070 H,O. C=44*67; H=5*98. ,, 27.4 C.C. nitrogen at 1 7 O and 766 mm. One gram of the nitrosate requires nearly 600 C.C. of cold alcohol to dissolve it, and the compound is very sparingly soluble in all organic media; we have not been able, therefore, to determine its molecular weight, but this behaviour, and a comparison of the temperature at which i t decomposes with the melting points of the derivatives herein described, and of 1 -nitrocamphene ( 5 6 O ) , indicate the bimolecular ex- pression, C20H,o012N6.The substance is insoluble in boiling aqueous potassium hydroxide and in hot concentrated hydrochloric acid ; it dissolves in fused phenol, and develops an intense green coloration when the solution is warmed gently with concentrated sulphuric acid, but the colour disappears on dilution and is not regenerated by alkalis. In fuming nitric acid, it dissolves slowly, without rise of temperature, and is precipitated un- changed on dilution ; concentrated sulphuric acid dissolves it less readily, but on warming gently a clear, deep brown solution is formed, from which gas is slowly evolved.Action of Piperidine on the Nitrosate. Ten grams of the nitrosate were covered with 8 grams of piperidine, when the liquid became hot and the crystals dissolved. Having com- pleted the action by heating for a short time on the water-bath, the viscous product was poured into water, yielding a crystalline solid weighing G grams. On recrystallising the substance twice from hot absolute alcohol, it was obtained in transparent, flattened prisms melt- ing a t 123'. 0.1988 gave 0.385'7 CO, and 0,1136 H,O. 0.2470 C-52.90; H=6*39. 0.1875 ,, 0.3640 CO, ,, 0,1064 H,O. C==52*94 ; H= 6.35. ,, 26.8 C.C.nitrogen at 16" and 756 mm. N= 12-59. C,,Hl,O,N, requires C == 53.10 j H = 6.19 ; N 1= 12.39 per cent. z 2328 FORSTER AND MICKLETHWAIT : These results show that the product is not a piperidide, but is pro- duced by elimination of the elements of nitrous acid from the fore- going substance. It is insoluble in hot dilute sulphuric acid and in a 10 per cent. solution of potassium hydroxide ; it gives no coloration with ferric chloride, is indifferent towards fuming nitric acid, and does not give Liebermann's reaction. Phosphorus pentachloride has no action on it. Boiling petroleum dissolves i t very sparingly, and although only moderately soluble in cold alcohol, it dissolves readily in the heated liquid. A solution containing 0.5920 gram in 25 C.C.of chloroform at 21' gave aD - '7'32' in a 2-dcm. tube, whence [.ID - 159.0". The transformation of the nitrosate into th6 compound C,,H,,O,N, can be effected also by the action of alcoholic ammonia, and, under certain conditions, by alcoholic potash. When the former agent is employed, and heated with the nitrosate under a reflux apparatus, the crystals become completely dissolved in about 15 minutes, and the smell of ammonia is then scarcely perceptible ; on cooling the liquid, an oil separates and rapidly solidifies. If alcoholic potash is used, it is necessary t o limit the quantity of alkali, because the product undergoes further decomposition if an excess is employed. Ten grams of the nitrosate were suspended in 25 C.C. of hot absolute alcohol and treated with 5 grams of potassium hydroxide i n the minimum of water.After five minutes on the water-bath, a clear, yellow solution was produced, from which a crystalline precipi- tate separated on cooling. This was identical with the product obtained by the action of piperidine, and, on evaporating the alcohol from the filtrate, a residue was obtained which dissolved very readily in water; this solution set free iodine from potassium iodide, and yielded a dark green oil when acidified. Evidence of the elimination of nitrous acid was obtained also in using piperidine. The filtrate from the solid substance precipitated by water was neutralised with dilute sulphuric acid, which precipitated a sticky, blue material ; on filtering the liquid, adding alkali, extracting with ether, and evaporating the solvent, an oil was obtained which gave Liebermann's reaction very intensely, and most probably con- sisted of nitrosopiperidine. Complete Hydrolysis of the Nitrosate.Although the compound C,,H,,O,N, is obtainable from the nitro- sate by the action alike of piperidine, alcoholic ammonia, and alcoholic potash, this fact is only true of the last named when the action is restricted, for if excess of the agent is employed the product is a,STUDIES IN THE CAMPHANE SERIES. PART xm. 329 potassium derivative which forms a dark brown solution in water and yields a green oil on acidification. This compound can be separated also as a by-product in the prepara- tion of the nitrosate, for if the chloroform filtrate from that substance is shaken with 10 per cent.potassium hydroxide, the latter becomes brown, and furnishes the green oil on treatment with acid. Owing to the unstable character of the liquid, we have not been able t o determine its composition, but crystalline derivatives have been obtained from it, and are described below. The ethereal solution, when dried with calcium chloride and evaporated, yields a bright green varnish, which turns brown spontaneously and evolves a gas without colour or odour; if a freshly prepared specimen is heated i n boiling water, it decomposes suddenly, emitting clouds of brown fumes with considerable violence, and becoming converted into a charred mass. I f a n attempt is made t o distil the green oil in steam the colour changes to brown, but nothing volatile is produced; the brown pro- duct, unlike the green substance from which it is obtained, is insoluble in sodium carbonate, but dissolves in caustic alkali.It has not been found possible t o obtain crystalline derivatives of the green oil by the action of phenyl isocyanate or of beuzoyl chloride. Concentrated hydrochloric acid does not eliminate hydroxglamine, atid reduction with sodium amalgam has failed to give a definite product ; oxidation with potassium permanganate takes place very readily in the alkaline solution, and appears to decompose the substance completely. Action of Potassiunt Perricyanide on the Green Oil. Twenty grams of the nitrosate were suspended in 150 C.C. of absolute alcohol and heated on the water-bath during two hours with 14 grams of caustic potash dissolved in the minimum quantity of water; the alcohol was then evaporated and the rssidue taken up with water, in which it dissolved cor~~pletely.To this liquid, which was pale brown, 500 C.C. of a 25 per cent. solution of potassium ferri- cyanide were added, when a dark brown colour was developed in the liquid, the temperature of which rose to about 40°, whilst slight effervescence occurred. After an interval of 12 hours, dilute sulphuric acid was added until a greenish-blue coloration was produced ; the viscous, brown oil which separated was removed and washed several times, when it became solid and was purified by reprecipitation from the solution in sodium carbonate, followed by crystallisation of the dried substance (about 14 grams) from light petroleum.The same substance has been obtained from nitrocamphene in the following manner. One hundred grams, after treatment with nitrogen330 FORSTER AND MICKLETHWAIT : peroxide in the manner described, having furnished 24.2 grams of the nitrosate, the chloroform filtrate was extracted with 300 C.C. of 30 per cent. potassium hydroxide solution, which became dark brown. This liquid was treated with 1200 C.C. of a 25 per cent. solution of potassium ferricyanide, and t.he mixture, which had evolved gas and risen in temperature, was acidified with dilute sulphuric acid after an interval of 3 hours; the brown oil quickly hardened and was redis- solved in sodium carbonate, filtered from little insoluble tarry matter, and reprecipitated. The pale brown solid obtained in this manner weighed 51.5 grams.As in the case of the nitrosate, we have encountered difficulties in analysing t h i s substance, which has, we believe, the empirical formula C10Hl405N2. 0.1786 gave 0.3275 CO, and 0.1067 H,O. 0.1954 ,, 19.8 C.C. nitrogen a t 20" and 763 mm. N = 11-63. C = 50.01 ; H = 6-64. C,oH,,05N, requires C = 49.59 ; H = 5-78 ; N = 11.57 per cent. It dissolves readily in organic media excepting light petroleum, 1000 C.C. of a boiling concentrated solution in the latter depositing 4.2 grams in the form of snow-white needles melting at 85-46". It dissolves readily in sodium carbonate forming a pale yellow liquid, and the solution in 2 per cent. sodium hydroxide yields an intense purple-blue precipitate with ferrous sulphate. The alcoholic solution develops with ethereal ferric chloride a red coloration which is not very intense, and on adding copper acetate dissolved in alcohol the deep bluish-green colour of the copper salt changes to grass-green, but no separation of crystals takes place.The compound does not decolorise bromine dissolved in chloroform, but hydrogen bromide is evolved on boiling the solution. The solution in phenol develops a green coloration when warmed with concentrnted sulphuric acid, chauging to a very deep bluish-green ; on dilution, the colour becomes pink and then changes to intense blue on adding alkali. Fuming nitric acid dissolves the substance without any rise of temperature taking place, and phosphorus pentachloride, nitrous acid, potassium permanganate, benzoyl chloride, alcoholic potasb, and boiling acetyl chloride are also without action.The substance is not affected by hot concentrated hydrochloric acid, and after heating it during 2 hours with alcohol and hydro- chloric acid in a sealed tube at looo, it crystallised from the liquid, and the filtrate did not reduce Fehling's solution even when boiled. Dry hydrogen chloride was passed into a solution of the ctimpound in methyl alcohol during 2 hours without producing a trace of a methyl derivative. By dissolving it in excess of standardised sodium hydroxide andSTUDIES IN THE CAMPHANE SERIES. PART XIII. 331 tit,rating with sulphuric acid in presence of phenolphthalein, con- cordant results have been obtained without difficulty. 0.0861 gram dissolved in 10 C.C. of sodium hydroxide solution (con- taining 3.926 grams per litre) required 5.7 C.C.of sulphuric acid (containing 4.92 grams per litre), whence 242 grams reqnire 46.0 grams NaOH. 0.1063 gram dissolved in 12 C.C. of sodium hydroxide solution required 6.7 C.C. of sulphuric acid, whence 342 grams require 46.0 grams NaOH. The ccmmonitim derivative separated when the substance was treated with concentrated ammonia, forming colourless needles which became yellow at about 115' and decompused violently a t 136O; after remaining during 2 days i n the desiccator, the substance did not change colour until heated a t about 140'; it decomposed a t 155'. N= 15.86. 0.2045 gave 27.8 C.C. nitrogen a t 18' and 767 mm. C,,H170,N, requires N = 16.21 per cent, The copFer derivative crystallised in blue needles on adding copper sulphate to the a,mmoniacal solution, becoming olive-green after 2 days in t h e desiccator.Cu = 7.72. (C,,H,,O,N,),Cu,C,,H,,O,N, requires Cu = S-0s per cent, 0 2152 gave 0.0208 CuO. The silver derivative formed a pale yellow, granular precipitate on adding silver nitrate (1 mol.) to a neutral solution of the ammonium derivative. 0.1326 gave 0-0404 Ag. Ag = 30.46. CloH1,0,N2Ag requires Ag = 30.96 per cent. It darkens rapidly on exposure to light, and dissolves in hot water. It will be recognised that the behaviour of the substance Cl,Hl,O,N, is remarkable, because, although its production by the action of potass- ium ferricyanide on an oximino-compound would suggest its classifica- tion as a secondary nitro-derivative, nevertheless, the acidity which characterises it is more pronounced than that of many carboxylic acids ; if i t belonged to t h e latter class, the indifference towards hydrogen chloride of a solution in methyl alcohol would be explained if the group were attached to tertiary carbon.The compound, however, although optically active t o a slight extent only, exhibits definite mutarotation, and we think that this fact, in conjunction with the experiments still t o be described, is evidence in support of the view that it is a secondary nitro-derivative. A solution containing 1,1925 grams in 25 C.C. of chloroform a t 200 was prepared in a darkened room, and transferred to the 2-dcm. tube332 FORSTER AND MICKLETHWAIT : without more than a minute's interval after dissolution ; the reading observed was 21', which fell to 10' while confirmatory observations were being made.In half a n hour, the solution gave aD -39', remaining constant at a, - l08', which was reached on the eleventh day. Thus, the initial and final specific rotatory powers are [a],, + 3.6' and [ - 11.9' respectively. Action of Yotccssiurn IZypobromite.--Ten grams were dissolved in aqueous potassium hydroxide and treated with potassium hypobromite prepared by adding 20 grams of bromine t o a n ice-cold, concentrated solution of caustic potash. A snow-white precipitate was foi.med immediately, and this was filtered, washed, and crystallised from hot alcohol, which deposited 13 grams ; on recrystallisation, i t was obtained in colourless needles melting at 157". 0.3314 gave 0,4543 CO, and 0.1106 H,O.0.2336 ,, 0,1367 AgBr. Br= 24.90. C,,H,,O,N,Br requires C = 37.38 ; H = 4.05 ; Br = 34.92 per cent. A solution containing 1.2415 grams in 25 C.C. of chloroform at 20" gave a, - 6'45' in a 2-dcm. tube, whence [a], - 68.0'. The substance dissolves sparingly in boiling light petroleum, from which it separates in minute needles, and is moderately soluble in benzene, alcohol, ethyl acetate, or glacial acetic acid, cryst,allising from the first named in well-formed, six-sided prisms ; acetone and chloroform dissolve i t freely. The Liobermann reaction is very intense in all its stages. When the bromo-derivative is heated with alcoholic potash, the compound C,,HI,O,N, is regenerated. Action of Hydroxylamine.-Ten grams of the substance were dis- solved in 250 c .~ . of abholute alcohol, and treated first with 20 grams of hydroxylamine hydrochloride aud then with 18.7 grams of potass- ium hydroxide, both dissolved in water; after 2 hours on the water- bath, the liquid was evaporated and filtered from the solid (1.2 grams) which separated on cooling. The filtrate was faintly alkaline and yielded a colourless precipitate (6.1 grams) on acidification. Both products were then crystallised from hot water, which deposited the former in lustrous, orange leaflets melting at 184". C = 37.39 ; H = 3.73. 0.1709 gave 19.4 C.C. nitrogen at 20" and 749 mm. N =I 12-80. C,,H,,O,N, requires N = 12-39 per cent. The substance is moderately soluble in alcohol, from which i t crys- tallises in thin, striated prisms.It dissolves in 2 per cent. sodium hydroxide, but gives no coloration with ferrous sulphate, and does not reduce Fehling's solution, although arnmoniacal silver nitrate is reduced immediately on boiling. The alcoholic solution develops a n intense purple coloration with ethereal ferric chloride, and, whenSTCDIES IN THE CAMPHANE SERIES. PART XIII. 333 treated with copper acetate in alcohol, destroys the colour of the first few drops and quickly yields a sage-green precipitate. It does not give Liebermann's reaction. The second product dissolves more readily in sodium carbonate than t h e foregoing substance, and crystsllises from boiling water in colour- less, transparent pyramids melting at 161°, the solution being acid to litmus. 0.3924 gave 26.4 C.C.nitrogen at 19" and 748 mm. N=7.61. CloHl,O,N requires K = 7.10 per cent. This compound gives no coloration with ethereal ferric chloride, and reduces ammoniacal silver nitrate very slightly on continued boiling. It does not, give Liebermann's reacbion, and gives no characteristic precipitate i n 2 per cent. sodium hydroxide with ferrous sulphate or with potsssium hypobromite. It is practically insoluble in light petroleum, dissolves very sparingly in chloroform and carbon bisulph- ide, and is only moderately soluble in hot alcohol or acetone. It neither decolorises dissolved bromine nor yields hydrogen bromide when warmed with the halogen, but the sodium carbonate solution reduces potassium permanganate freely. Beduction with AYodiunz Amalgam.--By this treatment, the com- pound C,,H1,0,N2 is converted into a deep red substance, and hydr- oxylamine is eliminated. Ten grams were dissolved in 50 C.C.of 10 per cent. sodium hydroxide and shaken with 360 grams of 2 per cent. sodium amalgam, which was added in quantities of 40 grams at intervals of half an hour, the liquid being kept cool and diluted occasionally with a few C.C. of water, With the first addition of amalgam, a turbidity appeared, followed by a pink coloration, which rapidly deepened to a n intense dark red .tint ; meanwhile, an ammoniacal odour became noticeable. When all the reducing agent had been used, a few C.C. of sodium carbonate were added, SO t h a t the product being soluble in both acids and alkalis, the next step, acidification, can be interrupted when effervescence begins.A vermilion preripitdte was thus obtained, and the filtrate reduced cold Fehling's solution immediately. The substance could not be recrystallised, but a specimen repre- cipitahed from a filtered solution in 10 per cent. potassium hydroxide was analysed. 0.1991 gave 15.2 C.C. nitrogen at 17" and 772 mm. N = 9-00, C,,H,,ON requires N = 8.48 per cent. C,,H3,0N, ,, N=S.92 ,, It is insoluble in light petroleum, but dissolves very freely in cold alcohol and in boiling water, forming red solutions which have no33% FORSTER AND MICKLETHWAIT : action on ammoniacal silver nitrate and Fehling's solution respectively. The solution in dilute sulphuric acid has the colour of potassium per- manganate, and the wine-red liquid produced by dissolving the sub- stance in 2 per cent.sodium hydroxide yields a dark brown precipitate with ferrous sulphate. An alcoholic solution gives no distinctive coloration with ethereal ferric chloride, but develops a magnificent purple with potassium hydroxide. Action of Potassium Hypobronzite 00% ihs Green Oil. Ten grams of the nitroeate were suspended in 75 C.C. of absolute alcohol and heated on the water-bath during 2 hours with 7 grams of caustic potash dissolved in the minimum quantity of water; tbe residue obtained on evaporation having been dissolved in ice-cold water, a freshly prepared solution of potassium hypobromite containing 30 grams of bromine was added. A heavy, yellow oil wasprecipitated, hardening immediateIy on treatment with cold water, and weighing 15 grams.This compound has been obtained also by treating with excess of potassium hypobromite the brown alkaline liquid formed on shaking wit,h aqueous potash the green chloroform filtrate from the nitrosate ; 16 grams were thus produced from 25 grams of nitrocamphene. The substance prepared by these methods dissolves in boiling light petroleum, and crystsllises in stellate aggregates of lustrouP, pale brown prisms melting a t 78'. 0.3201 gave 0.3040 CO, and 0.0885 H,O. C = 25.90 ; H = 3 09. 0.4382 ,, 22.6 C.C. nitrogen at 20" and 763 mm. N=5.93. 0.2542 ,, 0.2971 AgBr. Br=49*73. CloH,,O,N,Br, requires-c = 25.05 ; H = 2.30 ; N = 5.84 ; Br = 50.10 per cent. It is readily Foluble in ccld chloroform and ethyl acetate, and less freely in alcohol and acetic acid. A solution containing 1.2882 grams in 25 C.C.of chloroform a t 20' gives aD 26' in a 2-dcm. tube, whence [ + 4.2O. Although i t undergoes reduction in alcoholic solution with zinc dust, aluminium amalgam, and with potassium hydroxide, in no case has a crystalline product been obtained. The tribromo- derivative gives Liebermann's reaction with great intensity in all i t s stages. Met Ay Iccnainocnmpliene, C, oH,,*N H CH,. At one time it seemed possible that the object we had in view might be attained by the use of derivatives of aminocarnphene, and experiments were made with benzoylaminocamphene and methyl-STUDIES IN THE CAMPHANE SERIES. PART XIII. 335 aminocamphene, but without succesq. The latter substance was obtained by the process devised for the preparation of methylbornyl- amine (Trans., 1899, 75, 936) ; this consists in converting the benzyl- idene derivative of the primary base into the methiodide, and heating this with moist ethyl acetate, which hydrolyses it to benzaldehyde and the hydriodide of the methylated base. Six grams of benzylideneaminocamphene (Trans., 1901, 7Q, 650) were heated in a sealed tube with 22 grams of methyl iodide at 100' during 2 hourF, the product being treated with ether and filtered. The yellow crystals weighed 7 grams and had a faint odour of benz- aldehyde. 0.1309 gave 0.0828 AgT. I= 34.19. CloH1,*N:CH.C,H,,CH,I requires I = 33.34 per cent. 0.2188 ,, 0.1418 AgI. 1=34*21. Twenty-eight grams of this material were heated with 200 C.C. of undried ethyl acetate during 1 hour; 21 grams of methylaminocam- phene hydriodide were obtained and recrystallised from hot water. 0.2040 gave 0.1632 AgI. I = 43.23. C,,H,,NI requires I = 43.34 per cent. On decomposing the salt with caustic alkali, methglaminocamphene was obtained as a colourless oil which boils a t 202-203' under 756 mm. pressure, and has sp. gr. 0.91'71 at 22'. A solution contain- ing 0.5447 gram in 25 C.C. of absolute alcohol gave aD 1 O 1 7 ' in a 2-dcm. tube, whence [ aJD + 28.7'. The pkatinichloride melts and decomposes at 2 1 4 O . 0.1322 gave 0.0349 Pt. P t = 26.39. 09893 ,, 0.0763 Pt. Pt=26*37. (Cl,H,,N),,H2PtCI, requires Pt = 26.27 per cent, The salt dissolves readily in alcohol, from which it crysta!lises in minute needles. ROYAL COLLEGE OF SCIENCE, LONDON, SOUTH KENSIFGTOS, S. W.

ISSN:0368-1645    

DOI:10.1039/CT9048500325

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

336 STERN : THE SO-CALLED (( HYDROCELLULOSE.” XXXVII. - The So- ca Ued “ Hychocellulose.” By ARTHUR LANDAUER STERN, D.Sc. IT is well known t h a t all kinds of cellulose, when exposed to the action of certain reagents, lose their tenacity and become friable. This fact has hitherto been explained as being the result of the hydration of the cellulose, leading to the formation of bydrocellulose. All the evidence concerning this change appears to be contained in the work of A. Girard (Compt. vend., 1875, 81, 1105-1108; 1879, 88, 1322-1324 ; and Ann. China. Phys., 1881, [ v], 24, 337-384), who prepared hydrocellulose by several different methods, and having determined its empirical composition found this to agree fairly well with the formula C,,H,,O,l. The results of certain experiments carried out by the author in the course of another investigation threw doubt on the accuracy of Girard’s observations, and consequently some of his experiments were repeated.Girard prepared hydrocellulose by treating cellulose with cold sulphuric acid (sp. gr. 1-45), by the action of cold moist hydrogen chloride on air-dried cellulose, and by heating cellulose with dilute acids. The attempts made to prepare hydrocellulose by the first two of these methods proved unsuccessful, but the action of boiling 5 per cent. sulphuric acid on flax or cotton cellulose soon destroyed the tenacity of the fibres and converted the substance into a friable mass. As the change of 2C,H,,O, into CJ322011 is accompanied by an increase in weight of 5.6 per cent., it should be possible to detect this by quantitative experiments, Girard, however, states that under the most favourabie conditions the weight of hydrocellulose obtained is less than the weight of the original cellulose, and he explains this discrepancy by assuming that d-glucose is simultaneously produced, but adduces no evidence in support of this assumption beyond the fact that, after the reaction, the acid solution reduces Fehling’s soln tion.Experiments made to determine the relation between the weight of the cellulose taken and ( A ) the weight of the hydrocellulose and ( B ) the weight and nature of the other products of the reaction, gave the following results. A . (1) Flax cellulose, boiled for 24 hours in 5 per cent. sulphuric acid, lost 2.1 per cent., and was reduced to a powder.(2) Cotton cellulose, boiled for 1 hour with 5 per cent. sulphuric acid, similarly lost 3-9 per cent.STERN : THE SO-CALLED (( HYDROCELLULOSE.” 337 (3) Cotton cellulose, immersed in sulphuric acid (sp. gr. 1.45) for 16 hours at 26’, lost 3.3 per cent. ; the fibres mere rendered brittle, but were not converted into a powder. The following experiments show that this loss in weight is not a peculiar concomitant of the conversion of cellulose into hydrocellulose, but also occurs when hydrocellulose itself is submitted to the further action of the acid. The flax cellulose, which had been converted into hydrocellulose in the manner indicated by boiling with 5 per cent. sul- phuric acid for 2$ hours, was again submitted to the same process, when a further loss of 1.9 per cent.was observed, and the treatment being again repeated on the hydrocellulose remaining, there was an additional loss of 2.0 per cent. B. About 380 grams of purified cotton cellulose, covered with 5 per cent. sulphuric acid, were digested at 100” for 4 hours; the soluble matter was then filtered off and the ‘( hydrocellulose ” produced thoroughly washed with water. The sulphuric acid was removed from the solution by neut’ralisation with baryta, the precipitated barium sulphate filtered off, and the filtrate evaporated to a syrup in vucuo. This residue was treated with methyl alcohol, in which the greater portion dissolved. The total soluble products of the hydrolysis weighed 6.4 grams, or 1.8 per cent. of the cellulose employed. The syrup, which mas uncrystallisable, had an optical activity of + 37’ and a cupric reducing power K = 90 (d-glucose having K = 100).A portion of the syrup, when treated with phenylhydrazine acetate in the usual way, yielded a golden-yellow osazone closely resembling glucosazone, which crystallised in needles and melted a t 208’. Another portion, to which a small quantity of yeast had been added, lost 60 per cent. of its optical activity in a few days; the optical activity of the matter fermented was [a],=4So, and its K=107. All these facts indicate that one of the soluble products of the hydrolysis is d-glucose ; the amount obtained is, however, insufficient to explain Girard’s theory that the deficiency in the yield of hydrocellulose which is always found may be explaiied by the conversion of this deficiency in to d-glucose.The production of d-glucose in the conversion of ordinary cellulose into hydrocellulose is not, however, a peculiar characteristic of this change, as it is also formed when hydrocellulose is further acted on by hot dilute sulphuric acid. The hydrocellulose obtained in the last transformation was treated for a further period of 4 hours with 5 per cent. sulphuric acid a t 100”. The soluble products of the transformation, when separated in the same way, amounted to 5.3 grams, or 10.5 per cent. of the weight of hydrocellulose taken. A methyl-alcoholic solution of the syrupy product deposited crystals which had the following properties : c = 7.51 7 ; D = 3.972 ; [ aID = 36.9’ ;338 STERN : THE SO-CALLED '' HYDROCELLULOSE." Carbon ......Hydiogen ... and,afterrecrystallisation,gavethe following data: c = 2.582; D = 3.916; A solution of the recrgstallised product, when fermented with a small quantity of yeast, lost 58 per cent. of its optical activity in a few days, and another portion yielded a yellow, crystalline osazone resembling glucosazone and melting at 208'. The hydrocellulose residue of this reaction, when again treated in the same way, yielded 4.0 grams of soluble products, the methyl-alcoholic solution of which deposited crystals having the following properties : c = 4.778 ; D = 3.926 ; [ 0.1~ = 47.3' ; I< = 97.5. A portion put t o ferment with yeast lost 61 per cent. of its optical activity in a few days, and another portion yielded a yellow, crystalline osazone melting at 2 1 0 O .The hydrocellulose residue now remaining was again treated as before and 2.5 grams of soluble products were obtained, the methyl- alcoholic syrup of which gave crystals having the following properties ; c = 4.195 ; D = 3*S93 ; [ u J D = 45.6' ; K = 97.8. A portion of this sub- stance, when fermented with yeast for 10 days, a longer time than the previous fermentations, lost 97.8 per cent. of its optical activity, and another portion gave a yellow, crystalline osazone melting at 204'. Analysis of Hydroce1lulose.-Girard's results, which vary between 41.8 and 42.1 per cent. of carbon and 6.3-6.7 per cent. of hydrogen, although not very satisfactory, yet agree moderately well with the empirical formula C12H22011, which requires 42.1 per cent.of carbon and 6 4 per cent. of hydrogen. The celluloses employed in the present experiments mere burnt before and after having been exposed t o the action of acids as described above and yielded the following results : 45-90 ; K = 95-z.* 2i 4 I U 0 z E: 44.28 6-28 t ~ ____ ____ 44-39 44-44 44'27 _ _ _ _ - ~ 6-28 6'26 6'24 6 '22 - * c=Concentration in grams per 100 C.C. DZDiviaor ; a factor obtained by dividing the specific gravity minus 1, by c and multiplying the result by 1000. K =Cupric reducing power compared with that of d-glucoae as 100.STERN : THE SO-CALLED <' HYDROCELLULOSE." 339 Those figures agree very closely with the formula C,H1,O,. It appeared at first difficult to understand how Girard came to obtain his analytical figures, but this investigator's account of his experiments will render this quite clear.He states that hydrocellulose is easily oxidised on exposure to warm a i r ; at 80°, it becomes coloured, and at 100' this change takes place very rapidly. In several of the author's experiments, i t was found that, after the action of the acid, the cellulose, when washed in the usual way, was blackened on drying at loo", but in every case in which this took place, sulphuric acid was detected in the filtrate obtained by extracting the blackened mass with hot water. On the other hand, all the preparations of which the analyses are given above were dried in a current of dry air a t 100' ; in no case was the slightest colour produced, and the preparations did not contain sulphuric acid.As Girard's preparations becdme coloured when exposed to a temperature of looo, it is evident that they must have contained free acid, and as, on account of this, he only dried them at 35-40", it is extremely probable that they also contained water, and hence the low numbers obtained for the carbon and the high values for the hydrogen are explained. One of the author's specimens prepared by the action of sulphuric acid (sp. gr. 1.45) at 25" gave only 44.05 as the percentage of carbon, b u t in washing this specimen free from acid, a little ammonia had been added to one of the wash waters, and although it was thought that the cellulose had been properly washed, yet when another portion of the specimen was extracted with hot water, sulphuric acid was found in the filtrate, showing that a small amount of sulphate had been con- tained in the specimen burnt, thus accounting for the low percentage of carbon.It is evident from a consideration of these results that when cellu- lose is exposed to the action of hot dilute acids there is no formation of hydrocellulose ; the cellulose is partly hydrolysed with the produc- tion of soluble products, one of which is in all probability d-glucose. The cellulose residue, after exposure to the action of hot dilute acid for some hours, does not differ in elementary composition from the original cellulofie, but has been converted into a fine powder. A micro- scopic examination of the disintegrated cellulose at different stages of the reaction, shows that the disintegration is due to the fact that cer- tain portions of the fibre are more easily attacked than others, and when these portions of the fibres are converted into soluble products the whole fibre falls to pieces. Although this change is most marked i n the first stage of the reaction, yet each successive digestion results in the production of a finer product, until that obtained in the above- described experiments, after treatment for 16 hours, was so fine as to be most difficult to filter. The slowness of the action and the consequent long period of time340 CHATTAWAY : INTRAMOLECULAR REARRANGEMENT IN during which it was necessary to allow the hydrolysis to proceed in order to obtain a sufficient amount of soluble products, rendered it impossible to decide whether d-glucose was the only product of the hydrolysis or whether, as seems probable from Fenton's experiments, there are other soluble products (Trans., 1 98, 73, 554 ; 1899, 75, 423; 1901, 79, 361 and 807; and €'roc., 1901, 17, 166). Lsevulose, for example, would be destroyed in the foregoing experiments, owing to the protracted action of the hot acids.

ISSN:0368-1645    

DOI:10.1039/CT9048500336

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

340 CHATTAWAY : INTRAMOLECULAR REARRANGEMENT IN XXXVII I. -Intramolecular Reawangernent in Berizu- tives of the Aromatic Aminoketones. By FREDERICK DANIEL CHATTAWAY. THE acylchloroamino-derivatives of the aromatic ketones readily undergo the intramolecular rearrangement characteristic of aromatic chloroamides, in which the halogen radicle leaves the nitrogen and changes place with a hydrogen atom occupying an ortho- or para- position in the ring. The presence of the ketonic group does not, apparently, influence the rearrangement. As, however, the final transformation whereby both vacant positions are filled only takes place at a somewhat high temperature, the ketonic group becomes involved under the influence of the catalyst employed, uncryatallisable tarry substances are produced, and the yield of the disubstituted aminoketone is small.By these intramolecular changes, a number of substituted amino- ketones have been prepared, which are not easily obtained by direct substitution, this reaction as a rule only yielding a tarry product from which no pure substance can be isolated. The mode in which these substituted ketones are produced fixes their constitution, as in such transformations the halogen is known always t o take up the para- in preference to the ortho-position, whilst the meta-position with respect to the amino-group is never assumed.DERIVATIVES OF THE AROMATIC AMINOKETOSES. 341 Transformation of Acet yl- p -ch loro aminoclce t opAen om into 3 - CMoro- p- m e t ylarninoacetophenone, N Cl*CO*CH, NH*CO*CH, \/ CO*CH, \/ CO=CH, This transformation slowly takes place when a solution oE the chloroamide in chloroform containing about 5 per cent.of acetic acid is allowed to remain at the ordinary temperature, light being excluded; the change is complete in about 14 days. On evaporating off the chloroform, a red solid is left from which 3-chZoro-p-acetyl- aminowetophenone can be obtained by repeated crystallisation from alcohol. This substance crystallises in slender, colourless prisms (m. p. 163'). 0.3635 yielded 0,2520 AgC1. C1= 17.1'7. C,,H,,O,NCl requires C1= 16.75 per cent. 3-Chloro-p-acetyZchZoroaminocccetophenone, CH,*CO.C,H,Cl*NCI*CO*C~,, was prepared by adding a solution of 3-chloro-4-acetylaminoaceto- phenone dissolved in alcohol to an ice-cold solution of potassium hypochlorite containing an excess of potassium hydrogen carbonate ; it was extracted by chloroform, and, to complete the action, the solution was repeatedly shaken with fresh hypochlorous acid.The compound crystallises from petroleum (b. p. 60--80°) in clusters of colourless, transparent plates (m. p. 56'). 0.1746 liberated I = 13.S C.C. N/IO I. C1 (as NCl) = 14.01. C,,H,O,NCl, requires C1 (as NCI) = 14.41 per cent. When dissolved in glacial acetic acid and heated, it undergoes trans- formation, but the quantity of the crystalline dichloro-transformation product which could be isolated from the tarry product of the action was PO small that it was not further studied. 3-Chlor~-p-arninoacetophenone, CH;CO*C,H,Cl*NH,, was pre- pared by hydrolysing the acetyl derivative by heating i t for four hours with a mixture of alcohol and concentrated hydrochloric acid and decomposing the hydrochloride of the base with caustic potash.It crystallises from a mixture of chloroform and petroleum in short, four-sided, colourless prisms (m. p. 92'). 0.1959 yielded 0.1668 AgCl. VOL. LXXXV. A A C1= 21.05. C,H,ONCl require8 C1= 20.91 per cent.342 CHATTAWAY : INTRAMOLECULAR REARRANGEMENT IN 3-~h~oro-p-benxoy~am~noacstophelzone, CH,*CO C,H,Cl*NH*CO*c,B,, 3 -Ch loro - p-propion y Inminoacetophenone, crystallises from alcohol in slender, colourless needles (m. p. 132'). CH,*CO* C,H3C1*NH*CO*C2HS, crystallifies from a mixture of chloroform and petroleum in groups of slender, colourless needles (m. p. 115'). Transformation of Acetyl-p-chloroaminobenzop~~enone into 3-ChZoro- p-acetyla?ninobenzopherone, NCl*CO CH, NH- CO CH, - /\ I 1 \/ CO*C,H, + I q c 1 \/ CO*C,H, This transformation takes place slowly under similar conditions to those which bring about the transformation of the acetophenone derivative. When the chloroamide dissolved in chloroform containing 5 per cent.glacial acetic acid was allowed to remain at the ordinary temperature and screened from light, it became completely trans- formed in about 14 days. On evaporating off the chloroform, a viscid, oily substance was left, which, however, solidified t o a nearly colour- less mass on warming for a short time with a solution of potassium hydrogen carbonate. When repeatedly crystallised from alcohol, the pure 3-chloro-4-acety~arn~no6enzop?~enone, C6H5*CO*C6H,Cl*NH*C0 CH,, was obtained in colourless, rhombic plates (m.p. 99.5.). C,,H,,O,NCl requires C1= 12.96 per cent. C,H,-CO*C6H,C1*NC1 *Co*CH,, crystallises from a mixture of chloroform and petroleum (b. p. 60-80") in transparent, colourless plates (m. p. 102'). 0.2440 gave 0.1265 AgC1. 3-Chloro-p-ucety Zchloroaminobenxopl~e~~one, C1= 12.82. 0.3760 liberated I= 24.5 C.C. N/10 I. C1 (as NCl) = 11.55. C15Hl102NC12 requires GI (as NC1) = 11.51 per cent. 3-C~Eoro-p-aminoberxo~~~~one, C,H,=CO*C,H,Cl*NH,, was obtained by heating the slcetyl derivative for three hours on a water-bath with alcoholic hydrochloric acid and decomposing the hydrochloride of the base with caustic potash; it crystallises from a mixture of chloroform and petroleum in small, slender, colourless prisms (m.p. 1 4 0 O ) . 0.1942 gave 0.1209 AgC'l. 3-Chloro-p benxo yZamino6enxophenone, C,H,* CO*C6H,C1-N H*CO * C6H,, C1= 15.39. Cl3Hl,ONC1 requires C1= 15.31 per cent.DERIVATIVES OF THE AROMATIC AMINORETONES. 343 is sparingly soluble in alcohol, from which it crystallises in colourless, flattened prisms (m. p. 126'). 3-Ch Zoro- p-benzo yZe~lo~oanzinobenzo~henone, C6H5*CO*C6H3C1'NCl 0CO*C6H,, crystallises from light petroleum in short, colourless, flattened prisms with domed ends (m. p. 123'). 0.1404 liberated I = 7.5 C.C. N/10 I. 3- Cldos*o -p-propionykanzinobenxophenone, C1 (as NC1) = 9.46. C,,H,,O,NCI, requires C1 (as NC1) = 9.58 per cent, C, H 5* CO* C,H ,CL*rJH-CO *C,H,, crystallises from alcohol or a mixture of chloroform and petroleum in slender, colourless needles (m.p. 107.5'). 3-Chloro-p-pl.opionyIchloroa~~nobenzop~~none, C,K,.CO*C,H3C1.NCl0CO* C,H,, crystallises from a mixture of chloroform and petroleum i n colourless plates (m. p. 114"). 0.2790 liberated I=l'i.4 C.C. N/10 I. C1 (as NCl)= 11.05. C,6H,30,NCI, requires C1 (as NCl) = 11.01 per cent. I'ransformntion of AcetyZ-o-chloroami?zobenxophenone into 5-ChZoro- o-aeety Zcr,.Linobenxophenorae, NC1- CO*CH, NH*CO*CH, --+ <)CO*C,H, , U1 \/ This compound does not become transformed nearly so readily as the corresponding para-derivative, and remains apparently unchanged in chloroform solution containing 5 per cent. of acetic acid for zt period sufficient for the complete transformation of the latter. This transformation can, however, be effected, accompanied by some decomposition and the formation of tarry products, by dissolving the chloroamide in glacial acetic acid containing about 0.5 per cent.of hydrogen chloride and heating the solution in a sealed tube in a water-bath for a few hours. On pouring the product into water and washing with a dilute solution of potassium hydrogen carbonate in order t o remove the acid, a pale brown, tarry mass is obtained. On dissolving this in a little alcohol, the transformation product slowly separates in colourless needles. The behaviour of all similar derivatives leaves no doubt that the chlorine passes almost exclusively into the para-position with regard to the acetylamino-group. A A 2344 REARRANGEMENT OF THE AROMATIC AMINOKETONES. 5-ChZoro-o-acetyZa~~~inobenzop~~~~aone, C,H,*CO°CGH,C1*NH*CO.CH,, orystallises from alcohol in slender, colourless prisms (m.p. 117"). 0.2103 yielded 0.1104 AgC1. 5-Chloro-o-acetylchloroamino6enzophenone, Cl= 12.98. CI,H1202NC1 requires C1 E: 12.96 per cent. C,H,*CO.C,H,CloIYC1*CO'CH,, crystallises from a mixture of chloroform and petroleum in clusters of colourless plates (m. p. 107"). 0.2599 liberated I= 16.8 C.C. N / l O I. C1 (as NCl) = 11.46. C,,H,,O,NCI, requires C1 (as NC1) = 11 -51 per cent. 5-ChZoro-o-amino benzophenone, C,H, CO 4 C,H,Cl ON H,. -The ace ty 1 derivative of this base is hydrolysed only with difficulty, and requires prolonged boiling with excess of alcoholic hydrochloric acid. 5-Chloro- 2-aminobenzophenone is readily soluble i n chloroform or alcohol, spar- ingly so in petroleum ; it crystallises from a mixture of chloroform and light petroleum in slender, yellow needles (m.p. looo). Tvansfon,zation of 3-Chloro-p-acetyZc~Zoroanzi~zobenxop~enone into 3 : 5- Dic7Lloro-p-acetyla~nino6enxophenone7 NCl*CO*CH, NH*CO*CH, -3- \/ CO-C,H, \/ CO*C,H, The transformation of the acylchloroaminobenzophenones is exactly analogous t o that of the acylchloroamino-derivatives of the similarly constituted chloroanilines. The transforma tion of acetyl-p-chloroamino- benzophenone is eflected more readily than t h a t of acetyl-o-chloro- arninobenzophenone, and t h e transformation of the latter more readily than that of 3-chloro-p-acetylchloroaminobenzophenone. Even when dissolved in glacial acetic acid containing a little hydrogen chloride and heated at 100' for several hours, this compound undergoes no appreciable amount of transformation.Intramolecular rearrangement, however, occurs when the solution is heated for some hours a t 130-140" ; after eight hours at this tem- perature, the chloroamide was found t o have completely disappeared. Ou diluting the product and adding a slight excess of potassium hydro- gen carbonate t o neutralise the acid, a pale yellow, viscid mass was obtained which was readily soluble in warm alcohol, the solution slowly deposl ting needle-shaped crystals of the transformation product. The yield, however, is small, a considerable quantity of a tarry sub- otance bein6 fosi-ne ],SEPARATION OF P-CROTONIC ACID FROM U-CROTONIC ACID, 345 3 : 5-~ic~~lo~o-p-acet~Z~nainobenxo~henone, C,H,*CO*CGH2C1,*NH.CO.CH,, crystallises from alcohol in colourless, needle-shaped crystals (m. p. 1850). 0.1626 gave 0,1509 AgCl. C1= 22-94. C1,HllO,NCl2 requires C1= 23#02 per cent. The constitution of the compound follows from its mode of pre- paration, as the chlorine atoms can only enter the ortho-positions with respect to the acetylamino-group. 3 : ~-~~ch~o~o-p-nce€y~ch~oroc6na~nobenxop~enone, C,H,* CO.C,H,Cl,*NCl- CO-CH,, crystallises from a mixture of chloroform and petroleum in groups OF transparent, colourless plates (m. p. 118.). 0.1019 liberated I = 5 - 9 C.C. N/10 I. C1 (as NCI) = 10.26. C1,Hl,O,NCl, requires CL (as NCI) = 10.35 per cent. 3 : 5- Dichloro-p- amim~ benxophenone, C,H,- COO C,H2C 1 ;NH2, pre- pared by hydrolysing the acetyl compound by boiling with alcoholic hydrochloric acid, crystallises from alcohol in short, colourless prisms (m. p. 137"). ST. BAT1THOT,OJIEW'S HOSPITAL AND COLLEGE, LOXDON, E.C.

ISSN:0368-1645    

DOI:10.1039/CT9048500340

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

SEPARATION OF P-CROTONIC ACID FROM U-CROTONIC ACID, 345 XSXIX.-TlLe Sepcemtion of P-Crotonic Acid from a- Cyotonic Acid. By ROBERT SELBY ~IORRELL and ALBERT ERNEST BELLARS. THE separation of p-crotonic acid from a-crotonic acid is effected, according to Michael and Schulthess (J. pr. C'hern., 1892, [ii], 46, 245), by means of the different solubilities of the sodium salts in alcohol. One part of sodium a-crotonate dissolves in 340 parts of alcohol (98-99 per cent.) at 15", whilst at the same temperature, one part of sodium p-crotonate requires 12.7 parts of alcohol of the same strength; the more soluble p-crotonate is then decomposed by hydrochloric acid, and the free acid purified by distillation in vacuo. p-Crotonic acid, ob- tained by Michael's method or by the method described by Fittig and Kochs (AmnuZen, 1892,268, 15), is stated by J.Wislicenus (Chem. Centr., 1897, ii, 259) to contain a-crotonic acid, in spite of Michael's acid giving no precipitate in alcoholic precipitate on neutralisation346 MORRELL AND BELLARS: THE SEPARATION OF with alcoholic sodium hydroxide. The pure acid has been obtained (J. Wislicenus, Zoc. cit.) by transforming liquid p-crotonic acid, dissolved in alcohol, into its sodium salt, and by removing the sodium a-crotonate by concentrating the solution and precipitating the last traces of the salt by the addition of an equal volume of ether; the sodium p-crotonate left in solution is decomposed by hydrochloric acid, and the acid, which is purified by recrystallisation from pentane, crystallises in needles or prisms melting at; 15*45--15.5'; the yield must be small, and the method of preparation seems tedious.In a paper by one of us (Morrell and Hanson, Trans,, 1904, 85, 197), the optically active constituents of ap-dihydroxybutyric acid, prepared from a-crotonic acid, were described, and it was stated that the optically active constituents of a second up-dihydroxybutyric acid were under investigation. The oxidation of '' isocrotonic " acid, supplied by Kahlbaum, gave a n acid the brucine and quinine salts of which were virtually identi- cal with those of symmetrical ap-dihydroxybutyric acid, so that i t was necessary to devise a method of separation of the two isomeric acids, and to prepare salts of /3-crotonic acid, which are less soluble than the corresponding a-crotonates. The brucine salts of the two acids were found to have different solubilities, and the P-acid yielded the less soluble salt, but unfortunately these salts are very soluble in all ordinary solvents.The quinine salts, however, are sparingly soluble in water, and the salt of the P-acid is much less soluble than that of the a-acid; it is therefore quite easy to separate the two salts by crystallisation from water, and the quinine p-crotonate can be recrys- tallised from that solvent without undergoing any change in melting point. From the quinine salt, the barium p-crotonate has been pre- pared, and this has given the pure a,cid by treatment with dilute sulphuric acid in the presence of pure ether, The melting point agrees with that given by Wislicenus, namely, 15'.Determinations of the density, molecular weight, and molecular refraction have been made. The molecular weight in glacial acetic acid solution corresponds w i t h the formula C,H,O,, and there seems no justification for the double formula proposed by Wislicenus (Chem. Centr., 1897, ii, 259). Michael and Schulthess (Zoc. cit.) state that the purity of /I-crotonic acid can be shown by neutralising its alcoholic solution with 10 per cent. caustic soda solution; sodium p-crotonate is very soluble in alcohol, and, under the experimental conditions, no precipitate ought t o be formed on neutralisation. We have tested the p-crotonic acid prepared from the quinine salt, following Michael's directions, and have found that no insoluble sodium crotonate mas formed ; more- over, the determination of the solubility of sodium /3-crotonate gave values agreeing with bhose obtained by Michael.@-CROTONIC ACID FROM ~-CROTONIC ACID. 347 EXPERIMENTAL.Brucina a-Crotonate.-This salt, which was prepared by neutralising a boiling aqueous solution of a-crotonic acid with brucine, is exceed- ingly soluble in water, alcohol, or benzene; 5 grams dissolve in 7 C.C. of hot benzene, and the salt slowly crystallises out in hexagonal prisms, which soften a t 90' and melt at 125'. Quinine a-Crotor~ate.-This salt crystallises from a hot aqueous solu- tion in aggregates of slender needles, which melt a t 136' without decomposition ; a solubility determination a t 17' showed that 0.5903 gram was dissolved in 13-7 grams of solution, hence the solubility of the salt in water at 17' is 2.4." isoCotonic " Acid.-The acid was obtained from Kahlbaum, who stated that it was prepared by heating P-hydroxybutyric acid, and freed from a-crotonic acid, as far as possible, by distillation in vucuo and by freezing out the last traces of the a-isomeride at - 20'. Several analyses of the acid were made, but the percentages of carbon were invariably found to be too lorn (compare Michael and Schulthess, loc. cit.). 0.1845 gave 0.3732 CO, and 0.1145 H,O. C=55.16 ; H=6.89. 0,1950 ,, 0.3920 CO, ,, 0.1243 H,O. C = 54.82 ; H = 7.08. C,H,02 requires C = 55.8 ; H = 6.97 per cent. On distilling 100 grams of b L isocrotonic" acid, about 40 grams boiled at 87' under 15-30 mm. pressure; the residue in the distilling flask became solid at the ordinary temperature, and the distillate was no purer than the original acid.0.1773 gave 0.3515 CO, and 0.1190 H,O. The analysis showed that it was not possible to purify the acid by further distillation. The liquid p-crotonic acid passed slowly into a-crotonic acid and solidified completely. Brucine P-Crotonate.-This salt is very soluble in water, alcohol, or benzene ; from the last solvent, it crystallises out in prismatic needles, which melt between 98' and 100' without decomposition. Quinine P-Crotonate.-The salt was prepared from the crude p-cro- tonic acid, and also from the acid wbich had been freshly distilled; the first crop of crystals melted a t 147', and on recrystallisation from water the fraction which separated first melbed at 156-1558', the melting point being unchanged on repeated crystallisation from this solvent.The mother liquors, from the crystallisation of the fraction melting at 147', gave crystals which melted at 134-136'. It would seem as if the two quinine salts crystallised together in about C=54.06 j H=7*45.348 MORRELL AND BELLARS: THE SEPARATION OF equal quantities, and, on recrystallisation, separated into a less soluble form melting at 156-158' and a more soluble form melting at 134-136'. p-Crotonic acid, which had been distilled in vacuo at 87', gave a quinine salt which melted at 147". Seventy grams of the quinine salt (m. p. l47'), obtained from 30 grams of redistilled p-crotonic acid, gave, on recrystallisa.tion, 60 grams of salt melting a t 156'.The mother liquors were found to contain the quinine a-crotonate (m. p. 132'). There is no evidence that quinine p-crotonate changes into the a-salt on crystallisation from water. The quinine p-crotonate crystallises in prismatic needles ; an air-dried specimen of the crystals, on heating a t 105', does not lose in weight. A determina- tion of the solubility of the salt gave the following numbers: 13.5930 grams of a saturated aqueous solution at 17'contained 0.1410 gram of the salt, hence its solubility in water a t 17' is 1.04. 0,3045 gave 18 C.C. moist nitrogen a t 16' and 757 mm. 0.1858 ,, 0.4805 CO, and 0.1212 H,O. C = 70.5 ; H = 7.24. N = 6.97. C2,H2,02N2,C,H,0, requires C = 70.24 ; H = 7.31 ; N = 6.83 per cent. Bwiunz p-Crotonate.-The quinine p-crotonate (m.p. 157") was dissolved in hot water and decomposed by a slight excess of baryta water. The quinine was filtered off and a current of carbon dioxide passed through the filtrate in order to remove excess of baryta. The clear liquid was concentrated t o n small bulk in vacuo at 50' and poured into alcohol ; the barium salt was precipitated in large, lustrous, rhomboid plates, which contained a molecule of water of crystallisation. 0.9925 (air-dried) lost, at l l O o , 0.0562 H,O. 0.2255 (dried at 110') gave 0.1723 BaSO,. (C,H,02),Ba,H20 requires H,O = 5.53. Ba = 44-63 per cent. H,O=5*64. Ba=44*85. (C,H,O,),Ba requires p-Crotolzic Acid. The barium p-crotonate was covered with pure ether and a little water added; the calculated quantity of 10 per cent. sulphuric acid was added drop by drop, the mixture being thoroughly shaken; the barium sulphate mas removed by filtration and the clear ethereal solution of p-crotonic acid was concentrated in, VGCCZCO a t the ordinary temperature.On cooling, the liquid acid solidifies immediately in long needles melting a t 15'. Wislicenus gives the melting point of the acid as 15.5'; the melting point with the thermometer in the solid is 14-154P-CROTONIC ACID FROM a-CROTONIC ACID. 349 0,1856 gave 0,3765 GO, and 0.1161 H,O. C = 55.32 ; H = 6.94. 0.1895 ,, 0,3845 CO, ,, 0.1180 H,O. C=55.33; H=6*91. C4H,02 requires C = 55.8 ; H = 6.97 per cent. A molecular weight determination in glacial acetic acid gave the 0,3903 in 16.7390 glacial acetic acid gave At - 1.062'. M. W. = 85.6. The density of the acid was found to be Dg = 1.0342 ; Wislicenus (Eoc.cit.) obtained Di5 = 1.0313. Mr. Gold, of St. John's College, was kind enough to determine the refractive index of the acid for sodium light : p? = 1.4483, molecular refraction = 37.27. The molecular refraction for a-crotonic acid is 36.94 (Kannonikoff, J. p, Chenz., 1885, [ii], 31, 347). In order to test the purity of the p-crotonic acid obtained from the quinine salt, tbe following experiments were performed : (a) 0.5 gram of the acid was dissolved in 7.5 C.C. of absolute alcohol and neutralised by a 10 per cent. absolute alcoholic solution of sodium hydroxide. The solution remained quite clear, which showed t h a t the acid was free from a-crotonic acid. ( b ) Two grams of the acid mere dissolved in 29.5 C.C.of absolute alcohol and the solution carefully neutralised by the alcoholic sodium hydroxide solution. An exceedingly slight precipitate formed, which was found to contain sodium carbonate. After filtration, the solution was evaporated to dryness, and the solid residue was extracted with 50 C.C. of absolute alcohol; the solid dissolved completely. From the alcoholic solution, the sodium p-crotonate was obtained, analysed, and its solubility in the solvent was determined. 0.255, dried ztt looo, gave 0.1657 Na2S0,. Na=21. C,H,O,Na requires Na = 21.3 per cent. 4,759 grams of a saturated 99 per cent. alcoholic solution of sodium p-crotonate at 15" contained 0.3395 gram of the salt, therefore 1 part of the salt dissolves in 14.4 parts of 99 per cent. alcohol.Michael and Schulthess found that one part of the sodium ,f3-crotoaate dissolves in 16.7 parts of 99.5 per cent. alcohol a t ll", and in 12.7 parts of 98-99 per cent. alcohol a t 15O. following numbers : C,H,O, requires M. W. =86 per cent. TiLe Oxidation of Liquid p-Crotonic Acid. " isoCrotonic " acid, obtained from Kahl bauu, was oxidised by barium permanganate according t o the directions given by Fittig and Kochs (Annalen, 1892, 268, 16). The up-dihydroxybutyric acid was obtained as a syrup, although in one preparation some crystals appeared350 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. in the form of long prisms with domed shaped ends, identical in ap- pearance with those described by Fittig and Kochs (Zoc. cit.) as characteristic of up-dihydroxybutyric acid prepared from a-crotonic acid. The yield of the syrup was the same as in the case of the oxidation of a-crotonic acid. The brucine salt of this up-dihydroxy- butyric acid is identical in melting point, specific rotatory power, and solubility with the up-dihydroxybutyric acid described in a former paper. Fractional crystallisation of the brucine salt gave a pro- duct melting a t 285O, which amounted to more than 50 per cent. of the total weight of the salt taken. The “i~ocrotonic” acid con- tained so much of the a-crotonic acid that it was found impossible to confirm Pittig and Koch’s results. Investigation of the quinine salt gave the same results as in the case of the brucine salt. The propor- tion of quinine cis-up-dihydroxybutyrate was a t least 90 per cent. of the weight of the unrecrystallised quinine salt. The silver salt of this ap-dihydroxybutyric acid was prepared, and its solubility compared with that of the silver cis-up-dihydroxybutyrate. The solubilities a t 17’ were practically the same, being 3.2 and 3.1 ; the solubilities of the two up-dihydroxybutyrates at 15” and 13’ are 1.45 and 5.1 re- spectively (Fittig and Kochs, Zoc. cit.).

ISSN:0368-1645    

DOI:10.1039/CT9048500345

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

350 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. X L.-Certain Organic Phosphorus Compounds. By AUGUSTUS EDWARD DIXON, M.D. SOME few years ago, the author called attention to the existence of a kind of tautomerism, in which tbe mobility of hydrogen, or other monadic radicle, plays no part. The phenomenon, which takes the form of an apparent variability in the mode of attachment of a whole group, is observable amongst the so-called " thiocyanates " of organic acids, many of these exhibiting the power to interact, according to the conditions under which they are placed, either as such or as thio- carbimides (Trans,, 1901, 79, 541). Following up the study of this peculiar behaviour, which seems to be confined exclusively t o members of the cldas named,* the writer was led to inquire whether a like * The isomeric rearrangement of a thiocyanate into a thiocarbimide is well known, for instance, that of ally1 thiocyanate into the corresponding thiocarbamide, a change which occurs spontaneously on keeping. Amongst paraffinoid derivatives, the tendency to change is slight; nevertlieless, a case has been observed, for Hofmann has recorded (Ber., 1885, 18, 2197) thc partial conversion of methyl thio- cyanate into methylthiocarbimide by heating for several hours a t a temperature of some 50" above the boiling point of the former.But these rearrangements are notDIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. 351 power would be manifested by the thiocyanates of mineral acid radicles, and some evidence was adduced (Eoc. cit.) to show that phosphorus and phosphoryl thiocyanates (which, however, were only obtained in solution) possess t o a certain extent the characters of thiocarbimides.Since then, means have been found of isolating both these compounds with but little difficulty and the present paper includes a description of the methods employed, the properties of the products, and the results obtained by bringing them into contact with nitro- genous bases. Before proceeding to the experimental data, it should, perhaps, be recalled that many new facts have lately come t o our knowledge concerning the thiocyanates of organic radicles and their isomerides, the “ mustard-oils,” H. L. Wheeler having especially contributed in this direction. Amongst other things, it has now been established that double decomposition between metallic thiocyanates and halogen derivatives of substituted methanes does not necessarily lead to the formation of the corresponding thiocyanates, but that thio- carbimides are sometimes produced instead.Thus, potassium thio- cyanate, when heated with phenyl-p-tolylmethyl bromide dissolved in benzene, yields the t hiocarbimide, C,H,l\/le*CHPh*NUS, although benzyl-p-tolyl bromide is mainly converted into the corresponding thiocyanate (Wheeler and Jamieson, J. Amer. Chem. Xoc., 1902, 24, 746). Phenyl-a-naphthylmethyl bromide and di-a-naphthylmethyl bromide under like treatment yield the thiocarbimides Cl,H7*CHPh*NCS aud (C,,H7),CH*NCS respectively. Diphenylmethyl bromide gives either €’h,CH*SCN, or Ph,CH*NCS, according to the conditions (Wheeler, Zoc.cit., 1901, 26, 353), but ethyl phenyl-a-chloroacetate yields the thio- cyano-derivative, CO,Et*CHPh*SCN ; the latter, however, unites with aniline, giving rise to “diphenyl-t,b-thiohydantoin,” PhN:C<Egrg;>. Further evidence of the tendency of thiocyanogen compounds to alter the character of their grouping is shown by the fact that chloro- acetyl-a-naphthalide, CH,C1*CO*NH*CloH7, gives, with potassium thio- cyanate, a “ labile a-naphthyl-$- thiohydantoin,” (m. p. 147O), which changes, on boiling in dilute alcoholic solution, into 2> (m. p. 213-214’). Moreover, S-CH the stable form, Cl,H7N:C<NH, tautomeric in this sense, inasmuch as when once effected they are permanent ; a t least, conditions have not yet been discovered under which an alkyl thiocarbimide will hehave as the thiocganate of its own radicle.It may be noted incidentally that the *SCS group, when once established, caiinot be transferred by any known direct method from the radicle with which it is combined to another.352 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. from chloroacetyl-m-xylidide, the thiocyano-derivative, Me,C',H,* NH CO C H,* SCN, can be isolated, which readily undergoes isomeric change into the stable form of thiohydantoin (Johnson, Zoc. cit., 1903, 25, 483). It may be added here that the formuh given by Wheeler and others for the stable varieties confirm those previously advanced (Dixon, Trans., 1897, '71, 629) for the ordinary so-called thiohydsntoins. The present writer observed many years ago that chloroacetanilide, when heated in dilute alcohol with potassium thiocyanate, yields not only phenyl- tbiohydantoic acid, but., in addition, a considerable proportion (62 per cent.of the theoretical) of phenylthiohydantoin, a substance which is also produced either from chloroacetanilide and thiocarbamide, or from phenylthiocarbamide and ethyl chloroacetate (Meyer, Ber., 1877, 10, 1965). However, the fact that this substance results indifferently from compounds containing t hiocyano- or thiocarbimino-groups does not conclusively prove that the former radicle changes into the latter. Another interesting action, which shows the power of the 'SCN radicle t o combine occasionally with a base, is the union of 1 mol. of aniline with trimethylene thiocyanate, thereby forming phenyl-q-trimethylene- di t h iobiure t , CH2<CH:.CH *S*C(NH)>NPh s. C(NH) (Wheeler and Merriam, Zoc. cit., 1902, 24, 446). Since the electro-positive character of the unsatnrated hydrocarbon groups is commonly less marked than that of the saturated, i t might be antici- pated that the thiocyanates of pronoucced electro-negative radicles would tend still more readily to pass into the thiocarbimidic form, and to some extent this is true, for the derivatives of benzenoid acids exhibit mainly (although not exclusively) the properties of thiocarb- imides ; in fact, Miquel, the discoverer of benzoyl '' thiocyanate " (Ann. chim. phys., 1877, [v], 11, 300), states that if pure it is hydro- lysed by water into benzamide and carbon oxysulphide, but yields no thiocyanic acid, and hence ought to be regarded as a true thiocarb- imide.Now, the substance in question, when formed by heating benzoyl chloride dissolved in benzene with lead thiocyanate for a few milrutes, may give, by combination with alcohols or nitrogenous babes, yields of the corresponding additive products amounting to fully 90 per cent. of the theoretical (compare Trans., 1896, 89, 1603; 1899, '79, 379), and hence if benzoyl thiocynnate is formed at all in the initial decom- position, which necessarily occurs a t a very moderate temperature, its existence as such is short. On the other hand, thiocyanates derived from certain fatty acids appear capable of exhibiting the kind of tautomerism previously men- The case of acidic thiocyanates is somewhat complex.DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS.353 tioned, with respect to the CNS group : stearyl thiocyanate, for example, gave (Zoc. cit., 1602) with benzylaniline more than 95 per cent. of the possible yield of the trisubstitutod thiocarbamide, whilst with ammonia the products were substantially thiocyanic acid and stearamide. Occasionally, a substance of this class can not only act separately in either form, b u t also simultaneously in both : acetyl thiocyanate, for instance, is decomposed by water (IIXiquel, Zoc. cit.), mainly into acetic and thiocyanic acids ; it can unite almost quantitatively with p-tolu- idine to form acetyl-p-tolylthiocarbamide ; whilst if brought into contact with aniline at the ordinary temperature, i t yields acetyl- phenylthiocarbamide and acetanilide, together with aniline thiocyanate.I n relation to aniline, Dorm’s observation has already been mentioned, that the power of acetyl thiocyanate t o behave either as such, or as acetylthiocarbimide, is conditioned mainly by the temperature at which the interaction is brought about (Trans., 1901, 79, 543 ; Proc., 1904, If any analogy may be looked for between the thiocyanates of electro-negative organic, and of electro-negative mineral radicles, i t would presumably take the form of a similar capacity, on the part of members of the latter class, t 3 manifest thiocarbimidic in addition to thiocganic functions ; or possibly, under certain conditions, t o act as thiocarbimides, pure and simple. No investigation from this point of view fieems as yet to have been conducted, excepting a superficial one by the writer. The present study, indeed, notwithstanding that up- wards of two years have been devoted to it, has scarcely passed the preliminary stage, but circumstances having arisen which will for some little time interfere with the prosecution of this research, an account of the principal results so far attained is now submitted.20, 20)? Phosphorus (‘ FritiLiocyanute.” Phosphorus tricliloride interacts spontaneously with dry ammonium thiocyanate ; the violence of the direct action may be suitably checked by mixing the finely-powdered thiocyanate with enough benzene to make a thin paste, and then adding the phosphorus halide diluted with three or four times itsown volume of the samo solvent. The mixture instantly becomes hot, and must be kept in rapid motion for a short For instance, propionylthiocarbiniide and henzylaniline gave (Trans,, 1896, 69, 859) nearly 90 per ceii t.of the possible yield of p~opionylphenylbenzylthiocarbamide, but with pipcridiiie it aff’orcled piperidine thiocyanate. I n another experiment, sodium ethoxide was added to tile acetyl conipound, dissolved in benzene, in the hope of realising the change, NaOEt + AcNCS = NaOAc + EtNCS ; vigorous action occurred, the products being sodium thiocyanate and ethyl acetate, but not a trace of ethyl- thiocarbimide could be detected, * The behaviour of these substances is sonietimes very puzzling.354 DIXON : CER'L'AIN ORGANIC PHOSPHORUS COMPOUNDS. time, otherwise a portion of the contents may be projected out of the flask.It is well to use about one and a half times the amount of thio- cyanate calculated from t h e equation, PCJ, + 3KH,*SCN = 3NH4C1 + P(SCN),; if the process is successfully conducted, there is but little change of colour, and in a few minutes the benzene solution becomes practically free from chlorine. By using dilute solutions, all danger of violent action is precluded, but i t may then be necessary either t o allow the mixture t o remain for about a day, or to boil i n order to eliminate the chlorine, and in these circumstances a yellow or bright orange- coloured solid develops, which appears t o consist mainly of pseudo- sulphocyanogen together with isoperthiocyanic acid. When cool, the residue of ammonium chloride and thiocyanate is filtered off at the pump, washed a few times with dry benzene, and the clear filtrate heated on the water-bath under reduced pressure until no more solvent can be extracted.On distilling the pale brown liquid thus obtained in vucuo, the thermometer rose quickly t o about 168', when a few drops of liquid passed over ; the contents ol the flask now became very dark and semi-solid, and from this product, by careful heating, a clear, pale yellow oil could be distilIed, the whole distillate usually passing over within one or two degrees. In various preparations, the following boiling points and pressures were observed : 170°/20 mm. ; 172Oj21 mm. ; 173' and 175'/27 mm. ; 175'/28 mm., and 180°/30 mm. On rectification, two &pecimens were obtained boiling at 169'/20 mm.and at 161'114 mrn. respectively; the latter sample, when again rectified, boiled a t 163'/15 mm. ; i n all cases, a considerable amount of dark, viscid residue was left. These figures are mentioned in detail, because, although they seem to indicate a perfectly definite compound, reasons will be assigned later on for doubting whether the product is really homogeneous. The distillation is rather troublesome, being attended with much spirting and frothing of the viscid paste, and the slight irregularities noticeable in the boiling points are perhaps due t o t h e projection of liquid drops against the bulb of the thermometer. The best yield, from 14 grams of trichloride, was only 41 per cent. of the theoretical. The smaller yields obtained from larger batches were probably due t o the decomposition of the substance caused by prolonged exposure at the somewhat high temperature.Potassium thiocyanate interacts very imperfectly with phosphorus trichloride (compare Trans., 1901, '79, 545), and although the corre- sponding lead salt acts well enough, the mixture sometimes requires prolonged boiling in order t o complete the change, When exposed to air, the distilled oil slowly evolves fumes of thio-DlXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. 355 cyanic acid, but does not spontaneously inflame, even on warming. I n the cold, it has a faint alliaceous odour, which becomes penetrating and exceedingly disagreeable on heating the oil with water; this mixture is not luminous in a darkened room ; even when very slightly impure, the liquid soon darkens and becomes turbid.A specimen, when thrice distilled, was found t o have a sp. gr. 1.487 a t 1 5 ~ 5 ~ ; this figure differs considerably from that given by Miquel (Zoc. cit.), who found a sp. gr. 1,625 at 18' for a product distilled under the ordinary pressure. I n relztion to solvents, i t corresponded with his description in all respects, except one, which will be ment.ioned later. Analysis gave : S = 46.9 ; N = 20.1 ; P = 15.0. C,N,S,P requires S = 46.83 ; N = 20.48 ; P = 15.12 per cent. When thrown into water, the oil at oncecommences t o dissolve, but does not entirely disappear, the solution containing thiocyanic and phosphorous acids. These, however, are not the only products, for if i t is mixed with silver nitrate and the precipitated silver thiocyanate dissolved by ammonia, t,he liquid remains dark and turbid, owing t o the presence of a little silver sulphide; moreover, if it is heated with alkaline solution of lead salts, very perceptible desulphurisation occurs.Consequently, although the oil behaves mainly as a thiocyanate in so far as the aqueous extract is concerned, the latter also gives to some extent the reactions of a thiocarbimide. On the other hand, if the oil is dropped into hot alkaline solutions of lead or silver salts, copious desulphurisation occurs instantly, the substance thus exhibiting in a marked degree the cbaracters of a thiocarbimide. On mixing the oil (1 mol.) and aniline (3 mols.) in warm benzene, much heat was developed and a tenacious oil separated ; after prolonged exposure to air, this became partly crystallised, but when the oil was removed by means of acetone, the crystalline residue proved to be merely phenylthiocarbamide.With cooled solutions, a pasty, amor- phous solid was obtained, which hardened when kept out of contact with moisture, but which, when powdered aud washed successively with benzene and light petroleum, still retained a trace of viscid matter ; it softened at about 67" and melted somewhat indefinitely two degrees higher. The yellow powder contained a little aniline thiocyanate, for if shaken with water, in which it was practically insoluble, the liquid was distinctly reddened by ferric chloride, and gave with bleaching powder the violet reaction for aniline. When heated with water, it dissolved readily, a little hydrogen sulphide being evolved ; the soh- tion reacted freely for thiocyanic and phosphorous acids and for aniline, and deposited phenylthiocarbamide on cooling.It was easily soluble in ether, alcohol, and some other solvents, but when recovered from solution, either by evaporation or by precipitation, i t always separated356 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. either as a liquid or a paste, The indefinite melting point was sugges- tive of an impure compound, but as no satisfactory method of purifi- cation could be devised, the well-washed crude product was partially analysed, with the following results : Found, S=21*3; N=16*5; P=6*2. These figures agree only indifferently with the composition P(SCN),,3C6H,*NH, or C,,H2,N6P,P, which would require S = 19-83 ; N = 17-35 ; P = 6.4 per cent.o-Toluidine, when employed in a similar manner, yielded a smeary brown oil, from which only o-tolglthiocarbamide could be extracted. The distilled oil was soluble in alcohol, with which it interacted at once, considerable heat being developed ; thiocyanic acid escaped, and a viscid paste was left which did not crystitllise or become solid even after two months. It has already been mentioned that in one respect the phosphorus thiocyanate did not correspond with Miquel’s description. According t o this author, the substance is but very slowly acted on by water, which de- composes it into thiocyanic and phosphorous acids. This was not exactly the present writer’s experience, for cold water attacked the oil rapidly, the solution obtained by shaking the two together for a few seconds containing a large amount of thiocyanic acid.Yet, on attempting to determine quantitatively the amount of this acid, it was found that, although the oil rapidly diminished in bulk when first placed in contact with warm water, it couldnot be made to dissolve completely, even by prolonged boiling, nor did the substitution of fresh water for that now charged with the decomposition products appear to diminish the amount of residual oil ; moreover, the latter, after repeated extractions, ceased t o aflord any reaction for thiocyanic acid, even if kept for several hours in contact with water, but i t was copiously desulphur- ised by alkaline lead or silver salts. In fact, the liquid was now apparently free from phosphorus thiocyanate, a1 though i t still dis- played the characteristic properties of a true thiocarbimide.I n order to ascertain the nature of this residual oil, experiments were now conducted on a larger scale : 16.4 grams of freshly distilled oil were shaken with successive amounts of about 50 C.C. of hot water and then repeatedly boiled with this solvent ; the aqueous por- tions at first contained large quantities of phosphorous and thio- cyanic acids, but after some fifteen extractions, tho cold aqueous extract no longer developed any red coloration with ferric chloride, Cold water was used in this experiment, because it was found that, no matter how often the treatment with boiling water was performed, a trace of ferric thiocyanate always appeared.After a few additional extractions, the residual oil was drawn off, its amount in this experi-DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. 357 ment being 54 per cent. of the weight initially taken. I n another experiment with thrice-distilled oil, the yield was 65 per cent. When dried over calcium chloride, the oil was distilled under reduced pres- sure, the boiling points observed being 173-174' and 1 6 8 O under 22 mm. and 17 mm. pressure respectively ; distillation now occurred with much less bumping than before, the contents of the flask did not solidify or even tbicken, and the amount of dark-coloured residue was very small. It will be noted that the former boiling point lies very close to that observed €or an unwashed specimen, whilst the latter is not very far removed from the mean of 163' and 169O under 15 and 20 mm.pressure respectively, observed on rectifying the unwashed products. The distillate was a clear, colourless, highly refractive oil ; the sp. gr. of the two specimens were 1.483 and 1.488 at 1 6 O , whilst that of the unwashed oil, as mentioned above, was 1.487 a t 15*5O. Consider- ing that only 2 to 5 C.C. of liquid were used in the determinations, these figures are practically identical ; i n other words, the removal, by washing, of from about one-half to one-third of the substance of the oil did not materially affect either its specific gravity or its boiling point. These facts are consistent with the view that the oil is a homogeneous compound; for, if only slowly solubIe in water, a portion might be withdrawn, leaving ZL residue with properties unchanged, but this refers to the physical properties alone, and does not explain why hydrolysis no longer occurs after some extractions, or why water dis- Bolves only a portion of the oil.On examining the distillate, it was found to undergo copious de- sulphurisation when warmed with alkaline solutions of lead salts or when its alcoholic solution was mixed with ammoniacal silver nitrate. But when shaken with water, the aqueous portion gave not a trace of red coloration with ferric chloride, and hence, not only was the phosphorus trithiocyanate (assuming that to be the source of the thiocyanic acid produced by contact with water) completely removed by washing, but, moreover, the residual portion did not regain the power to behave as a thiocyanate after having been subjected to a moderately high temperature.Excepting that it was practically in- soluble in water, the new substance had properties very similar to those of the unwashed material, and when analysed gave the follow- ing results : Found, S = 47.2. N = 20.9 ; P = 15.2. C,N,S3P requires S = 46-83, N = 20.49 ; P = 15.12 per cent. Now if true phosphorus trithiocyannte is hydrolysed by contact with water, the liquid isolated by the foregoing method must be an isomeride, and hence, presumably, the hitherto unknown phosphorus VOL. LXXXV, B B358 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. trithiocarbimide. Obviously, the next step was to ascertain whether it possessed the characteristic property of uniting with a primary nitrogenous base so as to yield the corresponding thiocarbamide. In order to test this point, a benzene solution of aniline was slowly added from a burette to a weighed quantity of the pure oil, freely diluted with this solvent, and kept near the freeziDg point of the mixture.A finely-divided white solid a t once began to separate, and the addition of the aniline was continued until a portion of the filtered liquid, when treated with a few drops of the solution, just ceased to yield any further precipitate, this stage being reached when, for each mol. of the oil taken, one mol. of aniline bad been used. Excess of base was avoided, because i t readily combines with the solid product, turning it into a viscid paste. The white powder was filtered off and washed thoroughly with dry benzene ; on allowing the filtrate to evaporate, there was scarcely any residue, thus showing that the aniline had almost completely removed the dissolved oil; the solid product, when dry, amounted to nearly 98 per cent.of the total weight of materials used. When heated in a narrow tube, the substance melted sharply without effervescence at 116-1 1'7' (corr.), changing into a golden-yellow liquid. Found, S=32*1. N= 18.2 ; P= 10.25. C,H7N,S,P requires S = 32-21 ; N = 18.79 ; P = 10.40 per cent. Accordingly, the product was a definite additive compound, P(CNS),,C,H5*NH,. Cold water had practically no effect on it except- ing after prolonged contact, but if warmed on the water-bath the mixture gradually became clear, a little hydrogen sulphide being evolved; when this was boiled off, the solution contained a large amount of thiocyanic acid, and was freely desulphurised by heating with alkaline lead tartrate.The source of the desulphurisation was phenylthiocarbamide, which separated in large crystals as the liquid cooled; only a trace of aniline could be detected and the solution, when oxidised by nitric acid, gave the reactions of phosphoric acid with magnesia mixture and with ammonium molybdate. It is curious to note that, whilst the parent oil is scarcely affected by water, even at the boiling point, yet after union with 1 mol. of aniline the resultant compound is easily hydrolysed, the uncombined CNS groups when thus separated making their appearance mainly as thiocyanic acid, although a little hydrogen sulphide is also formed.I n order to follow more clearly the course of the hydrolysis, some quantitative experiments were carried out, a few of which may be mentioned. To determine the amount of hydrogen sulphide liberated, a weighedDIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. 350 quantity of the fiolid was digested on the water-bath for half an hour with excess of arsenious acid solution slightly acidified with hydro- chloric acid ; the arsenious sulphide was collected, washed, dissolved by boiling for some hours with water, and the arsenic estimated by standard iodine ; the sulphur thus precipitated amounted to about 4 per cent.. Then, by boiling a weighed quantity with water, allowing t o cool, and collecting the phenylthiocarbamide formed, it was found that six-sevenths of one-third of the total sulphur, or 9.2 per cent., came out in this form, instead of 10.7.The solution of a weighed quantity, hydrolysed by water alone, was next treated with excess of silver nitrate, the mixed sulphide and thiocyanate separated by means of ammonia, and the latter salt, after precipitation with dilute nitric acid, collected, dried at l l O o , and weighed ; the mean of three fairly concordant determinations was 18 per cent. of sulphur in the form of thiocyanic acid, thus accounting for 97 per cent. of the total sulphur. The last result was checked in another way, by colorimetric estimation with a ferric salt, using N/400 potassium thiocyanate as standard ; although this process is not very accurate, i t was thus found that approximately two-thirds of the sulphur were hydrolysed to thiocyanic acid.Neglecting the formation of the hydrogen sulphide, the hydrolysis takes the following course : one =NCS radicle is eliminated with the aniline residue as phenylthiocarbnmide, and the two remaining CNS groups appear as thiocyanic acid; these results may be summed up by the equation : PhNH*CS*NH*P(CNS), + 3H20 = CSW2H,Ph + BHSCN + H,PO,. Assuming, for the moment, that the parent compound is wholly thiocarbimidic as to the contained CNS, it may appear strange that of the three -NCS groups one alone should exhibit pronounced activity in uniting with aniline, but so far a8 this is concerned the case is not without a parallel, the author having already observed a similar peculiarity with carbonyldithiocarbimide, CO(NCS), ; this substance, when treated with aniline until the precipitation of solid matter was just complete, gave carbonylthiocarbimidophenylthiocarbamide, SCN*CO*NH*CS*NHPh (Trans., 1903, 83, 89).I n this case, it was found possible, by allowing the thiocarbimide t o remain for a day or so in contact with excess of base, to obtain the dithiocarbamide, CO(NH.CS*NHPh),, but with benzylaniline only 1 mol. could thus be added. From these few data, it would be unsafe to generalise; nevertheless, so far as they go, they tend to indicate that, as *NCS groups accumulate in the acid molecule, their characteristic power of uniting with primary and secondary nitrogenous bases to yield thio- carbarnides becomes weakened.This may be equally true for certain combinations with inorganic radicles, and, if so, when a single phos- B B 2360 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS, phorus atom is united with three supposed thiocarbimidic radicles, the fact that one alone is capable of readily discharging the function peculiar to these groups, although no more intelligible than before, is nevertheless not quite abnormal. Without making assumptions with regard to the nature of the con- tained CNS groups, it is convenient to call that portion of the phos- phoretted oil which is removed and hydrolysed by water, “phos- phorus thiocyanate,” and that fraction which is not, “ phosphorus thiocarbimide.” The monophenylthiocarbamidic derivative of phos- phorus thiocarbimide, when suspended in warm benzene and mixed with 2 mols.of aniline, united with the latter quantitatively, forming a viscid oil, which slowly hardened ; after powdering and washing with benzene, the ill-defined product resembled that obtained by the direct action of 3 mois. of aniline on one of the unwashed distillate, and when treated with hot water, underwent hydrolysis, yielding much aniline thioc y anate, toget her with phen yl t hiocarlnsmide. Found, S=19-’? ; P=5*9 ; P(CNS),,SPhNH, requires 19*S3 and 6.4 That the further quantity of aniline taken up by the monophenyl compound had not entered into true thiocarbamidic combination, was made evident by the result of hydrolysis, when only 30 per cent. of the total sulphur made its appearance in the form of phenylthiocarb- amide.It bas been stated above that phosphorus trithiocarbimide is not attacked by water, and this is practically true. But if the oil, repeatedly washed with boiling water until the residue, when vigorously shaken with the cold or tepid solvent, does not cause the latter to give the slightest coloration with ferric chloride, is now left in contact with cold water, thiocyanic acid slowly passes into solution, so that after a few days the colour reaction may again be produced. A few washings with hot water suffice to remove all trace of the acid, but on leaving the residue with a fresh quanhity of water for two or three days, thiocyanic acid can be found in solution, just as before : a sample of washed and distilled oil, thus treated nine times at intervals of five or six days, had in the end become perceptibly reduced in bulk, but the residual oil, when thoroughly washed with boiling water and then left in contact with the cold solvent, gave the reaction apparently as markedly as a t the beginning. When left for six months, with occasional changes of water, the oil had not disappeared, and what was left did not seem changed, except in amount.The solution, if decidedly reddened by ferric chloride, always gave a slight, but distinct, desulphurieation when heated with alkaline lead or silver per cent.DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. 361 salts ; it is therefore probable that the ‘‘ phosphorus thiocarbimide ” slowly dissolves in the water as such, but cannot accumulate t o any appreciable extent, because the solution soon undergoes hydrolysis.If the aqueous mixture is kept for a month, it still gives only a slight desulphurisation when freed from the oil, whilst the thiocyanic reaction has now become strongly marked. Sharply contrasted with this reversion, which is so slow and minimal that it might easily escape notice, is the copious and rapid productiou of thiocyanic acid, which occurs on dissolving the monophenyl compound in warm water ; a possible explanation is that, when once the molecule is broken by the splitting off of the group *NH*CS*NHPh (representing it as symmetrical), the residue becomes unstable, and decomposes forthwith into thiocyanic and phosphorous acids. It is not easy, from the facts a t present available, to understand the precise nature of the distillate first obtained from phosphorus trichloride and ammonium thiocyanate before its thiocyanic characters (with respect t o water) have been practically destroyed by washing.The view that phosphorus trithiocarbimide is first formed and then decomposes partially into trithiocyanate is contrary to experience with other thiocarbimides, and is further negatived by the fact that when the trithiocarbimide has once been freed from thiocynnate, it does not afford a trace of the latter on redistillation. On the other hand, the converse assumption is not without some basis, for whilst a specimen, only once distilled, but apparently pure, judging from the analytical results, lost only about half its weight on treatment with water, another, thrice distilled, lost only about one-third.However, the preparations were not always made under precisely identical conditions a s regards temperature, time, dilution, &c., so that this argument should not be pressed too far; and the direct evidence cannot yet be obtained, namely, t h a t pure “ phosphorus thiocyanate ” is able to change at all into the thiocarbimide, since no means is known whereby the former can be isolated. It might seem obvious, a t first sight, t h a t “phosphorus thiocyanate,” which is acted on readily by water, must be a substance chemically distinct from “ phosphorus thiocarbimide,” which is not ; but as the presence of much thiocymate has scarcely any perceptible effect on either the density or the boiling point of the latter, there can be but little dis- similarity between them in respect of these physical properties.So far as the present experiments have gone, the washed oil appears t o have a slightly higher boiling point than the unwashed, but the difference, if it exists, cannot exceed some two or three degrees within the limits of pressure specified. Amongst hydrocarbon derivatives, the thiocyanate of a given -radicle boils, on the average,362 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. some 11 or 1 2 O above the thiocarbimide,+ so that, unless the difference is very small in the case of acid derivatives, the only reason for supposing the original distilled oil to be a mixture of two distinct substances lies in the fact that the rate of attack by water undergoes great retardation as the process of washing is continued.As regards the power to unite with one or three mols. of base, it does not appear t o matter whether the (‘ thiocyanate ” is removed or not ; moreover, it will presently be shown that a phosphoryl derivative, not washed, gives additive products precisely similar to those obtained with the washed phosphorus ‘‘ trithiocarbimide,” Phosphorpl c 6 Z’hioc3anate.” When phosphoryl chloride, diluted with dry benzene or toluene, was allowed to remain in contact with about one and a half times the amount of carefully -dried potassium or ammonium thiocyanate required according to the equation : POCl, + SNH,*SCN = PO(SCN), + 3NH4C1, interaction took place spontaneously : the mixture was then separated by means of the pump into (1) a solid residue, and (2) a clear yellow filtrate, no longer smelling of oxychloride.When treated with cold water, this residue yielded chloride and unchanged thiocyanate, leaving a yellow, amorphous powder, mostly soluble in boiling water, and giving the reactions of isoperthiocyanic acid. The filtrate was heated on the steam-bath, under reduced pressure, until the solvent was eliminated, and the residue, a viscid, reddish-yellow syrup, was submitted to distillation in a vacuum. The clear, pale yellow, highly refractive oil thus obtained boiled at 1 7 5 O (uncorr.) under 21 mm. pres- sure ; i t had a faintly pungent odour, and slowly evolved fumes of thiocyanic acid when exposed to ordinary moist air. I f tolerably pure, it may be kept for weeks without material alteration, otherwise it quickly becomes turbid, depositing a red, pasty substance.The yield of distilled product was not very satisfactory, the best attained being only 43 per cent. of the calculated quantity. As the crude oil bumps and froths considerably, a relatively large flask must be used, and the amount of material taken should not be large, for when the distillation is much retarded a good deal of black t a r accumulates, which apparently is formed from the oil by prolonged heating a t the boiling temperature. A freshly distilled specimen was analysed, with the following results : * The difference in specific gravity is usually inconsiderable for each pair of isomerides.DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. 363 Found, N = 19.15 ; S = 43.7 ; P = 14.2.C,N,S,OP requires N = 19-02 ; S = 43.45 ; P = 14.02 per cent. The sp. gr. is 1-52 at 13.5'. When mixed with excess of cold water, the oil dissolved, under- going hydrolysis tolerably rapidly ; the solution gave with ferric chloride a deep blood-red coloration, and with ammonium molybdate or magnesia mixture the reactions of phosphoric acid. The change under these conditions is mainly that represented by the equation : PO(SCN), + 3H,O = 3HSCN + H,PO,, for a dilute solution, when treated successively with excess of ammonia and silver nitrate, became only slightly darkened, and was not markedly desulphurised by boiling with alkaline lead tartrate. Moreover, about half a gram of the fresh oil, when decomposed by cold water, and treated with ammonia and magnesia mixture, yielded a quantitative amount of phosphoric acid, as calculated from the above equation, So far, therefore, the substance displays mainly the properties of a thiocyanate, but when added directly t o and shaken with an alkaline solution of lead tartrate, a white precipitate was formed, which slowly became yellow and orange, and finally black; this change, which is due to the production of lead sulphide, occurred instantly on gently warming, and the alcoholic solution, when mixed with silver nitrate and ammonia, WAS abundantly desulphurised, even in the cold; in these circumstances, the substance exhibited markedly the characters of a thiocarbimide.In the case of the phosphoryl compound, it was not found possible to eliminate the thiocyanate, leaving a thiocarbimidic residue, for on shaking 5 grams of the oil with about 20 C.C.of cold water, heat was developed, and the whole of the oil, except a decigram or so, rapidly dissolved, and when left for some little time, a yellow solid appeared, which was found to consist principally of isoperthio- cyanic acid; with 14 grams of oil, a similar result was obtained. Since a thiocarbimide, as such, could not be isolated, an attempt was made to combine the oil with organic amines, so as to obtain substituted thiocarbamides, but the experimental difficulties are very great, for, although combination occurs readily enough, the products are very unsatisfactory. Even when formed from apparently pure materials, they are often far from pure, and although usually pre- senting the appearance of crystallisable compounds, they have, so far, resisted every attempt made in this direction.By contact with water or with solvents containing even traces of it, they are readily hydro- lysed, so that, after many failures and in the absence of any better method, carefully purified materials were used for the preparations ; the products were thoroughly washed successively with benzene and364 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. light petroleum, dried at the ordinary temperature as far as possible in the absence of moisture, and then analysed. It will be seen from what follows that phosphoryl thiocyanate is capable of fixing primary amines, of which 1 mol. is held for each SCN group present, and this, without the formation of basic thio- cyanate ; nevertheless, the products are not true thiocarbamides (or, if so, differ from those at present recognised), since, when hydrolysed, they yield, not thiocarbamide done, but a mixture of thiocarbamide with basic thiocyanate.The results obtained in the experiments were not invariably the same, although approximately so ; each account given below is that of observations actually made, and not the average of a number of experiments. Action, of Aniline.-Eight grams of the oil were mixed with three molecular proportions of aniline, each reagent being diluted with about twice its volume of dry benzene ; interaction occurred instantly, the temperature rising to the boiling point of the mixture, and a yellow, doughy paste separated, which quickly became hard, and, when broken up and dried, formed a mobile powder, the weight of which approximately equalled that of the materials taken, The sub- stance had no definite melting point ; i t became translucent at 89' and frothed at 95-97'.When added t o , water, it was apparently quite insoluble, the mixture, even after thorough shaking, being neutral to litmus, and giving no reaction with ferric chloride or with calcium hypochlorite solution ; consequently, the powder was free from aniline thiocyanate. When left for a n hour or so with cold water, the mixture began to give the red thiocyanate coloration with ferric chloride, which slowly increased with the time. But if boiled with water, the solid quickly dissolved, evolving a little hydrogen sul- phide and leaving a trace of viscid oil; the solution now obtained was in tensely acid, contained large amounts of aniline, thiocyanate, and phosphoric acid, and on cooling deposited large crystals of phenylthio- carbamide. The production of the latter is not due to isomeric change of the aniline thiocyanate through heating, for the original solid, when dissolved in cold spirit, is desulphurised by ammoniacal silver nitrate ; moreover, if it is dissolved in cold dilute aqueous caustic potash and treated with a lead salt, a white precipitate is formed, becoming successively yellow, orange, brown, and finally jet-black ; the last change occurs a t once on gently warming.It is unnecessary t o describe in further detail the properties of this compound, for they agreed in every respect with those observed for the product obtained from the cumene solution, supposed to contain phosphory 1 thiocyanate (Trans., 1901, 79, 5493.Concerning the last-named product, it was montioned (Zoc. cit.) that when hydrolysed with boiling water itDIXON : CERTAIN ORGANIC PHOSPHORC'S COMPOUKDS. 365 yielded barely one-third of the phenylthiocarbamide which should be formed according to the equation : PO(NH*CS*NHPh), + 3H,O = H,PO, + SCSN,H,Ph. Whether the limited production of phenylthiocarbamide was normal or otherwise could not then be decided, since it was uncertain whether the cumene solution contained one substance only. This time, how- ever, there could be little doubt as to the chemical individuality of the oil, seeing that, apart from the analytical figures, the whole 8 grams of product distilled within about lo.I n repeating the experiment, 5 grams of the aniline compound were dissolved in 50 C.C. of boiling water, and the solution filtered from a trace of viscid oil ; on cooling, pure phenylthiocarbamide was deposited, the weight being 1.4 grams, corresponding with 28 per cent. of the theoretical as reckoned above; in another experiment, 30 per cent. was obtained. A further small quantity remained in solution, but this could not safely be collected by evaporation to a small bulk, because the aniline thiocyanate present gradually changes, under the influence of heat, into phenylthiocarbamide. This result, seeing that the experiment was only a rough one, does not differ materially from that previously recorded. Although the substance used had been well washed with benzene, it was evideutly not quite pure, as shown by the ill-defined melting point, and by its failixre to dissolve perfectly in water; an estimation of sulphur gave 18.9 per cent.against 19.21 calculated for C2,H,,N,0S,P, and the nitrogen was also too low ; the phosphorus, however, was found = 6.5, the calculated number being 6.45 per cent. Until the metthods and results now given can be improved, it may provisionally be concluded that phosphoryl thiocyanate is a definite chemical compound, which, when in contact with water, behaves as a true thiocyanate, but in presence of benzene alone can quantitatively fix three molecules of aniline, thus behaving as a typical (tri)thiocarb- imide ; the product, although free from aniline thiocyanate, can, nevertheless, readily yield it by hydrolysis, together with a little hydrogen sulphide, somewhat less than one-third of the contained sulphur being simultaneously liberated in the form of phenylthiocarb- amide.Of the three CNS groups present in the molecule, it appears, therefore, tbat only one is capable of exerting the power peculiar to the thiocarbimidic residue, ..KCS, of uniting with an amine so as to yield an atomic complex devoid of thiocyanic characters; the two remaining groups, when once the former is saturated, appear to be thiocyanic in nature, although possessing a certain capacity to hold the base in combination.366 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. It is possible to bring about union between the thiocarbimidic group alone and aniline, leaving the other two groups uncombined, as shown by the following experiment.To a cooled solution containing 1 mol. OC freshly distilled oil in about ten times its volume of benzene, 1 mol. of aniline was very slowly added with constant stirring ; a minutely-divided, white, amorphous solid was precipitated, the liquor from which gave no further precipitate with aniline, and left scarcely any residue on evaporation ; the kolid, when thoroughly washed successively with benzene and light petroleum and dried by gently heating, was equal to 93 per cent. of the total weight of materials combined. Had the aniline combined equally with all the SCN groups, much thiocyanate must have been left, whilst the yield of solid could not have exceeded 53 per cent.of the total weight of the reagents. The powder softened at 119' and melted at 12O-12lo (cow.) ; it was insoluble, or nearly so, in cold water, the mixture giving a feeble reaction for thiocyanic acid, but, on warming, it soon dissolved, the solution being highly acid, and containing free phosphoric and thio- cyanic acids, together with phenylthiocarbamide. As usual, a trace of hydrogen sulphide was evolved, but the solution gave only a faint reaction for aniline. Analyses gave : S = 30*3 ; P = 9.95. C,H,N,OS,P requires S = 30.6 ; P = 9-87 per cent. The phenylthiocarbamide produced by hydrolysis was collected and dried at 100' ; it amounted, as in the case of the phosphorous analogue, to six-sevenths of that which could be formed according to the equa- tion : PhNH°CSoNH*YO(CNS), + 3H,O = CSN2H,Ph + H,PO, + 2HSCN.When the above monophenyl compound (1 mol.) was suspended in benzene and warmed on the water-bath with aniliue (2 mols.), com- bination occurred, a clear, brown oil being formed, which hardened to a brittle resin on cooling, the latter, when powdered, washed with benzene, and dried, amounting to 96 per cent. of the weight of materials taken ; it resembled in all respects the product obtained by treating the trithiocyanate directly with 3 mols. of aniline, and gave, on analysis, N- 17.3 and 8 = 18.8 per cent., the calculated values being N = 16'84 and S = 19.21 for PO(SCN),,3C,H,NHz. A portion, hydrolysed by warming with water for three-quarters of an hour, yielded 41 per cent. of its sulphur in the form of phenyl- thiocarbamide ; this unusually high percentage is probably due t o the transformation of a portion of tho aniline thiocyanate due to prolonged heating.Action of p-Tohidine (3 mols.).-When brought into contact with oneDIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. 367 another in warm dilute benzene solution, the reagents united vigorously, the mixture boiling freely, and a trace of hydrogen sulphide being evolved; on cooling, an oil was deposited, which, when left for a few days in a vacuum, hardened to a pale yellow, amber-like resin, still smelling of benzene. The solvent evaporates very slowly, for, on analysis eight days later, the nitrogen and sulphur, although giving the ratio N, : S, were both found to be more than 1 per cent.below the cal- culated values; eventually, the solvent was removed by gently warming the powdered substance in a flask, through which a current OF dry air was kept passing for some hours ; it now gave the following results : .Found N= 15-15 ; S= 17% ; P =5.8. C,,H,r,ON,S,P requires N = 15-53 ; S = 17-73 ; P = 5.72 per cent. The yield of dry solid was not far from quantitative (about 95 per cent.); no definite melting point could be observed, the substance gradually softening from 95' onwards, until at 100' it formed a liquid evolving a gas. When shaken with cold water, the mixture gave a scarcely percep- tible reaction for thiocyanic acid ; if-boiled, i t dissolved almost entirely, evolving a little hydrogen sulphide ; the solution, on cooling, deposited p-tolylthiocarbamide, and the mother liquor gave the reactions of thiocyanic acid, phosphoric acid and p-toluidine. A rough experiment, made as in the case of the corresponding phenyl homologue, gave, for 1 mol.of substance, five-sixths of a mol, of p-tolylthiocarbamide. Action of a-Naphthylamine (3 mols.) .-On mixing the reagents, precisely the same phenomena were observed as in the case of aniline, the product being a doughy mass, which quickly hardened; when broken up, washed, and dried, it formed a pale yellow powder, the weight of which amounted to 96 per cent. of that of the materials used. Found, S = 14.85 ; P = 4.6. Heated in a narrow tube, it frothed up a t 119-120'; cold water had no effect on the finely-powdered substance ; when heated, phos- phoric and thiocyanic acids passed into solution, and a bulky, white solid was left, which was recrystallised from alcohol and identified as a-naphth ylthiocarbamide.Another experiment was made, using only one molecular proportion of a-naphthylamine ; the semi-solid product, which amounted to 96 per cent. of the weight of materials taken, presently became hard and brittle. It had properties resembling those of the corresponding aniline derivative, but was dirty orange in coloui-, and gave very unsatisfactory numbers on analysis, every attempt to purify the sub- stance having failed. C33H270N6S3P requires S = 14.77 ; P = 4.77 per cent.368 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. Action of Benxylani1ine.-When equal mols. were brought together in benzene solution, the mixture became warm, but remained clear. On cooling, small, white crystals separated, which were thoroughly washed with benzene; they melted sharply a t 137-138" (uncorr.) and amounted t o exactly the sum of the weights of the materials employed.Found, N=13-9; 5=21.2; P = 7 * 1 ; C16H,,0N,S3P would require N = 13.89 ; S = 23.78 ; 9 = 7.67 per cent. The substance was insoluble in cold water, the mixture being neutral, and giving no red coloration with ferric chloride ; on boiling, there was little sign of solution, but the iron salt now produced a dis- tinct reddening. Warm dilute caustic potash attacked the compound, forming a basic oil, probably benzylaniline, and the solution contained much thiocyanic acid. But the mixture with caustic potash was not desulphurised by boiling with lead tartrate, and the alcoholic solution darkened only slightly when treated with ammoniacal silver nitrate, so that the product of hydrolysis did not contain any considerable propor- tion of aa-phenylbenzylthiocarbamide (Trans., 1893, 63, 325).The analytical numbers for sulphur and phosphorus being unsatisfactory, an attempt was made to crystallise the substance from alcohol, but the product, an acid syrup, refused to crystallise, and the experiment was abandoned. Xunzmccry and Conclusion. It appears from the foregoing experimental work that phosphoryl thio- cyanate is a definite chemical compound, behaving towards water exclu- sivelyasa thiocyauate. Distilled phosphorus thiocyanate, although appar- ently a definite substance, can be resolved, by treatment with water, into two fractions, one of which, like the whole of the phosphoryl compound, is hydrolysed with ease, whilst the other fails t o undergo hydrolysis, except t o a minimal extent, although its physical properties (specific gravity and boiling point) are practically the same as at first.More- over, between t h a t portion which no longer reacts with water and the original distillate, which may lose about half its substance by contact with this liquid, there is no material difference as regards power to combine with aniline, for either can unite with 3 mols. of this base, but holding only a portion (approximately one-third) of this amount in ordinary thiocarbamidic combination. So far, therefore, as total aniline-fixing power is concerned, it does not appear t o matter whether the phosphorous derivative holds its *CNS groups in a form capable of acting towards water as *SCN or otherwise : in any case, one of the three will behave as *NCS towards the base.Consistently with this unexpected result, phosphoryl thiocyanate, notwithstanding that water eliminates the whole of its *CNS a6DIXON : CERTAIN ORCANIC PHOSPHORUS COMPOUNDS. 369 thiocyanic acid (the formation of isoperthiocyanic acid is easily ex- plained by the interaction of the liberated phosphoric and thiocyanic acids), can also fix three mols. of aniline, of which only one appears as phenylthiocarbamide, when the product is bydrolysed. Again, if only one molecular proportion of aniline is presented to one of phosphoryl thiocyanate, it will not distribute itself uniformly over the contained *SCN, but will unite entirely with a single group, which behaves as *NCS in this senso, that practically the whole of the combined base may on hydrolysis be recovered as phenylthiocarbamide.I n like manner, if the phosphorous analogue, deprived by washing of prac- tically all its power of behaving towards water as thiocyanate, is treated with one mol. of aniline, the latter will be so fixed that it may be almost completely recovered in the form of phenylthiocnrbamide ; but if the additive product be combined with an additional 2 mole. of aniline, the compound thus obtained will still give only one mol. of phenylthiocarbamide when hydrolysed. The hydrolytic experiments were usually completed within a few minutes, the temperature being in the neighbourhood of SOo, so that the process, as conducted, could not lead t o any material isomeric re- arrangement of whatever basic thiocyanate might be formed; in these circumstances, the amount of substituted thiocarbamide produced was taken as a measure of the thiocarbimidic power available in each substance.Wheeler has proposed the treatment with thiolacetic acid as a means of distinguishing between thiocyanates and thiocarbimides (J. Anzer. Chem. SOC., 1901, 23, 285; Amaer. Chem. J., 1901, 26, 348), the sub- stances which yield carbon disulphide (and substituted amide) being regarded as thiocarbimides, and those which do not as thiocyanates. Although this appears to be a useful method of discrimination where hydrocarbon derivatives are concerned, it cannot be regarded as ab- solutely final in the case of acidic compounds ; or, a t most, i t can only be used to decide how the *CNS group behaves towards that particular substance a t the moment of interaction, and this information does not go far enough with acidic thiocyanates, which are all more or less prone to undergo tautomeric change.Applying this method, he decides that acetyl thiocyanate is a true thiocysnate, a conclusion arrived at by Miquel from another point of view, and which is doubtless perfectly correct under certain Conditions. But the totally different behaviour which it can exhibit on changing the conditions of interaction (Miquel calls it ‘‘ abnormal ”) is most easily explained by supposing t h e com- pound t o have assumed, for the time being, the thiocarbimidic con- figuration.It is conceivable that in the formation of acetylphenyl- thiocarbamide by the action of aniline, a compound, AcS*C(NM)*NHPh, might be the first product ; if, now, the acetyl group migrated to the370 DIXON : CERTAIN ORGANIC PHOSPHORUS COMPOUNDS. imino-group and the sulphur atom became doubly linked to carbon, the ‘‘ abnormal ” production of the disubstituted thiocarbamide could be explained. Indeed, the migration of the acetyl group in compounds already thiocarbamidic in structure is not unknown, Wheeler having adduced evidence (Amer. Chem. J., 1902, 27, 274) that the change of Hugershoff’s acetylphenylthiocarbamide (m. p. 139’) (Ber., 1899, 32, 3649) into the isomeride melting at 171’ occurs as follows : AcPhN*CS*NH, -+ AcNH-CS-NHPh.With the data hitherto secured, it is not possible to state with certainty what is the mechanism whereby such changes are produced; but the author at present holds the view that in so Par as a CNS compound unites spontaneously with aniline to yield a phenylated thiocarbamide or its immediate normal derivative it should be regarded as a thio- carbimide ; from this standpoint, it becomes necessary to postulate the existence of tautomerism amongst certain ‘‘ thiocyanates.” Another method of distinction proposed by Wheeler (Arne~. Chem. J., 1901, 26, 349) consists in reducing the alcoholic solution of the ON8 compound with sodium, when thiocyanic acid is produced from a thio- cyanate, but not from a thiocarbimide; this test, however, is too drastic for members of the acidic class.Thus, benzoyl thiocyanate unites directly with primary and secondary amines t o form thiocarb- amides ; with alcohols, to form alkyl esters of thiocarbamic acid, and with phenylhydrazine to form a disubstituted thiosemicarbazide. Its behaviour towards water has already been mentioned. Even with ammonia, which often brings about double decomposition amongst the acidic thiocarbimides, it yields benzoylthiocarbamide, and consequently there can be no question as to the marked preponderance of thiocarb- imidic character in this substance. Yet, as usual, a limit to the power of retaining the *NCS configuration can be reached, for on treating the compound with sodium, thiocyanic acid passes into solution. Wheeler also records certain observations by T. B. Johnson, showing that when it was made to interact with ethyl sodiornalonate, sodium formanilide, sodium phenoxide or ethyl sodioacetoacetate, the *NCS group was removed as sodium thiocyanate. In the light of all the facts now available with respect to the acidic “thiocyanates” as a class, i t seems tolerably safe to venture the general statement that there is no known member of this class, how- ever pronounced its thiocarbimidic characters may be, which cannot be made t o behave as a thiocyanate. Returning now to the phosphorus compounds, it must be admitted that, since no satisfactory means of purification could be found for their derivatives, the composition of the latter has been based on the analysis of somewhat ill-defined substances ; on the other hand, mostSODIUM HYPOCHLORITE AND AROMATIC SULPHONAMIDES. 371 of the foregoing experiments have been repeated much oftener than appears in the paper, so that the general results may be taken as being fairly trustworthy. Probably the selection of this particular class of substances a s objects of study was not a happy one, seeing that even when a single CNS group is combined with an acid radicle, it may lose its definite configuration and oscillate between *SCN and *KCS. When two such groups are present, one may be highly active, as *NCS, whilst the other is comparatively sluggish, and easily hydrolysed out of combination, as *SCN, although capable ultimately of exerting its full thiocarbimidic power. Under suitable conditions, the behaviour of carbonyldithiocarbimide, referred to earlier (p. 359), may be cited as a case in point. With three such groups attached to a single mineral radicle, their limited capacity to act as *NCS might perhaps almost have been anticipated. On the other hand, experiments conducted with the view of obtaining mono- and di-thiocyanates of purely inorganic acid radicles have hitherto proved unsuccessful. I n conclusion, the writer desires t o express his indebtedness to Mr. R. E. Doran for assistance rendered in connection with the experi- mental work described above. CHEMICAL DEPARTMENT, QUEEN'S COLLEGE, CORK.

ISSN:0368-1645    

DOI:10.1039/CT9048500350

出版商:RSC    

年代:1904

数据来源: RSC