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Proceedings of the Chemical Society, Vol. 10, No. 137 |
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Proceedings of the Chemical Society, London,
Volume 10,
Issue 137,
1894,
Page 81-98
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摘要:
Ism4ed 2/5/1894. PROCEEDINGS OF THE CHEMICAL SOCIETY. No. 137. Session 1893-94. April 19th, 1894. Dr. H. E. Armstrong, President, in the Chair. Messrs. W. Lloyd Williams, R. Curling Styles, and J. Cardwell Quinn were formally admitted Fellows of the Society. Certificates in favour of the following candidates were read for the first time :-George Donald, Arnold Print Works, North Adams, Mass. U.S. ; Robert John Flintoff-Haxby, Crumpsail Lane, Crumpsall, Manchester ; Sydney Walters Harris, 15, Lansdowne Terrace, Walters Road, Swansea; J. H. Hickens, North Devon Lodge, Cheltenham ; Wilmot Holt, Jun., The Park, Didsbury, Manchester ; Arthur Peach Hope, Salisbury Road, Leicester ; James McLeod, 2, Gladstone Ter- race, Paisley; E. Brooke Pike, 6, Lathom Road, East Ham; Herbert Stephen Shorthouse, 47, Pershore Road, Birmingham ; Ernest Alfred Smith, 17, Oval Road, Regent's Park, N.W.; Herbert W. Steel, Wedderburn, Paisley ; Edward B.Shuttleworth, Trinity Medical College, Toronto ; George Dupr6 Thudichum, Montrose, Dorset Road, Merton Park ; Robert Wright, 11,Eagle Parade, Buxton. Of the following papers those marked * were read:- "132. ('The magnetic rotations of derivatives of fatty acids containing halogens; of acetic and propionic acids, phosgene, and ethyliccarbonate." By W. H. Perkin, Ph.D., F.B.S. The first subject considered in the paper is the magnetic rotation of acetic and propionic acids in reference to their molecular corn- plexity. Prom the determiuations made at widely different tempera- tures it is considered that the kind of association of molecules referred to by Ramsay and Shields does not influence the results.In thecases of phosgene, ethjlic chloroformate, and ethjlic carbonate it is L shown that the two chlorine atoms in phosgene behave as if they bad two different values ; that in such derivatives as ethylic chloroformate, €or example, having the smaller value. On comparing this compound with phosgene and ethylic carbonate, it would appear that the two ethoxyl groups in this latter substance wliich displace the two chlorine atoms in phosgene, also have two separate values. The next section relates to the chloro- and bromo-derivatives of acetic acid and its ethereal salts. With respect to the acids it is found that alone or in aqueous solution they yield practically the same numbei-s.The effect of etherification on these acids, however, is found to be anomalous. Instead of changing in rotation by the same amount as in the case of acetic acid and its ethereal salts, the values for ethjl and methyl increase as the number of halogen atoms int'roduced. There is one exception, viz., dibromacetic acid. The alteration of the rotation of acetic acid and its ethereal salts by the introduction of chlorine is then considered. It is shown that difference8 corre- sponding to successive displacements in the case of chlorine do nut follow a regnlar order; but, with bromine, they generally increase with the displacements, and the fluctuations are shown to be similar in character to those exhibited by chlorine and bromine derivatives of methane.Ethylic iodoacetate was found to give lower results for iodine than propyl iodide. The rotatiou of ethylic a-chloro-pro- pionate furnishes a value for chlorine similar to that in ethylic dichloracetate. Ethylic trichlorlnctate gives an average value for chlorine somewhat lower than that of ethylic trichloracetate. The measurements of a-brornopropionic acid and butyric acids and their ethereal salts furnished the usual rotations for meinbers of a homologous series for the same difference of composiiion ; the usual value being obtained for a diaerence of CH2,and also for bromine. In the acids, however, the value is apparently smaller than in the ethereal salts, as these, like the ace& compounds, are changed by etberification more than the compounds not containing halogens.The difference in the values obtained for the chlorine and Iwomine compounds are then considered, and snggestions are made as to special circumstances which may influence the magnetic rotation. DISCUSSION. The PRES~DENTremarked 1bat Dr. Perkin's results afforded further evidence of the remarkable influence of several halogen atoms to which Tbomsen had first specially called attention in his tlhermochemical researches. The very noteworthy difference between the magnetic constant's of the chlorinated and brominated acids to which Dr. Perkin drew attention, which was correlated with an equally striking difference manifest on comparing the boiling points, served to suggest t’\?t the method of redncinq tbe results was scarcely such as to bring out the true magnetic constants. Dr.GLADSTONEcommented on the irreqularitieq in the values ob-tained for the cbloro-derivatives of acetic acid as compared with the corresponding bromo-derivatives. Mr. RODGERsupported the President’s statement that the character of Dr. Perkin’s results no doubt depended to some extent, on the mode of treating the experimentally observed quantities. In men- surements where the wave-length of the light and the strenqth of the magnetic field remained the same throughont, the difficulty in obtaining a measure of the moIecdar rotation in which the in- fluence of temperatnre on the rotatory power was either eliminated or allowed for.Dr. Perkin employed the ratio aM/d as determined for the substance to the corresponding quantity in the case of water as the vRlue of the molecular rotatinn. This ratio m-ould only be irrdependent of the temperature if a/d were the same function of the temperature for water and for the subst,ance. The early experiments of De la Rive, nr. Perkin’s own results, as well as observations RS yet unpublished by Mr. Watson and the speaker, have shown that this is not the case. Recently, Guje has proposed the expression or,Y%%d instead of a)I/d as a more probable measnre of the molecular rotation. At first sight (compare Proc., 1893, p. 2%) this new expression appears to be tbe more satisfactory.It may be shown, however, thatJ it can only give the correct measure of the molecular rotation if it is assumed that the medium consists of elementary cubes at the centre of each of which is a molecule, and the volume of each of which is proportiona1 to the molecular rolume. We should then regard each cube as representing the sphere of activity of the molecule, and con- sider that the tntal effect of the medium depends solelyon the number of cubes which the ray traverses. Whichever measnre be adopted, experiment shows that neither eliminates the effect of temperature, neither aid nor af 72 is constant : hence satisfactory conclusions can only be arrived at when the effect of temperature on magnetic rotation has been more fully studied and values of the molecular rotation have been measured at comparable temperatures.In the communication under discussion, Dr. Perkin has furnished extensive support to the conclusion that the effect; on a physical property brought about by replacing an atom of hydrogen in a methyl group by an atom of halogen vmies according as it is the first. second or third halogen atom which is thus united to tbe carbon atom. In their paper on viscosity (shortly to a,ppear in the PId. Trans.),Professor Thorpe and the speaker pointed out that in the case of viscosity, surface-energy, boiling point, and critical tem- 84 prature, the change produced on replacing the first hydrogen atom was the greatest, and that on replacing the third hydrogen atom the small6st ; whereas, in the case of molecular volume arid molecular refmetion, the reverse rule appeared to hold.The properties in the first group depend mainly on effects in play between molecules: the last two properties, on the ohher hand, are mainly the result of influences resident within the molecules. The sense in which the effect of substitution changed thus appeared to be correlated with the nature of the property dealt with. Dr. Perkin’s present results show, however, that in the case of the same property the substitution effect may vary in both senses, or the variation may even be irregn- Inr. Whether this result as well as the other anomalies observed by Dr. Perkin are due to the fact that the effect of temperature is not allowed for, or whether it is also due to hhe fact that the molecular complexity of some of the liquids examined influences the results, can only be decided when more is known regarding the mode in which the molecular rotation should be calculated, and when the effect of change of density has been more fully investigated.Dr. PERKIR’remarked that the effect of temperature on magnetic rotations, to which he had often drawn attention, is usually small with fatty compounds, although more considerable in tho aromatic series. In closing the discussion, the PRESIDENTadded that the impression he had gained from Dr. Perkin’s figures was that in order to take illto account the diverse nature of the chlorinated and broniinated acids, it was probably necessary to introduce a term into the calcula- tion which would give expression to the fact that whereas there was a great difference in boiling point between the di- and tri-bromo-de-rivatives. there was but a slight one between the corresponding chlorinated compounds. ”133.“The action of concentrated acids on certain metals when in contact with each other.” By George J. Burch, M.A., and J. W. Dodgson. In 1i90, James Keir (Phil. Trans., 1790, p. 367) announced that a mixture of strong nitric and sulphuric acids could be used for strip-ping the silver from old-plated copper goods. The authors have in-vestigated the chemical and electrical phenomena of this and other reactions of the same type, and now present. a preliminary account of tli e ir work.Experiments with a Silver-copper Couple.-A sheet of “pure ” silver was cut into strips, which were scraped bright,, bent into a U-shape, aucl weighed. To each was fitted a similar strip of copper, carefully 85 cleaned and weighed, the whole forming an elliptical ring, held together by the elasticity of the metals. A number of test-tubes arranged in a water bath contained the mixed acids diluted with various proportions of water. Each ring remained under the surface for 47 minutes, and was then rapidly removed, wiped, washed, and weighed. The liquid was not stirred during the ex- periment. Silver-Copper Couple, in a Mixture of 1part Nitric Acid of rel. dens. 1.436 with 5 parts H,SO, of rel.dens. 1.84 with various proportions of' Water runging from 1 to 10 molecules per molecule of H2S04. Tenaperatnre 20'' Cl Silver. Copper. Molecular proportions of water. Taken. Loss. 1 1Loss. Per unit Loss. Taken.area. None added 0.7710 0 * 0426 0 -00027 0 9013 1.3265 1 0 .'lo00 0 -0358 0 '00061 0 '0027 1*2082 2 0.7114 0* 0234 0 -00616 0 '00038 0 -0018 1* 1320 3 0 "i284 0 *0251 0 -00633 0 * 00075 0 4036 1* 3252 4 0 9395 0-0170 0 *00523 0 *00250 0 ~0100 1-1954 5 0 -7052 0 -0052 0 -00144 0 '00288 ~ 0.0127 1-2109 6 0-7505 0.0110 0.00399 0 '01792 0.0717 1-2671 7 0 -7290 0 -0176 0.00463 0 '03475 0.1526 097i5 8 0 * 7033 0 '0343 0 -00866 0 -05116 0.2456 1'3216 0 0 *69<57 0 -0268 0 -00827 0'05302 0 *2129 1-1854 10 0 -6342 0 '0300 0.00833 0 '05895 0 -2594 1-2055 In the stronger solutions, a yellowish-white powder separates from the gilver, and a, clear, heavy liquid of strong refracting power streams from it.Little or no gas is evolved. During a few seconds after immersion the copper is covered with a white froth. This clears away, and the surface remains bright. Probably, nearly all the loss of copper occurs at this stage. The liquid becomes of a pale greenish-yellow colour, and a good deal of an almost white powder is deposited. A blue tint only appears when six or more molecular proportions of water are present to one of sulphuric acid. When the dilution is represented by 8H,O + H,S04, nitrous fumes first begin to appear.It will be observed that the amount of silver dissolved is least with 5H20,after which it in-creases again, and that the copper, which is practically untouched at 3H,O, is now rapidly attacked. At temperaturas above 50" C. the results are somewhat different. Magnesium-Silver Couple.-In a mixture of 10 parts sulphuric acid of rel. dens. 1.84 with 1part nitric acid of sp. gr. 1.436, the magne- sinm retained its brilliant appearance during an hour and 20 minutes, while the silver dissolved steadily. No gas was evolved. The mag- nesium lost 0.0015 gram, and the silver lost 0.1167 gram, the ratio of the loss per unit area beiug & : 31g : : 61.5 : 1. Electrical Phenomena.-The difference of potential between two metals in concentrated acids cannot be measured with the qutldrant electromet8er in the ordinary way, because in certain cases the chemical changes are different according as the circuit is closed or open.The influence of each metal on the rate of solution of the other is in most cases strongly mavked. With the copper-silrei: couple the resistance increases rapidly on short circuit, apparently at the surface of the copper. The quantity of current is not propor- tional to the weight of silver dissolved. This part of the subject mill be dealt with in a future paper. Sodium and Xulpl~uricucid (rel. dens. 1*84).-A freshly-cut cube of sodium, about 5 min. each way, impaled on the end of a strip of tlie metal used, was dropped into a test-tube containing about 15 C.C.of tbe acid, the tube being immersed in a jar of water (16O), the mouth of which was inclined away from the operator. As a further precaution a glass screen was used. The initial action was in most cases over in less than five minutes. The results of the experiments may be summed up as follows. Sodium alone, weighted with a glass rod to sink it, was less rapidly attacked by strong sulphuric acid at 16" C. than by water. The action was moderate but steady. Rubbles of gas were freely given off, and very little heat was evolved. The sodium was com-pletely dissolved in about 20 minntes, a small quantity of a whitish substance being formed near it towards the en& of the process. The contact of another metal with eodium exerts an influence on the rate and manner of its solntion in strong sulphuric acid.In most cases the action of the solvent is much retarded. The gas evolved comes from the entire suijace of the platinum, carbon, 01-iron, when these substances are employed, and is given off freely from first to last. No bubbles appear on the sodium which is clean and bright. The iron-sodium couple lasted 40 miuutes, the platinum- sodium about two hours, and the carbon-sodium was still acting slowly after eight hours, In this case gas came from the sodium, and none from the carbon for the first 10 minutes after the initial effervescence was over. Then the sodium became quiescent, and biibbles rose from the carbon. Sulphur was separated after a while.With lead and tin the action was similar, but much slower. Thu sodium was not so clean and the liquor became very turbid. The tin acquired a brownish-yellow coating and tlie lend assumed a grey colour. It was several days before the sodiiim disappeared. 87 Zinc exerts comparatively little restraining action, but makes a very turbid solution. An aluminium-sodium couple, weighted with a glass rod to sink it, evolved torrents of gas, and after about five seconds the sodium caught fire. A magnesium-sodinm couple similarly weighted gave a, flash of light as it touched the liquid. Then, for about three seconds, there was a copious evolution of gas, and the sodium burst into flame while completely submerged. With the cadmium-sodium couple the action was extremely slow.Fewer bubbles came from the sodium than from the cadmium, which became covered with a brown film. The liquor was turbid. Coming now to those metals which produce ti markedly different effect. Nickel scarcely evolves any gas, but is soon coated near the sodiunz with a brownish film, while a few bubbles rise from the sodium. Antimony exerts the most powerful restraining influence of any substance yet tried. The initial action is very small. Bismuth be-haves in much the same way. Both these metals become coated with a film near the sodium. Very little gas is evolved, and what there is comes from the sodium, which remains for days undis-sdved. Silver in contact with sodium turns dark. Very few bubbles appear on either metal, but the sodium, which is quite claan, is visibly smaller after two hours.Thus a magnesium-silver couple is almost inart in the acid, and a sodium-silver couple acts very slowly, but a magnesium-sodium couple bursts into flame, whereas either metal separately would be a long time in dissolving. Copper evolves no gas, but becomes coated with the gas given off from the sodium, and presents a reddish fawn-colaured film. After an hour or so a secondary action sets in, apparently from the decom- position of some substance formed near the sodium ; and those part:; of the copper which remained bright are attacked, the production of an insoluble dark-brown compound, rendering the liquid turbid. The sodium is brilliantly clean, and during the first stage of the reaction evolves gas slowly.This gas has no perceptible smell, but turns paper moistened with iodate of potassium and starch solutiou faintly blue after a while. The acid liquid does not bleach litmus or indigo, and gives no precipitate, and only a sligbt browncolourationon boiling, witlt nitrate of silver. Iodine is only slightly decolourised by it, and it is not affected by permangannte to a greater extent than the fresh acid. The turbid liq!iid gives off sulphur dioxide on heating. *134. “The action of light on oxalic acid.” By A. Richardson. Downes and Blunt, in 1879, observed that solutions of oxalic acid evolve carbon dioxide when exposed to light. In the present paper the author shows that hydrogen peroxide is also formed.Experi-ments are described in which this was found to be the case with numerous specimens of oxalic acid obtained from diff eyent sources, and carefully purified. The presence of the peroxide was proved by the titanic acid and chromic acid tests. The decomposition of the acid was further studied in order to determine whether complete oxidation of the carbon to carbon dioxide occurred, or whether products of partial oxidation were also formed. The results of experiments in which the carbon dioxide evolved during the decomposition of a known weight of acid was estimated, showed that the oxidation of the carbon was complete. The absence of intermediate products of oxidatlion seem to in-dicate that t,he formation of the peroxide is the direct result of the oxidation of the hydrogen of the acid, and is not brought about by secondary changes.Experiments were also made in order to observe the influence of the concentration of the acid on the formation of the peroxide. The results obtained showed that while the t,otal amount of hydrogen peroxide formed in the solution increased with the concentration of the acid, the proportion of peroxide formed to acid decomposed simultaneously decreased. The author draws the following con-clusions :-(1) Hydrogen peroxide is stable in solutions of oxalic acid in khe dark. (2) It is fairly stable in these solutions when exposed to light if excess of oxygen is present. (3) R,apid decomposition of hydrogen peroxide occurs in solubion of oxalic acid in absence of oxygen when their solutions are exposed to light, “135.“English jute fibre.” By A. Pears, jun. In continuation of previous observations (Tran.~.,1893), the seed saved from the plants grown in 1892 was sown at two periods, March and June, 1893. Parallel with these, cultivations were made from Indian seed. The plants were cut down in the late autumn when the seed is mature, and the four specimens of fibre obtained were compared. Slight differences were observed in the resistance to hydrolysis arid in the percentages of cellulose, the spezimeiis from the early sowings being the better. One specimen from the English seed (1892) contained 43 per cent. of carbon and 6 per cent.of hydrogen. It furnished 8.5 per cent. of furfurd (calculated on the fibre), and absorbed 15 per cent. of chlorine. The two last numbers are similar to those obtained with the normal fibre-whereas the composition shows an important divergence in the percentage of carbon, the normal percentage being 46.5 It is evident, therefore, from the study of these artificial cultiva- tions, that they exhibit the essential features of jute-fibre, and differ chiefly in the degree of hydration, which is dependent on the conditions of growth. The specimen may in fact be regarded as a hydrated modification of the normal fibre, with which it corresponds in all the characteristic properties, differing merely in external features (colour, softness, &c.).“136. “Natural oxycelluloses. I. Celluloses of the Grarninea.” By C, Smith. The experiments, of which this communication is a preliminary account, are undertaken in extension of the results recently obtained by Messrs. Cross, Bevan and Beadle (Ber., 1893). The ‘(celluloses ” of esparto and the cereal straws, as isolated by the well-known processes of the paper maker, were further pmified, and (2) their ultimate composition, (2) the amount of fnrfural obtained on boiling with aqueous hydrochloric acid (1.06 rel. dens.) with following results. (1). 7--> (2).c. H. Purfural per cent. Straw L‘ Cellulose ” ... . 42.4 5.8 12.5 Esparto “ Cellulose ”. . . 41.4 5.6 12.2 These “ celluloses,” therefore, are oxycelluloses, and, since they do not give the reactions characteristic of the pentoses, they are of the type of those obtained by Cross and Bevan by regulated oxidation of the normal celluloses (Zoc. cit.).Such oxycelluloses being widely distributed in nature, it becomes important to study their physiology. A course of systematic observa- tions has therefore been undertaken on the germination and growth of the barley plant in relation to the composition and constitution of its permanent tissue (“ cellulose ”). It has already been observed that, by germination in the dark and growth of the sprouts (etiolated) until the endosperm is nearly exhausted, there is a considerable increase in the furfural-yielding constituents (60-80 per cent.), the early material of the tissue giving 5 per cent.furfural, and at the same time no pentose reaction, which b2 90 proves it to be an oxycellulose. The results are still mora marked in the case of the tissues of plants grown in the light. DISCUSSION. Mr. WARINGTONhoped that the authors would continue this inves- tigation, as t,he subject was of much importance in relation to the digestibility of animal food. They had already established the im-portant fact that the production of furfural can no longer be utilised for the estimation of the pentoses, since the osycellnloses also furnisli this compound. "137. "Preliminary note on the volatilisation of salts during evapora- tion." By G. H.Bailey, DSc., Ph.D. From experiments, carried out for the most part with the chlorides of the alkali metals, it was found that an appreciable amount of the salt was lost during evaporation of the aqueous solutions, although every precaution was med to prevent this occurring mechanically.The amount of loss was found to be greater with the haloid com-pound of elements of higher atomic weight, and also greater the more concentrated the solution. With lithium chloride of about one-fifth normal strength, it amounhed to 0.35 milligrams per litre of water evaporated, arid with calcium chloride of the same strength, 2.4 milligrams, whilst with lithium chloride containing about 38 grams to the litre the loss was 2.45 milligrams, and with ca3sium chloride containing 286 grams to the litre it was 18.86milligrams.From the results obtained, it seems likely that when accurate determinations have been made on a mare extended scale they may be the means of throwing light on the nature of solution and upon the vapour tension and vapour density of salts at comparatively low temperatures. The observations also reveal a. source of error which, in the case of some estimations, will involve the making of a large correction, and which must, at all events, receive consideration in all investigations where a high degree of accuracy is of essehal importance. 138. " Constitution of glycocine and its derivatives." By JojiSSakurai,Professor of Chemistry, Imperial University, Japan. Glycocine is usually represented as amido-acetic acid, NH2*CH, C02H, but, as was first suggested by Erlenmeyer and Sigel (Ann., 176, 3491, it ought to be regarded as an internal ammonium salt of the constitution H+YES , the analogy of glycocine with betake, and oc-0 its behaviour towards mustard oils (Marckwald and others, Be?.., 24, 3279) supporting the latter view of its constitution.Other pro-perties of glycocine are also in best accordance with the latter formula, and there is not a single reaction which needs to be ex- pressed by the ordinarily employed open formula. That, in spite of the evident claim of the internal ammonium theory to be exclusively adopted, the open formula is almost universally employed is due, partly, at any rate, to the erroneous manner in which the formation of glycocine has been hitherto represented, The change which occurs when ammonia acts upon chloracetic acid is not to be represented merely by the diagram We must admit that, in this case, ammonia not only goes to nentralise chloracetic acid, but also to form an ammonium chloride, the latter part of this change being analogous to that which occurs when ammonia acts on alkyl halides :-H29-Cl + 2NH3 = H2Q-NHSCl OC-OH OC-ONHI ' the ammonium compound thus formed then decomposing, by the action of heat, into glycocine and ammonium chloride :-This conception of the mode of formation of glycocine is not a matter of speculation, but is only an expression of actual facts, and it leads wecessarily to the internal ammonium theory of its constitution. The consideration of other modes of formation of glycocine leads to the same conclusion.Again, the modes of formation of sarkosine and beta'in can only be satisfactorily expressed in a manner similar to that above described in the case of glycocine. Hippuric acid, like glycocine itself, must a.lso be represented as a H,Q-l!j"H2*C OC6H5closed chain, oc-0 ; its acid character, feeble as it is, is easily understood from the circumstance that the nitrogen is com-bined with an acid group, namely, COCeH5. That hippuric acid and other amido-acids do not contain the group C02H, is supported by the fact that all attempts hitherto made to obtain acid chlorides from them have been attended with failure. 92 The formation of addition conapozinds of glycocine presents no diffi-culties to the acceptance of the closed formula; in fact, the ring opens by addition, the nitrogen atom being not yet known to be Capable of combining with more than five monovalent radicals.Thus, HzY-YK3 + H*C1 = HZY-NH 3C1 oc-0 OC-OH It is to be observed that in order to explain the formation of the potassium salt by the ordinary formula cd glycocine we must suppose that a ciouble decomposition first occurs with formation of potassium amido-acetate and nitric acid, and that the latter then unites to the amidogen group. Passing now to the ntetaZEic derivatives of glycocine, their formation likewise finds a most satisfactory explanation in the closed formula. Thus,the deep blue colour of the copper compound and its solubility in alkalis distinguish it from ordinary carboxylic salts of copper, and lead us to the conclusion that it is most probably a cuprammonium compound, a conception which can be easily expressed in the follow- ing manner :-If, however, we regarded the copper compound as an amidated deriva- tive, and gave it the constitution Cu(NH*Cj lf,.CO,H),, we should have to make the baseless assumption that the hydrogen of the carboxyl group remains unreplaced by copper, even when digested with an excess of cupric oxide. If, on the other hand, we regarded it as (NH2.CH,*C02)2Cu,taking glycocine as a carboxylic compound (an acid), because it dissolves oxide of copper and some other metallic oxides, we might argue ihnf ammoniam chloride or even ammonia itself, is also an acid ! Silver gljcocine must likewise be regarded as having the constitution -H2$I-TG A oc-0 '; this formula can alone account for the formation of amido-acetic ether, on the one hand, by the action of ethyl iodide- and the formation of hippuric acid, on the other, by the action of benzoyl chloride- B3 H?y-NHz*C 0CeH, + AgCI.IHzF-rH2Ag + C6H5CO*Cl= oc--0oc-0 It must be observed that in the latter change an opening of the ring, as in the case of the action of ethyl iodide on silver glycocine, could not occur, because both the radicles C1 and COC,H, are negative.If, on the other hand, silver glycocine were regarded either 2s NHAg*CH,*CO,H or NHZ.CH2*CO2Ag,we could not sstisfactoiily explain the formation of amidu-acetic ether and of hippuric acid re- spectively.The examination of the properties of di- and tri-glycolarnidic acids which are always represented as NH(CH,*C0zH)2 and N(CHz*C02H), respectively, goes to further support the correctness of the closed formula for glycocine. These compounds behave only as mono- and di-basic acids towards alkalis and alkaline earths ; it is only those of their salts, which contain silver, copper, and a few other metals, more or less characterised by the ease with which they form ammoiiiated derivatives, that may be regarded as di- and tri-basic. These facts are inexplicable by their accepted constitution, but receive an ample explanation from the following formulae :-Diglycolamidic acid.Triglycolamidic acid. H27-I7H2*C H2*COzB: H2v-Y H(CH,*COzH),oc-0 oc-0 All the so-called amido-acids must be regarded as constituted like glycocine. Thus asparagine and aspartic acid should be respectively represented by the formula+- Q0-Y YO-? (i'ZHS'NH3 and YzH3*NH,, C0.N Hz C0.0H a view which is supported by the properties of these compounds. According to this conception, there should exist not only two chemi- cally isomeric asparagins, as is predicted by the current theory, but also two aspartic acids, represented by- co--0 CO-OH At present only one aspartic acid is known, but there are reasons to believe that another will be discovered. Fiually, the term " aruido-acids " should be dropped from chemical nomenclature, in accordance with the internal ammonium theory o€ the constitution of these compounds, and replaced by the words glycocines and tnurines, to be applied respectively to the so-called amido-carboxylic acids and amido-snlphonic acids.Thus, alanine, asparagine, and aspnrtic acid should be called propionic, succinamic, and succinic glycols respectively, whilst yamido-propyl sulphonic acid (Gabriel and Lauer, Ber., 22. 2988) should be changed to tri-CH2*NH,ntethylene-taurine and represented by the formula CHz<CrrL.so2>O. 139. “Note on the constitution of glycocine.” By James Walker, D.Sc. In connection with the question as to the constitution of glycocine, which is raised by Professor Sakurai in the foregoing paper, Pro- fessor Diinstan suggested that I should bring together any physical facts which might bear on the subject.Physical methods throw at present little light on the constitution of glycocine. The only question which they decide with certainty is that the molecule of glycocine is not a double molecule of the formula T&*CHz*CO*O I ,as some have supposed, since the depression of the0 CO CK2 N freezing point, in its aqueous solutions shows that the molecular weight corresponds with the simple, and not with the double, formula. TO the objection which might be rsised, tlist this low molecular weight could be due to an electrolytic dissociation of the double molecule, there is the sufficient answer that an aqueous solution of glycocine is an extremely feeble conductor of electricity. I have found that a decinormal solution of the substance does not conduct very many times better than ordinary distilled London water.Whether the slight conductivity is due to the presence of impurities, or to-actual electrolytic dissociation o€ bhe glycocine, must remain for the present undecided. Even if glycocine were proved to be ionised in aqueous solution, it is not certain what the ions would be, for we do not know whether under these conditions glycocine acts as an acid or a base. I have shown (Zeit.physikaZ. Chem., 4, 331) that glycocine in an equivalent solution of hydrochloric acid acts as a base of nearly the same strength as thiazole ;but undoubtedly in an equira- lent solution of an alkali it would act in a corresponding manner as an acid.A comparison of the amount of hydrolysis in the two sets of salts may serve to settle whether glycocine in aqueous solution is acid, basic, or strictly neutral, and iC, is my intention to perform the necessary experiments. In as far as glycocine behaves as a, base, it must, according to Arrhenius’ theory, supply hydroxyl ions, which can only come from tne c~mpoundNH,OH*CH,.COOH, a hydrated form of glycocine, which in CHZ-70its turn might either be derived from NH,*CH,*COOH,or NHS-0I It is possible that the hydrated form may exist to a great extent in solution, while the solid form is anhydrous, for this is undoubtedly the case with betake. While physical methods, then, are mostly silent with regard to the constitution of glycocine itself, they yield decisive evidence that many glycocine derivatives must be represented by an open, and not by a closed, chain.Acetic acid has a dissociation constant K = 0,0018,very many times greater than any that could be attributed to glycocine, which ranks in point of conductivity with the phenols. Phenyl glycocine, NHPh*CH,*COOH, on the other hand, has a coii-stant K = 0.0041, so that the introduction of a phenyl group in the place oE one of the hydrogen atoms of the amidogen, bas raised the conductivity far above that of acetic acid. Consequently, if acetic acid contains a, carboxyl group, phenylglycocine must, & fortiori, contain one. The same is evident in still greater degree in tjhe case of hippuric acid, H = 0.0222, and aceturic acid, K = 0.0230.The amidobenzoic acids have dissociation constants less than that of acetic acid, but still incomparably greater than that of glycocine, so that they must be regarded as possessing a carboxyl group. If we are to trust to analogy, therefore, the evidence afforded by the electrical conductivity goes to show that glycocine has not tho ring constitution, but the ordinarily accepted constitution represented by the formula NH2.CH,.COOH. 140.“On the oxidation of the alkali metals.” By Wilmot Holt and W. Edgar Sims,B.Sc. The authors have examined the oxides of the alkali metals with a view to ascertain how far stability and composition of the oxides is dependent on the atomic, weight of the element from which it is derived, the observations already recorded being so conflicting, and, in many cases, so incomplete,, that it was found quite impossibie to make any generalisRtions from them.The general results of their examination are as follows :-1. Potassium and sodium (and probably lithium) are not attacked by perfectly dry oxygen, and may be distilled in it, without under- going oxidation. 2. Lithium, when oxidised in oxygen gives rise to the monoxide Li20, sodium (a member of the same grdup, though in the odd series) under certain conditions forms the monoxide NazO, whilst in the case of potassium it has been impossible to obtain the monoxide K,O. 96 3. Tbe ultimate products of oxidatioli are : with lit,hium the van-oxide and slight tmces of a peroxide; with sodium, the dioxide Nn202; and with potassinm, t’he tetroside K,04, which must be re-gfirded as the most definite and stdde oxides of these metals. 4.The monoxicie of potassium K20. is not formed by the oxidation of potaqsium in any of the oxides of nitrogen ns stated by previous observers, and there is no evidence either of the existence of this or of any lower oxide in the pure condition. 5. The only other oxides of which the Authors hare been able to find anv evidence, in addition to those mentioned under Section 3, are Na,O, K20, and K2O8,these only being obtained under certain con-ditions owing to their instability. 6. Both potassium and sodium, when oxidised in nitric oxide or the red oxides of nitropen.form varyving mixtures of nitrite and nitrate according to the conditions of the experiment. Later experiments will probably show that the metals rnbidinm and caesium, both of which have higher atomic weight than potas- sium, will combine with oxygen in still larger proportions. 141. “The actiorl of iodine and of methyl iodide on aconitine.” ByWyndharn R. Dunstan, F.R.S.,and H. A. D. Jowett, B.SI?. In 1885 Jurpens described a crystalline, dark red hyd&(li& of iodaronitine (C,H,,TNO,.,.HI), which he had obtained hg mixing etbereal solutions of iodine and aconitine, and crpstnllising the product from chloroform and ether. The percentage of iodine found in the salt. agreed closely with the formxla given above.By acting on the salt with dilute ammonia he obtained a brown, amorphous substance, which he supposed to be iodaconitine. The authors find that when iodine acts on aconitine, dissolved in various liquids, the product is a variable mixture of aconitine hydriodide, aconitine per-iodide, and an amorphoiis, neutral substance, which appears to be iodo-aconitine, but since it cannot be crystallieed it is difficult to characterise. The principal changes may be represented by the equations (1) 2CaH,,NO12 + I2 = CdLNO~2,HI+ C33H441N0,2,(2) CmH4,NO,,HI + TI, = C~~&NO~~HI,ZI~-The crystals obtained by Jurgens consist of an unstable wonitin periodide, which cannot be crystallised without, losing iodine. The dark brown crystals originally obtained gradually become lighter on recrystallisation, and finally are resolved into the colourless aconitine hydriodide.Analysis shows a gradually diminishing percentage of iodine as the recrystallisation is repeated until pure aconitine hydr-iodide is obtained. This sait was identified by its melting point {226”),amd also by its furnishing pure aconitine (m. p. 188-189”), when decomposed with dilute ammonia. 97 The same unstable periociide may be obtained hy adding iodine to an aqueous solution of aconitine hydriodide. The brown precipitate is crystallised from its solution in alcohol. In attetnpting to isolate iodaconiiine the mixture prepared by adding an ethereal solution of iodine to an ethereal solution of aconitiGe was dissolved in chloroform, and the soliltion was Phaken with dilute ammonia.By this means a substance was obtained from this solution which contained much aconitine, and also a smaller amount of an amorphous compound, which was separated from aconitine by precipitating a solution in chloroform with ether. All attempts to cr,ystnllise this substance have failed. It is a greyish powder, which melts indefinitely near 208", and is nearly insoluble in cold water, but rerzdilg dissolves in alcohol and chloroform. On analysis it furnished the percentage of iodine required by the formulse C,€€,,INO,,. It does not possess basic properties. In a previous communication (Trans., 51,403) it.has been shown that when aconitine is heated in a closed tube with methyl iodide it dissolves, and that on cooling the solution crystals separate which con- tain the percentage of iodine rpquired by aconitine rnethiodide.This substance has now been fui*t,her investigated, and it has been found that, the action of methyl iodide on aconitine is exceptional. After recrystallisation from a mixture of ether and chloroform, the crystals melted at 226", and agreed in all other respects with acon,itiize hydriodide. The action of methyl iodide 011 aconitine would seem to be represented by the equation 2C3,H,,K0,, -+ CHJ = C,,H,,NO,,HI + C,,H,,(CH,)NO,,, but although distinct) evidence of this simultaneous production of a methyl aconitine was obkained, all the methods employed to isolate it in a pure state have been un-successful. An impnre base was obtained wliich furnished a hydro-bromide melting near 218",but during the precipitation of this salt and the regeneration of the alkaloid from it, decomposition apparently occurred, since aconitine was finally obtained.It would thus appeal. that if methyl aconitine is formed in this reaction, it is so unstable that it cannot be isolated. Ot,her methods have been tried for its production, but these also have failed to furnish the compound. RESEARCH FUND. A meeting of the Research Fund Committee will be held in Jnne. Fellows who desire grants are requested to seud their applications to the Secretaries at Burlington House, not later than Tuesday, June 5th. 98 At the next meeting of the Society, on Thursday, May 3rd, there will be a ballot for the election of Fellows, and the following papers will be read :-“The structure and chemistry of the cyanogen flame.” By Professor Smithells. “The condition in which carbon exists in steel.” By J. 0. Arnold. “ a-Hydrindone and its derivatives.” By Dr. Kipping. “ Volatile compounds of lead sulphide.” By J. B. Hannay.
ISSN:0369-8718
DOI:10.1039/PL8941000081
出版商:RSC
年代:1894
数据来源: RSC
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