摘要:

108 DIVERS : PEHOXYLAMINESULPROKIC ACID. By EDWARD DIVERS. ALTHOUGH unrecorded in works on chemistry or chemical technology, i t has long been known to inspectors and workers of the lead-chamber process for manufacturing sulphuric acid, that when, through improper working of the chambers, sulphur dioxide is allowed to pass into the Gay-Lussac tower, i t produces with the nitrososulphuric acid, also present in the tower, what is called ‘‘ purple acid,’’ together with a n effervescence due to the escape of nitric oxide (Carpenter and Linder, J. Xoc. Chena. I r ~ d . , 1902, 21, 1492). Sabatier has shown (Cornpt. Tend., 1896, 122, 1417, 1479, and 1537; 123, 255) how t o give an intensely bluish-violet coloar, evidently the same as that of ‘6 purple acid,” to the monohydrate of sulphuric acid holding nitroso- sulphuric acid in solution, eitber by passing sulphur dioxide into it, or by mixing i t with sulphuric acid of similar strength containing dis- solved sulphur dioxide.Such a sulphuric acid solution of sulphur dioxide may also be treated for some time with a current of nitric oxide and a i r ; or, excluding air, the nitric oxide alone will produce the colour, when a very small quantity of either copper sulphate or ferric or ferrous sulphate has been previously dissolved in the acid. Lastly, certain metals and other substances serve to produce tbis colour, or a modification of it, by acting on nitrososulphuric acid in monohydrated sulphuric acid, among them being finely divided copper, silver, or mercury. Sabatier has not isolated the substance which gives this violet colour t o sulphuric acid treated by the foregoing processes, but has suggested that it may be the unknown acid OC Fremg’s sulphaxilate, which he renames nitrosodiszdphonic acid.Now, in the preceding paper on peroxylaminesulphonates, Haga has adduced reasons for doubting the correctness of Sabatier’s suggestion that the bluish-violet acid is sulphazilic acid, that is, peroxylamine- sulphonic acid. There is also one consideration which, although not mentioned by Haga, may, nevertheless, have affected his judgment. This is the fact that a substance which, according to Haga’s most con- clusive evidence, must be a peroxide, should be produced in the ways described by Sabatier. But this difficulty and those raised by Haga all seem to disappear when the changes which give rise to the acid and the very different conditions for the production of the salt and of the acid are all more closely examined, and leave nothing in the way of accepting the view that this acid is peroxylaminesulphonic acid.The fact that the violet acid is dissolved in sulphuric acid, whereas the violet salt is in aqueous solution, has to be taken into accountDIVERS : PEROXYLAMINESULPHONIC ACID. 109 when the differences in the behaviour of the two are under considera- tion. It will then be seen that these differences are really not greater than those between a sulphuric acid solution of nitrous acid (as nitroso- sulphuric acid) and an aqueous solution of potassium nitrite. The latter when acidified and the former when diluted both quickly lose most of the nitrous acid, there being no stable existence of this acid in the intermediate conditions.Potassium nitrite solution is un- affected by hydrogen peroxide or potassium permanganate, being, in fact, producible from nitric oxide by alkaline hydrogen peroxide (Carpenter and Linder, Zoc. cit.), and from hyponitrite by perman- ganate (Thum, Monutsh., 1893,14,294), whereas nitrous acid is converted by these reagents into nitric acid. Lead peroxide may therefore very well be active towards a sulphuric acid solution of peroxylamine- sulphonic acid, although it does not interact with an aqueous solution of its salts. Again, that sulphur dioxide should nut interact with peroxylaminesulphonic acid in presence of much sulphuric acid, and yet be very active towards a salt of the acid in water, may well be an instance of what indeed happens in the case of mercuric oxy-salts, on which, in presence of much sulphuric acid, sulphur dioxide is no longer active (Trans., 1886, 49, 576), or in that of ferric salts, which are very much more easily reduced by sulphur dioxide in the absence of eulphuric acid than in the presence of excess of it.Similarly, it may further be properly maintained that i t does not follow that hydroxylaminetrisulphonic acid should be produced from peroxylamine- sulphonic acid in sulphuric acid solution because its salt is produced in a neutral or an alkaline aqueous solution of a peroxylamine- eulphonate. This contention being admitted, the non-formation of this acid, observed by Haga, is not significant. Since the well-known compound, nitrososulphuric acid, is not a sulphonic derivative, as Sabatier takes it t o be, but the mixed anhydride of nitrous and sulphuric acids, the nature of its conversion into the violet acid is easy t o understand.Regarding the mixed anhydride as being simply nitrous anhydride (the sulphuric acid being undecomposed), the production from it of nitric oxide and per- oxylaminesulphonic acid is seen t o be only its usual decomposition into nitric oxide and nitric peroxide, except that the latter product is now sulphonated : 20(NO), + 4S0, + 2H20 = 2NO + [ON(SO,H),],. When metallic copper is used in place of sulphur dioxide, the genera- tion of the necessary sulphur dioxide by the action of the metal on the pyrosulphuric acid of the nitrososulphuric acid only introduces an interesting complication.Pyrosulphuric acid at once interacts with copper in the cold (Trans., 1885,47, 638).110 DIVERS : CONSTITUTION OF NITRIC PEROXIDE. There remains t o be considered the production of the purple acid along with nitrososulphuric acid from nitric oxide and sulphuric acid in the presence of cupric or ferric sulphate as a catalytic agent. The sulphuric acid being represented as existing in its pyro-state (the form in which it acts in presence of an oxide of nitrogen), the change is expressed by the equation: 6N0 + 40<s0;H so w = 4@<N$ SO H + [(SO,H),N0I2. As to the peroxidising action of pyrosulphuric acid here shown, it may be well to recall the action of the acid on metallic tin in presence of hydrochloric acid (Heumann and Koechlin, Be?.., 1882, 15, 420) : Sn + 4HC1+ O(SO,H), = SnCl, + 2S0, + 3H,O. I n this equation the stannic chloride and the sulphur dioxide together take the place of the peroxylaminesulphonic acid in the previous one, for [ON(SO,H),], can evidently be expanded into N,O, + 4S0, + 20H,. It is difficult to conceive of any other rational interpretations of Sabatier’s remarkable results than those given above, and these are all consistent with the assumption that the purple acid is not merely isomeric, but actually identical with peroxylaminesulphonic acid, and is therefore a peroximide and an exclusively trivalent nitrogen com- pound.

ISSN:0368-1645    

DOI:10.1039/CT9048500108

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

110 DIVERS : CONSTITUTION OF NITRIC PEROXIDE. X 11. - Cons tit u t iorL of Nitric Pel-oxide. By EDWARD DIVERS. IN a paper now appearing (this vol., p. 78), Haga has demonstrated that Fremy’s sulphaxilate is an oxime-peroxide and a trivalent nitrogen compound. If Hantzsch and Semple’s suggestion is accepted (Ber., 1895, 28, 2744; compare Piloty and Schwerin, Ber., 1901, 34, 1884 and 2354), that Fremy’s salt is also a sulphonated nitric peroxide, it follows that the constitution of nitric peroxide is a t last determined, being that of nitrosyl peroxide. Hantxsch and Semple must be right, for, after Haga’s researches, a sulphazilate as a peroxylaminesulphonate cannot be supposed to be other than a sulphonated nitric peroxide. It only remains, therefore, to show that nitric peroxide is a true peroxide in its chemical relations.It is formed from nitric oxide and oxygen, just as sodium peroxide is formed from sodium and oxygen, Nitrous acid cannot, indeed, be shown to pass simply into it and back again, as a hpdroxylamine-DIVERS : CONSTITUTION OF NITRIC PEBOXIDE. 111 disulphonate (sulphonated nitrous acid) changes into a peroxylamine- sulphonate, but that is only on account of its own instability and that oE nitrous acid. Its interaction with organic oximes, in which it converts these substances into peroxides and becomes hydrogenised into nitrous acid (Scholl), is in accordance with its nature as a true peroxide. Similarly, it converts a hy droxylamined is ulphonat e into a perox y lamines ulphonate Nitrosyl peroxide and a peroxylaminesulphonate both interact with water in essentially the same way, the apparent difference being due t o the limits imposed by the sulphonation in the case of the latter substance.The former yields half its nitrogen as nitric acid and half as nitrous acid, whilst the latter yields half its nitrogen as a mixed anhydrosulphate (hydroxylaminetrisulphonate) and the other half as nitrous acid and sulphonated nitrous acid (hydroxylaminedisulphonate) : 2N20, + 2H,O = ZHNO, + 2HN0,; 2N20z(S03K), + H,O = 2(S03K)2N*O*S03K + [HO*NO + HO*N(SO3K>,]. It would seem, therefore, that, wholly on the evidence afforded by Haga’s work, it can now be confidently asserted that llinitric peroxide is nitrosyl peroxide and a compound of exclusively trivalent nitrogen. The constitution of mao-nitric peroxide, in regard to these two points, remains to be considered, but can hardly be very different.Hantzsch and Semple have suggested (Zoc. cit.) that the bluish- violet dissolved form of a peroxylaminesulphonste corresponds with mono-nitric peroxide, and its crystalline form with di-nitric peroxide. Since then, Piloty and Schwerin (Zoc. cit.) have expressed the belief that porphyrexide, which has the colour of mono-nitric peroxide, may also be a derivative of this peroxide, because it contains the group :NO singly, as shown by the formula (C,HgN,):NO. Its molecular weight, however, has been only indirectly ascertained, that is, by cryoscopic determinations of those of its nitrate and its chloro- derivatives. That its molecular weight is not double as great is a re- markable fact,, for, in its chemical behaviour, and especially in its re- versible relation with porphyrexine, (C,HgN3):NOH, porphyrexide seems to belong to the class of oxime-peroxides Piloty and Schwerin do not indeed recognise this, and have instead come to the conclusion that the nitrogen of the group :NO in porphyrexide and in mono-nitric peroxide must be quadrivalent.I n the light of Haga’s experimental results, this view of the matter has become untenable, since por- phyrexide and the peroxylaminesulphonates appear to belong to the same class of nitroxy-compounds, as Piloty and Schwerin themselvea have pointed out. I n the few cases in which it has been possible to determine (Hags).112 DIVERS : COKSTITUTION OF NITRIC PEROXIDE.cryoscopically the molecular weight of a glyoxiine-peroxide, this has been found to include :NO twice. This result may be owing to the glyoxime constitution of these peroxides, but, even SO, there is still no peroxide, except mono-nitric peroxide, and possibly porphyrexide, the molecular weight of which is such that it contains the group :NO only onc0. The cccurrence of many nitroso-zompounds in a colour- less, solid form, and in a bluish-violet liquid form, does not lend much assistance in deciding the molecular weights of the two forms of a peroxylaminesulphonate, since they contain not :NO but *NO. But it must not be left out of sight that Piloty (who thinks otherwise, and has been followed by Schmidt, Bamberger, and others) has succeeded in showing that the white form of these compounds contains the group *NO twice, and that the deeply-coloured modification contains i t only once.But here the latter is the form which must be treated as the chemically active one, whilst the double weight found for the white form has t o be left uninterpreted chemically, as, for example, in the case of the formula (C,H,,NO), for nitroso-octane, I n the paper by Hantzsch and Semple (Zoc. cit.), there occurs, but in a foot-note only and without comment or explanation, the punctuated formula O*N:(SO,K),; whether this is to be regarded a8 a printer’s error for O:N:(SO,K), is uncertain, but if it is not, it indicates some recognition by these chemists of the presence of univalent oxygen, However this may be, the possibility of the nitrogen being quadria valent being inadmissible, the only solution of the matter seems to be to consider that both mono-nitric peroxide and porphyrexide are com- pounds of univalent oxygen, although still peroxides.The fact t h a t a molecular quantity, such as that formulated by HO, NO,, (SO,K),NO, or (C,H,N,)NO, is never met with singly in chemical interactions mili- tates against the acceptance of this explanation. Piloty and Schmerin, in discussing the quadrivalency of nitrogen, conceal this fact by stating that porphyrexide is produced from porphyrexine by the action of half an atom of oxygen, It is much more correct to hold with Haga that the molecule of peroxylaminesulphonate, and therefore also of mono- nitric peroxide and of porphyrexide, is not leas than that represented by [NO(SO,K),],, (NO,),, or (C,H,ON,),, as the case may be, if by molecule is meant the smallest chemically active weight of a substance.But still the fact remains that, when measured by comparison of their physical properties, the molecular weights of porphyrexide and red nitric peroxide are expressed by half the above formulae, and that probably the bluish-violet form of a peroxylaminesulphonate has also a molecular weight, which, when physically considered, should be expressed by the formula NO(SO,K),. These weights, only physically determined, have no chemical significance, and should be distinguished from their doubles, the truly chemical molecular weights. But, asSOLUBILITY CURVES OF THE HYDRATES OF NICKEL SULPHATE. 113 pseudo-chemical molecules, they must be represented as containing a univalent atom of oxygen. It is, after all, not so difficult to admit that oxygen may be univalent in a peroxide. I n fact, a true peroxide may be defined and differentiated from other oxides, as being a compound in which some or all of the oxygen is exerting on the rest of the compound only half its usual valency. Or, conversely, a peroxide may be defined as a compound containing oxygen which is either actually univalent or exterior and quasi-univalent. Apart from the unfamiliar nature of the conception of actually univalent oxygen, it seems natural enough to find a normal molecule of nitric peroxide dissociate a t a gentle heat into two identical but simpler ones, in consequence of the linked oxygen atoms becoming parted and losing valency. On the other hand, the assumption that nitrogen is quadrivalent does not accord with the result actually obtained, when by cooling nitric peroxide it is found that the valency of the nitrogen decreases instead of increas- ing, 2 0 : K :O becoming O:N*O*O*N:O.

ISSN:0368-1645    

DOI:10.1039/CT9048500110

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

SOLUBILITY CURVES OF THE HYDRATES OF NICKEL SULPHATE. 113 XIII.-The Solubility Curves of the Hydrates of Nickel Xzdphate. By BERTRAM DILLON STEELE, D.Sc., and F. M. G. JOHNSON. THE experiments recorded in this paper were undertaken with the object of determining the conditions of equilibrium and the composition of the phases in the two component system, nickel sulphate- water. Hydrates of nickel sulphate have been described containing 1, 2, 6, and 7 molecules of water. The heptahydrate, which is found in nature as the mineral moresonite, may be obtained by crystallisation at the ordinary temperature from neutral solutions of the salt. It occurs in the form of pale green, rhombic crystals isomorphous with heptahydratsd magnesium sulphate, and on prolonged exposure to the atmosphere becomes changed into aggregates of blue crystals having the composition NiSO,,GH,O.This change has, for a long time, been regarded as being brought about by the action of sunlight (Phillips and Cooper, Poggendorf s Annalem, 1879, 6, 194)) but Dobrosserdoff (J. Russ. Phys. Chem. Xoc., 1900, 32, 300) has recently shown that this is not the case, since sunlight has no effect on the heptahydrate, provided that the crystals are contained in a space saturated with water vapour and maintained a t a low temperature ; accordingly the VOL. LXXXV. I114 STEELE AND JOHNSON : THE SOLUBILITY CURVES OF reaction in question is a simple case of efflorescence. The same hexahydrate was obtained by Brooke and Phillips (Zoc. cit.) and by Pierre (Ann. Chim. Phys., 1846, [iii], 16, 252) in the form of blue, tetragonal crystals by crystallisation at the ordinary temperature from a solution containing sulphuric acid, and by Marignac aud Mitscherlich from neutral solutions a t about 40'.Isothermal crystallisation of neutral solutions a t temperatures between 60' and 70" yields a bright green, monoclinic salt which also contains 6 molecules of water. The dihydrate is described by h tard (C'ompt. rend., 1878,8'7, 602) as being formed by the action of strong sulphuric acid on the hexa- or hepta-hydrates, and Lescceur (Chem. Centr., 1895, i, 525) states that by adding concentrated sulphuric acid to a solution of nickel sulphate, a precipitate of the monohydrate is obtained. The study of the solubility curves of nickel sulphate between - 5 O and 100' has not indicated the existence of any hydrate containing less than 6 molecules of water of crystallisation.Solubility determina- tions have not been made at temperatures above loo', but from the curves of Etard and Engel (Compt. rend., 1888, 106,206) there appears to be a transition point at about 118', and on analysing the solid phase separating a t 131°, we found it to be the dihydrate, NiS0,,2H20. The solubility of nickel sulphate has been determined a t various temperatures by Tobler (Annulen, 1S55, 95, 193). His results, how- ever, differ considerably from ours, and are not sufficiently numerous to indicate the position of the various transition points. Preparation of the Hydrates. The heptahydrate was prepared by twice recrystallising the ordinary salt and shown to be pure by analysis.The salt used in estimating the solubilities a t a few temperatures was prepared by precipitating a saturated aqueous solution with alcohol, and was thus obtained in the form of very small, green, granular crystals containing 21.12 per cent. of nickel, the calculated value being 20.91. The foregoing salt, when left in contact with its saturated solution for some hours a t any temperature between 32" and 53', is converted into the blue hexahydrate, which was analysed with the following result: Found Ni = (1) 22.54; (2) 22.41. NiSO4,6H,O requires Ni = 22.23 per cent. The blue hexahydrate, employed in the experiments made between 32" and 53O, was prepared by the slow evaporation at the ordinary ternperxtnre of solutions containing 30 per cent. of sulphuric acid,THE HYDRATES OF NICKEL SULPHATE.115 The large crystals thus obtained were powdered and thoroughly washed with a saturated solution of nickel sulphate in order to remove sulphuric acid, If the heptahydrate or the blue hexahydrate is left in contact with the saturated solution at temperature above 54*, it very rapidly becomes converted into the bright green, monoclinic salt which, on analysis, was found to have the same composition as the blue tetragonal hydrate. Found, Ni = (1) 22.55; (2) 22.50. NiS04,6H20 requires Ni = 22.23 per cent. In order to determine the composition of the solid phase, which is present a t temperatures above 118O, a quantity of the dry hexahydrate was sealed up in a thick walled glass tube and heated for some hours at 131O. A little below this temperature, the substance partially melted with the formation of a clear green solution and a dull yellowish-green, amorphous solid, for the separation of which the following method was adopted.The tube containing the mixture was carefully inverted, so that; the greater part of the liquid drained away from the powder. After cooling in this position, i t was cut into two park, and the solid, placed on pieces of porous tile, was sealed up in another tube and again heated at 131'. The adherent liquid portion, which had solidified on cooling, again liquefied and was absorbed by the porous tile, leaving the new salt practically dry and pure, as indicated by the following analysis : Found, N i = (1) 30.8 ; (2) 30.57.NiS04,2H20 requires N i = 30.87 per cent. Solubility Determinations. The solubilities were determined by enclosing the salt, with the requisite amount of distilled water, in tubes provided with well-fitting india-rubber stoppers. The tubes were attached to a shaking appa- ratus driven by a Henrici hot-air motor, and immersed in a thermostat provided with a toluene gas regulator, by means of which the tempera- ture could be kept constant to n tenth of a degree. Preliminary experiments having shown that equilibrium was reached i n about, 12 hours, the tubes were shaken for twice that time to ensure saturation. The solutions were filtered within the thermostat in the following manner. The india-rubber stopper in the solubility tube contained a hole, which was closed with a glass rod during the shaking.When it was desired to filter the solution, the rod was withdrawn, and in its place was inserted a piece of glass tubing with a small bulb blown in 1 2116 STEELE AND JOHNSON: THE SOLUBILITY CURVES OF the centre, this bulb being packed with asbestos to serve as a filter. The other end of the tube passed through an india-rubber stopper, which fitted into a weighing bottle, and through which passed a glass tube long enough to reach out of the thermostat. The solubility tube was thus attached to a weighing bottle by a filtering tube, and by in- verting the two and applying suction to the projecting tube, the solution was filtered without having been for an instant removed from the bath. The filtrate in the weighing bottle was weighed and diluted t o 500 c.c., a convenient portion of this solution being taken for analysis.The nickel was estimated electrolytically, using a current density of 0.5 ampere, 8 to 10 hours being required for the electrolysis, which was carried out in a solution containing ammonium sulphate and excess of ammonia. All the solubility results (with the exception of those a t 0' and - 5') are the mean values of a t least two closely concordant determinations carried out in different vessels. Of the experiments recorded in Table I, the first was carried out in TABLE I.* (1) The solubility curve of NiS0,,7H20, Salt used. 1. NiS04,7H20 2. - 3. - 4. - 5. - 6. - 7. - 8. NiSO,,GH,O 9. NiS0,,7H20 10. NiS0,,6H20 11. NiSO,, 7H20 12. NiSO4,6H,O 13. NiS0,,7H20 14.'15. NiSd;,GH,O I Temprature. 1 Concentration. - 5" 0 9 15 22 '6 22'8 30.0 30.0 32.3 32.3 33.0 33 .o 34.0 34.0 34'0 25.74 27'22 31 -55 34.19 37 *go 38'88 42-46 42-47 44-02 43-57 45.74 43.35 45-5 43.84 43.82 Salt remaiuing. NiS0,,7H20 - - NiYO,, 7H20 NiSO,, 6H,O NiS0,,7H20 N SO,, 6H20 NiS0,.7H,O NiS04,6H,0 * I n this and the other tables in the paper, concentrations are expressed as parts by weight dissolved in 100 grams of water. a bath of brine surrounded by a mixture of powdered ice and salt, and maintained at a constant temperature by allowing a very slow current of warm brine to circulate through the bath. The second experiment was carried out in a bath of melting ice. For temperaturesTHE HYDRATES OF NICKEL SULPHATE. 117 below 30', the heptahydrate only was used in determining the solu- bilities.For temperatures between 30' and 34', a number of experi- ments were made, using both the heptahydrate and the blue hexahydrate in the hope that a portion of each curve extending beyond the transition point might be realised. This has been done for the heptahydrate, the metastable portion of the curve being repre- sented by experiments 9, 11, and 14, in Table I, which give solubilities of the heptnhydrate at temperatures close to the point of transition of this hydrate into the hexahydrate. I n experiment S, in which the solid phase was originally the blue hexahydrate, transformation rapidly took place into the green heptn- hydrate, and although many attempts were made, it was not found possible to obtain the metastable portion of the curve for the hexa- hydrate.I n the accompanying diagram (p. llS), the experiments from this table are represented by the curve ABC. TABLE 11. Solubility curve of NiSO,,GR,O (blue tetragonnl). Salt used. NiS0,,6W20 (blue) NiSO:: 7H,O NiSd,: 6H,O NiSO,, 7H,O NiSO4,6H,O (blue) I Temperature. 32.3" 33'0 34 .o 35.6 44'7 44.7 50.0 51.0 52 '0 53.0 54.5 Concentration. 43.57 43-35 43'84 43.79 48.05 47 -97 50.15. 50.66 52.34 52.34 52 -5 Salt remaining. NiSO,,GH,O (blue) - NiS0,,6H20 (green) On plotting the results collected in Tables I and IT, the two curves are found to interse'ct between 31' and 32'. The transition ioint corresponding with the change NiS0,,7H20 ZZ NiS0,,6H20 + satur- ated solution therefore lies very near to 31.5'. In order to confirm this point and in the hope of determining it with greater accuracy, experiments were carried out with a dilatometer, which assumed the usual form of a large thermometer with a graduated stem partially filled with a mixture of the heptahydrate, the blue tetragonal hexa- hydrate, and a certain amount of nz-xylene.The vessel, being ex- hausted to remove air bubbles from the salt, was then filled to the118 STEELE AND JOHNSON: THE SOLUBILITY CURVES OF Salt used. Tempera- ture. -- NiS04,6H,0 (blue) 54.5" y y } 57.0 NiS 0117 H20 required position with more of the hydrocarbon and placed in a bath at 30'. The temperature was now allowed to rise very slowly; a steady increase of volume occurred up to 31.4O, when there was a sudden break followed by a much smaller increase as the temperature was raised still further.The transition point may therefore be taken as lying between 31.4' and 31.6'. Concen- tration. Salt used. Concen- tration. -1- 52.50 NiS04,7H,0 70.0" 59-44 53.40 NiSO4,6H,O (blue) 73.0 60'72 Temperature. NiS04,6H,0 (blue)} NiS04,7H,0 3s TABLE In. 60,0 54.84 NiSO::7H2O " ] 80'o 63'17 Y P 89-0 67.90 $ 9 99.0 76-71 Throughout the series of determinations indicated in Table 111, The solubility data obtained in the neighbourhood of 52' indicate a the rem.aining salt is the green, monoclinic hexahydrate.THE HYDRATES OF NICKEL SULPHATE. 119 break in the curve, due to a second transition point, This inflexion, which is very slight and might be easily overlooked, is confirmed by the appearance of the residual solid phase after equilibrium is established.If we start with the blue, tetragonal hexahydrate, a t temperatures above 53" a very rapid change takes place, the blue substance giving place to a bright green solid having the same com- position. On the other hand, this green salt is' rapidly converted at temperatures slightly below 53" into the blue modification, and on plotting, on a large scale, the results given in Tables I1 and 111, the two curves are found to cut each other very close to 53". I n order to confirm this conclusion, experiments were made with a dilatorneter containing initially the blue hexahydrate mixed with a small quantity of the green salt. No indication of a break could be detected until the mixture was heated for sorce time at 70", when the salt was seen t o have changed into the green modification.The dilatometcr was then placed in a bath at 56" and allowed to cool slowly, when there was a steady contraction down to 54*0°, then little or no contrac- tion until 53-3", and then a steady contraction, but less than the original diminution. A duplicate experiment confirmed this result and also failed to detect any break on slowly raising the temperature from a point below 53". According to this result, the temperature corresponding with the change NiSO,,GH,O (blue tetragonal) Z NiSO,,GH,O (green monoclinic) lies between 53.3" and 54". Tho solubilities give this temperature as lying near 53", and 53.3" is pro- bably not far from the trce transition point. Since the solubility curves of the three salts, NiS04,7H20, NiS0,,6H20 (blue), and NiSO4,6H,O (green), lie so nearly in a straight line, it was thought that possibly a break in the curve between 55" and 100" might have been overlooked.In order t o test thie, analyses of the undissolved salt were made at 60°, 70°, and S9", and in all cases the salt was found to be the hexa- hydrate. Moreover, the solid phase at all temperatures between the above limits has the bright green colour characteristic of the mono- clinic hexahydrate. In the analysis of the solutions a t 89" and 9Y0, the saturated solution was separated from the undisso,lved salt by the method of decantation in a bent tube employed by EtartX and Engel (ZOC. cit.). Ice Curve and Cryohydrate Point. The ice curve was determined by measuring the temperature a t which ice began t o separate from solutions of nickel sulphate of known concentration, the measurements being carried out in Beckmann freezing point apparatus.120 SOLUBILITY CURVES OF THE HYDRATES OF NICKEL SULPHATE.The temperatures and concentrations from which the curve has been plotted are as follows : Temperature ... ... ... - 0.47' - 0.72" - 1.46" - 2.1 5" - 2.85' Concentration ..... 3.35 5-53 1 1 9 7 17.23 21.18 The cryohydrate point was fixed in the following manner. A solu- tion containing about 30 parts of the anhydrous sulphate, NiSO,, to 100 parts of water was placed in the inner tube of the Beckrnann apparatus, which was surrounded with a freezing mixture maintained at about -5", and the steady temperature at which ice and nickel sulphate separated was found t o be - 4.15'. Sicmmncy . The following is a summary of the results obtained with the system, nickel sulphate-water. (1) Quacl~uple Points. A. Cryohydrate point of the heptahydrate [ - 4.15'1. B. Transition point : heptahydrate Z hexahydrate (bIue) + satur- ated solution r31-5'1. C J D. Transition point : hexahydrate (blue) hexahydrate (grcen) [ 5 3 -3"]. ~ Transition point : hexahydrate (green) solution (not accurately determined). dihydrate + saturated (2) The Equilibcium Curves. The curves OA, ABC, BD, and DE in the diagram correspond with the solid phases : ice ; the heptahydrate, NiS0,,7H20 ; the blue hexahydrate, NiS04,6H,0 ; and the green monoclinic hexahydrate, NiSO4,6H,O, respectively. 31ACDONALD CHEMISTRY BUILDING, MCGILL UNIVERSITY, MONTREAL.

ISSN:0368-1645    

DOI:10.1039/CT9048500113

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

TEE RELATlVE STRENGTHS OF THE ALKALIKE HYDROXIDES. 121 XIV.- The Reltetive Strengths of the Alkaline Hydr- oxides and of Ammonia as &Ieasuwd by theilr Action on Cotarnine. By JAMES JOHNSTON DOBBIE, M.A., D.Sc., ALEXANDER LAUDER, B.Sc, and CHARLES KENNETH TINKLER, Research Student of the University of Edinburgh. IN a paper recently communicated to the Society (Trans., 1903, 83, 598), it was shown that the spectra of cotmarnine in ethereal or chloro- form solution, of cyanohydrocotarnine and of ethoxyhydrocotarnine are identical or nearly so with those of hydrocotarnine and its salts, whilst the spectra of dilute aqueous or alcoholic golutions are identical with those of the cotarnine salts. From this, it was argued that the substances in the first group are all constituted like hydrocotarnine, those in the second being like the cotarnine salts. This con- clusion is supported by the fact that, whilst the substances in the first group are colourless, those in the second are yellow.It was further shown that an ethereal or chloroform solution of cotarnine becomes yellow when treated with alcohol and gives absorption spectra which approach more and more nearly to those of the cotarnine salts as the quantity of alcohol is increased. On the other hand, when an aqueous solution is treated with sodium hydroxide or other soluble base, the reverse change takes place and the yellow colour gradually disappears ; the proportion of cotarnine which undergoes this change depending on the amount of basic hydroxide present. It was suggested that a fuller study of these reactions might throw light on the con- ditions of isomeric and tautomeric changes generally, and that it might be possible to use the action of the bases on cotarnine as a means of comparing their strengths.I n the present paper, we propose to give the results of some preliminary experiments on the latter subjeci;. I n our former paper, an account was given of the absorption curves of the two forms of cotarnine (Figs. I and 11) : and photographs of the spectra mere reproduced in Plates I and I1 (carbinol and ammonium forms respectively), which accompany the paper. Reference to these photographs will &ow thst the spectra of the two forms are highly characteristic. The change which cotarnine in aqueous solution uudergoes when122 DOBBIE, LAUDER, AND TINKLER : RELATIVE STRENGTHS acted on by sodium hydroxide depends, as already stated, on the quantity of this reagent present.After the addition of any given quantity of the hydroxide, a state of equilibrium between the two forms of cotarnine is established almost instantaneously and, provided that the temperature is kept constant, no further change takes place, a t any rate in moderately dilute solutions, even after a lapse of several hours. Each additional quantity of sodium hydroxide causes a further change until the ammonium form is all converted into the carbinol form. This is practically the case when a milligram-molecule of cotarnine is dissolved in one litre of a normal solution of sodium hydroxide. By photographing the spectra of the solution after each addition of the alkali hydroxide, the change from the one form to the other can be followed through all its phases.Figs. 17-24 of Plate 111, accom- panying the paper already quoted, show generally how the spectra of the ammonium form change into those of the carbinol form as the quantity of sodium hydroxide is increased. The spectra thus pbtained are in fact the spectra of mixtures of the two forms and can all be reproduced exactly by mixing together hydrocotarnine hydrochloride and cotarnine hydrochloride in the proper proportions. By preparing a series of such mixtures containing the two substances in known pro- portions, it is possible, from a comparison of their spectra with the spectra of an aqueous solution of cotarnine, which has been acted on by sodium hydroxide, to determine the amount of the ammonium form which has been changed into the oarbinol form.By using other soluble bases in place of sodium hydroxide, the data are obtained which are required for a comparison of their strengths. As already stated, the action of bases on cotarnine is so rapid t h a t no comparison of their strengths, founded on the amount of change produced by equimolecdar quantities in a given time, is possible. Temperature has a consider- able influence on the action, and consistent results can only be obtained when the experiments are carried out at the same tem- perature. * It mill be seen from the tabulated comparison of the results obtained a t 1 2 O and 1 8 O respectively (Table I) that the effect of heating is to diminish the action of the alkalis, a given quantity a t the higher temperature producing a smaller effect than the same quantity a t the lower temperature.The results are represented graphically in the accompanying curve (p. 123). * The results given in our previous paper were obtained a t the ordinary tempera- ture, without precautions being taken to ensure that the temperature was always the same. They therefore differ somewhat from those given in the present paper.123 0 Percentaye of the ammonium form of cotarni.ne converled into the carbinol form. TABLE I. Strength of Percentage of carbinol form produced. 94 93 89 87.5 N/20 82.5 80 N/50 70 65 sodium hydroxide. At 129 At 18". N/4 N/10 Nf 100 52.5 50124 DOBBIE, LAUDER, AND TINRLER : RELATIVE STRENGTHS I n Table IT, the results obtained at 12' by the action of equi- molecular solutions of the hydroxides of the alkali and alkaline earth metals and ammonia are given, and t h e results are represented graphically in the accompanying curve.The percentages give the amount of ammonium form which is converted into the carbinol form. 0 Perccntngc of the amnzonizcm form of cotarnine converted into the cnrhinol formOF TEE ALKALINE HYDROXIDES AND OF AMMONIA. 125 Streiigth of base. N A?/ 3 AT/ 4 N/2 ;j; n;/8 A y o N/14 N/16 A720 N/25 N / 3 2 AT/5 0 AT/70 N/100 N / Z O O ivf400 N/600 KO H. ~-___ 98.5 97.5 96'5 95 93 92.5 91 89 88 83 7 7 5 67 *5 62'5 52-5 42 *5 25 20 - - LiOH. - -- 98.5 97'5 96'5 94 93 92.5 90 88 85 82.5 77.5 70 65 57 -5 42 '5 30 20 __ I TABLE 11.NaO If. 98.5 97 95.5 94 93 92.5 91 89 87.5 82.5 80 77.5 70 60 52 5 40 25 20 - The hydroxides of lithium, sodium, and potassium give nearly identical curve$, showing that, so far as this reaction is concerned, they all have nearly the same strength. It is not possible t o get a sufficient quantity of calcium or barium hydroxide into solution in one litre of water t o convert a milligram-molecule of cotarnine entirely into the carbinol form, but that portion of the curve which can be drawn for these bases approximates closely to the corresponding portion of the curve f o r the hydroxides of the alkali metals, the slight difference between the curves indicating that the hydroxides of the alkali metals are the stronger. Some experiments mere made with thallium hydroxide, but, as solutions of this substance themselves possess considerable absorptive power, trustworthy results could only be obtained with dilute solutions.These data indicate that thallium hydroxide is a weaker base than the alkali hydroxides, but very much stronger than ammonia. A very concentrated solution of ammonia (more than nine times the strength of a normal solution) is required to convert the ammonium form of cotarnine entirely into the carbinol form. We propose to discuss the case of ammonia more fully in con- nection with investigations on the alkylated ammonias. The general result of our experiments is to show that in their action on cotarnine, the bases have the same relative strengths as in other reactions. The curves representing the relation between the amount126 DOBBIE, LAUDER, AND TINRLER : RELATIVE STRENGTHS of change and the quantity of base producing it are apparently hyper- bolic, but we have so far been unable to find an equation for them. The action of sodium hydroxide on an aqueous solution of cotarnine is capable of explanation in terms of the dissociation theory of electro- lytes.Cotarnine in dilute aqueous solution is a strong electrolyte (Hantzsch and Kalb, Ber., 1899, 23, 3109). It may, therefore, be assumed that the solution contains a mixture in equilibrium of the undissociated ammonium form together with the hydroxyl and other ion resulting from its dissociation, with practically none of the carbinol form. By the addition of sodium hydroxide the active mass of the hydroxyl ions is increased and the dissociation of the ammonium form is diminished. The ammonium form then passes into the carbinol form, in which dissociation is at a minimum, until the equilibrium is restored.The further addition of sodium hydroxide leads t o a repetition of these changes until, when the solution is normal, the ammonium form is practically all converted into the carbinol form. A very small quantity of sodium hydroxide produces no appreciable effect on an aqueous solution of cotarnine, but we have not found it possible to determine with accuracy the exact point a t which the solutions are isohydric. Experimental Details. The determinations of the percentages of the ammonium form of cotarnine converted into the carbinol form, which are given in this paper, were made by comparing photographs of the absorption spectra * of cotarnine in solution in sodium hydroxide, or other soluble base, with standard photographs of mixtures containing hydrocotarnine hydrochloride and cotarnine hydrochloride in known proportions.I n the preparation of the standard series of mixtutes used for this purpose, a solution containing 1 milligram-molecule of hydroco tarnine hydrochloride dissolved in one litre of water mas taken as the starting point. This was mixed with a solution of cotitrnine hydrochloride of the same equivalent strength in the proportions required to give a solution containing 97.5 per cent. of hydrocotarnine hydrochloride and * The method af photographing absorption spectra which we employ has already been sufficiently explained in former papers, see especially Trans., 1889, 55, 649, and the papers by Hartley therein cited.The reference lines employed were those given by an alloy of cadmium, tin, and lead. The photographs of the spectra, from which the data discussed in this paper have been derived, have not been re- produced as illustrations on account of the difficulty of obtaining reproductions sufficiently delicate to show the details of the spectra on which their accurate comparison is based. So far as photographs are necessary for the elucidation of the paper, this purpose is served by those already published (Dobbie, Laudcr, and Tin kler, Eoc. eit. ).OF THE ALKALINE HI~DROXIDES AND OF AMMONIA. 127 2.5 per cent, of cotarnine hydrochloride. The proportion of cotarnine bydrochloride to hydroco tarnine hydrochloride was increased by 2.5 per cent, a t a time until a solution containing 97.5 per cent.of the former and 2.5 per cent. of the latter was reached. The absorption spectra of these mixtures form a graduated series between the spectra characteristic of the two forms of cotarnine. The Reries of standard photographs having been prepared, i t is easy to estimate the amount of change produced in an aqueous solution of cotarnine by any given quantity of a soluble base, by photographing the spectra of the solution and comparing tho photographs with those of the reference series. If the photograph to be determined does not coincide exactly with any in the reference series, its position between two successive mixtures can always be found. A number of intermediate mixtures are then photographed until a photograph is obtained which exactly corresponds with the one under examination, the exact composition of the mixture in question being thus determined.In preparing the series of reference photographs, hydrocotarnine hydrochloride wds preferred t o the cyanohydrocotarnine formerly employed, on account of its greater stability and because of its solubility in water. These two substances have the same spectra. The spectra of mixtures of hydrocotarnine hydrochloride with cotarnine hydrochloride are identical with those obtained by passing the light through an equal thickness of the two solutions contained in separate cells. Thus the spectrum obtained by passing the light through a 20 mm.layer of a mixture of hydrocotarnine hydrochloride and cotarnine hydrochloride solutions, in equal proportions, is identical with that obtained by passing i t in succession through two cells each containing a layer 10 mm. thick of one of the solutions. The same result is obtained by using a 10 mm. cell filled with a n aqueous solution of cotarnine and another cell of equal thickness containing a concentrated sodium hydroxide solution of cotarnine. These results were confirmed by numerous experiments, in which layers of various thicknesses mere employed. In these experiments, the thickness of quartz employed was the same; when this precaution was not observed, the accuracy of the comparison was interfered with by the slight absorption due to the quartz plates. We hope to render the foregoing method more accurate by a modifi- cation of our apparatus, and by using hydrastinine in place of cotarnine. With cotarnine, i t is quite easy, in some parts of the series of mixtures of the two forms, to detect differences of 0.5 per cent. with certainty, but in mixtures containing a large proportion of the ammonium form it is not possible to detect with accuracy, differences of less than 2.5-5.0 per cent, The spectra of the ammonium form hydrastinine are more complicated than those of the corresponding128 PERKIN AND THQRPE: form of cotarnine, and admit of much smaller differences being readily distinguished. We have to express our thanks to Professor Crum Brown and to the authorities of the University of Edinburgh for kindly affording us facilities for conducting part of this work i n the University laboratory; and t o Professor W. N. Hartley for the use of the apparatus with which the experiments were carried out. MUSEUM OF SCIEKCE BSD AILT, ED INBU iw H

ISSN:0368-1645    

DOI:10.1039/CT9048500121

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

128 PERKIN AND THORPE: XV.-aa-Dirrzethylbulc(Ize-ap~-t.51.icarboxylic Acid, y-Keto- PP-di172etJ2Y~entc~rnetJaYlene-a-cai’boxylic Acid, and the Synthesis o f Inactive a- Campholactone of Inuctive a- Campholy tic Acid curd of ,8- Cam- pholytic Acid (isoLuuronolic A c i d ) . By WILLIAM HENRY PERKIN, jun., and JOCELYR FIELD THORPE. DURING the course of a long series of researches on the constitution of camphor and its derivatives, attention has been repeatedly directed t o the advisability of synthesising the more important substances obtained by the degradation of camphor, in order, thus, to definitely establish their constitution. It has frequently been found that analytical methods have, alone, not been sufficient to prove the constitutions of such degradation products, and in the more difficult cases, as, for example, in the determination of the constitutions of carnphoronic and isocamphoronic acids, a definite proof was first obtained by synthetical means (Perkin and Thorpe, Trans,, 1897, 71, 1169 ; 1899,75, 897; Perkin, Trans., 1902, 81, 246).I n continuing our experiments in this direction, we have endeavoured t o find some means of synthesising, not only open chain acids, such as those mentioned above, but also closed chain compounds more closely allied to camphor and camphoric acid, We hope that it may eventu- ally be found possible to prepare these substances themselves, in quantities sufficient for definite identification, by synthetical means, but the problem is an exceedingly difficult one.* In the present paper, we describe a series of reactions which has led * This investigation, an abstract of which appeared in the P~oceedings, 1903, 19, 61, was completed and this paper written before the publication of G.Iiomppa’s complete synthesis of camphoric and dehydrocaniphoric acids (Bcr., 1903, 36, 4832).~~-DIMETHYLBUTAKE-~P&TRICARHOXY LIC ACID. 129 t o the synthesis of inactive a-campholytic acid, and indirectly t o t h a t of P-campholytic acid (isolauronolic acid). When ethyl cyanoacetate is digested in alcoholic solution with sodium ethoxide and ethyl bromoisobutyrate, sodium bromide separ- ates and ethyl cyanodimethylsuccinate is formed, thus : C0,Et yH*CN CO,Et*CHNa*UN + CO,Et*CMe,Br = CO,Et.CBle, + NaEr (compare Bone and Sprankling, Trans., 1899, 75, S54). The sodium compound of this cyano-ester interacts readily with ethyl P-iodopropionate, forming ethyl P-cycLizo-aa-clinzethylbutarae-aps- tricurbox ylat e, C0,E t Q (CN)Na CO,Et*CMe, + CH,T*C H,*CO,Et = C0,Et *~(CN)*CH,*CH,*CO,Et C0,Et CMe2 + NaI, but, unfortunately, during this reaction, a large amount of the P-iodo- propionic ester is decomposed with the elimination of hydrogen iodide and formation of ethyl acrylate, CH,:CH*CO,Et, and by no variation in conditions could this be avoided. This loss of valuable material would have made further progress impossible had i t not been discovered that the acrylate thus produced may be converted into ethyl cyanodi- methylbutanetricarboxylate by the following series of reactions. Ethyl acrylate condense., with the sodium compound of ethyl cyano- acetate, yielding the sodium compound of ethyl a-cyanoglutarate, thus : CO2Et*CHN&*CN + CH,:CH*CO,Et = CO,Et*CNa( CN) *CH,*CH,*CO,Et, a n ester which had already been prepared by L.Barthe (Compt. Tend., 1894, 118, 1268) from the sodium compound of ethyl cyanoacetate and ethyl P-bromopropionate. The sodium compound of ethyl a-cyano- glutarute, when digested in alcoholic solution with ethyl a-bromoiso- butyrate, gives a good yield of ethyl cyanodimethylbutanetricarb- ox ylate, C0,Et*CNa(CN)*CH,*CH2*C02Et + CO,Et*CMe,Br = CO,Et*Q( CN)*CH,*CH,*CO,Et + NaBr, C0,Et*CMe2 When boiled with hydrochloric acid, this cyano-ester is hydrolysed with the elimination of carbon dioxide and formation of aa-dimethyl- butune-afl6-tricar boxglic m i d , VOL, LXXXV.K130 PERKLN AND THORPE: a crystalline, readily soluble acid which melts a t 155-151". When this acid is distilled under reduced pressure, it loses water and is con- verted into the intern-a2 up-ccnlhydride of dimethglbutanetricarboxylic acid, CH*C H,*CH,* C0,H /A / \ W-O*CO*C'Me, which melts a t 9 8 O and dissolves in water, regenerating the tribltsic acid. If the dry sodium salt of the acid is heated with acetic anhydride at 140°, carbon dioxide is evolved and a new acid is pro- duced,* decomposition taking place according t o the equation : The y-keto-PP-dimetlzylpentamethylene-a-carboxylic acid thus obtained melts at 109-llOo and yields an oxime and a sparingly soluble semi- carbazone; i t is isomeric with, and very closely allied to, the 6-keto- /3/3-dinzsthyZpentamethylene-a-carboxylic acid, ,CH,-- QO CMe, GH,' CO,H*CH\ which Perkin and Thorpe (Trans., 1901, 79, 782) obtained by the reduction of dimethyiketodicyclopentanedicarboxylic acid, and which melts a t 103".The latter acid is not easily acted on by sodium amalgam, b u t if a large excess is employed, i t is ultimately reduced to the corresponding hydroxydimethylpentamethylenecarboxylic acid This acid must exist in trans- and &-modifications, should, like all cis-y-hydroxy-acids, readily yield a the latter of which lactone, and since the acid (m. p. 115;) which-was actually obtained showed no tendency to lose water with formation of a lactone, it is evidently the trans- modification. On the other hand, it is interesting t o note that the y-keto-acid (m.p. l l O o ) , unlike the 8-keto-acid (m. p. 103O), is not reduced at all even when the aqueous solution of its sodium salt is boiled with a large excess of sodium amalgam, and this difference in behaviour is doubtless due t o the proximity of the >CMe, complex to the keto- * If this curious reaction should prove to be a general one, it will afford a con- venient means of synthesising many importaiit closed chain keto-acids and, for this reason, experiments are being carried out by one of us with the object of ascertaining the exact conditions under which the change takes place.U~-DIMETHYLBUTANE-~B~-TRICARBOXY LIC ACID. 131 group in the latter case. Reduction of the y-keto-acid may, however, be effected by adding sodium to the boiling alcoholic solution of the acid, when an a1 mos t quantitative y ie Id of trons-y-h ydrox y-PP-dime th y Z- psntccmethylene-a-carboxylic acid (m.p. 10 lo), is obtained. The most remarkable property of this acid is its great stability" since, although it is a y-hydroxy-acid, it does not yield a lactone on boiling with dilute sulphuric acid and, even wheln distilled, it passes over for the most part unchanged. This unusual stability, even of a trans-modification of a y-hydroxy- acid, led us to suspect that some intramolecular change might have taken place during the energetic reduction with sodium and alcohol, but tbat this is not the case is proved by the behaviour of the hydroxy-acid on treatment with chromic acid, when it is very readily oxidised and converted into the y-keto-acid from which it had been obtained by reduction. When t~ans-y-hydroxydimethylpentamethylenecarboxylic acid is heated with hydrobromic acid, i t yields y-b~omodim~thylpenta?~e~~yl~n~- carboxylic acid, and this viscid, syrupy substance, when boiIed with sodium carbonate, loses hydrogen bromide with the formation of dimethylcyclopentenecurhxylic acid (b.p. 2 36') ; * The reason for the remarkable stability of this hydroxy-acid is difficult to understand, but it niay be mentioned that other closed chain y-hydroxy-acids are known-for example, the y-hydroxyhexahydro-p-tolnic acid : /Ye CHzI CH,\/GH, ICH*OH, CH*CO,H prepared by Tiemann and Semmler (Ber. , 1895, 28, little tendency to yield lactones (compare Perkin 1375). 2143)--which also exhibit very and Tates, Trans., 1901, 79, On the other hand, trans-hydroxyhexahydro-xylic acid, OH'C'CH, c H/'WH* I 1 CH2\/CH'CH3 HC*CO,H ' in which the hydroxy-group is in the 6-position with respect to the carboxyl radicle, readily yields a lactone on distillation (Perkin and Lees, Trans., 1901, 79, 344), and this and other similar observations seem to point to the possibility of lactone formation taking place more readily in the 6- thaii in the y-position in ring compounds. E 2132 PERKIN AND THORPE: Action of Magnesium Methyl Iodide on Ethyl Ketodimethylpcnta- methylenecarboxylate.Formation of a-Campholactone und Synthesis of a-Cmnpholytic Acid and P-Campholytic Acid (is0 Lauronolic Acid). As stated on p. 128, the primary object of this research was the synthesis of closed chain compounds closely allied to camphor and this was accomplished i n the following way.E thy1 ketodimethylpent amet hylenecarboxylate is readily acted on by magnesium methyl iodide with the formation of several substances, among which is a new lactone produced according to the following scheme : CH,*FO CH;YMe(OMgI) CH,.yMe-O I 5% -+ I yille, -+- I y ~ e , 1 c1 H,*CH*CO,Et UH,* CH*CO,H U H,*CH--UO On account of its close relationship to campholactone, from which, indeed, it only differs in the reversal of the position of the lacfone group, this new lactone has been named inactive a-cumpho- lactone.* Inactive a-campholactone is an oil which smells strongly of pepper- mint; and distils at 155-157O under 50 mm. pressure ; when treated with hydrobromic acid, it yields inactive y- bromotrimetiiylpentamethylene- cavboxylic acid, which melts at 108" and, when digested with sodium carbonate, loses hydrogen bromide with the formation of the corresponding unsaturated acid : ++ I n the preliniinary notice of this research in the Proceedings (Zoc.cit.), we named the new lactone " isocampholactone " in order to ciiiphasise its great similarity to campholactone. We snbsequently found, however, that this name had already been given t o a lactone of unknown constitution which Noyes (Ber., 1895, 28, 553) had prepared by the action of nitrous acid on aniinolmronic acid. T'his latter lactone, which melts a t 23" and has quite different properties to our synthetical lactone, was not obtained in sufficient quantity for analysis, but i t s method of forination makes it probable that it is isoxieric (possibly stereoisomeric) with campholactone.Owing t o the nanie " isocampholactone " having been previously used by Noyes, we have altered that of our lactone to " a-campholactone."ACID. 133 CH,* ?Me-0 CH2-yMoBr I ?Me, I --+ I CAfe, -+ CH,*CH-CO CH,~H.CO,H The formula of this unsaturated acid is that of inactive a-cccmpholytic acid, an acid which was first obtained by one of us (Perkin, Trans., 1903, 83, 853) by the reduction of a-camphylic acid, C,H,,*CO,H, with sodium amalgam. I n order to prove that the synthetical acid is inuctive a-campholytic acid, it was digested with dilute eulphuric acid when crystals were formed which melted a t 132' and were easily identified as P-campholytic acid (isolauronolic m i d ) , the well- known remarkable isomeric change indicated by the f ormuh, CH-yMe CH,*yMe, OH,* CH* C0,H CH,*C*CO,H a-Campholytic acid.isolauronolic acid. having taken place. That the isolauronolic acid thus synthesised is iden- tical with the acid obtained from camphoric acid was shown by mixing equal quantities of the two preparations when the mixture melted at 132*, the melting point of the constituents. Furthermore, the synthetical acid, on oxidation with permanganate, yielded isolauronic acid. There can thus be no doubt that the above series of reactions consti- tutes a synthesis of both inactive a-campholytic acid and of isolauronolic acid (P-campholytic acid) and therefore the constitution of these important acids may now be taken as definitely established. If the formulE of a-campholactone and the derivatives obtained from i t are carefully examined, it will be a t once seen how very closely these synthetical substances are related t o camphoric acid.Thus if y-bromo t rime t h ylpen tame thy lenecar box ylic acid be taken as an example, it is only necessary t o replace the bromine atom in that substance by the carboxyl group in order to accomplish a synthesis of camphoric acid : CH,*yMeBr CH,*$!Me*CO,H CH,*CH*CO,H CH,* C H*CO,H Many experiments were made, under the most varied conditions, in the hope of being able to bring about this change, but with little success. Thus the bromo-acid and its ester mere treated with silver cyanide, with solid potassium cyanide, alone and in the presence of anhydrous hydrogen cyanide, and with aqueous and alcoholic solutions of potassium cyanide, but although small quantities of a crystalline sub- 1 p e 2 I p e ? I -+ I ?Me2 I I ?Me,134 PEREIN AND THORPE: stance having properties identical with those of i-camphoric acid were obtained in two cases (see p.146), the amount was too small for analysis and definite identification. The cause of the failure in these experiments is the great readiness with which the bromo-acid loses hydrogen bromide with the formation of a-campholytic acid. Again a-campholactone was heated with potassium cyanide and with anhydrous formic acid, but in both cases, a-campholytic acid was the product of the reaction. Lastly, a synthesis, similar to that of benzoic acid from bromobenzene by the action of magnesium powder and carbon dioxide, was attempted with the ester of bromotrimethylpentametbylene- carboxylic acid, but again without success.It has not been thought worth while to describe all these various experiments in detail in this paper, the above short account being sufficient to indicate the reactions which were attempted with the object of synthesising carnphoric acid from a-campholactone. Condensation oj Ethy I C yanodimetluJsuccinnte with Eth y I P-Iodopro- pionate. Formation of Ethyl Cyanodi~methylbutanetricarboxylate, CH,*CH,*C02Et co,Et* )<CMe2 CO,E t I n carrying out this condensation, it was found that even slight differences in temperature and other conditions had a very marked influence on the yield of the condensation product, and the best results were usually obtained by working in the following way.Sodium (23 grams) is dissolved in absolute alcohol (350 c.c.) and, after cooling thoroughly, mixed with ethyl cyanodimethylsuccinate (227 grams) and then ethyl /I-iodopropionate (228 grams) added in small quantities, care being taken, by cooling with water, that the temperature never rises above 25O. After 1 2 hours, the product is heated on the water- bath for 2 hours, water is then added, and the oily ester, which smells strongly of ethyl acrylat-e, is twice extracted with ether. The ethereal solution is thoroughly washed with water, dried over calcium chloride, and the ether very slowly distilled off; the residual oil is then distilled a t first under the ordinary pressure until the temperature rises to 130° in order that the ethyl acrylate which comes over below this may be collected for subsequent use (see p.136). The distillation flask is then attached to the vacuum apparatus and the distillation continued under 20 mm. pressure when, after several fractionatiuns, ethyE cycLnodimethylbzttanetricarboxyl~te is readily obtained pure as a colourless oil boiling a t about 210' (20 mm.). 0.2976 gave 11 -3 C.C. of nitrogen at 23' and 760 mm. N = 4.3. C,6H,@6N requires N = 4.3 per cent.aa-DIMETHYLBUT ANE-aps-TRfCnRBOXYLIC ACID. 1 35 The yield of this ester varies in a remarkable way in different experiments carried out, apparently, under precisely the same condi- tions. In one instance, an almost theoretical yield was obtained, but in other cases hardly a trace was produced, the average yield being about 25 per cent.of the theoretical. The remainder consists of ethyl acrylate and unchanged ethyl cyanodimethylsuccinate and sometimes a considerable quantity of an oil having a high boiling point is produced. I)irnethyZbutunetricarboxylic Acid, C0,H*CH<CMe,.002H CH,*CH,*CO,H The cyan ogen group in e t h y 1 cyanodi me t h y 1 bu tanetricar boxy lat e is hydrolysed only with great difficulty, even on long boiling with hydro- chloric or dilute sulphuric acid the process is far from complete, and it was only by employing concentrated sulphuric acid in the first instance that a satisfactory result was ultimately obtained. The cyano-ester (in quantities of 50 grams) is dissolved in an equal volume of concen- trated sulphuric acid, and, when the solution is cold, water is added until oily drops just comnience to separate, The whole is then boiled on the sand-bath, the alcohol produced being allowed to escape through the air-condenser, and small quantities of water are added from time to time in order to prevent charring, After 8 hours, the solution is diluted with an equal volume of water, saturated with ammonium sul- phate, and extracted several times with ether; the solvent is then evaporated and the residue dissolved in a small quantity of water and mixed with an equal volume of concentrated hydrochloric acid.After two days, the crystalline crust which has separated is collected and purified by recrystallisation from hydrochloric acid, from which it separates as a sandy powder.0.1444 gave 0.2615 CO, and 0.0860 H,O. C = 49.4 ; H = 6.6. 0.1295 ,, 0.2359 CO, ,, 0.0750 H,O. C=49*5 ; H=6*4. C,H,,O, requires C = 49.5 ; H = 6-4 per cent. Dimet~~llbzctccnetricurboxylic ucid melts a t 155-157" and is readily soluble in water, but sparingly so in concentrated hydrochloric acid. It is rather sparingly soluble in dry ether, and crystallises from this solvent in small, glistening prisms or leaflets. On titration with decinormal caustic soda, 0.201 8 gram neutralised 0.1 108 gram of NaOH, whereas this quantity of a tribasic acid, C,H,,O,, should neutralise 0.1110 gram of NaOH. The hydrochloric acid mother liquors from the purification of the acid contain a large quantity of very impure material ; this is extracted with ether, and, after evaporating off the solvent, the residue is esteri- fied by boiling with alcohol and sulphuric acid.The ester is extracted136 PERKIN AND THORPE: in the usual way and fractionated under reduced pressure, when pure ethyl dimetlLyEbutunets.icurboxylute, CMe,( C0,Et)-CH( CO,E t)*CH,*CH,* CO,E t, is obtained as a colourless oil boiling at about 195" (40 mm.). 0.1722 gave 0.3761 CO, and 0.1319 H,O. From this ester, the pure tribasic acid is rekdily obtained by hydro- C = 59.5 ; H = 8.5. C1,H,,06 requires C = 59.6 ; H = 8.6 per cent. lyfiis with concentrated hydrochloric acid. The Internal Anhydride of Di~netl~ylbutccn/Let~ic~i~box~lic Acid, C H*CH,*CH,*CO,H CO*O*CO*CMe, When dimethylbutanetricarboxylic acid is heated under reduced pressure (45 mm.), i t melts and then, at once, gives off water, and the anhydro-acid distils at about 255" as a viscid, colourless syrup which soon begins t o crystallise in stellate groups and gradually becomes solid.By dissolving in hot benzene and allowing to cool slowly, the substance is obtained in well-defined, four-sided plates, but if the solution is rapidly stirred, it separates as a sandy, crystalline pre- cipitate. 0.1776 gave 0.3503 CO, and 0.0959 H,O. C,Hl,O, requires C = 54.0 ; H = 6.0 per cent. The anhydride molts at 98" and is sparingly soluble i n cold water ; it dissolves, however, readily on boiling with water, and i f a n equal volume of hydrochloric acid is added t o the concentrated solution, cryst,als separate which melt at 155-157" aud consist of the pure tribasic acid.C=53*8; H=6*0. Formation of Ethyl ~yanod~rnethy~butanet,.icccrbox~Zc~~~ from Ethyl Acrylccte, Ethyl Cyanoucetacte, and Btli y l Brornoisobutyrate. The reasons which led to this method being carefully worked out are given in the introduction. Sodium (23 grams) was dissolved i n 300 grams of alcohol, mixed with ethyl cyancacetate (1 13 grams), and, after well cooling, ethyl acrylate (100 grams) added in several portions. The condensation takes place very rapidly and with evolu- tion of a considerable amount OF he&, and in a short time the whole of the sodium compound of the ethyl cyanoacetate will have passed into solution. The mixture is heated on the water-bath for about two hours, and until a drop of the liquid, on dilution with water, no~~-DIMETAYLBUTANE-~/~&TRICARBOXYLIC ACID.137 longer deposits an oil; it is then mixed with ethyl bromoisobutyrate (195 grams) and heated in soda-water bottles in a boiling salt-bath for eight hours. On diluting with water, extracting the oily product with ether, and fractionating under reduced pressure, pure ethyl cyano- dimethylbutanetricarboxylate is obtained, the yield being 75 -80 per cent. of the theoretical. 0.2646 gave 10.2 C.C. of nitrogen a t 20' and 765 mm. That this cyano-ester has the same constitution as that obtained by the process described on p. 134 was proved by hydrolysis with sulphuric acid, when a good yield of dimethylbutanetricarboxylic acid was obtained which melted a t 155-157O. N = 4.4. C,6H2s0,N requires N = 4.3 per cent. 0.1516 gave 0,2759 C'O, and 0.0886 H,O. Much of the acid required for this investigation was prepared by C = 49.6 ; H = 6.5.CoH,,06 requires C = 49.5 ; H = 6.4 per cent. the foregoing process. Purtiul Hpdmlysis of Ethyl C'ywnodimetl~~Zb~ctcclzetricccrbox?/kt~. During the course of this investigation, a number of experiments were instituted with the object of eliminating the carboxyl radicle adjacent to the cyanogen group in ethyl cyanodimethylbutanetricarb- oxylate, and the results obtained may be briefly described as follows. When an alcoholic solution of 12 grams of pure caustic potash is mixed with 35 grams of the cyano-ester and the whole allowed to remain overnight, a crystalline potassium salt separates in quantity, This was collected at the pump, washed with alcohol, in which it is sparingly soluble, and dried a t 100' ; it then weighed 10 grams.0.3484 gave 0.1781 K,SO,. K = 22.9. C,,H,,O,NK, requires K = 22.4 per cent. The constitution of this salt is probably represented by the formula It was very soluble in water and gave no precipitate on acidifying with hydrochloric acid ; the whole was therefore repeatedly extracted with ether, the ethereal solution dried over calcium chloride and evaporated, when a colourless oil was obtained, which, over sulphuric acid in a vacuum desiccator, became very viscid but did not crystal- lise. The analysis shows that this substance is ethyl dihydroge?z cyanodimet?~ylbzctanetrical.boxplate, corresponding with the above potass- ium salt.138 PERKIN AND THORPE: 0.1974 gave 8.3 C.C. of nitrogen a t 17" and 759 mm.C,,HI7O,N requires N = 5-2 per cent. When this dibasic acid is heated at 150°, i t decomposes with evolu- tion of carbon dioxide, and, when the evolution of gas has ceased, the residue distils almost completely at 345-250' (50 mm.) as a viscid oil which consists of ethyl ?&ydi*oge?a cyaPzodimethyZbzctanedicn~doxyZccte, N=4*9. 0 2138 gave 11.5 C.C. of nitrogen a t 20' and 759 mm. N=6*2. C,,H170,N requires N = 6.2 per cent. This acid is formed when the sodium salt of dimethylbutsnetri- carboxylic acid is heated with acetic anhydride. The sodium salt is prepared by dissoIving the pure acid (109 grams) in water, adding 80 grams of anhydrous sodium carbonate, and evaporating the alkaline liquid t o dryness. I n order t o obtain t h e salt as finely divided as possible, it is powdered and passed through a fine wire sieve, being then again dried at 100' and transferred t o a flask, into the neck of which is fitted a tube bent twice a t right angles.After adding 150 grams of freshly distilled acetic anhydride, the whole is slowly heated in a n oil-bath when it will be noticed that carbon dioxide begins to come off below loo', as can be readily seen by causing the tube attached t o the flask to dip under baryta water. The temperature is kept at 135-140' for about 6 hours, then 50 grams of acetic anhydride are added and the heating continued until the evolution of carbon dioxide has practically ceased, which is the case after about three hours. As soon as t h e product is cold, i t is esterified by adding an excess of a solution of one volume of sul- phuric acid in three volumes of alcohol and heating for 6 hours on the water-bath in an open flask in order t h a t as much ethyl acetate as possible may be removed by evaporation, The product, which smells stiongly of ethyl acetate, is diluted with water and extracted several times with ether ; the ethereal solution is then thoroughly washed with water and dilute sodium carbonate solution" and evaporated.On fractionating this oil under 100 mm. pressure, about 50 grams distil a t 160-180" leaving a viscid, nearly black residue? in the retort * The dark sodium carbonate extract, on acidifying and extracting with ether, yields a brown oil from which considerable quantities of ketodimethylpentamethyl- enecarboxylic acid may be obtained by treatment with semicarbazide or by esterifi- cation and distillation under reduced pressure and subsequent hydrolysis. t The residues from several preparations were mixed and fractionated underW-DIMETHY LBUTANE-C@-TRICARBOXY LIC ACID.139 and, on repeatedly fractionating the distillate, an oil (35 grams) is obtained which boils at 170-172' (100 mm.) and consists of pure ethyl ~tod~methy~pe~ztccmeth~~enecccrboxy~nte. 0.1765 gave 0.4196 CO, and 0.1397 H,O. C = 64.8 ; H = 8.8. 0,1584 ,, 0.3771 CO, ,, 0.1243 H,O. C=64.9; Hs8.7. C,,H,,O, requires C = 66.2 ; H = 8.7 per cent. This ester is hydrolysad by boiling with an excess of methyl-alcoholic potash ; the solution is diluted with water, neutmlised, and evaporated until free from alcohol.After acidifying with hydrochloric acid and extracting six times with pure ether, the ethereal solution is dried over calcium chloride and evaporated, when a pale yellow oil is obtained which, on cooling, rapidly solidifies. The mass is left in contact with porous porcelain t o remove a trace of oily impurity, and then dissolved in a small amount of water, from which the pure acid separates slowly in groups of colourless needles. 0,1485 gave 0,3360 GO, and 0,1043 H,O. C = 61.6 ; H= 7.8. 0.1634 ,, 0.3686 CO, ,? 0.1144 H,O. C = 61.5 ; H = 7.8. C,H,,O, requires C = 61.5 ; H = 7.7 per cent. Ketodirnethylpe~tamethyle~zecccr~oxylic cicid melts at 109-1 10' ; it dissolves readily in benzene, acetone, ether, alcohol, and chloroform, but is sparingly soluble in light petroleum.It is exceedingly soluble in hot water but much less so in the cold, and it may be obtained in long, colourless needles if the hot solution is allowed t o cool very slowly. The pure acid also crystallises readily from ether in the form of hard, glistening pribms. A slightly alkalke solution of the ammonium salt cf the acid gives no precipitate with barium or calcium chloride, even on boiling ; with copper sulphate, no precipitate is formed in the cold, but, on boiling, a pale blue, apparently crystalline, copper salt separates. The oxirne, C,H,,(C:N*OH)*CO,H, was prepared by dissolving the acid in a considerable excess of caustic potash solution, adding twice the calculated quantity of hydroxylamine hydrochloride, and allowing the whole to remain for two days.On acidifying with hydrochloric acid, a crystalline precipitate separated, which was extracted with ether, the ethereal solution was carefully dried with calcium chloride and evaporated t o a small bulk, when the oxime soon began t o separ- ate in crystalline crusts. 30 min. pressure, when about one-third distilled a t 150-190". This portion, on hydrolysis with hydrochloric acid, yielded a coiisiderable quantity of crude di- me thylbutanetricarboxy 1 ic acid, which was purified by recrys tallisati 017, first from hydrochloric acid and then from ether.140 PERKIN AND THOKPE: 0.203 gave 15.3 C.C. nitrogen at 19' and 737 mm. C,H,,O,N requires N = 8.2 per cent. KetozimedinaetJ~yZpentameth~ZenecarboxyZic acid melts at about 1 9 5 O , but it turns brown and commences to decompose below this tempera- ture.It is somewhat sparingly soluble even in boiling water, and separates, on cooling, as a sandy powder. I t dissolves readily in sodium carbonate, and, when heated in a test-tube, i t decomposes with a slight explosion, and yields an oily distillate which crystallises on cooling. The senaicccrbazoize, CG~11(C:N*NH.CO*NH2)*C0,H, separates at once a s a sandy powder when a concentrated aqueous solution of the acid is mixed with semicarbazide hydrochloride and sodium acetate, It melts at about 217' and is very sparingly soIubIe in water. N = 8.3. 0.1544 gave 26.6 C.C. nit'rogen at 19' and 751 mm. N = 19.5. C9HljO3N3 requires N = 19.7 per cent. Bedzcction of Ketodimet~?/~entametJ~~~enecc6~~o~yZ~c Acid. Formation of trans- y- IJycls.ox~/dinzeth y11,3entumetJLyleneca./.box~lic Acid, 7 H, YH O H CH, Chle, \/ CH *C 0,H It is stated in the introduction that ketodimethylpentamethylene- carboxylic acid is not reduced by sodium amalgam, and this was shown by the fact t h a t when 30 grams of the acid, dissolved in diIute aqueous caustic soda, was boiIed with 2500 grams of 4 per cent.sodium amalgam, and the solution subsequently acidified and extracted,with ether, almost the whole of t h e keto-acid was recovered unchanged. When, however, the boiling alcoholic' solution of the acid is treated with sodium, reduc- tion is readily effected. The pure acid (30 grams) was dissolved in about 500 C.C. of absolute alcohol, heated t o boiling in a reflux apparatus, and treated, as rapidly as possible, with 70 grams of sodium, boiling alcohol being added from time to time as the reaction slackened. The product was dissolved in much water, evaporated on t h e water-bath until free from alcohol, acidified with an excess of hydrochloric acid, and heated on the water-bath for half a n hour in the expectation that the hydroxy-acid, if present, would thus be con- verted into its lactone.As, however, no neutral oil separated, t h e whole was saturated with ammonium sulphate, and extracted 10 times with ether. The ethereal solution was dried over calcium chloride and evaporated, when 28 grams of a viscid oil remained and solidified on cooling. That no unchanged keto-acid was present i n this product was shown by treating a small portion with semicarbazide and sodium~~x-DIME'~HYLBUTANE-~@~-TRICA~~BOXY LIC ACID.141 acetate, when no trace of the very sparingly soluble semicarbazone (p. 140) was formed. Considerable dificulty was experienced in re- crystallising the crude reduced acid, but this was ultimately accom- plished by dissolving it in dry ether, adding an equal volume of benzene, and allowing the solution to evaporate slowly at the ordinary temperature. The crystalline crusts thus obtained were drained on porous porcelain, and dissolved in a small quantity of hot water, when, on slowly cooling, the pure acid separated in well-defined, glistening prisms. 0.1690 gave 0,3762 CO, and 0.1326 H,O. C=60-7 ; H=8.7. 0.1353 ,, 0'3012 CO, >, 0*1075 H,O. G 6 0 . 7 ; H=8.S. C,HI,03 requires C = 60.8 ; H = 8.S per cent. trans-y-HydroxydimethyZpent~~cmethyZenecarboxyZic acid melts a t 1OO-10lo and is readily soluble in water, alcohol, and ether.That it is a monobasic acid was shown by its behaviour with decinormal caustic soda, when 0.1977 gram of the acid required for neutralisition 0.0807 gram of NaOH, whereas this amount of a monobasic acid, C8Hl4O3, should neutralise 0.0506 gram of NaOH. This y-hydroxy-acid is remarkably stable, and shows no tendency to become converted into a lactone when boiled with dilute hydro- chloric or sulphuric acid, and, even on distillation, it does not yield a lactone, as is proved by the following experiment. Three grams of the pure acid were distilled under 40 mm. pressure, when the whole passed over a t 205--210° as a viscid, colourless oil resembling glycerol, and this, on cooling, solidified to a brittle, trans- parent, glassy mass.This product was completely soluble in cold dilute sodium carbonate solution, showing that it was not a lactone, and, without further purification, i t yielded numbers which differ little from those required by the hydroxy-acid. 0,1649 gave 0.3718 CO, and 0.1348 H,O. C = 61.4 ; H = 9.0. C,H,,03 requires C = 60.S ; H = 8.S per cent. Oxidation by Means of Chg*omic Acid.-Owing to the curious properties of this hydroxy-acid, it was thought necessary to investigate its behaviour on oxidation in order to prove that its constitution is that represented by the formula indicated on p. 140. The pure acid (2 grams) was dissolved in water, mixed with potassium dichromate (1-4 grams) and a small amount of sulphuric acid, and gradually heated to boiling when oxidittion readily took place.The product was extracted with ether, the ethereal solution dried over calcium chloride and evaporated to a small bulk, when crystalline crusts (1.5 grams) slowly separated, which melted a t logo, and consisted of pure ketodi- meth y Ipentameth y lenecarboxylic acid.142 PERKIN AND TRORPE: 0.1558 gave 0,3513 GO, and 0.1096 H,O. C=61.5; H=7*8, C,H,,O, requires C = 61.5 ; H = 7.7 per cent. y-Bromodimethylpentccmethylenecu~~oxyZ~c Acid, CH2*YHBr CH,*CH*CO,H I ?Me, ' CHZYH UH, *CH.CO,H cmd Dimethylcyclo~entenecarboxylic Acid, 1 ?Me, . Finely powdered y-hydroxydimethylpentamethylenecarboxylic acid dissolves readily in fuming hydrobromic acid (saturated a t OO), but the bromo-acid does not separate after a time as is the case with the corresponding trimethyl acid (see p.145). The solution was there- fore heated in a sealed tube at 1 O O O f o r about fifteen minutes, when, on cooling, an oily layer had separated on the surface of the hydrobromic acid. The whole was diluted with water, extracted with ether, the ethereal solution thoroughIy washed with water, dried over calcium chloride, and evaporat<ed, when an almost colourless oil remained which, after leaving for some hours over sulphuric acid in a vacuum desic- cator, was analysed with the following result : 0.3373 gave 0.2346 AgBr. Br =; 35.9. CsH,,O,Br requires Br = 36.2 per cent. y-Bromodimethyl~entameti~yZe~-Lecarboxylic acid, when prepared in this way, shows no signs of crystallising, even when left for a long time in a freezing mixture, and, on exposure to the air, it becomes darker and finally almost black.A quantity of the freshly prepared bromo-acid was dissolved in excess of sodium carbonate and boiled for several minutes ; the solution was then acidified and extracted with ether. After drying over calcium chloride and evaporating, an oil was obtained which distilled for the most part a t 160-170" (50 mm.), but there was a considerable quantity of a viscid oil left in the flask, which probably consisted of regenerated y-hydroxy-acid. The distil- late was fractionated under the ordinary pressure, when almost the whole passed over a t 236" (760 rum.) as a n oil which was colourless when hot but became deep sage-green on cooling, a behaviour often observed in connection with substances belonging to the camphor and terpene series.Owing to its method of formation, there can be no doubt that the oily acid thus obtained is dimetl~ylcycloperntenecarboxylic acid. That it is an unsaturated acid is shown by the fact that its solution in sodium carbonate instantly decolorises permanganate.U~-DIMETKYLBUTAN E-C@&TRICBRBOXY LIC ACID. 143 0.2128 gave 0.5315 CO, and 0.1638 H,O. C=68*2 ; H=8*5. 0.1730 ,, 0.4336 CO, ,, 0.1335 H,O. C=68.3; Hz8.6. C8Hl,0, requires C = 68.6 ; H = 8.6 per cent. 17126 Action of Magnesium Methyl Iodide on Ethyl Ketodimethyl- pentamethyZen,ecarboxylccte. Fornaation"of Inactive a-Campholactone. CH,*FMe-O I YVe, 1 . UH,*CH--CO After a long series of comparative experiments, t h e following pro- cess was ultimately adopted for the preparation of a-campholactone.Finely-divided magnesium filings (7.2 grams) are placed in a, 2 litre flask connected with a long water condenser aud covered with ether (300 c c.) which had been very carefully freed from water, and finally distilled over phosphoric oxide. Methyl iodide (45 grams) is then added in two portions, the vigorous reaction being kept under control by immersing the flask in ice water occasionally. Ethyl ketodimethylpentamethylenecarboxylate (37 grams) is dis- solved in pure ether (300 c.c.) in a large flask, connected with a reflux condenser, and immersed in powdered ice and water; the ethereal solution of magnesium methyl iodide is then cautiously poured down the condenser tube in several small quantities, the flask being well agitated and allowed t o cool thoroughly after each addition.As each quantity of the magnesium methyl iodide comes into contact with the ethereal solution of the keto-ester, a yellowish-white turbidity is produced, and ultimately the rnagnssium compound separates on the sides of the flask as a sticky mass. After half an hour, the pro- duct is decompossd by the careful addition of dilute hydrochloric acid, the yellow ethereal solution is separated, washed with dilute hydro- chloric acid and evaporated, and the residne, which is a mixture of the lactone, unchanged keto-ester, and a neutral substance (which has not yet been investigated), is treated as follows. The deep yellow oilis dissolved in methyl alcohol, and digested for 10 minutes with a solu- tion of caustic potash (20 grams) in methyl alcohol, by which means the lactone and keto-ester are hydrolysed; water is %hen added, and the neutral substance removed by extraction with ether.The aqueous solution is evaporated on the water-bath until free from ether and methyl alcohol; it is then diluted with water and acidified, when a viscid oil separates, which, on heating on the water-bath for 15 minutes, becomes limpid, owing to the conversion of the hydroxy-acid into the corresponding lactone. The whole is extracted with ether, the ethereal solution repeatedly washed with dilute aqueous sodium carbonate, dried over calcium chloride, and evaporated, when an oil144 PERKIN AND THOKPE: (6-8 grams) is obtained which, after repeated fractionation, distils constantly at 155-157' (50 mm.), and consists of pure inactive a-cam- pholactone.0.1649 gave 0.1227 (70, and 0.1392 H,O. C = 69.9 ; H = 9-3. 0.1485 ,, 0.3819 CO, ,, 0.1238 H,O. C = 70.0 ; H= 9.2. C,H,,O, requires C = 70.1 ; H = 9.1 per cent. Inactive a-campholactone is a pale yellow oil which has a most pungent odour of peppermint; it is readily volatile in steam, and distils under the ordinary pressure almost without decomposition. It is insoluble in sodium carbonate solution, but dissolves readily and completely in warm dilute aqueous caustic soda, and the well-cooled solution, on acidifying, remains clear for a considerable time, indicating that the hydroxy-acid corresponding with the lactone is present ; this acid is slowly decomposed a t the ordinary temperature, and more rapidly on warming, with a separation of the lactone.A special experi- ment was made in the hope of being able to obtain the hydroxy- acid in a crystalline condition, in order that a direct comparison might be made with the bydroxydihydrocampholytic acid described by Noyes* (Amer. CAem. J , 1894, 16, 307, 502 ; 1896, 18, 685), and which he considers has the same constitution, namely, CH,* FMe-OH CH,*CH*CO,H I p e , The pure lactone (2 grams) was dissolved in hot baryta water, the solution cooled with ice, 'acidified, and extracted with ether. On removing the ether by a current of dry air, a viscid oil remained, which was obviously the hydroxy-acid, since it dissolved readily and completely in dilute sodium carbonate solution. 0,1496 gave 0.3454 CO, and 0.1252 H,O.C,H,,O, requires C = 62.8 ; H = 9.3 per cent. Tnuctive y-cis-r7~ydro.xyts.imet?~ylpentametJ~~lenecur6~xylic acid, when lef ti over sulphuric acid in a vacuum desiccator, rapidly loses water with the formation of a-campholactone and, when boiled with hydrochloric acid, the change is complete in a few minutes. Hydroxydihydro- campholytic acid, on the contrary, is perfectly stable and, indeed, does not show any tendency t o yield a lactone even when boiled with acids; if then i t has the constitution represented above, i t must obviously be the tmns-modification. C = 64.0 ; H = 9.3. * Conipare Meyer and Jacobson (Lek~b~rch der 01.9. Chcnt., Vol. 11, 1021).~zcz-DIMETHYLBUTANE-CZ@~-TRICARBOXYLIC ACID.145 Inactive y-Bromotl.i~aethyZpentamethylenecccrboxylic Acid, CH,*QMeBr CH,*CH* CO,H and its Ethp? Ester. 1 ?Me2 When a-campholactone is mixed with three times its volume of fuming hydrobromic acid (saturated at 0.; it dissolves, but almost immediately the liquid clouds and a viscid oil separates on the surface of the acid. This oily layer soon darkens in colour and crystallises, and in preparing the pure bromo-acid i t is best to stir vigorously with a glass rod, so that solidification may be complete before decomposition sets in. The solid is thoroughly washed with water to remove hydrobromic acid and spread on porous porcelain t o separate the oily impurity. The residue, which should be almost colourless, is made into a paste with a small quantity of formic acid (sp.gr. 1.22) and again transferred t o porous porcelain, and after the operation has been repeated, a colourless, crystalline mass is obtained which softens at 105O and melts at about 108' with decom- position. 0.2203 gave 0.1'735 AgBr. Br= 33.5. C,H,,O,Br requires Br = 34.0 per cent. Inactive y-bromotrimethylpentamethylenecarboxylic acid readily decomposes with loss of hydrogen bromide and formation of inuctive a-campholytic acid (see p. 147) and therefore no attempts were made to purify it by recrystallisation. As explained in the introduction, i t is exactly similar in its chemical properties t o the hydrobromide of a-campholytic acid (cistrans-campholytic acid), which, according t o Noyes (Bey., 1898, 28, 551), melts at 98-100O and decomposes in moist air, evolving hydrogen bromide.The ethyl ester, C8H1,Br*C02Et.-In preparing this ester, the pure lactone (4 grams) was mixed with phosphorous pentabromide (15 grams), when a vigorous action took place and much hydrogen bromide was evolved. After 10 minutes, the whole was heated on the water-bath for 5 minutes and then poured, in a thin stream, into a large excess of absolute alcohol. As soon as the reaction Elad subsided, the solution mas allowed to cool, diluted with water, and the heavy oil extracted with ether, the ethereal solution was washed with water and dilute sodium carbonate solution, dried over calcium chloride, evaporated, and the &residual oil rapidly fractionated under 70 mm. pressure. A small quantity of oil passed over bdow 165' and then almost VOL.LXXXV, L146 PERKIN AND THORPE: the whole of the remainder distilled at 165-170' leaving only a small, black residue in the flask. 0.1854 gave 0,1377 AgBr. Br = 31.6. C,,H,,O,Br requires Br = 305 per cent. This oil was made the starting-point in a long series of experiments instituted i n the hope of synthesising camphoric acid (see p. 133) but without success. The above analysis and general properties of the oil leave, however, scarcely any doubt that it is inactive etlql y-bromotrimethylpentanzeth ylenecurboxylate. Action of Potussiuna Cycmide on Bromot~inaetl~?llZ,elztan~et~yl~ne- carboxylic Acid.-It was stated in the introduction that, in experiment- ing on the action of cyanides on this bromo-acid, an acid identical in properties with i-camphoric acid was obtained in very small quantities in two cases.I n one instance, the experiment was carried out as follows : freshly prepared bromotrimethylpentamethylenecarboxylic acid (10 grams) was dissolved in alcohol, mixed with a concentrated aqueous solution of pure potassium cyanide (5 grams) and 5 C.C. of anhydrous hydrogen cyanide, the mixture being allowed to remain for -14 days. The dark brown product was heated on t h e water-bath for one hour, evaporated, and the residue mixed with concentrated hydro- chloric acid and, after remaining overnight, heated for three hours on the water-bath. Water was then added and the whole distilled in steam until the distillate was free from P-campholytic acid (see p. 147). The residue was digested with animal charcoal, filtered, evaporated t o a small bulk, and repeatedly extracted with ether, when a yellow oil was obtained which became semi-solid when left for some weeks over sulphuric acid.This substance was drained on porous porcelain until all the oil had been absorbed and the residue recryatallised from a little water. As the crystalline product, which could not have weighed more than a few milligrams, melted indefinitely between 189' and 190', it was heated in a test-tube with a small quantity of acetic anhydride when, on cooling, crystals separated which were drained on porous porcelain and washed with a little acetic anhydride. These crystals closely resembled the anhydride of i-camphoric acid, since they melted at 215-217O and gave on hydrolysis an acid, melting at 204', whereas i-camphoric acid melts at 200--203° and yields an anhydride melting a t 2 2 1 O .Unfortunately, the amount a t our disposal was quite in- sufficient t o enable us to establish the identity of the substance by analysis.* * The method of formation of this small quantity of acid and its properties leave scarcely room for doubt that i t was i-camphoric acid, and experiments were in progress which it was hoped would have yielded enough material for definiteaa-DIMETHYLBUTANE-a,8&TRICARBOXYLlc ACID. 147 CHrVMe UH,*CH*CO,H Synthesis of Inuctive a-Campholytic Acid, I YRle, , and of C H,* ?Me, CH-C*CO,H gMe P-Campholytic Acid (isoLazcronolic Acid), 1 When y-bromotrimethylpentamethylenecarboxylic acid is mixed with excess of sodium carbonate solution, i t rapidly dissolves, and if the liquid is heated just to boiling, cooled, and acidified with hydro- chloric acid, a viscid, oily layer of inccctive a-campholytic acid separates.This mas extracted with ether, the ethereal solution washed until quite free from hydrochloric acid, dried over calcium chloride, evaporated, and the residual oil distilled under reduced pressure, when the whole passed over at 162-164" (45 mm.) as a colourless, viscid oil. 0.1441 gave 0,3696 CO, and 0,1185 H,O. C,H,,O, requires C = 70.1 ; H = 9.1 per cent. Methyl a-CamphoZytate.-This ester was prepared by leaving the acid in contact with methyl alcohol and sulphuric acid for a short timeand then precipitating with water. After extracting with ether, washing with sodium carbonate, drying over calcium chloride, and evaporating, an oil was obtained which distilled constantly at 200".C= 69.9 ; H = 9.1. 0.1475 gave 0.3882 CO, and 0.1287 H,@. C,H,,*CO,Me requires C = 71.4 ; H = 9.5 per cent. On hydrolysis with caustic potash and acidifying, this ester yielded liquid a-campholytic acid, showing that no isomeric change had taken place during esterification (see below). That the acid obtained in the way described above was inactive a-campholytic acid and identical with the acid first obtained by the reduction of a-camphylic acid with sodium amalgam (Trans., 1903, 83, 853) was proved by digesting a small quantity with 25 per cent. sulphuric acid for a few minutes, when, on cooling, a mass of crystals of /3-campholytic acid (isolauronolic acid) separated. These mere collected, washed with water, and recrystallised from dilute acetic acid, when leaflets were obtained which melted a t 1 3 0 O . 0.16S1 gave 0.4318 CO, and 0.1394 H,O. C = 71.7 ; H= 9.7. C = 70.0 ; H=9*1. C,H,,O, requires C = 70.1 ; H= 9.1 per cent. identification. In the meantime, Komppa (Zoc. cit. ) has published his brilliaiit synthesis of camphoris acid, which, once for all, establishes the correctness of Rredt's formula, and it is therefore quite unnecessary to investigate our much less satis- factory process any further. L 3148 NEEDHAM AND PERKIN : 0-NITROBENZOYLACETIC ACID. The identity of this acid with the P-campholytic acid, obtained by the action of aluminium chloride on camphoric anhydride, was proved, firstly, by mixing equal quantities of the two acids, when no alteration in the melting point could be detected, and, secondly, by converting the synthetical acid into isolauronic acid by oxidation. Two grams of the synthetical acid were dissolved in aqueous sodium carbonate, cooled with powdered ice, and then 2 per cent. potassium permanganate solution run in, drop by drop, until the pink colour just remained. The slight excess was destroyed by the addition of sodium sulphite, the whole was then heated to boiling and filtered, and the filtrate evaporated t o a small bulk. The yellow liquid gave, on acidifying, il mass of pale yellow crystals which, after crystallising from water, melted a t 133' and consisted of pure isolauronic acid. 0-1149 gave 0.2720 CO, and 0.0753 H,O. C,H,,O, requires C = 64.3 ; H = 7.1 per cent. Inactive a-campholytic acid has been repeatedly obtained during the course of the experiments which have been carried out with y-bromo- trimethylpentamethylenecarboxylic acid and with a-campholactone. Thus, for example, i t is formed almost quantitatively when the bromo-acid is digested with potassium cyanide in alcoholic solution and when a-campholactone is heated with dry potassium cyanide a t 1 1 oo. C = 64.5 ; H = 7.3. The authors wish t o express their thanks to Mr. D. T. Jones for his valuable assistance in carrying out these experiments, and to state t h a t much of the expense incurred during this investigation has been met by repeated grants from the Government Grant Fund of the Royal Society. OWENS COLLEGE, MANCHESTER.

ISSN:0368-1645    

DOI:10.1039/CT9048500128

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

148 NEEDHAM AND PERKIN : 0-NITROBENZOYLACETIC ACID. XVI.-o-Nitrobenzoylcccetic Acid. By EDWARD RUSHTON NEEDHAM and WILLIAM HENRY PERKIN, jun. IN the year 1881 (Bey., 14, 1742), Baeyer showed that, when ethyl o-nitrophenylpropiolate is treated with sulphuric acid and the product poured into water, ethyl isatogenate is formed, and in explain- ing this remarkable process, he assumed that intramolecular changq took place according t o the scheme C,H,*C C,H,>C\ I It1 --f I / 1 / 0 2 NO, C*CO,Et N---C --.CO,EtNEEDHAM AND PERKIN : 0-NITROBENZOYLACETIC ACID. 149 At a later date (Bey., 1882, 15, 780) the same author, having dis- covered the reduction of ethyl isatogenate to ethyl indoxanthinate, explained this reaction by modifying the formula of the former ester and represented its relationship to the latter thus : C,H,*CO U,H,*CO -+ I I NH--C(OH)*CO,Et I I N--C:* C0,Et '\ / 0 Ethyl isatogenate.Ethyl indouanthinate. Subsequently he published a preliminary notice on benzoylacetic acid (Ber., 1882, 15, 2705) showing that its ethyl ester is produced when ethyl phenylpropiolate is dissolved in sulphuric acid and the product poured on t o ice. As far as we know, no explanation of the remarkable intramolecular change from ethyl o-nitrophenylpropiolate to ethyl isatogenate has ever been published, but the following series of changes has always appeared to one of us to be a possible explanation. Just as ethyl phenylpropiolate when acted on by sulphuric acid takes up the elements of water yielding ethyl benzoylacetate, so in the case of ethyl o-nitrophenylpropiolate the first product of the reaction is probably ethyl o-nitrobenzoylacetate, which is then con- verted into ethyl isatogenate by an internal condensation brought about by the excess of sulphuric acid present : During the course of a long series of researches on ethyl benzoyl- acetate, carried out some years ago, many attempts were made to prepare ethyl o-nitrobenzoylacetate, not only with the object of test- ing the above view of the mechanism of the formation of ethyl isatogenate, but also on account of the close relationship which exists between ethyl o-nitrobenzoylacetste and many members of the indigo group.The attempts were, however, all unsuccessful at the time. I n 1896 (Anndelz, 291, 67) Claisen described a very convenient method for preparing ethyl benzoylacetate, which consists in acting on two molecules of ethyl sodioacetoacetate with bennoyl chloride and then decomposing the sodium compound of ethyl benzoylaceto- acetate thus produced by boiling with ammonia and ammonium chloride :150 NEEDHAM AND PERKIN : 0-NITROBENZOYLACETIC ACID. 2CH,*CO*CHNa*C02Et + C,H,*COCl = c ~ ~ , : ~ ~ > C N a * C 0 2 E t + CH,*CO*CH;CO,Et + NaCl 22:gE>CNa*CO,Et + H,O = C6H,*CO-CH2*C02Et + CH,*CO,Na.This process gives an excellent yield, and is not only much simpler than the preparation from ethyl phenylpropiolate and sulphuric acid, but is also to be preferred t o the earlier method of Claisen and Lowman (Ber., 1887, 20, 6 5 3 ) which consists in acting on a mixture of ethyl henzoate and ethyl acetate with sodium. After experimenting with Claisen's process with very satisfactory results, we endeavoured to prepare ethyl o-nitrobenzoylacetate by a similar series of reactions, and were ultimately successful.When the ethyl sodioacetoacetate is treated with o-nitrobenzoyl chloride under the conditions described in the experimental part of this paper, the sodium compound of ethyl 0-nitrobenzoylacetoacetate, is produced, and, when this is decomposed with hydrochloric acid, a red oil is obtained, which consists of nearly pure ethyl o-nitrobenzoyl- acetoacetate, This substance is not new, but has already been prepared by Geve- koht (Annalen, 1883, 221, 323), who proved its constitution by show- ing that, when boiled with dilute sulphuric acid, it yields o-nitroaceto- phenone, N0,*C,H4*CO*CH,. When the sodium compound of ethyl o-nitrobenzoylacetoacetate is digested with ammonia and ammonium chloride, it is decomposed with the elimination of the acetyl group, and a red oil is produced which is crude ethp? o-nitrobenxoylmtate, N 0,.C,H,* CO*CH2*C0,Eb. This is readily purified by conversion into the green, crystalline, copper compound, NO,~C,H,-CO*CHCu~*CO,Et, and is thus obtained as a pale reddish-brown oil, which in its properties closely resembles ethyl benaoy lace tate. Experiments were next made on the action of concentrated sulphuric acid on ethyl o-nitrobenzoylacetate in the expectation t h a t ethyl isatogenate would result, but we found, to our surprise, that the sulphuric acid had simply acted as a hydrolysing agent, and that the product of the action was o-nitrobenxoylacetic mid, ~O,*C,H,~CO*CH,*CO,H.Even when the ester was heated with sulphuric acid at 90°, largeNEEDHAM AND PERKIN : 0-NITROBENZOYLACETIC ACID. 151 quantities of o-nitrobenzoylacetic acid were formed, showing clearly that under these conditions there is no tendency for internal condensa- tion to take place between the nitro-group and the methylene radicle. The experiments described in this paper clearly prove that ethyl o-nitrobenzoylacetate is not an intermediate step in the conversion of ethyl o-nitrophenylpropiolate into ethyl isatogenate, and the problem of the mechanism of this remarkable reaction therefore remains un- solved. I n this conversion of ethyl o-nitrophenylpropiolate into ethyl isa- togenate, it is possible that an additive componnd with sulphuric acid may first be formed, this substance then undergoing internal condensa- tion to yield a product, which, when decomposed with water, gives rise t o ethyl isatogenate : C6H,*C U,H,*~*SO, 1 lli --f I I --+ NO, CH, CO,E t NO, C'*CO,Et Prepration of Ethyl o-Nitrobenxoykc~cetouceta~e, NO,*C:,H,*CO*5!€€*CO,Et CH,-CO I n preparing considerable quantities of this ester, we used a process based on the conditions recommended by Claisen (Annulen; 1896, 291, 67) for the preparation of ethyl benzoylacetate, and which differs in many respects from that described by Gevekoht (Annalen, 1883, 221, 323).o-Nitrobenzoic acid (100 grams) contained in a fractionating flask is gradually mixed with phosphorus pentachloride (135 grams), and as soon as the reaction, which commences in the cold, has slackened, the whole is heated on the water-bath until the crystals of the acid have entirely dissolved.The flask is then connected with the vacuum apparatus, and the phosphorus oxychloride distilled off a t the lowest possible temperature. Sodium (31 grams) is now dissolved in 400 grams of absolute alcohol, and the solution made up to 500 C.C. by the addition of more alcohol. Pure ethyl acetoacetate (90 grams) is mixed with 250 C.C. of the sodium ethoxide solution, the whole cooled to Oo, and 56 grams of the o-nitrobenzoyl chloride added in small quantities at a time and with frequent shakiag,care being taken that the temperature does not rise above 5'. After half an hour, 125 C.C.of the sodium ethoxide solution are added, and, after152 NEEDHAM AND PERKTN : 0-NITROBENZOYLACETIC ACID, thoroughly mixing, 28 grams of the acid chloride run in under the same conditions as before, then the whole is again left for half an hour and treated with the rest of the sodium cthoxide and o-nitrobenzoyl chloride. After remaining overnight a t the ordinary temperature, the thick, yellow precipitate, which consists of the sodium compound of ethyl o-nitrobenzoylacetoacetate mixed with sodium chloride, is collected a t the pump, and washed first with alcohol, and then with ether. It is then added to excess of dilute hydrochloric acid, cooled by the addition of powdered ice, and the whole shaken thoroughly with ether, The ethereal solution is washed with dilute aqueous sodium hydrogen carbonate, dried over calcium chloride, and evapor- ated, when a brownish-red oil is obtained which consists of nearly pure ethyl o-nitrobeia,yoyl~~~etoaceta~~.0.1696 gave 8.0 C.C. of nitrogen a t 20' and 750 mm. C,,H,,O,N requires N = 5 *O per cent. Ethyl o-nitrobenzoylacetoacetate is a reddish-brown oil which gives a reddish-violet coloration when its solution in alcohol is mixed with ferric chloride. It dissolves in dilute aqueous caustic potash, and on adding a concentrated solution of this reagent a crystalline potassium compound, C,,H,,O,NK, separates (compare Gevekoht, Zoc. cit.). N=5*3. Ethyl o-Nitrobenxoylcccetate, NO, C,H,* CO -CH, C0,E t. I n the preparation of ethyl o-nitrobenzoylacetate from ethyl o-nitro- benzoylacetoacetate, a method similar to that employed by Claisen (ZOC. cit.) in analogous cases, was adopted.The crude sodium compound of ethyl o-nitrobenzoylacetoacetate, in quantities of 100 grams, was mixed milh a solution of ammonium chloride (25 grams) in water (500 c.c.) ; 10 C.C. of concentrated aqueous ammonia, diluted with 90 C.C. of water, were then added, and the mass vigorously stirred with a turbine, As soon as the sodium compound had completely dissolved, the whole was mixed with powdered ice, acidified with hydrochloric acid, and at once extracted with ether, After washing with water, drying over anhydrous sodium sulphate and evaporating, crude ethyl o-nitrobenzoylacetate remains as a brown oil, the yield being about 50 grams. This ester was purified in the follow- ing way.A solution of the blue cuprammonium compound, prepared by adding ammonia in slight excess to copper sulphate, was placed in a strong bottle, mixed with the crude ethyl o-nitrobenzoylacetate dis- solved i n ten times its volume of ether, and vigorously shaken on t h e machine for 6 hours; the deep green copper compound, which had separated, was collected and washed, first with water and then with ether After drying in a vacuum desiccat,or, the copper compound wasNEEDHAM AND PERKIN : 0-NITHOBENZOYLACETIC ACID. 153 rapidly dissolved in excess of boiling toluene, from which it separates usually as a green powder, but if the crystallisation takes place very slowly and from dilute solutions, the substance is sometimes obtained in the form of definite violet crystals.When heated, this compound explodes with the formation of a thick, brown smoke, a behaviour which rendered its analysis very difficult. Ultimately the substance was first decomposed by gently warming with concentrated sulphuric acid, and, after driving off the excess of sulphuric acid, t.he residue was heated over the blowpipe, but,, even in this way, a slight loss wag unavoid- able. 0.3050 give 0.0406 CuO. Cu= 10.7. N02*C6H,*CO*CHCu~-CU2Et requires c u = 11.8 per cent. 0.4172 ,, 0.0568 CUO. CU= 11.0. I n order t o obtain pure ethyl o-nitrobenzoylacetate, the copper com- pound was ground t o a fine paste with water, mixed with powdered ice, and decomposed by shaking with dilute hydrochloric acid and ether. The ethereal solution was washed thoroughly with water and dilute aqueous sodium hydrogen carbonate, dried over anhydrous sodium sulphate, evaporated, and the residual light brown oil left in a vacuum desiccator over sulphuric acid for two days.0.1481 gave 0.3034 CO, and 0.0641 H,O. C = 55.8 ; H= 4.8. 0.2459 ,, 12.2 C.C. of nitrogen a t 17' and 754 mm. N=5*9. C,,H,,O,N requires C = 55.7 ; H = 4-6 ; N = 5.9 per cent. EtlqZ O-~Litrobenxoylacetafe has, so far, not been obtained in a crystal- line condition ; when cooled to - loo, it solidifies to a transparent resin which does not crystallise on rubbing. The alcoholic solution gives, with ferric chloride, an intense orange-red coloration which has a much yellower tint than that shown by either ethyl p- or nz-nitrobenzoyl- acetate. It dissolves readily and completely in dilute caustic potash solution, forming an intense yellow solution, and is reprecipitated on the addition of acids, but if the yellow solution is mixed with concen- trated aqueous caustic potash, a deep yellow, viscid oil separates, which when stirred vigorously, solidifies to a yellow cake of crystals, con- sisting of the potassium derivative of ethyl o-nitrobenxoylacetate, NO,*C,H,*CO.CHK*CO,Et.This product was drained on porous porcelain, rubbed up with a little water, and again transferred to porous porcelain, and after repeating this process, it was dried at 100' and analysed with the following result : 0.1450 gave 0.0466 K,SO,. This potassium compound dissolves readily in water and when K = 14.4. CI1HloO,NK requires K = 14.2 per cent.154 NEEDHAM AND PERKIN : 0-NITROBENZOYLACETIC ACID.acidified and extracted with ether, pure ethyl o-nitrobenzoylacetate is obtained as an almost colourless oil. When ethyl o-nitrobenzoylacetate is dissolved in dilute aqueous caustic soda and a strong solution of caustic Eodn added, the sodium compound is precipitated, but it is much more soluble than the potassium compound, and was not further investigated. Attempts were made to prepare the pure sodium com- pound by adding ether to the solution of the ester in the calculated quantity of sodium ethoxide, but no separation took place. If the same experiment is carried out with either ethyl p - or nz-nitrobenzoyl- acetate, the sodium compound separates a t once as a deep yellow, crystalline precipitate.o-Nitro besmoglacetic m i d , N0,*C6H,*CO* CH,. C0,H. When ethyl o-nitrobenzoylacetate dissolves in concentrated sulphuric acid heat is generated, arid the dark brown solution, when left for two or three days and then diluted with powdered ice, yields a brown solid which becomes almost colourless when drained on porous porcelain. The solid residue, which consists of almost pure o-nitro- benzoylacetic acid, may be crystallised from water if the operation is rapidly carried out, but otherwise there is a great loss owing t o de- composition into o-nitroacetophenone and carbon dioxide. The colour- less needles thus obtained were dried over sulphuric acid and analysed with the following results : 0.1756 gave 0.3351 CO, and 0.0575 H,O. 0.2274 ,, 13.2 C.C. of nitrogen at 16" and 760 mm.N=tiT. o-NdrobenzoyZacetic acid melts at about 117-1 20' with vigorous decomposition, evidently yielding carbon dioxide and o-nitroaceto- phenone. It is readily soluble in alcohol and almost insoluble in cold, light petroleum ; it dissolves moderately readily in warm benzene, and crystallises on cooling in colourless needles. The alcoholic solution of the pure acid gives a deep red coloration with ferric chloride. The composition of the acid was further controlled by titration, when it was found that 0.177 gram required for neutralisation 0.0335 gram of caustic soda, whereas this amount OF a monobasic acid, C:,H,O,N, should neutralise 0.0339 gram of the alkali. I n order to study the decomposition products of o-nitrobenzoylacetic acid, 3 grams of the piire acid were boiled with water, when a brisk effervescence took place, due to the evolution of carbon dioxide, and a heavy oil separated. This was extracted with ether, the ethereal solution washed with dilute aqueous sodium carbonate, dried over calcium chloride and evaporated, when an oil remained which was identified as o-nitroacetophenone. C = 52.0 ; H = 3.4. CgH70,N requires C = 51.7. H = 3.3 ; N = 6.7 per cent.MODIFICATIONS OF aayTRIMETHYLGLUThCONIC AClD. 155 0.1601 gave 11.9 C.C. of nitrogen at 15' and 745 mm. C,H,O,N requires N=8.5 per cent. Five grams of pure ethyl o-nitrobenzoylacetate were dissolved in 20 C.C. of concentrated Eulphuric acid and heated in a water-bath at 90' for 10 minutes. On cooling and diluting with ice, a solid soon separated which consisted of nearly pure o-nitro benzoylacetic acid, and was finally purified in the manner already described. N = 8.4. 0,2251 gave 13.1 C.C. of nitrogen at 15' and 750 mm. C,H70,N requires N = 6.7 per cent. This experiment shows that the ethyl ester when heated with con- centrated sulphuric acid is simply hydrolysed without undergoing any internal condensation. N = 6.8. THX OWENS COLLEGE, MA?~CKESTER.

ISSN:0368-1645    

DOI:10.1039/CT9048500148

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

MODIFICATIONS OF aa'y-TRIMETHYLGLUTACONIC AClD. 155 XVIL-The cis- and trans-ModiJicntions of aay- Tri- met h y lg lutaco nic Acid. By WILLIAM HENRY PERKIN, jun., and ALICE EhirLY SMITH, B.Sc., 1851 Exhibition Scholar of University College, Brngor. IN a recently published paper (Trans., 1903, , 772), i t was shown that when ethyl aay-trimethylacetonedicarboxylate, CO,Et*CMe,*CO*C HMe*CO,E t, is reduced with sodium amalgam, it is converted into a mixture of the stereoisomeric modifications of /3-hydroxy-aay-trimethylglutaric acid, C0,H.C Me,. QH* 0 H Cis, rn. p. 115". CO,H*CMeH CO,€€*CMe,*~H*OH T~uns, m. p. 155". HCMe*CO,H * Both the cis- and trcms-acids, when t,rexted successively with phos- phorus pentachloride and diethylanilhe, yield truns-aay-trimethyl- glutaconic acid, which melts at 150" : CO,H*CMe,*CH(OH)* CHMe*CO,H --f C02H*CMe,*CHC1*C HMe*CO,H -+ CO,H*CMe,*CH:CMe*CO,H.The trans-hydroxy-acid, when rapidly heated in small quantities, distils without decomposition, whereas the cis-hydroxy-acid is readily decomposed on distillation, forming an oily acid (see below) and a neutral crystalline substance, C,H,,O, (m. p. 8So), and it was suggested156 PERKIN AND SMITH: THE CIS- AND that this latter is probably the anhydride of the cis-modification of aay-trimethylglutaconic acid : C0,H'CMe;FH ;OH; flO*CMe,'gH CO,H*CMe*H.i -* O-CO---CMe * .._. We have continued the investigation, and find that this view of the constitution of the substance CsH,,,O, is correct. It is insoluble in aqueous sodium carbonate, but dissolves in warm dilute alkalis, and the solution, on acidifying and extracting with ether, yields cis-aay- trinzethy Zglutaconic a c i d , , as a colourless, crystalline CO,H*CMe,*fiH CO,H*CMe substance which melts at 125'.cis-py-dibromo-aay-trimet?~yZgZutai.ic m i d , CO,H *CMe, CHBr 'CMeBr *CO,H, which melts at 168" and is isomeric with the corresponding tvams-acid described in the previous paper (loc. cit., p. 779). It was stated above that the trans-hydroxy-acid, when heated in small quantities, distils with little decomposition, and we now find that, when considerable quantities of the acid are slowly heated, decomposition sets in, and a semi-solid distillate is obtained which consists of the above-mentioned anhydride of cis-trimethylglutaconic acid and an oily acid boiling a t about 213'.The latter is crotoclzylcli?li,et?~ylacetic acid, produced from aay-trimethyl- glutaconic acid by the elimination of carbon dioxide according to the eqna tion : When this acid is tmated with bromine, i t is readily converted into C0,H'Ci\le,'CH:CMe*C02H = CO,H*CMe;CH:CHMe + GO,. Crotonyldimethylacetic acid is also formed in considerable quantities during the preparation of the anhydride of cis-trimethylglutaconic acid by the distillation of cis-hydroxytrimethylglutaric acid (see above). It is an unsaturated acid mhicb, when digested with dilute sulphuric acid, is converted into the lantone of y-hydroxy-aay-trimethylbutyric acid, ?Me,*CR,*FHXe co- 0 ' a substance which has already been described by Anschutz arid Gillet (Arznalen, 1888, 247, 107), who obtained it from aa-dimethyllaevulic acid, CO,H*CMe,*CH;COMe, by reduction with sodium amalgam and named it a-dimethylvalerolactone.When crotonyldimethylacetic acid is treated with bromine, the colour rapidly disappears, but, even at low temperatures and in the dark, hydrogen bromide is eliminated. The product of this reaction-TRANS-MODTFICATIOKS OF ~~~-TRIMETHYLGLUTXCONIC ACID. 157 a neutral, crystalline substance melting at 83'-is evidently the Zactone of P-bromo-y-hydroxy-aay-trirrzet~~ylbzLtyric acid, produced in the following way : YMe,'CH:CHMe + Br, = ~Me,*CHBr*CHMeBr r= CO,H C0,H e,*CHBr YHMe co-- 0 ) but the ease with which the dibromo-acid loses hydrogen bromide is very unusual. cis-aay-Trintetl~ylgl2~tnc~~zic Acid, C0,H.C Me2 CH: CMe* CO,H.I n preparing this acid, pure cis-hydroxytrimethylglutaric acid was rapidly distilled in small quantities and under the ordinary pressure, when carbon dioxide and water vapour were given off and an oily distillate was obtained, which, on cooling, became semi-solid; this mass was cooled in a freezing mixture and collected at the pump on a funnel surrounded with ice and salt, the residue being then left in contact with porous porcelain until the oily impurity had been completely absorbed. By recrystallisation from light petroleum, colourless needles were obtained which melted at 88'. 0.1239 gave 0.2829 CO, and 0,0748 H,O. C,H,,O, requires C = 62.3 ; H = 6.5 per cent. The anhydride of cis-ti.imethylylutaconic acid is very readily soluble in chloroform and in ether, less so in cold benzene, and sparingly so in cold light petroleum.The solution in chloroform does not decolorise bromine, and when the benzene solution is mixed with aniline, no crystalline anilic acid separates. The anhydride is almost insoluble in cold water, but it dissolves on warming and is not a t once hydrolysed, since, if the solution is rapidly cooled and shaken, a con- siderable amount of the anhydride crystallises out unchanged. It is insoluble in cold sodium carbonate solution, but dissolves readily in warm dilute aqueous caustic potash, and on acidifying a clear solution is obtained. I n order to isolate the very readily soluble cis-acid, the liquid was saturated with ammonium sulphate, when the acid separated in needles ; the whole was then extracted three times with ether, the ethereal solution dried over calcium chloride and evaporated, and the solid residue purified by recrystallisation from a very small quantity of water.C = 65.7 ; H = 6.7. 0.1507 gave 0,3103 GO, and 0.0945 HgO. C=56*2 ; H = 7.0. C,HI20, requires C = 55.8 ; H = 7.0 per cent,158 MODlFICATIONS OF aary-TRIMETHYLGLUTACONIC ACID. cis-aay-TrimethyZgZutaco?lic acid melts at about 125" with evolution of gas and is readily soluble in water, chIoroform, benzene, alcohol, or ether ; its solution in aqueous sodium carbonate decolorises permanganate, but not instantaneously. When the acid is exposed to dry bromine vapour for about three hours and the excess of bromine removed over caustic potash in a vacuum desiccator, a solid residue is obtained which crystallises from formic acid (sp. gr.1*22), in which it is very sparingly sdluble, in hard, crystalline crusts. The analysis shows that this acid, which melts at about 1 6 8 O with decomposition, is cis-&di- bromo-aay-trimethylglutaric acid, C0,H*CMe,*CHBr*CMeBr*C02H. 0.1929 gave 0.2180 AgBr. Br= 48.1. C,H,,04Br, requires Br = 48.2 per cent. CrotonyZdi.nzetl~ylacetic Acid, C0,H*CMe2*CH:CHMe. The oily filtrate, which had been separated from the crystals of the anhydride of cis- trimethylglutaconic acid, was dissolved in ether and the ethereal solution extracted with sodium carbonate, by which means the crotonyldimethylacetic acid is dissolved, whereas t'he above anhydride, which is still present in considerable quantities, remains in the ether.After acidifying and extracting with ether, an oily acid was obtained which distilled a t 210-220", and as this still contained traces of anhydride, the treatment with sodium carbonate was repeated and the acid again distilled, when almost the whole quantity passed over a t 213" as a colourless oil having a penetrating and most disagreeable odour. 0.1291 gave 0.3088 CO, and 0*1101 H,O. C7H1202 requires C = 65.6 ; H = 9.4 per cent. When boiIed with 25 per cent. sulpburic acid for a few minutes, crotonyldimethylacetic acid is readily and almost completely converted into the lactone of y-hydroxy-aay-trimethylbutyric acid, ~Me2*CH,*~HMe co- 0 - The product was extracted with ether, the ethereal solution washed with dilute aqueous sodium carbonate, dried over calcium chloride, and evaporated, when a colourless oil remained, which smelt strongly of camphor and crystallised on cooling.The crystals, when left in contact with porous porcelain until quite dry, melted at 48-52". C = 65.5 ; H = 9.4. C= 65.2 ; .H= 9.4. 0.1760 gave 0.4232 CO, and 0,1494 H,O. This lactone has already been prepared by Anschutz and aillet C7H,,0, requires C = 65.5 ; H = 9.4 per cent.DERIVATIVES OF P-RESORCYLIC ACID. 159 (Annulen, 1888, 247, 107,) who give 52' as the: melting point. Crotonyldimethylacetic acid dissolves in chloroform, and if the solution is treated with bromine a t the ordinary temperature the colour dis- appears, heat is generated, and a considerable quantity of hydrogen bromide is produced. This formation of hydrogen bromide cannot be avoided by keeping the chloroform solution in a blackened test tube at 0' and adding the bromine slowly. On allowing the product oll brominntion t o evaporate spontaneously, a colourless residue is obtained, which crystallises from light petroleum (b. p. 50-60') in long prisms and melts at 82-83'. 0.3020 gave 0.2748 AgBr. As stated in the introduction, this substance is evidently the Zccctoxe Br = 38.8. C7H,,0,Br requires Br = 38.7 per cent. of p-bromo-y-?~yc~roxy-aay-t.r.inzetl~ylbutyric acid. THE OWESS COLLEGE, MAN CH ESTER.

ISSN:0368-1645    

DOI:10.1039/CT9048500155

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

DERIVATIVES OF P-RESORCYLIC ACID. 159 XVIIL--Derivatives of p-Resorcylic Acid and of P'ro- t ocutechzLic A cid. By WILLIAM HENRY PERKIN, jun., and E~IANUEL SCHIESS. DURING the course of a long series of researches on the constitution of brazilin and haematoxylin, it was found necessary, for the purposes of comparison, t o prepare and investigate several new derivatives of resorcinol and catechol, and in this paper we give a brief account of some of the compounds which were thus prepared. Dim&yZresorcyEc Acid, (~!teO),C,H;CO,H, am? its MetlqZ a d BthpE Esters. Methyl diniethyz-P-resorcylate, ( MeO)2C6 H;CO,?He, is readily obtained when P-resorcylic acid is treated with caustic potash and methyl sulphate in aqueous solution. It is thus seen that the hydroxyl group in P-resorcylic acid, which is in the o-position with respect to the carb- oxyl group? may be methylated by means of aqueous caustic potash and methyl sulphate, whereas, as is well known, the hjdroxyl group in the above position in this and other similar compounds is hardly attacked by the usual treatment with alcoholic potash and methyl iodide.P-Resorcylic acid (30 grams) is dissolved i n 240 grams of 10 per160 PEliKIN AND SCHIESS : DERIVATIVES OF cent. aqueous caustic soda, and then methyl sulphate (65 grams) added in small quantities a t a time. After each addition, the bottIe containing the mixture is vigorously shaken on the machine and cooled, if necessary, no further quantity being added until the last portion has been completely decomposed. Care is also taken, by add- ing small quantities of strong caustic soda solution from time to time, t h a t the liquid is always strongly alkaline.The oil which separates is extracted with ether, the ethereal solution washed with dilute aqueous caustic soda, dried over calciumchloride, and evaporated, and the residual oil fractionated under reduced pressure, when almost the whole distils a t 160-162" (13 mm.). The boiling point of this oil under the ordinary pressure was observed to be 294-296". 0.226 1 gave 0.4978 CO, and 0.1 126 H,O. C,,H1,O, requires C = 61 -2 ; H -- 6.1 per cent. The yield of methyl dimethyl-/I-resorcylate (which does not appear t o have been previously prepared) varies considerably, but is usually 30-40 per ceut. of the theoretical. As, however, by acidifying the alkaline liquids, quantities of methyl- and dimethyl-P-resorcylic acids may be precipitated and used in a subsequent operation, the total yield from a given quantity of /3-resorcylic acid is actually much greater than this.When the above methyl ester is boiled with alcoholic potash for a few minutes and the solution, after evapo- rating with water, acidified with hydrochloric acid, dimethyl- P-resorcylic acid separates at once, and after recrystallising melts at 10s". C = 60.9 ; H = 6.1. Bth y I Dimeth y I-p-resorqlate, (MeO),C,H, C 0,E t. This ester was prepared by boiling dimethyl-a-resorcylic acid with alcohol and sulphuric acid for about 6 hours, and t h m adding water and extracting with ether. After washing with sodium carbonate, drying over calcium chloride, and distilling off the ether, an oil was obtained which distilled constantly a t 170" under 13 mm.pressure. 0.1331 gave 0.3080 CO, and 0.0826 H,O. C = 62.8 ; H = 6-9. CllH,,O, requires C = 62.9 ; H = 6.7 per cent. 2 : 4-Din~,etl~oxyhe~~xo~laceto~~~eno.lze, (MeO),C,H,* C0.C H2*CO*C,H5. This substance is produced by the condensation of ethyl P-resorcylate and acetophenone in the presence of sgdium, and in our first experi- ments, which were carried out under ordinary conditions (see, for example, Kostanecki, Rrifycki, and Tambor, Bey., 1900, 33, 3413), great diBculty mas experienced in isolating more than traces of the crystalline product of the reaction. On using, however, conditions6-RESORCYLIC ACID AND OF PROTOCATECHUIC ACID. 161 similar to those recommended by the Farbwerke vorm.Rleister, Lucius, and Briining (Bey., 1890, 23, Be$ 40 ; see also Bulow and Riess, ibid., 1902, 35, 3902), we were able t o obtain an excellent yield of 2 : 4-dimethoxybenxoylacetophenone. Ethy 1 dimethyl-P-resorcylate (21 grams) is dissolved i n dry ether, mixed with acetophenone (12 grams) and treated with finely divided sodium (2.5 grams).* Any rise of temperature is prevented by placing the flask in ice-water, the reaction is promoted by repeated shaking, and after two hours the flask is allowed to remain overnight at the ordinary temperature. The sodium gradually passes into solution and the sodium compound separates as a crystalline powder, the whole ultimately becoming a semi-solid mass. In order to isolate the dimethoxy benzoylacetophenone, the product is made slightly acid by the addition of dilute acetic acid, extracted with ether, the ethereal solution washed with dilute sodium carbonate solution and well agitated on the machine with aqueous copper acetate until no further separation of the green copper derivative takes place.This is collected a t the pump, washed with water and alcohol, and purified by recrystallisation from benzene, f rom which the copper derivative of 2 : 4-di~~aethoxybenxoyIcccetop~ieno?~e separates in slender, green needles containing one molecule of benzene of cry stallisation,? 0.2335 gave 0.0259 CuO. Cu=8.6. C,4H,,0,Cu,C'6H6 requires Cu = 8.4 per cent. After drying at l l O o until constant, the following complete analysis was made : 0,1803 gave 0,4277 GO,, 0*0778 H,O, and 0.0226 CuO.C=64*'i; H=4*8; CU=~O*O. C,4H8008Cu requires C = 64.9 ; H = 4.8 ; Cu = 10.0 per cent. The pure copper compound was then mixed with excess of dilute hydrochloric acid and the diketone extracted with ether, the ethereal solution was washed with water until free from copper, dried over calcium chloride, and evaporated, when a n oil was obtained which rapidly solidified. The substance was further purified by recrystallisa- tion from alcohol, from which i t separates in plates. 0.1501 gave 0.3948 GO, and 0.0779 H,O. C = 71.7 ; H = 5.8. C17H,,0, requires C = 7 1 -8 ; H = 5.7 per cent. 2 : 4-Dimethoxybenxoylacetop?~enone melts at 55" and is readily soluble * This condition is best ohtairied by melting the sodium uuder boiling toluene It is noteworthy that the copper derivative of 3 : 5-dimethoxybenzoylaceto- and then shaking vigorouuly.phenone also crystallises with one molecule of benzene (Bulow and Riess, Zoc. cit.). VOL. LXXXV. M162 PEREIN AND SCHIESS : DERIVATIVES OF in benzene, ether, and chloroform, more sparingly in alcohol and light petroleum. Its solution in alcohol gives with ferric chloride an intense reddish-brown coloration. 2 : 4-Dimethoxycinnamic Acid, (MeO),C,H,*CH:CH* CO,H. This acid was first obtained from umbelliferone by Will and Tie- mann (Ber., 1882,15,2080 ; 1883,16,2116) in two forms--a- and ,%- which melt a t 138' and 184' respectively, and obviously represent the cis- and trans-modifications of the acid. Since it mas probable that we should require considerable quantities of this acid, a number of experiments were made with the object of preparing the substance synthetically, with the result thd, two methods were devised by which it may be readily obtained in quantity from dimethyl-P-resorcyl- aldehyde.Method I. Preparation of 2 ; 4-Dimetl7~oxycinnurc Acid from Di- methyl-P-resorcylaZdeh~~e by the Action of Sodium Acetate and Acetic Anhydride. Dimethyl-/3-resorcylaldehyde (10 grams) is intimately mixed with anhydrous sodium acetate (10 grams) and heated with acetic anhydride (30 grams) in a reflux apparatus for 20 hours i n an ail-bath at 170". The brown mass is diluted with water and the excess of acetic acid removed by distillation in steam, the residue is then made alkaline by adding sodium carbonate, and allowed t o remain until quite cold.The unchanged aldehyde which separates is filtered off, the filtrate acidified with hydrochloric acid, and the very sparingly soluble di- methoxycinnamic acid, which separates a t once, collected and purified by recrystallisation from acetic acid. The acid thus obtained is the @modification and melts at 186'. 0,1420 gave 0.3317 CU, and 0*0780 H20. C = 63.7 ; H = 6.1. Cl1H1,O4 requires C = 63.5 ; H = 5.8 per cent. Method 11. Prepuration of Ethyl 3 : 4-0imet?~oxycinnamuts, (MeO),C,H,*CH:CH*CO,Et, by the Condensntion of Dimethyl- P-resorcylaldehyde with Ethyl Acetate in the presence of #odium. This ethyl ester was first prepared by the esterification of the acid with alcohol and sulphuric acid, and was thus obtained as a crystalline kolid which melted at 61' and distilled at 210-212" under 13 mm, pressure.Subsequently it was discovered that i t can be obtained directly, and in a yield of at least 80 per cent. of the theoretical amount, by@-RESORCYLIC ACID AND OF PROTOCATECHUIC ACID. 163 the general method devised by Claisen (Ber., 1890, 23, 977), and which appears to be not nearly so well known as it deserves to be. Dimethyl-P-resorcylaldehyde (1 6.6 grams) is dissolved in 30 grams of ethyl acetate (which has been carefully freed from water and alcohol) and then finely divided sodium (2.5 grams, see foot-note, p. 161) added all at once, The sodium begins to act immediately, and, after two hours in ice-water, the mixture is left overnight at the ordinary temperature, when a11 the sodium will have disappeared.The dark brown liquid is acidified with dilute acetic acid, extracted with ether, the ethereal solution well washed, dried over calcium chioride, and evaporated, when an oil is obtained which rapidly solidifies. I n purifjing t h i s substance, i t is best to distil the product first under reduced pressure, when almost the whole passes over at 208 -212' (13 mm.), leaving only a small quantity of resinous matter in the retort. The distillate, which solidifies at once, is pure enough for most experiments, but for analysis the substance was recrystallisod from light petroleum, from which it separated in slender needles melting at 61". 0.1518 gave 0.3668 CO, and 0.0941 H,O. C,,H,,O, requires C = 66.1 ; H = 6.8 per cent. Ethp? 2 : 4-dinzetl~ox?/cinszanzate is readily soluble in alcohol, ether, or benzene, but sparingly so in cold light petroleum.Attempts were made to convert this ester into ethyl dimethoxyphenyl-ap-dibromo- propionate by the action of bromine, but, so far, these have not been successful. When bromine is added to the chloroform solution of the ester, dark decomposition products are formed, and hydrogen bromide is evolved even a t 0'. Possibly under different conditions, a method of avoiding this decomposition and substitution may be found, and further experiments with this end in view are in progress. C = 65.9 ; H= 6.9. 3 : 4-Dinaet~oxycinrzccmic Acid, (MeO),C6H,*CH:CH*C0,H. The metbyl ester of this acid is formed when 3 : 4-dihydroxycinnamic acid (caffeic acid) or either of its two isomeric 3- and 4-monomethyl derivatives, (MeO)(OH)C6H,*OH:CH*C0,H, called respectively ferulic and isoferulic acids, is heated with methyl iodide and caustic potash in methyl alcoholic solution (Tiemann and Nagai, Ber., 1878, 11, 652 ; Tiemann and Will, ibid,, 1881, 14, 959).The melting point of the methyl ester is given as 64O, and that of the free acid as lSO-18lo. Although 2 : 4-dimethoxycinnamic acid (see p. 162) exists in two well-defined stereoisomeric forms, the 3:4-dimethoxy-acid has, so far, only been obtained in the one modification. In our experiments on the synthesis of 3 : 4-dimethoxy- cinnamic acid, w0 employed in the first instance an exactly similar M 2164 DERIVATIVES OF P-RESORCYLTC ACID. process to that described in the case of the 2 : 4-dimethoxy-acid, that is, we heated a mixture of 3 : 4-dimethoxybenzaldehyde (di- met hylcatecholaldehyde) and sodium acetate with acetic anhydride.The yield of acid obtained was upwards oE 50 per cent. of the aldehyde employed, and a good deal of the latter was recovered unchanged. 3 : 4-Dimethoxycinnamic acid melts at 180' and crystallises from acetic acid in needles ; it is very sparingly soluble in water. 0.1439 gave 0.3358 CO, and 0.0739 H,O. C = 63.6 ; H = 5.7. C,,H120, requires C = 63.5 ; H = 5.S per cent. Ethyl 3 : 4-Dimethoxycinnamccte, ( MeO),CoH,*CK:C H*CO,Et. When 3 : 4-dimethoxybenzaldehyde is condensed with ethyl acetate under the conditions described in the case of the preparation of the ethyl salt of the 2 : 4-dimethoxy-acid (p. 162) and the product purified by fractionation, ethyl 3 : 4-dimethoxycinnamate is readily obtained pure and in a yield of 85 per cent.of that theoretically possible. It crystallises from light petroleum in plates, melts a t 59", and distils at 196-197O under 13 mm. pressure. 0.1507 gave 0.3642 CO, and 0.0936 H,O. It dissolves readily in alcohol, benzene, or chloroform, but is sparingly C = 65.9 ; H = 6.9. C,,H,,O, requires C = 66.1 ; K = 6.8 per cent. soluble in light petroleum. Ethyl 3 : 4- Diclnet?~oxyyo7~enyZ-a~-clibromo~~o~iona~~, (MeO),C,H,'CH Br'C HBr*CO,Et, and 3 : 4-Dimet?~oxypl~enylpropioZic Acid, (MeO),C,H8*CiC*C0,H. In its behaviour towards bromine, ethyl 3 : 4-dimethoxycinnamate shows much greater stability than the corresponding 2 : 4-dimethoxy- compound (p. 163), and this enabled us to prepare, without much difficulty, considerable quantities of the dibromo-additive product in a pure condition.Ethyl 3 : 4-dimethoxycinnamate (23.6 grams) is dissolved in chloroform (40 gramq), the solution cooled with ice-water, and then 16 grams of bromine, dissolved i n 30 grams of chloroform, gradually added. When the colour of the bromine has disappeared, the chloroform is removed at as low a temperature as possible, by distillation under reduced pressure, and the oily residue then solidifies t o a hard, yellow, crystalline cake. After triturating with cold light petroleum and filtering at the pump, the substance is then crystallised from the same solvent.THE FORMATION OF PHLOROGLUCINOL. 165 0.2218 gave 0.2092 AgBr. Br= 40.2. C,,H,,O,Br, requires Br = 40.4 per cent. Ethyt 3 : 4-dirnethoxyp?$en yZ-a~-dibronzopopio nate cr ys tallises from light petroleum in colourless needles and melts at llO-lllo ; it is readily soluble in alcohol, ether, benzene, chloroform, or hot light petroleum, but sparingly so iu the latter solvent in the cold.3 : 4 - D z ' r n e t h o x y ~ h s ~ ~ o p i o l i c mid is readily obtained when ethyl 3 : 4-dimethoxyphenyl-~~-dibromopropionate (1 rnol.) is digested for 8 hours with a large excess of alcoholic potash (6 mols.). The product is evaporated on the water-bath to remove the bulk of the alcohol, the residue dissolved in water, and neutralised with hydrochloric acid. After filtering from a small quantity of dark resinous matter which usually separates, the clear solution is acidified, when the new acid is precipitated in white flocks. It is colIected a t the pump, washed thoroughly with water, dried on porous porcelain, and purified by recrystallisation from benzene, 0.1426 gave 0,3338 CO, and 0,0694 H,O. C = 63.9 ; H = 5.0. C,,H,,O, requires C = 64-1 ; H = 4.8 per cent. 3 : 4-l)imethoxypl~enyZ~opioZic acid melts a t 149' with decomposition and is readily soluble in alcohol, but sparingly so in cold benzene or chloroform; it dissolves very sparingly in hot water and is almost insoluble in the cold; it crystallises best from benzene, from which i t separates in colourless, microscopic needles, THE OWENS COLLEGE, MANCIIESTER.

ISSN:0368-1645    

DOI:10.1039/CT9048500159

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

THE FORMATION OF PHLOROGLUCINOL. 165 XIX.-The li’ormation o f Phloroglucilzol by the Inter- action o f Ethyl Maloizate with its Sodium Derivutzve. By CHARLES WATSON MOORE. IN the year 1885, Baeyer made the important discovery that when ethyl malonate is heated with its sodium derivative a t 145O, condensation takes place and a derivative of phloroglucinol is formed which melts a t 104O, and which Baeyer considered was ethyl phloro- glucinoltricarboxylate, C,(OH),(CO,Et), (Bell., 1885, 18, 345’7). During the course of an investigation involving the use of ethyl malonate, the author was led to reinvestigate this matter, and has been able t o prove that the substance formed under the conditions employed166 MOORE: THE FORMATION OF PHLOROGLUCINOL BY THE by Baeyer is ethyl phloroglucinoldicarboxylate, C,H(OH),(CO,Et),, and not the above-mentioned tricarboxylate.Since the difference in percentage composition between these two esters is small (a fact which accounts for the mistakes which have arisen as t o its composition), the molecular weight was determined in benzene solution by the cryoscopic method, and two determinations gave 270 and 273, whereas the molecular weights of the dicarboxylic and tricarboxylic esters are 270 and 342 respectively. The determination of the ethoxyl groups, which was kindly carried out by Dr. W. H. Perkin, sen., in his new modification of Zeisel's apparatus (Trans., 1903, 83, 1367), also gave numbers which clearly show that the substance is a dicarboxylic ester. When treated with bromine, it yields a bromo-compound having the com position C,Br(OH),( CO,Et),, which was first prepared by Oscar Bally (Bey., 1888, 21, 1770), the process being a simple case of sub- stitution of hydrogen by bromine, whereas Bally, who supposed that the original ester was the tricarboxylic ester, was forced to assume that, during bromination, elimination of ethyl bromide and carbon dioxide had taken place, in order to account for the composition of the bromo-compound.If then the product of the condensation of ethyl malonate with its sodium compound is the dicarboxylic ester, i t follows that during the condensation, elimination of ethyl alcohol and carbon dioxide must have taken place, and, in proof of this, the author finds that the mixture invariably contains considerable quantities of sodium carbonate.Since ethyl phloroglucinoldicarboxylate readily yields a triacetyl compound when heated with acetic anhydride, there can scarcely be a doubt that its constit:ition is represented by the formula : C0,Et OHAOH H\)CO,Et OH Ethyl Pldorog lzccino Zdicarboxylate, C,H( OH),( C0,Xt) ,. During this investigation, the above ester was repeatedly prepared according to the directions given by Baeyer (Zoc. cit.), but the purifi- cation was found to be tedious, for the compound, as Baeyer states, is yellow, and the alcoholic solution must be boiled for a long time with animal charcoal before the yellow colour can be removed. The pure ester, after repeated crystallisation, melted at 107" (Baeyer gives 104O), and was analysed with the following result :INTERACTION OF ETHYL MALONATE 167 0.2014 gave 0.3944 CO, and 0,0948 H,O.C = 53.6 ; H = 5.2. C,H(OH),(CO,Et), requires C = 53.3 ; H = 5.2 per cent.. C,(OH ) ,(CO,Et), ?, C=52.6; H=5*2 ?, The analytical numbers given by Baeyer are C = 52.4 ; H = 5.2 per cent. As the difference in the percentage composition of the di- and tri-carboxylic esters is so small, the molecular weight was determined by the cryoscopic method, using benzene as the solvent. Two experi- ments gave the values 270 and 273, whereas the molecular weight of the dibasic ester, C,,H,,07, is 270, and that of the tribasic ester, C,,H,,O,, is 342. The view that the ester is ethyl phloroglucinoldicarboxylate received further confirmation from the determination of the ethoxyl groups by Dr. W. H. Perkin." 0.3436 gave 0.5641 A.gI, corresponding with OEt = 31.5.The dibasic ester, C,,H,,07, contains OEt = 33.3 per cent. The tribasic ester, C,,H,,O,, ,, C)Et=39*4 ,, 0.3504 ,, 0.5807 AgI, 9 ? ,, )) =31.8. Ethyl Triacet y Zpliloroglucinolcliarbox~~c~te, C,H ( C,H,O,) 3( CO,E t),. This substance, which has already been described by Oscar Bally (Ber , 1888, 21, 1768), was prepared by his method. After repeated recrystallisation from alcohol, it was obtained as a colourless, crystal- line mass which melted at 96' (the m. p. 75-76' given by Bally is evidently a clerical error). 0.1488 gave 0,2970 CO, and 0.0690 H,O. Bally found C=53*9 and H=5.0, a result which agrees fairly well with the above, but he assumed that his substance was the triacetyl compound of ethyl phloroglucinoltricarboxylate.C = 54-4 ; H = 5.1. C,,H,,O1, requires C = 54.5 ; H = 5.0 per cent. EtlqE Bromoph Eorog Zzccin oldicar box2 late, CbBr (OH) 3( C0,E t ) 2. This substance was first obtained by Bally (Zoc. cit.) by treating the ester prepared by Baeyer's process with bromine in chloroform solution, I n this preparation also, Bally's directions were carefully followed and the bromo-compound was obtained, exactly as he describes, in colourless needles melting at 128'. The results obtained on analysis were : C = 40.9 ; H -- 3.7 ; Br = 22.8. C,,H130,Br requires C = 41.2 ; H = 3.7 ; Br = 22.8 per cent. * The determination of ethoxyl groups always gives figures rather lower than the theoretical, the loss being apparently due to the conversion of a small amount of the ethyl iodide into ethylene during the process168 THE FORNATION OF PHLOROGZUCINOL.The analytical results obtained by Bally agree fairly well with those just given, and it is curious that he should assume, in order t o explain the composition of this bromo-compound, that, during the bromina- tion, carbon dioxide and ethyl bromide are eliminated, thus convert- ing ethyl phloroglucinoltricarboxylate into ethyl bromophloroglucinol- dicarboxylate, whereas there is no indication of any such elimination of carbon dioxide. That carbon dioxide is formed during the condensation of ethyI malonate with its sodium compound by the process recommended by Baeyer was proved by carrying out the operation in a flask fitted with a dropping funnel, and through which hydrogen was passing during the whole operation.On adding hydrochloric acid through the dropping funnel to the product and lending the gases through baryta water, it was a t once seen that quantities of carbon dioxide were being evolved. Prepamtion of Ethyl Pl~ZorogZucinoldicccr6ox~Zat~ by Heating Ethyl Sodionzcdo.lc;ate with Ethyl McLZonute in AZcohoZic Ayolutioiz. This method, which gives a pure product much more readily than that described by Baeyer, was carried out as follows. Sodium (14.4 grams) is dissolved in alcohol (200 grams) and, when nearly cold, mixed with 200 grams of ethyl malonate. The mixture, while still warm, is transferred to soda-water bottles and heated in a boiling brine bath a t 105-108° for 15 hours. The white precipitate, which separates during this operation, consists of the sodium compound of ethyl phloroglucinoldicarboxylate mixed with sodium carbonate ; it is collected at the pump, mashed with alcohol, and then dissolved in water acidified with hydrochloric acid, when carbon dioxide is evolved and the ester precipitated as an almost colourless crystalline mass. After one crystallisation from alcohol, the ester was perfectly colourless and melted a t 106-107°. 0.1736 gave 0.3393 CO, and 0,0815 H,O. C6H(OH),(C0,Et), requires C = 53.3 ; H = 5.2 per cent. This ester yields phloroglucinol on hydrolysis, and its identity with the ester prepared by Baeyer’s process was proved by mixing equal quantities of the two specimens when there was no alteration in the melting point. The yield obtained in alcoholic solution is practically the same as that obtained by .Raeyer’s process, but a large amount of ethyl malonate may be recovered and used in a subsequent operation. C = 53.3 ; H = 5.2. THE OWENS COLLEGE, __ -. -__ BIIANCIIEGTEH.

ISSN:0368-1645    

DOI:10.1039/CT9048500165

出版商:RSC    

年代:1904

数据来源: RSC

摘要:

TATTERSALL : THE RESOLUTION OF DL-METHYLHYDRTNDAMINE. 169 X X.-The Resolution of dl-Methylhydrindccmine. Iso- meric Xcllts of d- and 1-nlethylhyd7~indamiizes with d- CrhLo1.oca1,~pho.i.sulp12onic ,4 cid. By GEORGE TATTERSALL, B.Sc. IN a recent communication (Tattersall and Hipping, Trans., 1903, 83, 9 1 S), a method was described by which &methyl hydrindamine could be resolved into its enantiomorphously related components by the use of d-bromocamphorsulphonic acid. As the yield of these salts of the d- and E-bases was always small compared with the quantity of original material taken, and also varied considerably with the conditions of the experiment, the author, at Dr. Kipping’s suggestion, attempted to find a more satisfactory process for the resolution of the dl-base. Experiments then showed that d-tartaric acid is a more suitable agent with which t o effect the resolution.When a solution of this acid is added to dl-methylhydrindamine in sufficient quantity to form the hydrogen tartrate and the product fractionated from wster a t the ordinary temperature, an excellent separation of the d- and I-bases is effected. The most sparingly soluble fractions, which contain the hydrogen tartrate of the d-base in a pure condition, amount to about one-third of the whole material. The purification of the bases was carried out by converting the first fractions, containing chiefly the d-base, and the last fractions (the remaining two-thirds) into the d-bromocamphorsulphonates separately, and finally fractionating the products by crystallising from water.The production of isomeric salts by the combination of d- and I-methylhydrindamines with d-bromocamphorsulphonic acid has been already described (Tattersall and Kipping, Zoc. cit.), and in this paper an account is given of similar experiments made with d-chloro- camphorsulphonic acid and the same bases. The salt of each base, prepared from very carefully purified materials, was subjected t o repeated fractional crystallisation and the final fractions examiued. I n both cases, the melting points of suc- cessive fractions were found to decrease from the first to the last, this behaviour corresponding with that observed in the case of the bromo- camphorsulphonates. An important point of difference between the chlorocamphorsulphonates and the bromocamphorsulphonates, however, is that in the case oE the former aoid the specific rotations of the last fractions are higher than those of the first fractions, whereas with the latter acid the reverse is the case.These generalisations are true170 TATTERSALL : TEE RESOLUTION OF DL-METHYLHYDRINDAbIINE. both for aqueous and chloroform solutions. The following table summarises the results obtained : I-Metbylhydrindamine d-chlorocamphorsulphonate. , . 11. 13. 111 ci~loroform. In water. First fraction 239' + 3.3' + 34.2' Last ,, 23 1-233' s.0 35.s d-Methylhydrindamine d-chlorocamphorsulphonnte. I: a I D . < 7 M. p. In chloroform. In water. First fraction 247' + 56' + 60' Last ,, 225-230' 63 63 These results are similar t o those obtained with the hydrind- amine d-chlorocamphorsulphonates (Kipping, Trans., 1903, 83, 902), but it mas not found possible to isolate the isomerides of higher specific rotation.EXPERIMENTAL. About 30 grams of purified dl-methylhydrindamine d-bromo- camphorsulphonate, obtained as previously described (Tattersall and Kipping, Zoc. cit.), was decomposed with barium hydroxide and the base distilled in steam. A solution of d-tartaric acid was added to the distillate until the latter was just acid, and then a further equal quantity of acid in order that the hydrogen tartrate might be produced. The solution was evaporated and the salt fractionally crystallised. The first deposit on recrystallisation was obtained in vitreous prisms, whilst the mother liquors slowly deposited clusters of small, opaque crystals.When the fractionation had proceeded SO far that the first deposit had been twice crystallised, the first two fractions mere examined. The first was found t o be hydrated and when dried, melted at about 150'; the second was almost anhydrous and melted at 190° (approximately). The fractions were therefore different. The first fraction, amounting to about one-fourth or one-third of the whole, was decomposed with caustic potash, the base distilled in steam, the distillate neutralised with d-bromocamphorsulphonic acid, and the solution evaporated and crystallised, when the salt of d-methylhy drindamine was obtained. The sparingly soluble fractions of the hydrogen tartrate therefore contain the d-base. Owing to the dificulty usually experienced in obtaining a pure saltTATTERSATJL : THE RESOLUTION OF DL-METHYLEYDRINDAMIKE.171 from the mother liquors, and considering the great ease with which dLmethylhydrindamine d-bromocamphorsulphonate can be separated from the salt of the d- or Z-base, the last fractions were decomposed with caustic potash, the base distilled in steam and combined with d-bromocamphorsulphonic acid. On crystallising, the salt of &methyl- hydrindamine first separated and the salt of the dl-base was found in the mother liquors. The d-base can, obviously, be obtained pure from the first deposits of the hydrogen tartrate, but the purification of the I-base was always carried out by converting the last fractions into the &-bromocamphor- sulphonate. By this process, about two-thirds of the original dE-base can be resolved into its enantiomorphously related components, d-MethyEhydrindamine Hydrogen Tartrate, C,,H,,N, CqH606, 2H20.- This salt crystallises from water in long, vitreous, hydrated prisms which become opaque on warming in contact with a solution of the salt ; it is moderately soluble in alcohol or water, but more sparingly so in the latter solvent than the corresponding salt of the Lbase, and is practically insoluble in chloroform, ether, ethyl acetate, and light petroleum.The melting point of the dried salt, is 153-155', being somewhat indefinite owing to slight decomposition. The water was estimated in air-dried samples by determining the loss of weight at 100'. 2.6761 lost 0.3868. H,O= 10.7. C,oH1,N,C4H,0,,2H20 requires H,O = 10.8 per ceut.The specific and molecular rotations were determined in aqusous solution with samples of the anhydrous salt, 20 C.C. of solution being used. + Weight of salt, aD. [.ID. "ID, 0.5376 + 1 -74O + 32.4' + 98*0° 0.5925 1-99 33.6 99.7 As the molecular rotation of d-tartaric acid in the metallic hydrogen tartrates is [MID +42O, that of the base would be [MI, +57', a value which agrees very closely with that ([MID + 60') previously deter- mined from an examination of the d-bromocamphorsulphonates (Tat- tersall and Kipping, Eoc. cit.). I-Nethylhydrindamine Hydyogen Tartrate, CloH1,N,C,H,06.-This salt crystallises from water in aggregates of small, vitreous, an- hydrous prisms, which are readily soluble in water, sparingly so in * A 200 mni. tube was used in all the polarimetric observations recorded iu this paper.172 TATTERSALL : THE RESOLUTION OF DL-METHYLHYDRINDAMINE.alcohol, and practically insoluble in chloroform, ethyl acetate, ether, and light petroleum ; it melts a t 197' with slight decomposition. The specific and molecular rotations were determined in aqueous solution with samples dried a t loo', 20 C.C. of solution being used. Weight of salt. Q1). [a],,. [hlIlJ. 0.7076 - 0.36' - 5.0' - 14.8' 0.6649 0.32 4.s 14.3 I n this case, aleo, the calculated value for the molecular rotation of the Lbase, namely, [MID - 56*5O, agrees closely with t h a t previously deduced from the optical examination of the d-bromocamphorsulph- onates. 1- Met hylh y dr indamine d- Chlo~ocamphorsuZph onate, C,oHl,N,CloH,,OCl*SO,H. This salt was prepared in the usual way, the I-methylhydrindarnine being carefully purified by the crystallisation of its d-bromocamphor- sulphonate. The product was subjected to prolonged fractional crys- tallisation from water and separated into eight fractions.At the conclusion of the fractionation, the melting points of the several fractions were determined, those of the first and last fractions being 239' and 231-233' respective!y. The other fractions each melted over a range of 2-3', the values gradually decreasing from the melting point of the first fraction to that of the last. These fractions all crystallised in anhydrous needles resembling the corre- sponding salt with d-bromocamphorsulphonic acid. The first and last fractions were dried a t 100" and examined polari- metrically in chloroform and aqueous solutions.First Frccction. Weight of salt. Solvent. Vol. of solution. a, I. 0.3496 Chloroform 20 C.C. + 0.12' 11. 0.3351 9 , 1, 0.1 1 I. 0.3496 Water 9 , 1-19 XI. 0.3351 ,? ?I 1.15 Last Fraction. I. 0-3294 Chloroform 20 C.C. +0.27' 11. 0.3327 9 9 ,, 0.26 I. 0.3294 Water 9 ) 1.18 11. 0.3327 9 9 ?) 1.19 [a]: [ M I D +3*4' + 14.0' 3.28 13.5 34.1 140.8 34.3 141.6 + 8.2" + 33.8" 7.8 32.2 35.8 147.8 35.8 147.8TATTERSALL : THE RESOLUTION OF DL-METHYLHPDRINDAMINE. 173 It will be noticed that the specific rotations of the last fraction are higher than those of the first both in chloroform and in aqueous solutions. This conclusively proves t h a t the observed difference in rotation cannot be dug to any impurity, although the absence of the latter was independently proved, as in all previous experiments.The existence of isomeric salts is therefore established in this case. d-Methylhydrindomine d-Chlorocrcmphorsulplmnate, C,,H,,N,C,~H~,OCl*SO,H. d-Methylhydrindamine, purified by the crystallisation of its bromo- oarnphorsulphonate, was corn bined with d -chlorocamphorsul phonic acid, the product subjected to fractional crystalllsztion from water, and the melting points of the successive fractions determined. The first fraction melted at 247' and the last a t 225-230'. The intermediate fractions had melting points which, extending over a small range, gradually decreased from the melting point of the first fraction to that of the last. These fractions all separated in anhydrous needles resembling the corresponding bromocamphor- sulphonate.The first and last fractions were dried at 100' and examined polarimetrically in chloroform and aqueous solutions. First Pruct ion. Weight of salt. I. 0.3912 11. 0-3953 I. 0.4049 11. 0.4013 1. 0,3696 11. 0.3911 I. 0-3696 11. 0.3917 Solvent. Vol. of solution a,,. Chloroform 20 C.C. + 2-20' 9 , $ 9 2.20 Water J 1 2.44 9 ) 7 9 2.41 Last Fraction. Chloroform 20 C.C. + 2.35' Water Y9 2.34 ,I 1 , 2.43 $7 91 2-44 In the foregoing tables, numbera I and c a ID. + 56*2O 55-7 60-2 60.1 + 63.6' 62-2 63.4 62.4 I1 indicate [BfID. + 231.1' 230.0 248-6 248.2 + 262.6' 256.8 261.8 257.7 different portions of the same sample of material. The data show that the specific rotations of the last fraction are higher than those of the first, and for the same reasons as in previous cases, these results establish the existence of isomeric salts. The materials used in this investigation were part of those VOL. LXXXV. N174 COHEN AND MILLER: OXIDATION OF THE previously employed in a former research, and were provided out of a grant made by the Government Grant Committee of the Royal Society. The author desires to express his thanks t o Professor Kippiog for theinterest he has taken in this research. UNIVERSITY COLLEGE, NOTTIK GH A M.

ISSN:0368-1645    

DOI:10.1039/CT9048500169

出版商:RSC    

年代:1904

数据来源: RSC