摘要:

82 ABSORPTlON OF NITRIC OXIDE IN UAS ANALYSIS. XI.-Absorption of Nit& Oxide in Gas Analpis. By EDWARD DIVERS. IT is well known that the vapour tension of nitric oxide, dissolved in the solution of a ferrous salt, interferes with the use of this reagent to remove nitric oxide from other gases. There is, however, another absorbent for nitric oxide which leaves nothing to be desired, whose use and value have remained unknown. This is a strong solution of either sodium or potassium sulphite to which a little alkali hydroxide has been added. It quickly absorbs every trace of nitric oxide, which it fixes in the form of hyponitrososulphate, Na,N,02S0,. I haveINTERACTION OF NITRIC OXIDE WlTE SILVER NITRATE. 83 already made satisfactory use of it to analyse the mixture of nitric oxide and nitrogen which is left on heating silver hyponitrite and allowing the solid and gaseous products to cool in contact with each other. The sulphite need not be very pure, the presence of sulphate or carbonate being of no importance. If carbon dioxide or other acid gasis present along with the nitric oxide, it is removed by alkali before using the sulphite mixture.

ISSN:0368-1645    

DOI:10.1039/CT8997500082

出版商:RSC    

年代:1899

数据来源: RSC

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INTERACTION OF NITRIC OXIDE WlTE SILVER NITRATE. 83 XII.-Interaction of Nitric Oxide with Silver Nitrate. By EDWARD DIVERS. HAVING reason to think that silver nitrate might interact with nitric oxide if heated in it, and there being no information obtainable on this point, I have made some experiments on the action of nitric oxide on silver nitrate, as well as on other nitrates, I n the first place, something had to be ascertained as to the be- haviour of silver nitrate when heated alone, Heated for 15 minutes in dry air or carbon dioxide, it suffers no chemical change until the temperature is close to the melting point of sulphur (444'), and the slight decomposition which occurs at that temperature, being accom- panied by an action on the glass, may be due to that action. A minute quantity of oxygen seems to be liberated, and there is a very slight greying of the faintly yellow liquid ; on cooling and dissolving, there is slight turbidity from the presence of silver, and a trace of nitrite can be detected.Only at a much higher temperature does the salt decompose with free effervescence, and then nitric peroxide accompanies the oxygen, and silver is deposited j even then, nitrite is present in the mass only in very small quantity at any time, there never being enough to remain undissolved when the nitrate is treated with a little water. This is sufficient, howewr, to show that the pri- mary decomposition of silver nitrate by heat alone is into silver nitrite and oxygen, the instability of silver nitrite a t much lower tempera- tures, although diminished by the presence of nitrate (Trans., 1871, 24, 85), accounting fully for its being found in such small quantity when the temperature is high, and for the production of nitric peroxide and silver instead.As determined by Carnelley, the melting point of silver nitrate is 217'. The nitric oxide used for the experiments was prepared by the ferrous sulphate method, stored for 2 days in a glass gas-holder, and dried in its passage to the silver nitrate by a sulphuric acid column, At starting, the air in the drying apparatus and in the tube containing ( 3 284 INTERACTION OF NITRIC OXIDE WITH SILVER NITRATE. the silver nitrate was expelled by carbon dioxide, the silver nitrate being heated in the gas, in order to dry it. Interaction between the silver nitrate and the nitric oxide was recognised by the reddening of the gas, and at the end of an experiment the gases were expelled by carbon dioxide before opening the tube.Silver nitrate, when heated in nitric oxide, is strongly affected by it, being freely decomposed a t a much lower temperature than that at which it decomposes when heated alone, the nitric oxide becoming oxidised. The action commences, perhaps, at 150°, but this is doubtful ; at the melting point of the salt, it becomes marked, and at the boiling point of mercury considerable, but even at this temperature it is a long time before the decomposition is complete, the progress Qf the change gradually becoming slower, For some time, the products are silver nitrite and nitric peroxide, AgNO, + NO = AgNO, + NO,, but vexy little silver is liberated, the nitrite being almost wholly pre- served for a long time, through combination with the undecomposed nitrate, But when, as the nitrate becomes decomposed, the nitrite is no longer unprotected, i t suffers decomposition, as usual, into silver and nitric peroxide ; finally, nothing but silver remains.Thsoretically, it is quite probable that nitric oxide does not, after all, act directly on silver nitrate. For, making the allowable suppo- sition that, to a minute extent, silver nitrate decomposes into silver nitrite and oxygen, a t temperatnres much below that a t which it does so sensibly, the nitric oxide may be regarded as being active by com- bining with this oxygen, and thus, by removing it, greatly hastening the spontaneous decomposition of the nitrate.This decomposition, thus assisted, and occurring at temperatures at which silver nitrite is comparatively stable in presence of nitrate, the nitrite remains, although at higher temperatures it. decomposes almost as fast as it is formed from the nitrate. According to this theory, silver nitrate is not actually decomposed by nitric oxide, but only decomposes much more rapidly in its presence, in consequence of its interaction with one of the products of decomposition. For practical purposes, silver nitrate and nitric oxide may, however, be treated as acting on each other when heated together. Nitric oxide has no action on sodium potassium or barium nitrate, even at the temperature of boiling sulphur. Lead nitrate soon begins to decompose by heat alone, and nitric oxide seems to be without effect on its decomposition. According to Stas, lead nitrate begins t o decompose somewhere above 200O; I find that, for its fairly free decomposition, a temperature not much below 400° is required. A t the boiling point of sulphur even, the decompo- sition proceeds a t such a moderate rate that only after 10 minutes heating does the salt show distinct signs of fusing. No nitrite is pro-DIVERS: PREPARATION OF PURE ALKALI NITRITES. 85 duced, but a very little peroxide of lead is formed. By washing the mass with cold water, and then boiling it out with water, the beauti- ful, crystalline, white salt, Pb(OH)NO,, can be obtained in abundance.

ISSN:0368-1645    

DOI:10.1039/CT8997500083

出版商:RSC    

年代:1899

数据来源: RSC

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DIVERS: PREPARATION OF PURE ALKALI NITRITES. 85 XII1.--PrepcLration of Pure Alkali Nitrites. By EDWARD .DIVERS. WHEN pure sodium or potassium nitrite is wanted, it is customary to prepare silver nitrite from crude alkali nitrite, and convert this again into alkali nitrite by means of sodium or potassium chloride. The crude nitrite must be nearly free from sulphate, and either before or after adding the silver nitrate to it, nitric acid must beadded until all the hydroxide and carbonate are neutralised. The silver nitrite is got in the most convenient form for washing by precipitating it from con- centrated solutions. Silver chloride is very sensibly soluble in a concentrated solution of alkali nitrite, and when the solution is no longer clouded by the addition of more alkali chloride, it already contains this salt in excess.Therefore, somewhat large dilution is necessary, and this entails, of course, much evaporation afterwards. The silver nitrite process is evidently not a very satisfactory one, and when sodium nitrite is wanted pure, it is better to recrystallise, three times over, the commercial 96 per cent. sodium nitrite, well draining each time on the suction funnel. A concentrated solution of the crude salt should be left to clear from lead turbidity for two days, or be filtered cold through a fine filter; the lead carbonate is more soluble in the hot nitrite solution than in the cold, After separating the lead, the solution should be fully neutralised with nitric acid before evaporation for crystallising. Potassium nitrite is too soluble and deliquescent to be conveniently purified in a similar way.A most satisfactory and simple process for preparing either sodium or potassium nitrite, when the pure hydroxide or carbonate is at command, is to saturate this with red nitrous fumes under appropriate conditions. That nitrites can be thus obtained is known to every chemist, was known to Gay-Lussac in 1816, and was described by Fritzsche in 1840, but it has hitherto been stated and believed that much nitrate is then unavoidably formed along with the nitrite, That is a mistake, and therefore this note is published. If obvious precautions of the simplest kind are taken, so little nitrate, if any, is formed as to be hardly detectable with certainty in presence of so much nitrite. Consequently, if the quantity of pure alkali taken is known, a solution of given strength in nitrite is perhaps better prepared in this way than in any other.86 DIVERS: PREPARATION OF PURE ALKALI NITRITES.Avoiding, so far as practicable, the use of cork and caoutchouc, nitrous gases, from nitric acid and starch or arsenious oxide, are passed into the concentrated solution of the hydroxide or carbonate until the alkali is quite neutralised. Sodium carbonate alone is somewhat inconvenient, because of its sparing solubility, but this may be circumvented by adding it, finely divided and in sufficient quantity, t o its own saturated solution, just before passing the gases and by often shaking the vessel during their absorption. To prevent free access of air, the nitrite is prepared in a flask with its mouth kept loosely closed while the gases are passing; it is not necessary to cool the flask.The strength of -the nitric acid and the temperature of the generator of the nitrous gases must be so regulated that just a little nitric oxide is in excesfi of the nitric peroxide, and therefore is passing unabsorbed, as a guarantee that the latter does not act on the solution in absence of its equivalent of the former and thus produce some nitrate. To free the gases from volatilised nitric acid, they may be passed through a bottle or tube, either empty or packed loosely with cotton. The finished solution must be almost neutral, and if acid must be boiled until neutral, before exposing it to the air. A concen- trated solution of alkali nitrite dissolves a little nitrous acid without decomposing it, as water alone would.To get the salt in the solid state or to crystallise out the sodium nitrite where it is necessary to be sure of absence of all nitrate in it, the solution may be freely evaporated, even at a boiling heat, without decomposing or oxidising it. The alkali nitrites have been very imperfectly described, and need examination. I n the meantime, some points in their description are here given. Sodium nitrite and potassium nitrites are distinctly though faintly yollow, and give markedly yellow solutions in a little water. They are very slightly alkaline to litmus. At 1 5 O , 5 parts of sodium nitrite requires 6 parts of water to dissolve it; potassium nitrite is soluble in about one-third of its weight of water.Sodium nitrite melts at 27 1' (mercury-thread immersed). Sodium nitrite is moderately deliquescent, remaining dry in winter-cold air ; potassium nitrite is exceedingly deliquescent, and is obtained in very small, thick, prismatic crystals, whilst sodium nitrite crystallises in very thin, flattened prisms, often very large. Sodium nitrite is well known to be anhydrous; not so potassium nitrite, crystals of which are reputed to contain $H20. I have, however, examined small, but distinct and separate, crystals taken from the upper part of some kilos. of the commercial salt, which had become well drained by long standing. They were removed in very dry weather and weighed, and then found to lose hardly 1 per cent. on fusion. The anhydrous character of the potassium salt was further ascertained by testing a cake of minute crystals, prepared by myself, which had been pressed,REDUCTION OF AN ALKALI NITRITE BY AN ALKALI METAL. 87 under cover, between porous tiles, in cold, dry air ; the loss of weight on heating, much above looo, was a little over 1 per cent., and the percentage of potassium was 45.30, instead of 45.88, required for the anhydrous salt. Somewhat remarkably, the point as to hydration of potassium nitrite was examined independently is the same year, 1863, by Lang and by Hampe, with identical results, indicating the composition expressed by 2KNO,+H,O, but both these chemists made the determination on a magma of indistinct crystals, which had been dried in a vacuum desiccator.

ISSN:0368-1645    

DOI:10.1039/CT8997500085

出版商:RSC    

年代:1899

数据来源: RSC

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REDUCTION OF AN ALKALI NITRITE BY AN ALKALI METAL. 87 XIV.-Reduction o f an Alkali Nitrite by an Alkali L7Metal. By EDWARD DIVEBS, M.D., D.Sc., F.R.S. IT is already known what are the products which may result from the action of sodium amalgam on a solution of sodium nitrate or nitrite. Schonbein (1861) first observed the formation of nitrite by the action of metallic sodium on a solution of a nitrate; and de Wilde (1863) that nitrous oxide, nitrogen, and ammonia are the products of the action of sodium amalgam on a solution of potassium, sodium, or am- monium nitrate, or on potassium nitrite; he found that, except alkali hydroxide, nothing else is produced, and, in particular, no hydrogen, Some years later (l870), however, it was recognised by Fremy, aided by a suggestion of Maumenb’s, that hydroxylamine, or what appeared to be hydroxylamine, was a product of the reduction, Then came (18’71) my own discovery of the hyponitrites, together with the observation that alkali nitrates in solution are largely convertible into nitrites by sodium amalgam, an extension of Schonbein’s experience.Lastly, Haga and I (1896) proved that the actively reducing sub- stance observed by Fremy is actually hydroxylamine, as it had been taken to be by Mailmen6 and by him, and not hydrazine, as it might have been.. By a mistake, already pointed out and corrected by me (AnmaZen, 1897, 295, 366), the discovery of the hyponitrites has been in recent years attributed to MaumenB. It will suflice here to say that this veteran French chemist has, it so happens, published, in another connection, that he had not experimentally investigated the reductiou of nitrites in solution, and that, far from laying claim to the discovery of hyponitrites, he at first denied its truth on theoretical grounds (Trans., 1872,25, 7’72; Chem.News, 25, 153 and 285). Nitrous oxide, nitrogen, hydroxylamine, ammonia, sodium hypo- nitrite, and sodium hydroxide (from the nitrite as well as from the88 DIVERS: REDUCTION OF AN metal), are, according to my experience, always produced in the re- duction of sodium nitrite or nitrate by sodium amalgam, but in pro- portions which vary greatly within well-marked limits. Nearly one-sixth of the nitrogen can be obtained as sodium hyponitrite in one way of working, or scarcely.any at all in another.So, too, the range of production of hydroxylamine is from nearly 9 per cent. of the nitrogen of the nitrite down to one-third per cent. The presence of ammonia may be very strongly manifest, or be hardly perceptible and escape notice, The two gases, nitrous oxide and nitrogen, together represent a t least 80 per cent. of the total nitrogen, and may vary in relative proportion to the extent of either of them being nearly absent. Necessarily, all the sodium of the nitrate or nitrite, not left as hyponitrite, appears as hydroxide, along with t h a t derived from the metallic sodium used as the reducing agent. So long as any nitrite remains, hydrogen does not occur among the products, unless a very large quantity of water is present;, whilst, if there is very little water, hydrogen is not evolved even after all the nitrite is gone.Within the limits indicated, the proportioning of the products of tho reduction is well under control. The concentration of the solu- tion of nitrite, or, to put i t better, the relative quantity of water present, exercises most influence, the only other circumstance affect- ing the course of the reduction being the temperature. The concen- tration of the sodium in the amalgam and the proportions of the sodium and the nitrite have no direct effect on thereduction. Work- ing with a sufficiently concentrated solution of nitrite, the proportions of the products remain constant throughout the reduction of the nitrite. Probably this is the case also when an exceedingly dilute solution is used j but with a, somewhat dilute solution, say 1 in 30, there is some difference, due t o the fact that the presence or absence of much sodium hydroxide modifies the proportions of the products, and that this substance is generated so largely.A dilute solution of sodium nitrite may be made to behave as a concentrated solution in the mode of its reduction by nearly saturating it with sodium hydroxide before bringing it in contact with the sodium amalgam j but the addition of sodium hydroxide to a concentrated solution of nitrite before reducing it by the amalgam has no sensible effect, for the reason, no doubt, that, in the reduction of the nitrite as it actually occurs, about 3; mols. of sodium hydroxide are produced for 1 mol. of nitrite reduced, quite enough, therefore, of itself to make the water of a concentrated solution almost proof against the action of sodium.With a large quantity of water prasent, the sodium hydroxide formed is not enough to render the water inactive, and in this is to be found the explanation of the great difference observed in the proportions ofALKALI NITRITE BY AN ALKALI METAL. 89 bhe products, according as the nitrite is dissolved in much or little water. I n order to produce as much hyponitrite as possible, little more is necessary than to work with a concentrated solution of the nitrite (1 of sodium nitrite to 3 or 3$ water), to add the amalgam in some excess, and not to allow the temperature to rise above 100'. To get as much hydyoxylamine as possible, the solution of nitrite must be dilute (say 1 in SO), and be kept cold during the addition of the amalgam.To preserve the hydroxylamine from reduction to ammonia, the solution must be kept well agitated over the amalgam, and be poured off from it as soon as nearly all the nitrite has been reduced. Much more time is needed to reduce a dilute solution than a concen- trated one. The best conditions for producing much hydroxylamine do not allow of much more than half the maximum yield of hypo- nitrite being obtainod at the same time. To get much nitrous oxide, the temperature of the solution must be kept as low as possible, whilst to get much nitrogen, the temperature must be kept high, the strength of the solution of nitrite being without effect, The reduction of a very dilute solution of sodium nitrite kept very cold is attended with very little effervescence, because the quantity of nitrogen produced is very small and the nitrous oxide remains dissolved, although it is readily evolved on warming, De Wilde has determined the proportions of the gases to each other, but only when the nitrite (or nitrate) was in excess of the sodium ; that however, is sufficient, since qualitative examination of the gases has shown me that variations in the proportions of salt and metal are without sensible influence on the composition of the gases, and also that this remains apparently unchanged during the progress of the reduction if the temperature is kept tolerably uniform. De Wilde found that dilute solutions of nitrite or nitrate of sodium or potassium gave larger quantities of nitrous oxide in proportion to nitrogen when the solutions mere dilute than when they were concentrated, from which it might seem that the strength of the solution does affect the proportions of the gases to each other; but in the experiments conducted by de Wilde, the much greater rise of temperature when concentrated solutions are acted on fully accounts for the results he obtained.Ammonia can always be detected from the beginning of the reduc- tion (Thum thought not), but its amount may be minute throughout, It can be got in considerable quantity by using a cold dilute solution, as for producing hydroxylamine, and, after the main action is over, shaking it with amalgam in a stoppered bottle until all the hydroxyl- amine has disappeared. It can also be got somewhat concentrated for a short time by dropping the concentrated solution of the nitrite on90 DIVERS! REDUCTION OF AN to much solid sodium amalgam, as was first observed by de Wilde but even then much hyponitrite is produced.Very hot and dilute solutions of nitrite treated with sodium amalgam give little else than ammonia and nitrogen, The reduction of potassium nitrite by potassium amalgam closely resembles that of the sodium salt by sodium amalgam, in every respect, both quantitative and qualitative. If, for the moment, nitrogen and hydroxylamine be disregarded, as they well may be, since their proportions become very small under suitable circumstances, the nitrite may then be said to be reduced simply to hyponitrite and much of this hydrolysed into nitrous oxide and sodium hydroxide.This, at one time, I, as well as other chemists, supposed to be the case. But, for a long time now, I have felt that most of the nitrous oxide and sodium hydroxide must have another origin. "hum has expressed himself in the same sense, basing his opinion upon the comparative stability of sodium hyponitrite in strongly alkaline solution, for it is only gradually decomposed even when boiled with it. This fact by itself, however, is not inconsistent with the assumption that the nitrous oxide and sodium hydroxide represent decomposed hyponitrite. But it does not stand alone ; for (a) Hot concentrated solutions of nitrite yield quite as much hyponitrite as cold ones, unless the temperature is well above loo", and even then the yield does not fall off much.( 6 ) I n all cases, the effervescence accompanying the formation of hyponitrite goes on exclusively at the surface of contact with the amalgam. ( c ) Low production of hyponitrite is not attended with higher production of nitrous oxide. All these facts are opposed to the view that the nitrite is all reduced to hyponitrite in the first place ; so, too, is what follows. Although the proportions of the products of the reduction of the nitrite vary greatly with the circumstances, it is only within well- marked limits; thus, of the nitrite reduced there is from a sixth, under one set of conditions, to almost a fifth, under other conditions, which becomes partly hyponitrite and partly hydroxylamine (and ammonia), whilst the rest becomes nitrogen and nitrous oxide, one o r the other predominating, according to circumstances. So, too, in one extreme case, nearly all of the one-sixth of the nitrite will change into hyponitrite, very little becoming hydroxylamine ; or, on the other hand, of nearly one-fifth of the nitrite more than half may be converted into hydroxylamine, only the rest of the fifth becoming hyponitrite.It may, therefore, safely be assumed that about one- fifth of the nitrite tends to, or is able to, become hyponitrite, although barely one-sixth of the nitrate can yet be secured as this salt, because either some of this fifth becomes hydroxylamine, or else a little of the hyponitrite is hydrolysed at once or during theALKALI NITRITE BY AN ALKALI METAL. 91 process of isolating it.With that assumption to give more precision t o the statement, it may be affirmed that many experiments under varied conditions have shown that about a fifth of the nitrite is decomposed by sodium amalgam in one way, and four-fifths in another way ; in the one, hyponitrite, hydroxylamine, and alkali (with a very little ammonia and nitrous oxide as secondary products) are formed, and in the other, nitrogen, nitrous oxide, and alkali; so that when much hydroxylamine is formed it is at the expense of hyponitrite only, and when much nitrogen is produced it is at the expense of the nitrous oxide only. But although this is the case, the hydroxylamine does not seem t o be derived from the hyponitrite, or the nitrogen from the nitrous oxide, but, rather, the one pair of substances is derived from one transition product, and the other pair from another transition product.It was pointed out in my first paper that sodium amalgam does not act on hyponitrite, and this has since been more fully established by Dunstan and Dymond, and again by Thum ; according to the last-named chemist, hyponitrous acid is not reduced even by zinc and boiling dilute sulphuric acid. In confirmation of my earlier state- ment, I can now assert that sodium amalgam has no action whatever on a solution of sodium hyponitrite saturated with sodium hydroxide, even at 80' (and, no doubt, at higher temperatures), and when in con- tact with it for days together ; no hydroxylamine, ammonia, nitrogen, or hydrogen is produced. I n weaker alkaline solutions, hydrogen is very slowly evolved, but still without the hyponitrite being affected.Weak alkaline solutions of sodium hyponitrite, however, slowly decompose of themselves, and then some of the nitrous oxide may possibly get reduced by the sodium amalgam. As for the nitrogen, it is evident that only while nitrous oxide remains in solution and comes in contact with the amalgam can it be reduced, even i f it is then (see p. 95). Yet, in order to get much nitrogen in place of nitrous oxide, it is necessary t o work with hot solutions, when the solubility of nitrous oxide is at its lowest. It is riot essential that the quantity of nitrite should be small in propor- tion to the sodium, temperature alone appears to be the condition determining the formation of nitrogen in place of nitross oxide.In other words, weak solutions of nitrite and excess of amalgam in no degree favour the production of nitrogen rather than of nitrous oxide, and the proportion of nitrogen is not greater in the gases esca.ping towards the end of a reduction than at the beginning. Very different is it with ammonia, which is trulya product of the reduction of hydroxylamine (in non-acid solution), and the formation of which takes place principally during the final action of the amalgam. Against the notion, highly improbable as it is, that the92 DIVERS: REDUCTION OF AN nitrogen may come from yet undecomposed nitrite and already formed ammonia, which would also account for the comparative absence of ammonia in the earlier part of the reduction, there may be adduced de Wilde’s observation, that ammonium nitrate, when reduced by sodium amalgam, gives much more nitrous oxide in proportion to nitrogen than potassium or sodium nitrate does, no doubt because there is less rise in temperature.Without speculating on the constitution of a nitrite, we are able to see from the interactions between ethylic iodide and silver nitrite that a nitrite may react both as an oxylic salt, NaONO, and as a halide, NaNO,. From the reduction by sodium there will then first result the radicles NaON= and NaNO; from the former, or sodox- imido-radicle, may well come the hyponitrite and hydroxylamine, and from the other, or sodium nitroside radicle, the nitrous oxide and nitrogen. I n accordance with the facts observed, the sodoximide, in concentrated alkaline solution, will condense to sodium hyponitrite, stable against reduction, or, in very dilute alkaline solution, will, by hydrolysis and reduction, become alkali and hydroxylamine.The hypothetical nitroside will also condense and simply hydrolysa into nitrous oxide and alkali, mainly at low temperatures, or will become reduced and hydrolysed into nitrogen and alkali, principally a t higher temperatures. To establish the points in the reduction of the two nitrites by their respective metals, here described, I have made very many experiments, usually working on quarter-gram molecules of nitrite. The hypo- nitrite obtained was weighed as silver salt, The hydroxylamine was estimated by the quantity of metallic silver it yielded, and in this way: the black precipitate it causes in silver nitrate solution, in presence of alkali, being largely suboxide, was washed with cold dilute nitric acid and ammonia alternately, and the residual brownish metallic silver weighed and calculated into hydroxylamine by the ratio 2Ag : NH,O, experiments (described in the next paragraph) with solution of hydroxylamine sulphate of similar dilution and alkalinity having shown that this could be done accurately enough.The important observation, made by Thum, that hydroxylamine, when oxidised by suitably alkalised mercuric oxide, silver oxide, or cupric hydroxide, will yield a little hyponitrite and nitrite, induced me t o ascertain whether, in my experiments, the destruction of hydroxyl- amine in this way, sometimes in considerable quantity, might not account for some of the hyponitrite afterwards found to be present.To ascertain whether this took place, I made a blank experiment very similarto those made in studying the reduction of sodium nitrite, except that sodium hyponitrite itself was absent. Thus, bydroxyl-ALKALI NITRITE BY AN ALKALI METAL. 93 amine sulphate, 1.5 grams ( = 0.6 gram hydroxylamine) was dissolved along with 32 grams of sodium hydroxide in nearly 2 litres of water, and then a solution was run in, with stirring, of 7.6 grams of silver nitrate, which was a considerable excess, such as was used in the other experi- ments. The abundant, black precipitate was washed, exhausted with ice cold, dilute nitric acid, and the solution, neutralised as usual in my other experiments, gave no silver reaction for silver hyponitrite, and nothing more than a slow and very slight action on permanganic acid, which might be due to a trace of either nitrous or hyponitrous acid.It was easily seen that some nitrous acid was formed, by applying the iodide and starch test. Under the circumstances of my experiments, therefore, even when 7 per cent. of the nitrite had been reduced to hydroxylamine, there could have been no perceptible production of hyponitrite during the after oxidation of the hydroxylamine. The metallic silver, washed out with dilute nitric acid* and ammonia, weighed 3.8 grams, the calculated quantity being 3-95 grams. The nitrite detected in the mother liquor of the black precipitate had been formed in too small a quantity to materially affect the woight of the metallic silver, Generally, sodium hydroxide was approximately estimated, after all the hyponitrite had been precipitated, by titration of the mother liquor with nitric acid, and of the silver oxide that had been precipitated along with tho silver hyponitrite and the metallic silver.The amalgam used was of approximately known strength, ascertained, not by sampling, which is impracticable, but by uniformly preparing successive quanti- ties, and sacrificing one to assay by dilute sulphuric acid and weighing the sodium as sulphate; after use in reducing nitrite, the sodium re- maining in the mercury was sometimes determined in the same way. Nitrous oxide and nitrogen were not measured; their total nitrogen was found by difference, and their proportions had been sufficiently ascertained by de Wilde, as I have already said; but their relative abundance was estimated by a burning splint of wood, the reduction of the nitrite being always conducted in a loosely closed flask. The range of this reaction was from that of a gas utterly extinguishing combustion to that of one which supported it most vividly; in any uniformly conducted experiment, the gases evolved towards the end behaved like those given off at first.To ascertain the effect on its reduction by sodium of adding sodium * It was proved many years ago that silver is insoluble in dilute nitric acid, the presence of nitrous acid being necessary to make it dissolve. But the contrary has been since asserted to be true where the silver is finely divided, as when precipi- tated.This error, as I must regard it, is due to precipitated silver when black or blackish containing suboxide, which gives it its colour : this is resolved by acids into oxide' of silver, which dissolves, and metallic silver, which is left. VOL. LXXV H94 REDUCTION OF AN ALKALI NITRITE BY AN ALKALI METAL. hydroxide to a concentrated solution of sodium nitrite (negative as this proved to be), two methods were adopted. I n one, the amalgam was covered with a cold saturated solution of sodium hydroxide, which has no action on it, and then the concentrated solution of nitrite was slowly added; at first, the alkali greatly impedes the action of the amalgam on the nitrite, but when more of the solution of the latter is added, the action goes on faster and to the end, and gives the usual large proportion of hyponitrite with very little hydroxylamine.In the other, a, concentrated solution of sodium nitrite and sodium hydroxide was treated with some of the amalgam; then more sodium nitrite was added, and then more amalgam, The result was the same as before. The object of working in this way was to obtain the effect, if any, of the most concentrated alkali from the first, without having to deal afterwards with a very large excess of alkali when the analysis had to be made, I have also tried to ascertain the effect of diminishing the amount of alkali present. I n acid reducing mixtures, nitrous acid becomes largely converted into hydroxylamine without production of hypo- nitrous acid, so that it seems probable that, could the alkali formed in the reduction of the nitrite by sodium be neutralised nearlyas fast as it is produced, much hydroxylamine would be obtained and very little hyponitrite.The use of the ordinary acids for the purpose in such a way as to give conclusive evidence on the point does not seem to be practicable, whilst the great rapidity of the process of reduction makes the use of carbon dioxide (Aschan, Ber., 1891, 24, 1865) very unpromising. I have, therefore, tried the effect of adding ammonium acid carbonate along with the sodium nitrite, expecting the ammonia to be inactive. In one case, where I used the amalgam in large excess, much ammonium amalgam was formed, and, what was quite unexpected, neither hyponitrite nor hydroxylamine. In another experiment, in which the nitrite was kept in excess of the amalgam, the previous addition of the ammonium carbonate in excess was without any effect ; the nitrite solution had to be used slightly dilute because of the carbonate, and gave, therefore, a little less hyponitrite (about 12.7 per cent.of the nitrite consumed) and a little more hydroxylamine (about 3 per cent.) than in the best way of working for hyponitrite. The presence of the ammonium carbonate was, therefore, without effect, the reaction between the nitrite and the sodium being already complete when the sodium oxide comes in contact with the water and ammonium carbonate. I satisfied myself that a fairly concentrated solution of nitrite is uniformly reduced from the commencement to the end of the reaction if the temperature is kept tolerably constant, the method employed being to examine the gases in the way described, and the hyponitriteDIVERS : HYPONITRfTES ; THEfR PROPERTfES, ETC. $5 and hydroxylamine as follows. To a solution of nitrite, one-half only of the quantity of sodium amalgam required to reduce it WM added, and it was then found to contain hyponitrite and hydroxylamine in the same relative proportion as if the nitrite had been fully reduced (with cooling), and in approximately half the quantities the nitr'ite would have yielded if the full amount of sodium amalgam had been added, Sodium amalgam was proved to have little or no action on nitrous oxide by exposing the gas for a long time to its action. The amalgam was liquid, and, when shaken up with the moist nitrous oxide in a stoppered bottle, coated the sides of the bottle. With occasional vigorous shaking, the bottle was kept closed four days ; when opened, it was found to contain the nitrous oxide little, if at all, deteriorated as a supporter of combustion. In another similar experiment, a saturated solution of sodium hydroxide was poured over the amalgam ; in this case, the amalgam did not coat the sides of the bottle, but the solution served to keep the dissolved nitrous oxide in contact with the amalgam. The bottle was often vigorously shaken, and was not opened until after four days, The nitrous oxide was almost or qtiite unchanged. Holt and aims have studied the oxidation of sodium and potassium by nitrous oxide, but only at much higher temperatures than those in these experiments, which were at 25-30'. IMPERIAL TOKYO UNIVERSITY, JAPAN.

ISSN:0368-1645    

DOI:10.1039/CT8997500087

出版商:RSC    

年代:1899

数据来源: RSC

摘要:

DIVERS : HYPONITRfTES ; THEfR PROPERTfES, ETC. $5 XV.-Hyponitrites ; their Properties, and their Pre- paration by Sodium or Potassium. By EDWARD DIVERS, M.D.; D.Sc., F.R.8. THE hyponitrites have received the attention of many chemists besides myself since their discovery in 1871, and even this year new ways of forming them and the new working of an old method have been published, Yet much has been left to be put on record before a fairly correct and full history of these salts can be said to have been given, and the present paper is meant to be the necessary supplement to what has already been published. Way8 fmming Hyponitrites. No writer on hyponitrites in recent years has ahown himself acquainted with all the known ways of getting these salts, or even with the most productive.The following complete list is valuable, H 296 DIVERS : HYPONITRITES ; THEIR PROPERTIES, AND THEIR therefore, and is of special interest as bringing t o g e h r the various modes of formation of these salts. 1, Reduction of an alkali nitrite by the amalgam of its metal (Divers, 1871). 2. Reduction of an alkali nitrite by ferrous hydroxide (Zorn, 1882 ; Dunstap and Dymond). 3. Reduction of (hypo)nitrososulphates by sodium amalgam (Divers and Haga, 1885). 4. Reduction of nitric oxide by alkali stannite (Divers and Hagn, 1885). 5. Reduction of nitric oxide by ferrous hydroxide (Dunstan and Dymond, 1887). 6. Decomposition of a hydroxyamidosulphonate by alkali (Divers and Haga, 1889). 7, Oxidation of hydroxylamine by sodium hypobromite (Kolotow, 1890).8. Oxidation of hydroxylamine by mercuric oxide, silver oxide, or cupric hydroxide (Thum, 1893). 9. Interaction of hydroxylamine and nitrous acid (Thum, H. Wis- licenus, Paal and Kretschmer, Tanatar, 1893). 10. Oxidation of hydroxylamine by benzenesulphonic chloride and alkali (Piloty, 1.896). 11. Interaction, in methylic alcohol, of hydroxylamine with nitrous gases (Kaufmann, 1898, Annalen, 299, 98). 12. Interaction, in methylic alcohol, of hydroxycarbamide and nitrous gases (Hantzsch, 1898). 13. Interaction of dimethylhydroxynitrosocarbamide and alkali (Hantzsch and Sauer, 1898). Menke’s reduction of fused alkali nitrate by iron, and RBy’s reduc- tion of mercuric nitrite by potassium cyanide in solution, are not included in the list, because both reductions are very doubtful, and require confirmation before they can be accepted.I n the present paper, only the original method of preparing hyponitrites will be treated of. Preparatioh of Sodium Hyponitrite Xolution by the Reduction of Sodium Nitrite with Sodium Amalgam. Sodium nitrite can be converted by sodium amalgam in the easiest and quickest imaginable way into fully one-sixth of its equivalent of sodium hyponitrite; this remains in solution, and is pure but for the presence of much sodium hydroxide. From this solution, the sodium salt itself, as well as silver hyponitrite, can be at once pro- pared, nearly pure and with hardly any loss. The solution, ifPREPARATION BY SODIUM OR POTASSIUM. 97 cautiously neutralised, is also at once fit for preparisg lead, copper, mercury, and some other salts.The neutralisation is known to be complete when a little of the solution just ceases to give black oxide when mixed with a drop of a dilute solution of mercurous nitrate. Others who have tried this method, and particularly Hantzsch and Kaufmann, got far less favourable results. Pure sodium nitrite is necessary, but that can now be prepared very simply (this vol., p. 85). I n order to get as much hyponitrite as possible and as little hydroxylamine, the nitrite must be in con- centrated solution; three times its weight of water seems to be the best quantity to dissolve it in when operating in the way to be described. Using these proportions, there is enough water to form, with the sodium oxide produced, a solution of the composition NaOH + 3H20, which is a nearly saturated solution of NaOH,H,O at the mean temperature." In presence of 80 much hydroxide, the water is also quite saturated with hyponitrite, a small quantity of this salt even separating when the solution is kept a t 0' for a time.To reduce sodium nitrite in cold concentrated solution, 29 atoms of sodium are needed, the additional half atom being consumed in the unavoidable formation of some nitrogen, hydroxylamine, and ammonia. This accords we11 enough with the statement in my first paper, as a first approximation, that not more than 4 atoms are active on sodium nitrate. In practice, however, 3 atoms of sodium should be used in reducing sodium nitrite, partly because it is wanted afterwards to reduce hydroxylamine, and partly because it is im- portant that all the nitrite should be reduced, and this, notwith- standing statements to the contrary, can only be accomplished quickly in presence of a good excess of sodium. The strength of the amalgam is not an essential point; I have, however, found it most con- venient to work with a soft, solid amalgam having the composition (NaHg&, or 23 grams of sodium to 1600 grams of mercury.? The temperature, also, is not of importance i E only the solution of nitrite is concentrated, and although i t may in fact rise nearly to 100' with- out harm, it is better t o follow my original direction to keep the flask in a stream of cold water during the reduction.It is, however, preferable to cool it, particularly in warm weather, by means of a brine and ice bath, as then the amalgam can be added much faster without producing any great evaporation.The temperature of the solution during the reduction then ranges, with a convenient rate of * Sodium hydroxide forms a saturated solution at 1 5 O in its own weight of water. j- Tanatar erred in supposing that I recommended the use of hard amalgam, When cooled, this solution deposits large pointed prisms of the monhvdrate. and his supposed improvement of my process is not one infact.98 MVERS : HYPONITRITES ; THEIR PROPERTIES, AND THEIR working, from 5' to 25O, and the time taken to add 23 grams of sodium need not be more than 10 minutes. From a quarter to a half gram-molecule of sodium nitrite is a con- venient quantity to work on, and the solution is best contained in a 350 to 450 C.C.pear-shaped, wide mouthed flask, lying very obliquely in the cooling bath while the amalgam is added by means of a spatula. The last fourth of the amalgam may be put into the flask as rapidly as it can be, and the flask may then be removed from the bath. It is kept actively rotated for 10-15 minutes, during which the temperature will rise to about 40' and then fall. The solution and mercury are next poured into a narrow mouthed stoppered bottle so as to half fill it, the thick, aqueous solution adhering to the flask being washed into the bottle, but the water used should be limited to 2 Qr 3 C.C. if it is desired to obtain the solid sodium salt, The whole is now violently shaken for 10 minutes or so, so as to destroy all the hydroxylamine.To ascertain this, a drop of the solution is tested by diluting it and adding a drop of silver nitrate solution, and a slight excess of dilute nitric acid ; there should not be the slightest black tint due to silver reduced by hydroxylamine. No gas is liberated during the shaking, but a very strong odour of ammonia is developed. Strange to say, a minute quantity of nitrite is still present, and it 6eems almost impossible to entirely remove it, although it can be so far reduced by an hour's shaking of the solution with the amalgam that the acidified solution does not blue potassium iodide and starch until it has stood for about an hour. On separating the solution from the amalgam and exposing it in a dish overnight over sulphuric acid, under reduced pressure, it will be free from ammonia, and is virtually a pure and stable concen- trated solution of sodium hyponitrite and hydroxide.As here described, the preparation of a solution of sodium hypo- nitrite ready for use is the same as that followed by me in 1871 (with nitrate), except the important modification in the manner of removing the hydroxylamine. When silver hyponitrite is prepared from the crude solution, the hydroxylamine gets destroyed by silver oxide, as I pointed aut in the addendum to my first paper. Zorn, as ap improvement, introduced the use of mercuric oxide, on the ground that destruction of some silver hyponitrite was thus avoided, but he overlooked the fact that it is the silver oxide, just as it is mer- curic oxide, which becomes decomposed, the hyponitrite or any other acid radicle being untouched by the hydroxylamine in alkaline solu- tion.Whether, therefore, mercuric oxide, or silver nitrate, or mer- curic nitrate is used, and the precipitated metal then separated, the result is just the same in concentrated alkaline solutions, except that the dropping in a solution of the nitrate is more easy to carry outPREPARATION BY SODIUM OR POTASSIUM. 09 than stirring up with mercuric oxide. Further, where the alkaline solution is very weak, the use of mercury compounds is not without objection, as a little mercuric oxide remains in solution. But whether silver or mercury oxide is employed, the result is unsatisfactory, for, as Thum has pointed out, both these oxides, in destroying the hydr- mylamine, regenerate nitrite.Not, however, that Thum himself found this prevented him from successfully purifying the silver hypo- nitrite from nitrite by thorough washing and reprecipitation. Ber- thelot and Ogier, Paal and Kretschmer, and I myself, have not, however, met with the same success, as I found it necessary, in order to get silver hyponitrite free from all trace of nitrite, to begin by precipitating it in the absenco of nitrite. Nevertheless, far from casting doubt on Thum’s statement, I believe his silver salt to have been some of the purest ever prepared, from the account he has given of the properties of hyponitrous acid, No one, however, will be disposed to deny the superiority of sodium as a means of removing the hydroxylamine from the solution. An almost pure solution of sodium hyponitrite can be conveniently got by dissolving the freshly prepared, hydrated, solid salt in water.Sodium ibdide, or potassium iodide and the silver salt, will also furnish a solution of alkali hyponitrite. To get a solution for precipitating purposes, Thum proceeded in an indirect way, first preparing a solu- tion of hyponitrous acid, and then adding enough sodium hydroxide to make the solution neutral to phenolphthalein, an effective but very wasteful process. Kirschner also, wanting ft solution for precipitating purposes, used sodium chloride and silver hyponitrite, which, in a complex and wasteful way, he made t o yield a solution which although mixed with much chloride and nitrate, was practically free from silver. Sodium Hyponitrite.In 1878, Menke gave full analyses of crystals of a stable salt having the composition of sodium hyponitrite containing 6H,O, which he had prepared by deflagrating in an iron crucible a mixture of sodium nitrate and iron filings, keeping the product at a red heat for an hour in a fire of charcoal rather than of gas, boiling the mass with water, filtering off iron oxide, evaporating, and leaving to crystallise. He makes no reference in his paper to the large amount of sodium hydroxide he must have had to deal with, although this should have seriously affected the procedure. In 1882, Zorn sub- mitted Menke’s method to a thorough examination, but failed to obtain the leas& trace of hyponitrite; he found, however, that ferrous hydroxide, acting on a solation of sodium nitrite, did produce sodium hyponitrite (in solution).His suggestion that Menke had mistaken100 DIVERS : HYPONITRITES ; THEIR PROPERTIES, AND THEIR carbonate for hyponitrite takes no account of the fact that the nitrogen and water in the salt were repeatedly determined. It can now, however, be stated with certainty that Menke's salt was not the sodium hyponitrite obtaicable by reducing sodium nitrite by sodium amalgam and water, for this differs from it in degree of hydration, stability, and in other properties. D. H. Jackson (Proc., 1893) described two ways in which he had succeeded in preparing sodium hyponitrite, but with such difficulty that he was deterred from investigating its properties; indeed, he merely mentions, in proof o€ his success, that he obtained crystals which con- tained the theoretical proportion of sodium, but this happens to be no proof at all, as sodium carbonate has just the same content of sodium j moreover, the hyponitrite is a hydrated salt which cannot be ren- dered anhydrous without some decomposition, and although of crystal- line texture, the salt can hardly be described as occurring in crystals.Nevertheless, his success in getting the salt is not to be doubted. One of the methods he adopted was to reduce a concentrated solution of sodium nitrate by sodium amalgam, evaporate the solution in a vacuum until the salt crystallised, and wash the crystals with alcohol to free them from sodium hydroxide. With some modification, the process he followed is an excellent one. To obtain sodium hyponitrite from the somewhat thick solution pre- prepared as already described, it is first passed through a Gooch asbestos filter well covered from the air ; it contains 1 mol. of sodium hydroxide to 3 mols.of water, and is a saturated solution of the hydroxide, whilst thereare about 21h atoms of sodium present as hydroxide to 1 as hyponitrite. Cooling alone will cause the separation of the hypo- nitrite, and the solution readily loses water in a vacuum over sulphuric acid until it retains only about 2 mols. to 1 mol. sodium hydroxide, when almost the whole of the sodium hyponitrite will have separated j at 25-30', this will happen in about 40 hours, the salt separating as minute, crystalline granules, some of which adhere to the walls of the dish, but most of them being deposited as a thick crust on the surface of the solution, Below 1 5 O , the mother liquor readily deposits crystals of the monhydrate of sodium hydroxide, and as evaporation is slower in the cold, it is better, for both reasons, to conduct the operation in a warm room.The only effective way of separating the salt from its viscid mother liquor is by the pump and a Gooch crucible unlined with asbestos; draining on a tile is impossible. I n the same apparatus, it is washed with absolute alcohol and then transferred to a basin and gently triturated with fresh portions of alcohol until all the sodium hydroxide has been removed. If now drained on a good tile, it is the nearly pure hydrated salt, but very unstable, losing both water and nitrousPREPARATION BY SODIUM OR POTASSIUM.101 oxide, and consequently becoming contaminated again with sodium hydroxide ; if, however, it is promptly dried in a vacuum desiccator, it bocomes anhydrous before i t has undergone much decomposition, and is then quite stable in dry air. The amount of the hydrated sodium hyponitrite should be quite one-sixth of the calculated quantity, and the mother liquor will then be too poor in hyponitrite t o be used as a source of silver hyponitrite. A modification of the method, which gives an equally good yield, is to precipitate the salt by absolute alcohol instead of evaporating ; the only precaution necessary is to prevent, as far as possible, the salt from becoming attached to the walls of the vessel. A large quantity of alcohol is required, because of the very large proportion of sodium hydroxide which is present.A few drops of the solution are added to the alcohol in a flask and at once violently shaken with it until the hyponitrite has completely solidified ; then gradually the rest of the solu- tion is poured in with very active agitation. I f abundance of alcohol is used from the first, with thorough mixing, very little of the salt will remain in solution and very little adhere to the flask; with less alcohol at first, a notable quantity of the salt is lost by being kept in solution, for although it is afterwards slowly deposited, it is not then in a serviceable condition, and much salt is liable to adhere to the flask, which can, indeed, be dissolved out in water, and be reprecipitated by alcohol, but only with very great loss.The action of sodium chloride on silver hyponitrite (see p. 106) is complex and quite unsuitable for the preparation of a solution of pure sodium hyponitrite. Nevertheless, such a solution, charged as it is with sodium chloride, and containing, besides, some silver hyponitrite dissolved in it, deposits sodium hyponitrite when mixed with much absolute alcohol, and this constitutes Jackson’s second method of getting the salt; i t always, however, contains a little chloride mixed with it. The granular form of sodium hyponitrite is most marked in i t when it has been separated from a highly concentrated solution of sodium hydroxide ; when it is redissolved in a very little water and the solu- tion rapidly evaporated in an exhausted desiccator, the salt separates as an almost structureless membrane on the surface, andthere readily becomes opaque and apparently anhydrous.In the ordinary desiccator, a finely granulated crust forms. I have never obtained it in crystals. The salt, when quite freshly prepared, has an exceedingly mild, alkaline taste. The attempts to determine the degree of hydration of the salt have been unsatisfactory because of its instability, but they point to the formula (NaON), + 5H,O. That formula requires 23.47 per cent. sodium, whilst analysis of the salt weighed as soon as it was almost102 DIVERS ! UYPONITRITES ; THEIR PROPERTIES, AND TEEIR free from alcohol, gave 23.66 per cent. I n place of 30.61 per cent. for the hyponitrite ion, 28.10 per cent.was obtained by dissolving the satt in water and precipitating with silver nitrate, a deficiency fairly attributable to decomposition before the silver nitrite could be added ; for, asproved by Zorn, this way of estimating hyponitrous acid is accurate. Loss of weight in the vacuum desiccator gave 44-91 per cent,, whilst the calculated quantity of water is 45.92 per cent., but the difference is easily accounted for as due to loss of nitrous oxide, and, indeed, would be even greater but for the fact that this loss involves fixation of water by sodium oxide. The anhydrous salt, somewhat decomposed, is non-coherent and opaque, and in appearance much like that of magnesia aZ6a ; heat is evolved when it dissolves iu water, and it is insoluble in alcohol. The an- hydrous salt only slowly takes up water from a solution of sodium hypo- nitrite, Heated in a closely-covered vessel, it yields nitrogen and sodium oxide mixed with some nitrate, 3(NaON), = 2N2 + 2Na20 + 2NaN0,.The salt bears a heat of 300° without decomposing, and then melts and effervesces ; glass, platinum, and even silver are freely attacked by the fused mass, and the product hisses when water is added to it. Sodium hydroxide and nitrite are the solid products when the hydrated salt is quickly heated, and nitrous oxide, as well as nitrogen, is given off, Strong sulphuric acid decomposes the salt, with production of odour- less, white vapours, and does not form nitrosylsulphate if the sodium salt is pure. The salt, or a fairly concentrated solution of it, effervesces with a dilute acid like a carbonate.The solution, with the respective re- agents, gives a precipitate of calcium hyponitrite and of most other hyponitrites a t once. It dissolves a little silver hyponitrife and decom- poses silver chloride (see the account of silver hyponitrite, p. 106). Dry sodium hyponitrite is not decomposed by carbon dioxide, and, since the hydrated or dissolved salt partly decomposes by interaction with the water, its power of fixing carbon dioxide does not indicate that it is directly decomposable by that substance. The solution, when boiled, decomposes moderately fast into hydroxide and nitrous oxide. If allowed to stand for a day, a trace of nitrite is formed (see p. 114). Potamiurn Hyponitrite; Potassium Amalgam. The preparation of a solution of potassium hyponitrite is throughout like that of a solution of the sodium salt. It is only necessary, therefore, to say something concerning the potassium amalgam which is required, concerning which as a reagent little or nothing has been published.PREPARATION BY SODIUM OR POTASSIUM.103 Merely for convenience in working, the composition of the potassium amalgam should correspond pretty closely, in parts by weight, to that recommended for the sodium amalgam, namely, (Hg14K)2, or 2800 of mercury to 39 of potassium, this being the weakest amalgam that is solid, a pasty amalgam like that of sodium not being obtainable. Although it crystallises in simple cubes, often very large, which are so sharp angled that they can hardly be introduced into a flask without fracturing it, these crystals are very easily crushed in a porcelain mortar, and are then in a state quite convenient for use.Sodium or potassium amalgam not stronger than here recommended (1 kilo. of mercury to 14 grams of alkali metal) is particularly easy to prepare in Draper's way, that is, by melting the sodium or potassium under solid paraffin and adding the mercury to it, at first very gradually. The operation can be performed on the open table. I n spite of the fact that more heat is evolved, according to Berthelot's numbers, the action is less violent in preparing potassium amalgam than it is in the case of sodium amalgam. Potassium, also, nearly always requires to be well stirred with a glass rod to bring about its first contact with the mercury under the paraffin;" sodium never does.When all the mercury has been added, either amalgam requires good stirring in order to dissolve all lumps, and should again be stirred when solidifying, in order to disturb crystallisation as much as possible. The specific gravity of the paraffin is about the same as that of potassium, but paraffin expands so very greatly in melting that the po- tassium readily sinks in it when it is in the liquid state. Muhlhaeuser, many years ago, melted sodium under petroleum and then added the mercury to it, and, in recent years, Nef has recommended the use of toluene, which boils freely by the heat produced in the union of the metals, But toluene could hardly be used in making potassium amalgam, because of its specific gravity. A highly concentrated solution of potassium hyponitrite and hydroxide having been prepared, the hyponitrite can be precipitated by absolute alcohol, but only very incompletely, and some of what is precipitated is afterwards dissolved away in washing it with more alcahol. The preparation of this salt is, therefore, less satisfactory than that of the sodium salt.Another way of making potassium hyponitrite is to decompose silver hyponitrite with exactly the right quantity of solution of potassium iodide, By rapid evaporation under reduced pressure, the solution can be qoncentrated, although with partial decomposition, preparatory to treating it with absolute alcohol, and it can even be dried up, so as to * This is probably due to the fact that the potassium presses but lightly upon the mercury on account of its specific gravity not greatly exceeding that of the paraffin, and not because of any chemical difference.104 DIVERS : HYPONITRITES ; THEIX PROPICRTIES, AND THEIR yield the impure solid salt.The cold of evaporation in a vacuum bas sometimes caused the separation from the concentrated solution of hydrated crystals, which, however, melt when placed on filter paper ; otherwise, the salt is obtained anhydrous in minute, prismatic crystals. The salt decomposes more rapidly than the sodium salt, but is stable when quite dry. It is soluble in 90 per cent. spirit, and slightly even in absolute alcohol. Its aqueous or alcoholic solution yields silver hyponitrite with silver nitrate, dissolves silver hyponitrite to some extent, and in other respects behaves like one of sodium hyponitrite.It has not been obtained sufficiently undecomposed to be fit for quantitative analysis. Preparation of Silver Hyponitrite. The hyponitrites were discovered through the production of the silver salt, and since that discovery this hyponitrite has been prepared and redescribed by many chemists ; all deviations from the account I first gave of it are, however, incorrect, and the only additional observa- tions that have been made are that it can be obtained in a purer state than I got it at first, and that it gives off nitric peroxide when heated. The very poor success in obtaining it in satisfactory quantity in recent years is remarkable (see p. 97) ; this seems to be due to erroneous methods of procedure, either in reducing the nitrite or in converting the sodium hyponitrite into the silver salt.The concentrated solution of sodium hyponitrite and hydroxide, already described, is diluted and mixed with just sufficient silver sulphate or silver nitrate, dissolved in much water, to precipitate the hyponitrite ; for it is unnecessary to aeutralise the sodium hydroxide. (Neutralisation can, indeed, precede precipitation, if desired, as in pre- paring mercury and other hyponitrites, but in the case of the silver salt it is quite unnecessary, and there is a risk of loss of hyponitrite.) Silver sulphate should be used if it is essential to exclude nitrate from the silver hyponitrite ; for, as will be shown, washing and reprecipitating are but imperfect means of purifying the precipitate.Supposing a half gram- molecule of sodium nitrite to have been reduced, the alkaline solution, diluted to three timesitsvolumeor more, is mixed with 13 grams of silver sulphate or 14 grams of silvernitrate dissolved in about 3 litres of water, and the mixture stirred vigorously at once and continuously for 5 minutes, in order to convert the silver oxide into silver hyponitrite. After the precipitate has nearly all subsided, the turbid liquor, if bright yellow rather than brownish, is decanted and more silver solution added to it until, after stirring well, some brown silver oxide remains, when the whole is poured back and stirred up with the main pre- cipitate, and then left to settle. Good daylight is almost essentialPREPARATION BY SODIUM OR POTASSIUM.105 for judging the colour of the precipitate when finishing, but the precipitate should not be exposed to light more than is absolutely necessary. After washing somewhat by decantation, the precipitate is stirred up with successive portions of highly dilute sulphuric acid (3 or 4 per mille) until this fails to become fully neutralised, and shows, there- fore, when poured off and mixed with a drop of sodium carbonate, a slight yellow opalescence due to silver hyponitrite. The precipitate, after being washed with water by decantation until the washings no longer contain sulphate, is stirred up with water containing a trace of sodium carbonate, and, finally, again washed with water. It is then collected on a filter and dried in the dark in a vacuum.When thus dried, it may be heated for a time to 100' in dry air without change and become still drier. It is now usually as pure as it is possible to get it. As, however, the operations are not always so perfectly carried out as to ensure this degree of purity, it is desirable some- times to submit the salt to further treatment, prehrably before it has been dried. I n that case, it is dissolved, in portions a t a time, in 3 per mille ice cold dilute sulphuric acid, and is either ex- peditiously filtered, if necessary, into some sodium carbonate solution, or, if not, is a t once made alkaline with sodium carbonate. The re- precipitated salt is then treated with sulphuric acid and washed in exactly the same manner as the original precipitate. Even after reprecipitation, the silver hyponitrite obtained from 34.5 grams of sodium nitrite will weigh about 11 grams.The process for preparing silver hyponitrite just given differs from that contained in my first paper in not neutralising the sodium hydroxide with acetic acid, in taking silver sulphate instead of nitrate, sulphuric acid in place of nitric acid, and sodium carbonate in place of ammonia, and in some minor details. Theuse of sulphuric acid is not new, that acid having been first used by van der Plaats, but the motive for the change is new and has been already given. Cold dilute sulphuric acid .is not in the least less active than nitric acid in decomposing silver hyponitrite ; in fact, unless very dilute, it is more active in consequence of silver sulphate crystallising out. Sodium carbonate (used by Haga and me in 1884, Trans., 45, 78) is to be preferred to ammonia for precipitating the salt, as being more sensitive, and because the last trace of ammonia is difficult to wash out of the silver salt (as Hantzsch and Kaufmann found, see p.114). It is easy to ensure absence of all silver carbonate, along with complete precipitation of the hyponitrite, because of the solubility of the carbonate in the excess of carbon dioxide always present in the solution.106 DIVERS : HYPONITRITES ; THEIR PROPEkTIES, AND THEIR Properties of Silver Hyponitrite. Silver hyponitrite is bright yellow, and when pale in colour it generally contains a trace of ammonia or loosely combined silver oxide. If along with such impurity there is also black silver sub- oxide, the colour becomes dull greyish-yellow, but when other impurities are absent, the presence of a little black oxide renders it somewhat bright green, as seen principally in the crude salt prepared by the hydroxyamidosulphonate method.The difference in colour observed has even suggested the possibility of the existence of different modifications, but there is really nothing to support this notion. If precipitated from strongly alkaline solution, or from concen- trated solutions of the sodium salt and silver nitrate, or in rubbing the calcium salt with strong solution of silver nitrate, silver hypo- nitrite is dense, but when precipitated by neutralising its solution in dilute acid, it is flocculent and bulky. When deposited from its ammoniacal solution through evaporation or large dilution with water, it is crystalline (Kirschner ; but also see Paal and Kretschmer).It is slightly more soluble in water than silver chloride, and is dissolved by very dilute nitric or sulphuric acid, so as to be recover- able on quickly neutralising the acid. The nitric acid required to dissolve it is considerable, being about 3 equivalents. The sulphuric acid solution very soon deposits silver sulphate. Acetic acid dissolves it only very slightly in the cold j phosphoric acid dissolves it, but not very freely. It is dissolved by ammonia solution, but only sparingly when this is very dilute, and the same salt can be recovered either by neutraliskg or dissipating the ammonia. It is also soluble in ammonium carbonate solution, and very slightly in ammonium nitrate solution.Of particular interest is its solubility to a slight extent in hyponitrous acid solution, and to a greater degree in solution of an alkali hyponitrite. Strong sulphuric acid acts energetically, the heat of reaction being itself quite sufficient to decompose some of the salt, a fact which accounts for the production of some nitric peroxide and nitrosyl sulphate (see effects of heating, p. 108). It is not decomposed by a cold solution of sodium carbonate, or by one of sodium hydroxide if it is weak. It is fully decomposed by its equivalent of potassium iodide in solution, but only imperfectly by a solution of sodium chloride, if the latter is not in considerable excess. When a solution of sodium chloride is shaken with excess of undried silver hyponitrite, decomposition ceases when the two sodium salts in the solution are in the proportion of 18 eq.of chloride to 25 eq, of hyponitrite, or, by weight, 4 of chloride to 6 of anhydrous It is readily oxidised by strong nitric acid.PREPARATION BY SODIUM OR POTASSIUM. 107 hvponitrite. Absolute alcohol in large excess effects a, partial separation of the two sodium salts, as already described. Silver hyponitrite in the moist state is not entirely stable, for it decomposes even a t the ordinary temperature, although exceedingly slowly ; light and heat quicken the change, the former modifying it tosome extent. The decomposition is made evident by the salt losing its bright colour, by its answering to the iodide and starch test for a nitrite, and by its yielding up to water more silver salt (not nitrite, but nitrate apparently) than its own very slight solubility would account for.The salt may be washed with boiling water, or even be boiled with water, without any very apparent result, but continuous boiling not only has marked effect in decomposing it, but an action which grows in intensity, even though the water is frequently re- placed. The water is found to contain silver nitrate, whilst the solid salt gives the reaction for nitrite. Masses of moist precipitate retain their colour outside while drying in a thermostat, but become greyish inside. Silver hyponitrite dissolved in a solution of sodium or potassium hyponitrite decomposes on standing, anc? very quickly on boiling, reduced silver being deposited and sodium nitrate formed in solution.Bright diffused light causes enough change in a few hours-bright sunlight in a few minutes-to allow of nitrite being detected. The colour change caused by light has been variously described; as a matter of fact, in the sufficiently pure salt under water, it is such that the bright yellow hyponitrite becomes covered with a somewhat bright brown, flocculent substance, very like silver oxide, which, per- haps, it is; the blackening or greying, which has been observed by others to be caused by light, must have been due to impurities, although time, as just described, brings about a greying of the salt. Silver hyponitrite is least sensitive to light when dry and exposed to dry air. The main change which occurs in the moist salt, slight as it is, is evidently similar to that caused by heat.The salt prepared by the hydroxyamidosulphonate method generally shows an unreal stability, due apparently to presence in it of a trace of sulphite, as will be explained when the properties of a hyponitrous acid solution are treated of j for, in that connection, it has to be taken into con- sideration that, like many other precipitated substances, silver hyponitrite is difficult to obtain of high purity. The very slight atmospheric oxidation of moist silver hyponitrite, described by Haga and me (Trans., 1884,45, p. 78) I now regard as being, not the oxidation of the salt itself, but of nitric oxide produced by the very slowly decomposing salt, which is then retained as nitrate and nitrite in the salt j the result would be the same as if the salt itself were oxidised.108 DIVERS : HYPONITRITES j THEIR PROPERTIES, AND THEIR Efects of Heating Silver Hyponitrite.In my first paper, it is stated that silver hyponitrite is decomposed by a moderate heat into nitric oxide, metallic silver, and a little silver nitrate-in this respect resembling silver nitrite, and that it does not fuse or exhibit any other change except that from a bright yellow to a silver-white colour. That is still a correct statement, so far as it goes, but it is imperfect. In 1887, van der Plaats stated that silver hyponitrite decomposes explosively when heated ; presumably his preparation contained acetate. Thum, who, in 1893, rightly denied its explosive character, observed that, in decomposing by heat, the bright yellow salt becomes dark brown before assuming the white d o u r of silver, while Kirschner found (1898) that the salt became temporarily black.Thum’s observation was due, I think, to the very dense red, almost opaque, hot nitric peroxide which then pours forth, and through which at times the solid mass does look very dark. Kirschner’s observation may be due also to this cause, or to his hypo- nitrite having contained sulphite. However this may be, the salt decomposes with only the change of colour I have described, and in a lump of the precipitate the change can be followed by the change in position of the sharp boundary line between the bright yellow salt and the bright white metal, just as it can be followed in calcium oxalate decomposing by heat ; there is no brown or black intermediate stage.Thum seems to have found no silver nitrate, but observed the production of dense red fumes even when the salt was heated in an atmosphere of carbon dioxide, and at a temperature not much (1) above 100’. From the important observation of the generation of nitric peroxide, he concluded that the decomposition of silver hypo- nitrite by heat is probably into silver, nitrogen, and nitric peroxide. I had, of course, seen, in my early work, the production of red fumes, but had attributed this to the nitric oxide meeting the air, and to the decomposition at a higher temperature of the silver nitrate which had been formed. The further sCudy of the decomposition which I have made has proved t h a t metallic silver, silver nitrate, nitric peroxide, nitric oxide, nitrogen, and possibly a trace of nitrite are always produced.Having assured myself that nitric peroxide, as well as nitric oxide, is evolved by silver hyponitrite when heated, I exposed some to heat in a rapid current of carbon dioxide, in order to sweep away as fast as I could the nitric peroxide that was produced.; for the production of nitric peroxide may sufficiently account for that of silver nitrate secondarily. The nitric peroxide and the metallic silver could give the nitrate (Divers and Shimidzu, Trans., 1885, 47,630), but it seems improbable that these two substances being produced would thenPREPARATION BY SODIUM OR POTABSIUM. 109 immediately interact at the same temperature. There is, however, no reason why the nitric peroxide of the decomposed part of the salt should not act on the undecomposed portion and thus produce nitrate, such interaction readily taking place.My experiment recorded above was instituted to see whether I could not almost prevent the forma- tion of nitrate. The attempt failed, for I found silver nitrate in the residue equivalent to as much as ,+th of the total silver, but this result does not disprove that the nitrate really is formed in the way suggested. The nature and composition of the gaseous products were mcertained by heating the salt in a vacuum. The quantity of salt taken was in each experiment so proportioned to the capacity of the little flask or bulb in which it was heated that the volume of the gases at the common temperature and pressure should be a little less than the capacity of the bulb.The air was removed from the bulb holding the salt by means of the mercury pump, while the bulb was kept in boiling water to ensure the dryness of the salt. When exhausted, the buIb was sealed off, and the silver hyponitrite decomposed by heating the bulb in a bath. Thus heated in the absence of air and moisture, the salt exhibits scarcely any change below 140°, and only slow decomposition between 140" and 160', but above these tem- peratures the change is soon complete. The metallic silver is slightly caked together, presumably by the silver nitrate, and the gases are faintly red between 140' and 150°, and orange-red at 160° and above. On allowing the vessel to cool, the gases become colourless, but regain their colour just as before when the vessel is again heated, and these changes can be repeated any number of times.To examine the contents of the bulb when cold, its point was broken off under water, and the small rise of water into the neck of the bulb marked j then the bulb was transferred to a small trough of strong solution of sodium sulphite in order to absorb the nitric oxide (this vol., p. 82). After an hour or longer, the residual gag was examined and measured by bringing the bulb mouth upwards, testing the gas &s to odour and power to support combustion, and then filling it with water from a burette up to the mark already made, and afterwards to the mouth in order to learn the volumes of the gases when corrected for temperature and pressure.The volumes could be only approxi- mately measured in this way, but quite well enough for the purpose. The metallic silver was weighed, and from its weight and that of the hyponitrite, that of the silver nitrate became known. In one experi- ment, the bulb was at once freely opened to the air, and the gases rapidly blown out ; in this way, the nitric oxide showed its presence by reddening in the air, and both the silver and the silver nitrate were directly determined. VOL. LXXV. I110 DIVERS : HYPONITRITES ; THEIR PROPERTIES, AND THEIR These experiments established the production of nitrogen, as well as that of the other substances, and the non-production OF any appre- ciable quantity of nitrous oxide. The quantitative results were that, when the decomposition is slowly effected, as between 140' and '160', silver hyponitrite yields about 27 per cent.of its nitrogen in the free state, and about 20 per cent. when the decomposition is rapidly accomplished at higher temperatures. The silver nitrate was formed in quantities corresponding with those of the nitrogen, according to the equation 3(AgON), = 4Ag + 2AgN0, + 2N,, but that, of course, proved nothing, since the whole of the nitrate might have been formed by the nitric peroxide during the cooling, as certainly much of it must have been, On the other hand, the limited quantities of ni6rogen generated gives full proof that much nitric oxide is either primarily formed or comes from interaction between hyponitrite and peroxide, besides what undoubtedly comes from the interaction of the nitric peroxide and metallic silver during the cooling.Were none of the nitrogen of the salt to become nitric oxide, the free nitrogen would be half of the total nitrogen, instead of only three- or four- fifteenths as found. From the facts observed, it seems to me to be highly probable that silver hyponitrite decomposes into silver, nitrogen, and nitric peroxide, according to the equation 2(AgON), = 4Ag + Na + 2N02, and that interaction then occurs between the hyponitrite not yet decomposed and some of the nitric peroxide, thus : ( AgON), + 4N0, = 2AgN0, + 4N0, and, theref ore, that the decomposition of silver hyponitrite into silver and nitric oxide does not occur directly. It remains to explain the absorption and regeneration of nitric peroxide by cooling and heating the gases in contact with the solid residue of the decomposed hyponitrite.The interaction of silver and nitric peroxide in the cold, already referred to, explains the disap pearance of the nitric peroxide, half of its nitrogen becoming nitrate and half nitric oxide. The regeneration of nitric peroxide a t such low temperatures as those in the neighbourhood of 150" is explained by experiments of mine recorded in a separate note (this vol., p. 83). The silver nitrate and nitric oxide interact to produce nitric peroxide, andat first nitrite, but ultimately silver itself, AgNO, + NO = Ag + 2N0,. As to the Existence of Silver Nitrito-hpponitrite, Nitrato-hyponitrite, and Nitrato-nitrite. Silver Nitmto-nitrite.-I have made new experiments on the union of silver nitrate with silver nitrite, first examined by me in 1871 (Trans., 24, 85). Silver nitrite, mixed with a little less than its equivalent of silver nitrate, suffers only slight decomposition until itPREPARATION BY SODIUM OR POTASSIUM. 111 melts along with the nitrate at about 1309 The fused salts solidify at about 126O fo a translucent, greenish-yellow, crystalline mass, except in the uppermost part, where it is opaque from the presence of bubbles and metallic silver.This upper part removed, the rest can be fused again without suffering further change, and even be heated nearly to 180' without decomposing. Silver nitrite, heated alone, shows marked change of colour when the temperature has reached 120°, gives red fumes a t about 140', and very freely decomposes below 180° without showing signs of fusing.Silver nitrate does not fuse below 217O (Carnelly). The low melting point of the mixture of the two salts, and the increased stability of the nitrite, are, however, the only facts showing that there is any chemical union, for water separates the two salts. Nocn-sxisternce of Nitrato-hy~onitrite.-5ilver hyponitrite (4 parts) and silver nitrate (5 parts), in intimate mixture, were heated in a bath. No change was observed until 175' was reached, when fusion and the evolution of red fumes occurred. The hyponitrite had then disap- peared, and the fusion may be attributed to the decomposition of the hyponitrite, as usual, into nitric oxide, among other things, and to the interaction of this nitric oxide with some of the nitrate to form the fusible nitrato-nitrite.The attempt was also made to prepare a compound of the two salts in presence of water, there being some grounds to expect success. Calcium hyponitrite, a nearly insoluble salt, was ground up with excess of a very concentrated solution of silver nitrate, and a dense and strongly yellow precipitate obtained, which was washed with water until all the calcium salt had been removed ; the precipitate was still yielding up a little silver nitrate when the washing was stopped. Drained on a tile and dried in a vacuum, it proved to be somewhat sensitive to light and to heat, but, as it contained 76.94 per cent, of silver, and could have been washed more free from silver nitrate, a combination of the two salts stable in water does not exist.All that can be said is that silver hyponitrite requires long washing to remove the last portions of silver nitrate. Nitrito-hyponitrite also non-existent.-In a paper already referred to, I have recorded obtaining a minute quantity of what appeared to be hyponitrite, when partially decomposing silver nitrite by heat, that is, a bright yellow substance insoluble in water and soluble in ammonia. Silver hyponitrite and silver nitrite, heated together, show no change until decomposition and the escape of red fumes occur, and then all hyponitrite has been destroyed. When making known his observation of the interaction of hydroxyl. amine and nitrous acid in 1893, Paal stated that, from a solution of I have failed to get this again.I 2112 DIVERS : HYPONITRLTES ; THEIR PROPERTIES, AND THEIR alkali hyponitrite which also contained nitrite, silver nitrate had pre- cipitated a substance which, although it was like silver hyponitrite, proved to be a silver nitrito-hyponitrite. It gave no silver nitrite, even to hot water, and could be dissolved in cold dilute nitric acid, and he reprecipitated with ammonia without suffering change in composition. It was less stable than the simple hyponitrite when heated, gave the reactions of a nitrite along with those of a hyponitrite, and yielded numbers (not quoted), on analysis for silver, which agreed nearly with that required by the formula Ag,N,O,. Ten years previously, Berthelot and Ogier, probably under similar conditions, got similar re- sults, except that they were led by their analysis to give the formula Ag4N,0, to the substance they had obtained.It is true that, in spite of endeavours to purify it, silver hyponitrite retains with obstinacy enough nitrite to give the iodide and starch reaction for a nitrite, and that it often, through the presence of impurities, gives low results for the silver; but, beyond these admissions, I cannot subscribe to the accounts given by the chemists just named as to the existence of com- pounds of silver hyponitrite with silver nitrite, I have reduced sodium nitrite by sodium amalgam as usual, and dissolved in the solution one-sixth as much more sodium nitrite as had been reduced, thus getting hyponitrite and nitrite together in solution in about equivalent proportions, in accordance with the experience recorded in this paper.The precipitation of silver hyponitrite was then proceeded with, in one experiment, without previous neutralisa- tion of sodium hydroxide, and in another experiment after neutralisa- tion of the alkali. The result was the same in both experiments. There was a bright yellow precipitate, not noticeably different from ordinary hyponitrite, and the mother liquor retained much alkali nitrite or silver nitrite in the respective cases ; the precipitate was repeatedly washed with cold water, but the washing was stopped when very little silver was being extracted. It proved to be somewhat sensitive to light and heat. It was dried in the cold and in a vacuum, spd the silver was then determinod ; this was 76.9 per cent.Nitrite could be easily detected in it, but the compound Ag,N,O, would have only 74 per cent. of silver, and Ag4N40, only 76 per cent. Besides this, by prolonged washing the hyponitrite can be made much purer, These experiments, therefore, afford no evidence of the existence of such a compound as Paal has described. Properties of a Xolution of Hyponitrous Acid. Solutions of hyponitrous acid are always prepared in one way, namely, by decomposing silver hyponitrite with just sufficient dilute hydrochloric acid. Hyponitrous acid has been obtained by HantzschPREPARATION BY SODIUM OR POTASSIUM. 113 and Eaufmann in crystals very deliquescent and very unstable, by using dry ether in place of water in its preparation.The acid in dilute solution reddens litmus not so strongly as nitric acid, but much more than carbonic acid, On drying the reddened litmus paper, it becomes blue again. A solution of the acid becomes neutral to litmus when half the quantity of baryta water or alkali required to form the normal salt has been added (Zorn), and such a solution, by de- composition, soon acquires the property of blueing red litmus paper. When neutral to litmus, the solution is also neutral to phenol- phthalein (Thum). When neutralised with baryta, and very rapidly evaporated under reduced pressure, hyponitrous acid yields an acid salt which is crystalline and extremely unstable (Zorn). It decomposes silver carbonate, if not also lead and other car- bonates; it also decomposes silver nitrate and snlphate.It does not oxidise hydrogen iodide (iodide and starch reagent), and is not oxidised by iodine solution or by the air. It is oxidised by nitrous acid and the stronger oxidising agents. No way of deoxidising or hydrogenising hyponitrous acid is known ; it entirely resists the action of sodium amalgam, and also, according to Thum, that of zinc and sulphuric acid. Ethylic hyponitrite is reduced, apparently, by tin and acetic or hydrochloric acid to alcohol and nitrogen, according to Zorn, but as, also according to him, it slowly decomposes by itself, when moist, into nitrogen, alcohol, and aldehyde, there is sufficient reason to doubt that this reduction by tin and acid is anything more than the hydrogenisation of the aldehyde. Hyponitrous acid slowly decomposes into nitrous oxide and water.A strong solution soon effervesces, gently in the cold, freely when heated, just like a solution of carbon dioxide, and some hyponitrites in presence of only a little water effervesce with an acid. A solu- tion of one or two grams of the acid in a litre of water kept in ice hardly falls noticeably in strength in one hour, but at 25-30' it may lose a sixth of the acid by decomposition in 24 hours; at a lower temperature, Thum observed a loss only half as great in the same time. Alkali hyponitrites in solution also decompose into nitrous oxide and alkali, gradually in the cold and rapidly when heated j alkali hydroxides impede the decomposition, and when highly concentrated stop it altogether, apparently (see p. 98) ; neutraliaa- tion of the alkali even by carbonic acid hastens the decomposition, as a matter of course, but there is no evidence that carbonic acid is able to decompose a hyponitrite, as it has been said to do.Hyponitrous acid solution dissolves silver hyponitrite slightly. The alkali salts of hyponitrous acid dissolve silver hyponitrite some- what more freely, and also decompose silver chloride (see p. 102);114 DIVERS : HYPONITRITES ; THEIR PROPERTIES, AND THEIR they give precipitates with barium and calcium Baits, and with solutions of most metallic salts. Other substances are liable to be present in the solution of hypo- nitrous acid, and this fact has certainly caused the properties of the acid to be wrongly described in some respects. In one point, this is the case in my first paper, in which, however, there was a warning that the crude solution of the acid, which had been examined, might have reacted as it did partly through the presence of other unrecog- nised substances in it.That solution decolorised iodine water, and prevented the action of nitrous acid on an iodide ; this, however, was not due to the hyponitrous acid, but to a very little hydroxyl- amino, the presence of which was unrecognised. Kirschner has again given to hyponitrous acid the property of decolorising iodine water to a slight extent. I n his case, the substance acting on the iodine must have been a trace of sulphur dioxide, for he made his solution of ‘he acid from silver hyponitrite that had been prepared by the hydroxyamidosulphonate method.I can confirm the accuracy of his observation. Even when the silver hyponitrite has been most care- fully precipitated so as to avoid all sensible precipitation of sulphite, and has been dissolved in dilute acid and reprecipitated, it still gives a solution of hyponitrous acid capable of acting on a very little iodine water ; but then no more iodine was taken up although there was hyponitrous acid in the solution. On the other hand, the acid prepared from silver hyponitrite not derived from hydroxyamido- sulphonate does not decolorise iodine at all, as Thum first pointed out. Hyponitrous acid, according to van der Plaats, liberates iodine from potassium iodide; according to Thum and my first paper, it does not, whilst according to Hantzsch and Kaufmann it is only just at first that it does not do so.The last-named chemists, therefore, state that the acid does not itself liberate iodine, but quickly begins to yield nitrous acid which does liberate it. They also found hypo- nitrous acid to yield ammonia, but in a later publication Hantzsch and Sauer state that the ammonia was an impurity in the silver hypo- nitrite from which the acid had been prepared. Even with the simultaneous formation of the ammonia, it is difficult to understand the generation of nitrous acid. These authors, invoking the aid of tautomerism, suppose that the hydrogen leaves oxygen for nitrogen, giving the unknown substance HN:O, which then becomes NH, + N,O,, and these again pass into HNO, + N, + OH2. In place of this series of improbable-I would say, unnatural-changes, I suggest that, if indeed such change occurs at all, it must be into water, nitric oxide, and nitrogen, the nitric oxide then oxidising to nitrous acid.But I am strongly disposed to deny that hyponitrous acid decomposesPREPARATION BY SODIUM OR POTA8SIUM. 115 of itself into anything but what are certainly its main products, nitrous oxide and writer. My reasons are several. First, there ia the unlikelihood that the diazo-radicle, N:N, should resolve itself into mono-nitrogen compounds, such as NO, NH,, NO*OH or (NO),O, in- stead of (N,)O. Secondly, there is the fact that time comes in a~ the condition of the production of nitrous acid, and that a rise in tem- perature does not. A solution of hyponitrous acid of fair purity, if boiled or quickly evaporated gives nothing but nitrous oxide and water ; and only very slowly and to a very small extent does nitrous acid appear in a cold solution of the purest acid.Thirdly, the greater the care taken to reduce and exclude all nitrite in preparing the hyponitrous acid solution, the longer will be the time before any sensible quantity of nitrous acid develops, and the more gradually will the quantity increase. From these facts, the almost necessary inferenceis that the whole of the nitrite has never been entirely removed or excluded in preparing the acid, and that what has been left, although too minute in quantity to affect the iodide teat (which requires 1 in 20 millions, according t o Warington), yet multiplies itself by interaction with the hyponitrous acid, forming nitric oxide, which is further oxidised to nitrous acid by the air dissolved in the solution (HNO), + BHNO, = 2H,O + 4NO-4HN02.This aerial oxi- dation can be demonstrated in such a solution of hyponitrous acid ~EI that which Hantzsch and Kaufmann employed in. their experiments, which gave the blue of the iodide test almost immediately ; it is only necessary to leave one portion of the solution in a deep, narrow vesael, such as a test tube half full, and another portion in a shallow basin for 10 minutes, and then apply the test, when the solution in the basin will be found to liberate more iodine than that in the tube. If, in reducing the sodium nitrite, its concentrated solution is shaken with excess of the amalgam for an hour or two after its main reduction, and the solution is then either diluted, acidified cautiously with dilute sul- phuric acid, and tested, or is precipitated by silver sulphate, away from the light as far as practicable, and the precipitate washed in the dark and converted into the acid and tested, either solution, when mixed with the iodide reagent, will not blue in the least for an hour or more in the dark, and provided the constituents of the reagent are pure enough and properly used." Against the view, which may be advanced, that hyponitrous acid becomes nitrous acid through oxidation by the air, I must point out * My way of applying the test is that followed by Warington (Chem.News, 1885, 61, 39), except that, having potassium iodide of high quality, I used it instead of Trommsdorf's zinc iodide solution. In the dark, a blank test will remain for hours without the least blueing.There is no advantage in ubing aoetic acid in place of pure sulphuric or hydrochloric acid.116 DIVERS : HYPONITRITES ; THEIR PROPERTIES, AND THEIR that it is difficult to admit that if the nitrous acid has such origin, it ahould form so very slowly. A way occurred to me which must be used for deciding this point, so far as the exclusion of nitrous acid goes, but it has, in my opinion, not served to do so. If, in preparing sodium oximidosulphonate, the sulphur dioxide is used in excess, every trace of nitrite ought, presumably, to be sulphonated; if, then, the oximido- aulphonate is fully hydrolysed into hydroxyamidosulphonate, as it presumably can be, then, when the latter is converted into hyponitrite and aulphite by potassium hydroxide, there will be no oximido- sulphonate present to simultaneously revert to nitrite and aulphite.Therefore, the silver hyponitrite from such a source should be obtain- able absolutely free from nitrite, and should furnish a solution of hyponitrous acid also free from nitrous acid. Such silver hyponitrite I endeavoured to prepare, and then tested the acid got from it. The issue was, however, complicated by the fact that such an acid is not quite free from sulphurous acid, as was shown by its decolorising a minute quantity of iodine solution. That it also did not act for a time on the iodide and starch reagent was due in part to this cause. The solution did, however, give a blue coloration with the reagent sooner than a corresponding blank test.But this was no proof that hypo- nitrous acid passes spontaneously into nitrous acid, for, first, there is the possibility of nitrous acid having been present through incomplete sulphonation and hydrolysis in preparing the hyponitrite j this nitrous acid would, indeed, have been converted into nitric oxide by the sulphurous acid retained by the silver salt, but when all this was gone, the nitric oxide would have become nitrous acid again by oxidation. Secondly, it is almost certain that the oxidation of the sulphurous acid by the air would have induced oxidation of some hypo- nitrous acid, in accordance with the observations of Mohr, M. Traube, van’t Hoff and Jorissen, Engler and Wild, Bach, &c.Qztantitatiwe E s t i m t h of B~pnitrous Acid.-Hyponitrous acid can be estimated accurately, both gravimetrically (Zorn) and volumetrically (Thum). Solutions of the free acid, or of its alkali salts in water, or of its other salts in very dilute and cold nitric acid are mixed with excess of silver nitrate, and then the free acid is just neutralised with sodium carbonate or with ammonia. The washed precipitate is either dried and weighed as such, or weighed as metal or as chloride. Volumetrically, the acid can be estimated in solution in the free state and unmixed with any other acid, by adding excess of solution of potassium permanganate, leaving it for a quarter of an hour, then adding sulphuric acid, allowing it to remain for another quarter of an hour, warming to 30°, adding a known quantity of oxalic acid sufficient to decolorise, and, finally, titrating back with permanganate.The hyponitrous acid is thus oxidised to nitric acid. The oxalic acid shouldPBEPARATION BY SODIUM OR POTASSIUBiZ. 117 be decinormal, and the solution of permanganate be volumetricallg equivalent to it. Ferrous sulphate is unsuitable for use in place of oxalic acid. Hantzsch and Sauer failed to get good results, because they deviated from Thum’s direo- tions by acidifying the permanganate before adding it to the hypo- nitrite. Kirschner also was unsuccessful with this process, but his failure is also explained by his deviation from Thum’s directions. He added nearly insoluble salts, such as the barium, strontium, or silver hyponitrite, to the potassium permanganate, so that the base of the salt was present, and the hyponitrous acid locally in excess of the per- manganate ; he then added the sulphuric acid, apparently immediately, and used ferrous sulphate for titrating back, Taking 5 C.C.of normal hydrochloric acid, largely diluting it, adding ice and a cream of precipitated silver hyponitrite so as to exactly use up all the hydrochloric acid, making up to 100 c.c., and decanting from the bulk of the silver chloride, I obtained a solution which, although somewhat turbid from silver chloride, gave, in successive portions of 20 c.c., all tested within an hour, quantitative results corresponding well with 0.155 gram hyponitrous acid in 100 c.c., that is, the quantity equivalent to the hydrochloric acid taken ; next day, the remainder of the solution (in very hot weather) showed the presence of 0.131 gram of the acid in 100 C.C.Thum found that, in alkaline solution, alkali hyponitrite is quanti- tatively converted into nitrite by permanganate. Although I have not examined this point myself, I find that nitrite is thus formed, and thak nitric acid is formed in Thum’s acid permanganate method. Kirschner doubts that either is produced, The process is an excellent one. Barium, Strontium, and Calcium Hyponitritee. Barium hyponitrite has been obtained by Zorn, Maquenne, and Kirschner, and is most simply prepared by adding barium chloride to a concentrated solution of sodium hyponitrite and stirring well. It is crystalline, almost insoluble, and an unstable and exceedingly efflorescent salt, but Kirschner has succeeded in determining its water of crystallisation satisfactorily.I t s formula is BaN,O, + 4H,O. A crystalline acid salt exists (Zorn). Strontium hyponitrite, SrN202 + 5H20, Maquenne, Kirschner. Calcium hyponitrite, CaN,O, + 4H,O, Maquenne, Kirschner. This is crystalline, very sparingly soluble, stable, not losing its water even over sulphuric acid. I find that it can be easily precipitated from a fairly concentrated solution of sodium hyponitrite, and can thus be prepared more easily than in the ways followed by Maquenne and by118 DIVERS : HYPONITRITES ; THEIR PROPERTIES, AND THEIR Kirschner, using the silver salt. On account of its stability, it is a good hyponitrite to keep in stock. It is sufficiently soluble for its solution to serve to show the reactions of a hyponitrite with silver, mercuric, mercurouB, copper, lead, and other salts.Calcium, Xtrontium, am? Barium Hypnnitrosoacetate8. Some remarkable salts have been described by Maquenne, having the composition expressed by the formuls CaN2O2,Ca(C2H3O2)2,(C2H402)2 + 4820 j SrN202,Sr(C2H30,)2,(C2H402)2 + 3H20 ; BaN202&3( C2H,O,)2,( C2H402)2 + 3H20. 1: have prepared and partly analysed the calcium salt, following Maquenne’s process, which i s to dissolve calcium hyponitrite in 30 per cent. acetic acid until the new salt begins to crystallise out. I kept the acid at about 50’ while dissolving in it nearly as much of the calcium salt as it would take up, the salt being deposited on cooling. It is remarkable that this can be done without causing more than very slight effervescence.The salt crystallises in short prisms, stable for many days, very soluble in water, in which it giyes, with silver nitrate, the yellow hyponitrite. In spite of its acid composition, it is neutral or even slightly alkaline to litmus. To account for its existence and neutral reaction, I suggest for it the constitution expressed by the formula This represents it as being normal calcium acetate with one-fourth of its oxylic oxygen replaced by the hyponitrite radicle, or as a double anhydride of calcium acetate and hyponitrite. It is thus made out to have a constitution analogous to that of a (hypo)nitrososulphate, as determined by Haga and me (Trans., 1895, 67, 1098), Simple hyponitrosoacetic acid, C2H,0*0 *N2*-OH, would be isomeric with acetonitrosohydroxamic acid,aC2H,0 *N(NO)*OH, which Hantzsch and Sauer have been trying to prepare.The hyponitrosoacetates are much more stable in water than the (hypo)nitrososulphates, a difference perhaps connected with the fact that sulphuric acid ionises largely, while both acetic acid and hyponitrous acid ionise very little. Heated with water, the hyponitrosoacetates decompose like the (hypo)- nitrososulphates do in cold water.PBEPARATION BY SODIUM OR POTASSIUM. I19 Mercuric Hyponitdte. Mercuric hyponitrite is a particularly interesting salt and has not as yet been described. R&y has, indeed, described some compounds which he regards as being basic mercuric hyponitrites, but obtained under conditions suggesting the probability that they are something quite different; moreover, he has not as yet proved them to be corn- pounds of this class.One of them he obtained by the interaction of solutions of mercuric nitrite and potassium cyanide, a very interesting and remarkable result, should it be confirmed. I n any case, his pre- cipitates appear to have nothing at all in common with the normal salt here described, and cannot be obtained in the ordinary way. The existence of this salt was indicated by me in 1871. Mercuric hyponitrite is obtained from sodium hyponitrite and mercuric nitrate by precipitation ; the solution of sodium hyponitrite and hydroxide, obtained by reducing sodium nitrite, is largely diluted and, while ice cold, nearly or quite neutralised with dilute nitric acid j it is then (mercurous nitrate serving as indicator, see p.97) poured into a mercuric nitrate solution, which must not be in excess and should contain as little free acid as possible. The slightly turbid mother liquor is quickly decanted from the precipitate formed, and after being neutralised with sodium carbonate is mixed with more mercuric nitrate, the whole poured back on to the main precipitate, stirred up with it, and soon again decanted. The precipitate should be washed quickly by decantation, since it is liable to be quickly destroyed by the slightly acid mother liquor. It is a flocculent, cream-coloured precipitate, easily washed on the filter, and dries up to a light buff-coloured powder, this colour being due, probably, to incipient change into the mercurous salt.Dried quickly in the air, on a porous tile, it is hydrated, having the formula (HgN20,),+3H20, but if dried in the desiccator it is anhydrous. Being a little sensitive to light, it should be dried in the dark. It dissolves in hydrochloric acid and in sodium chloride solution, but it is unstable, changing into the mercurous salt, and, therefore, is liable to show turbidity in the chloride solutions. The mercury, precipitated as sulphide from a solution of the anhydrous salt in hydrochloric acid, was found to be 76.71 per cent., the formula HgN,02 requiring 76-92 per cent. Its solubility in excess of sodium chloride does not prevent mercuric chloride giving a precipitate with sodium hyponitrite. The solubility of the salt in sodium chloride is a qualitative proof of its normal composition.The alkalinity of the solution is caused by the sodium hyponitrite generated in it. Potassium hydroxide at once decomposes mercuric hyponitrite into oxide, without showing any120 DIVERS : HYPONITRITES ; THEIR PROPERTIES, AND THEIR tendency to produce basic salts. In very dilute alkali, the precipitate is slightly soluble. What makes this salt so remarkable, not only as a hyponitrite, but as a mercuric salt, is the nature of the decomposition which it under- goes. Slowly or quickly, it decomposes into mercurous hyponitrite and nitric oxide-some of the latter, oxidised by the air, converting some hyponitrite into nitrate. No other mercuric salt decomposes into mercurous salt, although many cupric salts change into cuprous salts.Ferric oxalate shows just the same kind of change, namely, into ferrous oxalate and carbon dioxide. The most closely related change, however, is that of sodium (hypo)nitrososulphate into sulphite and nitric oxide, the very phenomena being similar, so that, except for the colour change, I might describe my experience with this salt in the words of the paper by Haga and me on sodium (hypo)nitrososulphate (Trans. 1895, 67, 1095). Thus, having on one occasion left some grams of salt all night in the desiccator in the form of a pressed cake, j u s t as removed from the filter, I noticed, when weighing it between watch-glasses, that it was losing weight on the balance-pan. When the glasses were opened, a strong nitrous odour was observed, the cake soon became grey, white on the surface, and, being left loosely covered, grew very hot and gave out torrents of nitric oxide ; it then cooled, and underwent no further change, even in the course of months. The whitish colour of the cake was found not to penetrate beyond a milli- metre into it, the inside being of a uniform yolk-yellow, and consisting of mercurous hyponitrite.The surface-coating proved to be mercurous nitrate, largely soluble in water, and had evidently been produced with the assistance of the oxygen of the air, Not always, however, does the change occur in this striking and rapid way;its progress being gradual and almost imperceptible until complete. Mercuric hypouitrite is decomposed by heat largely into mercuric oxide and nitrous oxide, but partly into metal and nitric oxide, Other Hyponitriles.Bercuq*oua Hyponitri&---This salt has been prepared and analysed by Thum (Inaug. Dim., Prag. 1893), who used sodium hyponitrite and mercurous nitrate in obtaining it. The possibility of getting it by the spontaneous decomposition of mercuric hyponitrite has just been described. RGy has also evidently obtained it in a very impure state, not further examined. It can be prepared in the same way as mercuric hyponitrite, using mercurous nitrate in place of mercuric nitrate. It is of a full yellow colour, is blackened by even the weakest solution of alkali, and is soluble in dilute nitric acid, fromPREPARATION BY SODIUM OR POTASSIUM. 121 which it can be precipitated by sodium carbonate. IB is a stable salt, but is blackened by bright light.Its decomposition by heat resembles that of the mercuric salt, except that much more metal is produced, as is natural. Composition, (HgON),. Cup& Hydroxide Hyponitrite.-This salt was described by me in 1871, and was also obtained by Kolotow in 1890, but was first fully examined by Thum, and bas again been examined by Kirscbner; being a basic salt, its precipitation from normal sodium hyponitrite leaves an acid mother liquor, on neutralising which much more of the salt precipitates. It is of a bright pea-green colour, and very stable. It may be boiled with water without losing its colour, but is decom- posed by sodium hydroxide and is soluble in dilute acids and ammonia. Thum has shown its composition to be Cu(0H)NO. It gives water, cupric and cuprous oxides, and nitrous and nitric oxides when heated.By adding copper sulphate in excess to hydroxylamine sulphate and then a very little ammonia, it can also be precipitated in small quantity. I have tried to get it by precipitating sodium hyponitrite by copper sulphate in presence of free hydroxylamine, but, first, cuprous oxide precipitated and then, by aerial oxidation, the basic cupric hyponitrite, which in composition is equivalent to that of cuprous hyponitrite combined with hydroxyl (see above). Lead Hyponitrite.-This salt was also briefly described by me and has been prepared and analysed by Thum; Kirschner has again pre- pared and analysed it, but not in a pure state. The precipitate is cream-yellow and flocculent, but soon becomes very dense and sulphur- yellow ; its first state is probably that of a hydrate; Kirschner has mistaken it for a basic salt.As Thum has pointed out, the yellow precipitate, when formed in a weak acid solution, is crystalline and just like ammonium phosphomolybdate. It is soluble in dilute nitric acid, and is decomposed by sodium hydroxide, but not by sodium carbonate in the cold. Ammonium Hydrogen Hyponitrite.-This salt has been described by Hantzsch and Kaufmann, who found it to be exceedingly unstable, as was to be expected. That the normal salt could not exist had already been pointed out by me, and by Zorn ; D. H. Jackson believes, how- ever, that he did obtain it in small quantity in prismatic crystals, but this is exceedingly improbable.Ethylic Hyponitrite.-This alkylic salt was prepared by Zorn, and its vapour-density taken by him. It is very explosive, and is not saponi- fied by potassium hydroxide. In the moist state, it slowly decomposes into nitrogen, alcohol, and aldehyde. Benzylic Hyponitrite.-Hantzsch and Kaufmann have prepared Cupws hyponitrite cannot be formed. The yellow salt is PbN,O,.122 DIVERS : HYPONlTRITES ; THEIR PROPERTIES, AND THEIR benzylic hyponitrite and determined its molecular magnitude cryoscopi- cally. It undergoes similar decomposition to the ethylic salt. Constitution of the Hyponitrites. Molecular Magnitude.-In my first paper, nothing could be said as to the molecular magnitude and constitution of the hyponitrites. In 1878, Zorn fully determined their molecular magnitude, finding it to be that containing N,, first, by establishing the existence of an acid barium salt and illustrating the similarity of hyponitrites to carbonates (a point which had already been noticed by me), and then by preparing ethylic hyponitrite and taking its vapour-density a t reduced pressure (Hofmann’s method).It would, therefore, be unjust to the memory of this chemist to admit Hantzsch’s claim (AnmaZen, 1898, 299,68) to have finally established this point by determining cryoscopi- cally, in conjunction with Kaufmann, the molecular magnitude of hyponitrous acid in water and of benzylic hyponitrite in acetic acid, valuable as these determinations are. The possibility of determining the molecule of the acid in its solution in water rests upon the fact, slso ascertained by these chemists, that the acid only slightly ionises even in very dilute solution.Maquenne, by a somewhat uncertain form of the cryoscopic method, has also shown that, in calcium hypo- nitrosoacetate, the hyponitrite radicle cannot be less than N202. The strong alkalinity of the alkali salts, and the want of action on litmus of their partially-neutralised solution, first pointed out by me, and the solubility, although only slight, of silver hyponitrite in hypo- nitrous acid solution (Thum) and in alkali hyponitrite solution, are also facts in accordance with the dihydric composition of the acid. Other chemical evidence of the diazo-grouping in hyponitrites is afforded by the fact of the difficulty, if not impossibility, OF deoxidising or hydrogenising them (see p.113). The derivation of hyponitrites from the interaction of hydroxylamine and nitrous acid would only afford evidence of the diazo-magnitude of the molecule, if the hypo- nitrite produced were much larger in quantity than what can be obtained from hydroxylamine by other oxidising agents, or from nitrous acid by other reducing agents, My colleague, Assistant Professor Ikeda, has kindly made some determinations of the molecular magnitude of sodium hyponitrite by Loewenherz’s method (Zeit. physikal. Cliem, 1896,18, 70), in which the lowering of the freezing point of melted hydrated sodium sulphate by another sodium salt is observed j Loewenherz found that sodium salts behave towards the water of hydrated sodium sulphate almost as non- electrolytes.Prof. Ikeda, in his experiments, employed sodium thiosulphate ia place of sulphate, but only because he had been workingPREPARATION BY SODIUM OR POTASSIUM. 128 with that d t , and had had large experience with it. Unfortunately, the anhydrous sodium hyponitrite I could furnish at the time was contaminated with 4 or 5 per cent. of carbonate (same mol. wt.), SO that the determination of the molecular magnitude cam only be regarded as approximate. But it is amply sufficient to decide between NaON = 53, and (NaON), = 106, if that were any longer necessary, after Zorn's decisive researches, supplemented by those of Hantasch and Kaufmann. Prof. Ikeda has given me the following details. M. p. of Na,S,O, + 5H,O = 48.4' (Tilden found 48.5') ; H. of fusion = 42.8 Cal.(Ikeda) ; Wt. of thiosulphate used = 40.9 grams ; Wt. of sodium hyponitrite used = g grams ; Dp. of solidifying pt. = ATo ; Mol. wt. of hyponitrite = m. 9 AT". m. 0.152 0.115 156 0.467 0.509 108 1.066 1.260 100 1,238 1.507 97 In cases where no decomposition of the salt occurs, the method gives results too high, as, for example, 78.6 instead of 69, for sodium nitrite ; but taking into consideration the partial hydrolysis of the hyponitrite that certainly takes place, its molecular weight is clearly indicated as 106 rather than 53. Constitzctioln.-The constitution (HNO), seems to be excluded by considerations of valency, but the positive evidence for (HON), is ample. Zorn's observation that ethylic hyponitrite decomposes into nitrogen and alcohol (and aldehyde), even in presence of reducing agents, establishes the diazo-grouping in hyponitrites.Ammonia or other amine is never produced in the decomposition of any hypo- nitrite. Then the conversion of a hydroxyamidosulphonate into hypo- nitrite affords a beautiful demonstration of the oxylic constitution of the hyponitrites, 2HO*NH*S03Na -/- 4NaOH = Na0N:NONa + 2NaS0,Nn + 4X,O. Hantzsch and Sauer have also given an equally convincing proof of the same point, by introducing nitrosyl into dimethylhydroxycarb- amide and decomposing the product by alkali (see below). The facts that cuprous hyponitrite cannot exist, and, on the other hand, that the mercurous hyponitrite, and not the mercuric salt, is stable, point also to the metals being united to the oxygen, and not to the nitrogen.124 DIVERS : HYPONITBITES ; THEIR PROPERTIEG, ETC.Hantzsch and Sauer, in their desire to prove that nitramine is not HJY-NO,, but a stereoisomeride of hyponitrous acid, would have it that their interesting formation of hyponitrous acid from dimethyl- hydroxynitrosocarbamide is analogous to that of nitramine from nitrosourethane, EtO*CO(N,O,H) + HOH = H(N202H) + EtO*COOH ; NMe,* UO(N,O,H) + HOH = H(N,O,H) + NMe,. COOH (decomposing). However, by displaying what (N,O,H) conceals, namely, the difference between the nitramine and the isonitramine, Thiele. Hantzsch. EtO*CO *NH*NO,, or EtO*CO*N-N* OH + H,O = NH,*NO,, or HN-N* OH + &c. \O’ ‘0’ NMe,*CO*N(OH)NO + H20 = N(0H):NOH + &c., it becomes evident that the hydrogen of the water (or metal of the alkali) goes, in the case of the nitramine, to the amidic nitrogen united to the carbonyl, whilst, in the case of the isonitramine, it goes to the nitroxy- or nitroso-nitrogen not united to the carbonyl, even if Hantzsch and Sauer’s free resort to tautomery could be justified. Surely, this difference is too great to allow of nitramine being t,reated as a probable or actual stereoisomeride of hyponitrous acid. Hantzsch’s formula, KO *N-N- SO,K, for potassium (hypo)nitrososulphate has been shown by Haga and me to have nothing favouring its preference t o that of KO*N:N*O*SO,K, which has so much to be said for it. A ~ h g y of Hyponitrites to Carbonates-of N, to GO.-In hardly forming salts with the feebler metal radicles, such as aluminium and ferricum ; in decomposing readily into anhydride and water ; and in having its soluble normal salts with very alkaline reaction, hypo- nitrous acid resembles carbonic acid, as was indicated in my first paper. Zorn, also, in one of his papers, dwells on the analogy of the one acid to the other, pointing out that the salts have the same molecular magnitude, since N, and CO are both 28. As is well known, the physical properties of nitrogen and carbon monoxides are throughout almost identical. The radicles, carbonyl and dinitrogen, also are both bivalent, and occur combined with oxylic, imidic, and alkjl radicles. Thus, CO(ONa), and COONa(0H) find their analogues in N,(ONa), and N,ONa(OH). Just as ferric oxalate, Fe2(C20202)S, becomes Fe2(C,0,0,), + ZCOO, so Hg,(N2O2), becomes Hg,(N,O,) + 2N0. COO corresponds with N20 ; also C0:NAg to N2:NAg. Lastly, ketonic compounds are perhaps represented by azo-compounds. \O’KIPPING: DEBLVATIVES OF CAMPHORIC ACID. PART 111, 125 Bib Ziograph y . H. Davy, Researches, 1800, 254 ; Hess, Ann. Phys. Chem., 1828,12, 257 ; Pklouze, Ann. Chim. Phys., 1835, [ii] 60,151 ; Schoenbien, Lp. Chem., 1861, 84, 202; De Wilde, Bull. Ac. BeZg., 1863, [ii], 15, 560, and Ann,, 1864, Suppt?., 3, 175 ; Fremy, Compt. rend., 1870,70,66 and 1208 ; Maumenk, Compt. rend., 1870, 70, 149 ; J. Ch. Xoc., 1872, 25, 7 7 2 ; Ch. News, 1872, 25, 153 and 285 ; Thiorie gbnGrrccle de I’actim chimique (Paris : Dunod), 1880,- 286 ; Divers, Proc. Roy. Xoc., 1871, 18, 425 and, in part, Ch. New$, 23, 206; Ber., 1866, 29, 2324; Ann., 1897, 295, 366 ; Divers and Haga, J, Ch, Xoc., 1884, 45, 78 ; 1885, 47, 203 and 361; Proc. Ch. Xoc., 1887, 3, 119; J. Ch. Xoc., 1889,55, 760 ; 1896,69, 1610 ; Zorn, Ber., 1877,10,1306 ; 1878,11,1630 and 2217; 1879, 12, 1509; 1882,15, 1007 and 1258; van der Plaats, Ber,, 1877, 10, 1507 ; Menke, J. Ch. Xoc., 1878, 33, 401 ; Berthelot and Ogier, Compt. rend., 1883,96, 30 and 84 ; Berthelot, Compt. rend., 1889, 108, 1286; Dunstan and Dymond, J. Ch. Xoc., 1887, 51, 646 ; Dunstan, Proc. Ch. Xoc., 1887, 3, 121 ; Maquenne, Compt. rend., 1889, 108, 1303; Kolotow, J. ph. Ru~s., 1890, 23, 3; Abstr. in Chern. Centr., 1891, i, 1859, and Bull. Xoc. Chim., 1891, [iii], 6, 924; Thum, Inaug. Diss., prccg., 1893 and, in part, Monatsh., 1893, 14, 294; w. Wislicenus, Ber., 1893, 28, 771 ; Paal, Ber., 1893, 26, 1026; D. H. Jackson, Proc. Ch. Xoc., 1893, 9, 210 ; Tanatar, J. Izecss. Ch. Xoc., 1893, ti], 25, 342; Ber., Ref., 763; Ber., 1894, 27, 187; 1896, 20, 1039 ; Hantzsch, Ber., 1896,29,1394 ; Hantzsch and Kaufmann, Ann., 1896, a92, 317; Hantzsch and Sauer, Ber., 1898, 299, 67; Piloty, Ber., 1896, 29, 1559; RAY, J. Ch. Xoc., 1897, 71, 347, 1097, and 1105; Kirschner, Zsit. anorg. Chem., 1898, 16, 424.

ISSN:0368-1645    

DOI:10.1039/CT8997500095

出版商:RSC    

年代:1899

数据来源: RSC

摘要:

KIPPING: DEBLVATIVES OF CAMPHORIC ACID. PART 111, 125 XVI.-Derivatives of Canz-phoric Acid. Part 111. By FREDERIC STANLEY KIPPINGI, Ph.D., D.Sc,, F.R.8. THE h t of these papers on derivatives of camphoric acid (Trans., 1896, 89, 913) contained an account of a number of optically active acids and other compounds which had been obtained from s-bromo- camphoric acid, in the coilrm of attempts to open the closed chain contained in this simple substitution product of camphoric acid a t a different point from that at which it is broken in the oxidation of camphoric acid, the parent substance, to camphoronic acid. The principal acids, which have already been described, were obtained in the following manner. .n-Bromocamphoric acid was treated with an alkali and thus converted into (a) trans-acamphanic acid, VOL.LXXV. K126 KIPPING: DEBIVATIVES OF CAMPHORIC ACID. PART 111. C10H1,O4, a monocarboxylic acid containing a lactone ring, and ( b ) rr-hydroxycamphoric acid, C10Hl6O5 j these two compounds mere oxidised by nitric acid to one and the aame traw-rr-camphotricarboxylic acid, from which the cis-isomeride was also obtained. The further oxidation of trans-rr-camphotricarboxy~ic acid being attended with considerable difficulty, owing to the great stability of the compound, it was converted into its monobromo-substitution pro- duct and the latter was then decomposed with water ; in this way, two isomeric lactones of the composition C10H1206, derived from a hydroxycamphotricarboxylic acid, C10H1407, were obtained, but these derivatives, like the parent substlance, were found to be very stable, and could not be made to yield satisfactory oxidation products.Having failed t o obtain any easily oxidisable derivative of cam- phoric acid by these means, attempts were next made to oxidise cis-- camphanic acid, C10H1404, an interesting compound obtained by the distillation of its isomeride trans-rr-camphanic acid ; these experiments were successful in a measure, inasmuch as a crystalline hydroxy-cis-rr- camphanic acid was thus obtained, but this compound, like the others just mentioned, effectually resisted further oxidation. It will be seen from this brief statement that the main object of this investigation had been defeated by the stability of these different substitution products of camphoric acid, all OF which still contained the closed chain of the parent substance; moreover, the difficulty oE obtaining material sufficient for oxidation experiments on the large scale rendered it almost impossible to proceed further on these lines, It was necessary, therefore, to try and attack the r-brornocamphoric acid in a somewhat different manner, namely, to convert it, if possible, into a dibromo-compound, and then to substitute hydroxyl for one, or both, of the bromine atoms, and thus obtain in a more direct manner a substitution product which might be oxidisable.The results of these experiments are described in this paper. When r-bromocamphoric acid is brominated, it is converted, in almost theoretical quantities, into a substance of the composition CI0Hl2Br2O3, which, for reasons given later, is named r w *-dibrornocam- phoric anhydride ; this substance crystallises in magnificent rhombic plates, and on hydrolysis with concentrated nitric acid it is trans- formed into aw-dibromocsmphoric acid, C,oH1,Br,O,, a substance which in many respects is very similar to r-bromocamphoric acid and other halogen derivatives of this compound which have been described (compare Lapworth and Kipping, Trans., 1897,71, 15).mu-Dibromocamphoric acid is decomposed when it is heated alone or with water, yielding hydrogen bromide and an acid of the composition * The letter w has been previously used to denote a certain position in the molecule of camphoric acid (compare Trans., 1896, 69, 61, and 916).KIPPING: DERIVATIVES OF CAMPHORIC ACID.PART 111. 127 C1,HI,BrO,, which, from its method of formation, must be regarded as a lactonic monocarboxylic acid ; for this and other reasons, this compound is named a-bromo-w-cam@ianic acid. It crystallises in orthorhombic prisms, and both its amaide, C,H,,BrO,* CO *NH,, and methylic salt, C,H,,BrO,*COOMe, are well-defined compounds. When ?r-bromo-w-camphanic acid is treated with alkalis, it yields a crystalline product which is identical with hydroxy-cis-a-camphanic acid, the oxidation product of cis-a-camphanic acid ; this hydroxy-acid is also formed by the action of excess of alkali on rrw-dibromocam- phoric anhydride. When, on the other hand, ?r-bromo-w-camphanic acid is boiled with nitric acid and silver nitrate, it is converted intoa compound of the composition C1,H,,O,, which is identical with one of the iaomeric lactones of hydroxycampho tricarboxylic acid. These transformations, the chemical properties of the various com- pounds, and the relations existing between these and other substitu- tion products of camphoric acid, can only be elucidated by making use of some structural formula for camphoric acid, and in previous papers Bredt’s formula was employed because it accounted for all the facts under discussion in a satisfactory manner, and a t the same time seemed to have more evidence in its favour than any other of the many formulte which had then been suggested.The recent publica- tion of an important paper by W. H. Perkin, junr. (Trans., 1898, 73, 796), in which a new formula for camphoric acid is propounded, has certainly necessitated a modification of this last statement ; never- theless, the difference between Bredt’s and Perkin’s formulae is OF such a kind as to require little, if any, alteration in the views which have been advanced in explaining the relationship of these r-derivatives.On inspection, it will be seen that these two formuls, which are given below, differ merely in this, namely, that one of the >CH, groups in Bredt’s is transferred, in Perkin’s formula, to a - position between the >CMe, and >CH*COOH groups. Bredt. Perkin. This change does not effect any of the author’s previous arguments, which wwe mainly based on stereochemical considerations, and, ill fact, only makes this difference, that the n-camphanic acids, according to Perkin’s formula, may, but do not necessarily, contain a 6- instead of a y-lactone ring, K 2128 KIPPING: DERIVATIVES OF CAMPHORIC ACID.PART 111. Making use, then, of Perkin's formula, and representing n-bromo- camphoric acid by I (below), the substitution of bromine for hydrogen would afford a dibromocamphoric acid which must be represented by formula 11, because in the formation of this substance the bromine doubtless displaces the same tertiary hydrogen atom as that which is expelled in the formation of w-bromocamphoric anhydride from ordinary camphoric acid. I. s-Bromocamphoric acid. 11. ?rw-Dibromocamphoric acid. n-Bromo-w-camphanic acid, which is formed from the dibromo-acid with the greatest readiness, just as w-camphanic acid is very easily produced from w-bromocamphoric acid, might be represented by one of several isomeric formulae, of which, however, it is unnecessary t o give examples, as it is possible t o select the most probable one from a con- aideretion of the following facts and arguments.I n the first place, there are strong grounds for supposing that the ?r-bromine atom, namely, that which is a constituent of the -CH,Br group, is still present in this bromocamphanic acid, because it is known that the wbrornine atom in w-bromocamphoric acid is very easily eliminated as hydrogen bromide by the action of boiling water, whereasw-bromo- camphoric acid is comparatively stable under these conditions ; in the second place, the bromocamphanic acid in question offers considerable resistance t o the attack of oxidising agents, whereas had it been formed by the elimination of the *-bromine atom, it should resemble trans-r-camphanic acid in behaviour and be easily oxidisable to a bromo-tricar boxylic acid.A comparatively simple way of settling this question as to which of the two halogen atoms is eliminated from the dibromo-acid offered itself, namely, to prepare a rr-bromo-w-chlorocamphoric anhydride by chlorinating the .Ir-hromo-acid, and then t o convert this substance into the substituted camphanic acid by treatment with boiling water. On making these experiments, it was found that the n-brorno-w-chloro- camphoric anhydride, CloH,,BrC1O, was readily acted on by boiling water with formation of hydrogen chloride and a bromocamphanic acid identical with that obtained from the dibromo-anhydride..It follows, therefore, that the bromo-acid in question is a ?r-bromo-w- camphanic acid, and its constitution may be expressed by one of the following stereoisomeric formulze.KIPPING : DERIVATIVES OF AH, c H,--- C%o---, CAMPHORIC ACID. PART 111. 129 C 1 I I 111. 1- Bromo-cis-w-camphanic acid. IV. 1.Bromo-trans-w-camphanic aaid. Now it seems probable that the first of these two formula repre. sents the configuration of the acid better than does the second, in spite of the fact that this view necessitates the assumption that intramole- cular change occurs in the formation of the acid from Ty-dibromo- camphoric anhydride ; when the properties of ordinary w-camphania acid are considered, it must be admitted that this compound is probably a cis-lactonic acid, because the hydroxy-acid, of which it forms salts on treatment with alkalis, is nct known in the free state, but immedi- ately passes into its lactone ; w-camphanic acid, therefore, is doubtless stereochemically analogous t o cis-n-camphanic acid, whereas the trans- w-camphanic acid, corresponding with the unstable trans-~-camphanic acid, has not yet been prepared.IC is probable, then, that when w-bromooamphoric anhydride i s converted into w-camphanic acid, the carboxyl group changes its position stereochemically, just as it is known to do to a considerable extent in the reduction of w-bromocamphorio anhydride, a reaction which affords a mixture of cis- and trang-, or d- and d-iso-camphorio acids (Aschan, Acta Xoc. Jcient. fsnn., 21, [v], p.195). The conclusion thus arrived at, namely, that r-bromooamphanic acid has the configuration represented by formula 111, is in accord- ance with the behaviour of this substance, and also accounts for its conversion into hydroxy-cis-7-camphanic acid j when treated with potash, it may be supposed that it first gives a salt of w-hydroxy-r- bromocamphoric acid, the w-lactone ring undergoing hydrolysis, and that then potadsium bromide is eliminated with formation of a different lactone ring, namely, that which is acid. V. a-Bromo-cis-w-camphanic acid. VI. contained in cis-wcamphanic w-Hydroxy-cis-1-camphanic acid. The last formula (VI) indicates the possible existence of a dilactone, which would be derived from hydroxy-cis-r-camphanic acid by the elimination of one molecule of water from the remaining -OH and130 KIPPING: DERIVATIVES OF CAMPHORIC ACID.PART 111. 4OOH groups ; although the isolation of such a substance has not yet been accomplished, indications of its formation have been observed, and the neutral crystalline compound obtained by bromina- ting trans-n-camphanic acid (Trans, 1896, 69, 934), or the neutral oily product formed in the decomposition of m-dibromocamphoric anhydride (see later), may possibly be a compound of this kind ; it is by no means improbable, however, that the existence of one lactone ring may, owing to stereochemical causes, hinder the formation of a second one, and thus render it difficult to obtain such a dilactone by ordinary methods. The further oxidation of the compounds obtained from dibromo- camphoric anhydride has not yet been accomplished with satisfactory results in a single case; to give an instance of the difficulty of oxidising some of these products, it may be mentioned that a small quantity of the lactone of w-hydroxycamphotricarboxylic acid may be heated a t 100' with a mixture of concentrated nitric and hydro- chloric acids, or with a mixture of concentrated nitric and sulphuric acids, and after several hours treatment, the lactone is deposited unchanged on keeping the solution a t ordinary temperatures.Most of the compounds described in this paper are readily obtain- able in well-defined crystals, and the author has again to express his thanks to Mr. W. J. Pope for a number of interesting reports on the crystallographic characters of the various substances which have been submitted to him for examination.Part of the cost of this, and of all the other investigations on cam- phor derivatives, which have been published by the author, alone and in conjunction with Mr. W. J. Pope and Dr. A. Lapworth, has been defrayed by grants from the Royal Society, for which the author desires to express his thanks to the Government Grant Committee. EXPERIMENTAL. rw-Bibrornocamphhoric Anhydride, C,H12Br,<CO).0. co Dry n-bromocamphoric acid (Trans., 1896, 69, 924), which has been freed from a-nitro-ar-dibromocamphor by washing with chloroform, is ground up with about one-tenth of its weight of amorphous phos- phorus, and gradually treated with bromine in a Wiirtz flask; when the first vigorous action has subsided, the flask is heated on a water- bath and the addition of bromine continued very slowly, so that the quantity added in the course of about 3 hours is approximately twice the weight of the acid taken.During this operation, the evolution of hydrogen bromide gradually slackens, but without ceasing entirely, and bromine also escapes in small quantities, so that the end of theRIPPING: DERIVATIVES OF CAMPHORIC ACID. PART In. 181 normal reaction is difficult to recognise. The excess of bromine having been expelled, the product, which consists of a red, crystalline mass, saturated with a red oil, is well agitated with successive small quantities of cold water, and then with a little cold dilute alcohol ; these liquids remove most of the oily impurity, leaving a pale reddish or greenish crystalline product, the weight of which is rather greater than that of the original acid, the average yield amounting to about 90 per cent.of the theoretical. A small quantity of a crystalline bye- product is obtained from the alcoholic washings, but the examination of this substance is not completed. The crude anhydride is very easily purified, without appreciable loss, by dissolving it in boiling chloroform, and precipitating the filtered solution with ether, repeating these operations if necessary ; a sample thus purified and dried over sulphuric acid was analysed. 0.1779 gave 0.2307 GO, and 0.0643 H,O. C = 35-36; H= 4.01. 0.1248 ,, 0.1426 AgBr. Br = 47.8. G,,,HzzBrzO, requires C = 35.29 ; H = 3-52 ; Br = 4'7.06 per cent.Dibromocamphoric anhydride is readily soluble in boiling chloro- form, from which it crystallises in large, transparent plates (see below) melting a t 209--210° * ; it is also readily soluble in boiling ethylic acetate, acetic acid, and cold acetone, moderately in cold benzene, and sparingly in cold ether and alcohol. It sublimes readily when heated in a test-tube, giving a solid sublimate of lustrous prisms. It seems not to be acted on by boiling quinoline, from which it separates again on cooling, but when heated with aniline it is vigorously attacked ; i t dissolves in warm, concentrated, sulphuric acid with evolution of hydrogen bromide, and on heating more strongly the solution darkens in colour considerably. Boiling water slowly converts the anhydride into bromooamphanic acid and hydrogen bromide, and a boiling solution of half a molecular proportion of sodium carbonate in dilute alcohol brings about a similar change ; boiling alcoholic or aqueous potash in excess causes the elimination of both the bromine atoms with formation of the potassium salt of hydroxy-cis-n-camphanic acid or dihydroxycamphoric acid. Fusion with potash a t a moderately low temperature also results in the formation of a salt, from which w-hydroxy-cis-~-cam- phanic acid is liberated on the addition of a mineral acid, but other products appear to be formed in small quantities.When silver nitrate is added to a solution of the dibrmo-anhydride in acetic acid, the separation of silver bromide soon commences, and after prolonged boiling ut-hydroxy-cis-n-camphanic acid can be isolated from the solu- tion ; the y-lactone of hydroxycamphotricarboxylic acid (Trans., 1896, * For corrections to be applied to these melting points, see Trans., 1897, 71, 963,132 KIPPINCI: DERIVATIVES OF CAMPHORIC ACID.PAM' 111. Number of I observations. 88, 961) also seems to be produced under these conditions by the oxidation of the dihydroxycamphoric acid, which is probably formed as an intermediate product, but the isolation of the lactone is not very easy. For the determina- tion of its specific rotation, a solution in chloroform of 1.158 grams was diluted to 25 c.c., and examined a t 14' in a 200 mm. tube; the mean of 7 observations gave a= - 2*S0, from which [a],= - 31*2'.* The following is Mr. W. J. Pope's account of the crystals of the dibromo-anhydride, which were obtained by spontaneous evaporation of its solution in chloroform.'' ?rw-Dibromocamphoric anhydride crystallises in transparent, rhom- boidal-shaped, orthorhombic plates (Fig. 1) possessing a calcite-like lustre. The dominant form is always the pinacoid a{100), and the form q(O11) is usually the next largest ; these two forms give fairly good reflections. The prism ~ ( 1 1 0 ) is, as a rule, much smaller than q(O11), and the pinacoid b(010) is generally very small ; the form r(101) is always small but bright, and is frequently absent. FIU. 1. Dibromocamphoric anhydride is laevorotatory. Limits. '( Crystalline system.-Orthorhombic. a : b : c = 1.4844 : 1 : 0.7083. (( Forms observed.-a(lOO}, b{010), p{110}, q(O11), ~(101).'( The following measurements were obtained. ap=lOO : 110 pp= 110 : 110 b p = O l O : 110 qq=oii : oii qq=o11 : 011 bq = 010 : 011 ar = 100 : A01 rr=lOl : 101 34 18 29 24 29 37 18 26 55'44'- 56'17' 67 31 - 68 12 33 30- 34 24 109 1-109 40 54 23 - 54 59 70 14- 70 54 64 3 - 64 51 50 47 - 51 35 Mean. 56" 2' 67 54 33 59 109 24 54 41 70 37 64 27 51 2 Calculated. I 67'56' 33 58 109 23 54 41 30" 64 29 30 51 1 - * The polarimeter used in these determinations could only be read to 6', and so the results may not be very accurate.ICIPPIX?cf: DERIVATIVLCS OF CAMPHORIC ACID. PART 111. 133 ‘ I The facw of the zone [OOl] are striated with lines parallel to the c-axis; these lines are sufficiently well developed as frequently to disturb the measurements in that zone.The optic axial plane is c(OOl), and the axis-b is a bisectrix of negative double refraction ; the optic axial angle is very large, but the 6-axis is probably the acute bisectrix. There is a fairly good cleavage on a(lOO}, and the cleavage faces are usually marked by the striations noted above ; it is note- worthy that the crystals are always tabular on a(lO0). After melting on a microscope slide under a cover slip in the usual way, the substance solidifies readily to a cubic modification ; when the plate cools to about 60°, this changes to a doubly refracting biaxial modification made up of large individual fragments which, as cooling continues, crack across perpendicularly to their long directions. The pieces are frequently perpendicular to an optic axis? and are marked by interlaced straight striations.The double refraction seems to be of negative sign, and the modification is in all probability with the crystals measured above.” nw-Dibvomocmpho& Acid, C,H,,Br,(COOH),. It has been shown in previous papers that when an anhydride cannot be converted into the corresponding acid by treatment with alkalis or with boiling water, owing to elimination of the elements of a halogen acid, as, for example, in the case of the anhydrides of w-bromocamphoric acid (Trans., 1896, 69, l), r-bromocamphoric acid (Trans., 1896, 69, 927), and n-chlorocamphoric acid (Lapworth and Kipping, Trans., 1897, 71, l), this conversion is easily accomplished by using concentrated nitric acid as the hydrolysing agent. This method can be applied with very satisfactory results for the prepara- tion of dibromocamphoric acid from its anhydride.Dibromocamphoric anhydride dissolves readily in hot, concentrated nitric acid (sp. gr. 1*4), and if the solution be cooled after heating during a few minutes only, most of the anhydride is deposited unchanged; if, however, the nitric acid solution be heated on a water- bath in an evaporating dish, crystals of the dibromo-acid begin to separate after a short time, neither nitrous fumes nor bromine being evolved in any appreciable quantity. When most of the nitric acid has evaporated, a little water is added to precipitate the rest of the dibromo-acid, and the colourless crystals are then separated and dried in the air. This product is generally free from anhydride, but should the latter be present, it is easily removed by washing the crystals with a little cold chloroform, in which the acid is insoluble, or nearly so.134 KIPPING: DERIVATIVES OF CAMPHORIC ACID.PART 111. For analysis, a sample wag treated in this way, and then recrystal- lised from ether and dried a t looo until constant in weight. 0.1682 gave 0.2076 CO, and 0.0624 H,O. C,,H,,Br,O, requires C = 3352 ; H = 3.91 per cent. pw-Dibromocamphoric acid crystallises from ether, in which it is very readily soluble, in microscopic, four-sided plates ; it dissolves freely in cold acetone, ethylic acetate, and methylic alcohol, but is almost insoluble in benzene as well as in chloroform. It melts a t about 210°, effervescing, owing to the escape of water vapour and hydrogen bromide, and becoming slightly brown, but like w-bromo- camphoric acid and all the n-halogen derivatives of camphoric acid, it is stable a t looo, and does not lose in weight even after having been heated during several hours.It is practically insoluble in boiling water, although just sufficiently soluble to impart to the water an acid reaction after heating for a few minutes ; i t is probable, however, that the dibromo-acid does not dissolve unchanged, and that the acidity of the Eolution is due to hydrobromic and 7r-bromocamphanic acids, since these two compounds are rapidly produced when a solution of the dibromo-acid in dilute methylic alcohol is boiled. Hot concentrated nitric acid dissolves dibromocamphoric acid freely, and on cooling beautiful, transparent, flat, four-sided crystals are deposited, but they are not large enough to be suitable for goniometric examination.The acid dissolves in dilute sodium carbonate, forming apparently the corresponding sodium salt, as on acidifying a freshly prepared solution with a mineral acid, dibromocamphoric acid is repre- cipitated j when, however, such a solution of the acid is boiled for a few minutes and then acidified, crystals of p-bromocamphanic acid are deposited, hydrogen bromide having been eliminated. When dibromocamphoric acid is heated in a test-tube over a small flame, it first melts with effervescence and then distils, charring very slightly but evolving hydrogen bromide, and apparently traces of carbonic anhydride ; the crystalline distillate consists of a mixture of m-dibromocamphoric anhydride and an acid melting a t 176O, which is doubtless n-bromoeamphanic acid.No attempts were made t o prepare salts of the dibromo-acid, on account of the readiness with which it is decomposed by water, alkali carbonates, and alkalis. It is interesting to note the relative stability of hot solutions of the acid in concentrated nitric acid and in water respectively; whereas the former may be heated during several hours without suffering any appreciable change, elimination of hydrogen bromide takes place rapidly in the aqueous solutions ; this behaviour i s similar to that of r-bromocamphoric acid. C = 33.66 ; H = 4.12.KIPPING: DERIVATIVES OF CAMFHORIC ACID, PART 111. 135 r-Bromo-w-chlorocamphoric Anhydride, C,Hl,BrCl~o>O.0 The object of preparing this compound has already been stated ; the method was the following. Dry powdered r-bromocamphoric acid was treated with a slight excess of the theoretical quantity of phosphorus pentachloride, the colourless liquid product heated on a water-bath, and dry chlorine slowly bubbled into it for about 4 hours, or until the evolution of hydrogen chloride almost ceased. The pale yellow oil thus obtained was gradually treated with ice cold water, whereon it quickly solidified, and was then purified by washing with water and dilute alcohol successively ; for analysis, a sample was recrystallised twice from chloroform and then dried over sulphuric acid. 0*1576 gave 0,2349 CO, and 0,0602 H,O. C,oHl,CIBrO, requires C = 40.62 ; H = 4.06 per cent.?r-Bromo-w-chlorocamphoric anhydride, like the corresponding di- bromo-compound, crystallises best from chloroform, from which it is deposited in lustrous prisms (see later) melting a t 214-215', or 5' higher than its analogue ; a mixture of the dibromo- and chlorobromo- anhydrides shows no sign of melting until the temperature rises to 209--210°-the melting point of the former-an indication of the isomorphism of the two compounds which was confirmed by the crystallographic examination made by Mr. W. J. Pope (see p. 136). In most respects, the properties of r-bromo-w-chlorocamphoric anhp- dride are so similar to those of the corresponding dibromo-compound that further description is unnecessary, but one rather interesting difference in behaviour may perhaps be noted.When the chlorobrornc- compound is crystallised from a mixture of chloroform and ether, it is sometimes deposited in long, slender prisms, or needles, as well as in the compact prisms already referred to ; these two kinds of crystals differ, not only in appearance, but also in behaviour, as the former become opaque wben kept over sulphuric acid or heated on a water- bath, whereas the latter remain transparent ; both forms, however, melt at 214-215O. Experiments showed that the needles are formed when the crystal- lisation of the ethereal chloroform solution takes place a t low temperatures, as, for example, a t - 5 O , whereas, when the solution is kept at about the ordinary atmospheric temperature, one or other, or both forms may be deposited ; ethereal chloroform solutions of the dibromo-anhydride, crystallised at temperatures just below Oo, did not deposit anything but the rbombic prisms described above, C=40*65 ; H=4.24.136 KIPPING: DERIVATIVES OF CAMFHORIC ACID.PART 111. This anhydride, like the corresponding dibromo-compound, is laevo- rotatory ; a solution of 1.153 grams in chloroform diluted to 25 c.c., and examined a t 14' in a 200 mm. tube, gave u = -- 2 4 O as the average of seven observations : hence [ a ] , = - 26*1°,* rw-Chlorobromocamphoric anhydride crystallises in large, trans- parent, orthorhombic prisms (Fig. 2), which appear rather more lustrous than the crystals of the corresponding dibromo-compound. The dominant form, as in the latter case, is usually the pinacoid a{lOO), but the form p{lOO} is sometimes the most developed ; the pinacoid b{010} is also usually well developed, and q{Oll} is generally broader than in dibromocamphoric anhydride.The crystals of the latter give much better results on measurement than do those of the com- pound now described. FIG. 2. '' Crystalline system.-Orthorhombic. "Forms observed : a{100}, b(010), p{110}, q{O11}, r{lOl}. '' The following measurements were obtained, CG : b : c = 1.4789 : 1 : 0.7107. Angle. ap=lOO : 1_10 pp=llO : 110 bp=O10 : 110 qq=Oll: 011 bq=010 : 011 514'011 : 011 a?= 100 : 101 Number of observations, 47 32 21 38 43 44 13 Limits. 55" 1'- 56'54' 6749- 69 2 33 20 - 34 48 108 42 -109 57 53 39- 55 10 69 57 - 71 28 63 19- 65 6 Mean. 55'56' 68 31 34 7 109 16 54 3 8 70 48 64 24 Calculated. - 68' 8' 34 4 109 12 54 36 64 20 - The forms in the zone [OOl], and more especially the pinacoid a(100}, are marked with striations parallel to the c-axis. The optic axial plane is c(OOl}, and the axis b is the acute bisectrix ; the double * Compare footnote, p.132.ICIPPING : DERIVATIVES OF CAMPEORIC ACID. PART 1x1. 137 refraction is negative in sign, and the optic axial angle is large. There is a very poor conchoidal cleavage on a(100). "After melting on a microscope slide under a cover slip, the com- pound solidifies readily, yielding a singly-refracting cubic modification ; this, before it cools to the atmospheric temperature, changes to a biaxial doubly-refracting modification, which is formed in large plates very similar to those constituting the film of the corresponding dibromo-derivative.These plates are marked with interlaced, straight striations, and are frequently perpendicular to an acute bisectrix of large axial angle and of negative double refraction. " As would be expected from the chemical relationship between the two compounds, rrw-dibromo- and rrw-chlorobromo-camphoric anhydride are isomorphous; the axial ratios are of the same order and cor- responding angles, as shown in the following table, do not differ greatly in the two cases, alb clb alc ap=lOO : 110 bp=OlO : 110 cp=OOl : 011 6q=010 : 011 ar= 100 : 101 cr-001 : 101 1.4844 0 *7083 2,0958 56" 2' 33 58 35 18 30" 54 41 30 64 29 30 25 30 30 1.4789 0-7107 2.0809 55"56' 34 4 35 24 54 36 64 20 25 40 Differences -t 0-0065 + 0.0149 4- 0'6' 4-0 530 3 .0 9 3 0 - 0'0024 - 0 6 - 0 5 30" -0930 " I t will be seen that the dimensions measured in the zone [OOl] differ least in the two cases, whilst those in the parametral zone [OlO] exhibit the greatest differences. The same forms are present on crystals of both anhydrides and striations parallel to the zone axis observed in the zone [OOl] are also observed in both cases. '( Amongst the differences may be noted that the crystals of the dibromo-compound show a much better cleavage parallel to (100) than do those of the chlorobromo-derivative; again, the crystals of the former are really much better developed and give more trustworthy measurements than those of the latter substance. Further, there is a well-marked difference in habit. Crystals of the dibromo-anhydride are always tabular, whilst those of the chlorobromo-derivative are much more prismatic in habit; this is mainly due t o a large develop- ment of the forms ~(110) and 6(010) on the latter crystals, '<The behaviour of the two substances after melting and solidification is, in accordance with the isomorphism, extremely similar."138 HIPPING: DEBIVATIVES OF CAMPHORIC ACID.PART 111. .rr-Bromo-w-chZorocamplioTic Acid, C,H,2BrC1(COOH)2. This acid can be prepared from its anhydride by the same method as that employed in the case of the dibromo-anhydride, namely, by dissolving the anhydride in concentrated nitric acid (sp. gr. 1*4), and then evaporating the solution on the water-bath. The colourless crystals of the acid are dried on porous earthenware, washed with a little chloroform to remove traces o€ unchanged anhydride which may be present, and then dried a t looo; for the analysis, a sample was re- crystallised from ether, as the crystals retain small quantities of occluded nitric acid, which is not easily expelled even a t 100'.0.1689 gave 0.2395 CO, and 0.0693 H20. C = 38.67 ; H = 4-56, CloH,,BrC1O, requires C = 38.29 ; H = 4.46 per cent. ?r-Bromour-chlorocamphoric acid is a microcrystalline, colourlesa powder, as prepared in the above manner ; it melts at about 197" when heated fairly slowly from about 80°, effervescing vigorously, but as this temperature is a decomposition rather than a melting point, it varies a little with the rapidity of heating. There is, however, a much larger difference between the melting points of the bromochloro- and dibromo-acids, than between those of the corresponding anhydrides.In all ordinary properties, the bromochloro-acid resembles the dibromo- compound ; it is, however, rather more soluble in boiling water, from which it separates in long, transparent prisms, which seem to contain water of crystallisation, as they become opaque when heated and melt at about 197O. It separates from cold concentrated nitric acid in nodular, opaque masses, and from ethereal chloroform in colourless, transparent, well-defined microscopic prisms ; its behaviour towards boiling water is referred to later. co r-Bromocamphanic Acid, COOH* C8H,,Br<- I Various methods can be adopted for preparing this compound from dibromocamphoric anhydride, or from the corresponding acid, some of which have already been mentioned.It may be obtained in large quantities by boiling the finely divided anhydride with a large volume of water, but as this process occupies a long time, owing to the slight solubility of the anhydride, the following method is more convenient. The anhydride is dissolved in a small quantity of boiling acetic acid, and after adding a little water until a turbidity is justproduced ih the hot solution, the latter is heated on a sand-bath, more waterKIPPING: DERIVATIVES OF CAMPEORIC ACID. PART 111. 139 being added from time to time as the anhydride decomposes ; during this process, the solution almost invariably acquires a distinct bright pink colour, which slowly changes to brown, the liquid then depositing traces of some tarry matter, doubtless due to impurity in the (crude) anhydride used.The hot solution is finally filtered, and on cooling the r-bromocamphanic acid is deposited in almost colourless needles ; further quantities are obtained on evaporating the mother liquors, the yield being practically theoretical, For analysis, a sample was purified by recrystallisation from a mixture of ethylic acetate and chloroform and dried a t 100". 0.1576 gave 0,2518 GO, and 0.0697 H,O. C = 43.57; H = 4.91. C,,H,,BrO, requires C = 43.32 j H = 4.69 per cent. r-Bromocamphanic acid usually separates from hot water, in which it is only modercltely easily soluble, in small, well-defined, lustrous prisms, which do not lose in weight at 100". It is comparatively sparingly soluble i n boiling benzene, and only moderately so in boiling chloroform, but it dissolves readily in acetic acid, alcohol, and ethylic acetate; i t crystallises best from cold, dilute acetic acid, from which it is deposited in transparent prisms described later.It melts at 176-177Owithout decomposing, but when heated a t its boiling point it darkens considerably and seems to give off a little hydrogen bromide ; the distillate soon crystallises on cooling, and consists of slightly im- pure bromocamphanic acid. r-Bromocamphanic acid is a very stable substance in many respects, and boiling nitric acid, dilute or concentrated, does not oxidise any appreciable quantity of it in the course of a few hours. Prolonged boiling with a solution of chromic anhydride and dilute sulphuric acid seems to result simply in the elimination of hydrogen bromide, the bromocamphanic acid being converted into hydroxy-cis*-camphanic acid ; the last-named compound is also formed when the bromo-acid is boiled with an aqueous solution of silver nitrate, but other substances are also produced.When the acid is treated with ammonia under suitable conditions, a product is obtained which is almost insoluble in water, but which has not yet been analysed or examined. Mr. Pope's description of this substance is as follows. I' The crystals of bromocamphanic acid are very beautiful, transparent, orthorhombic prisms (Fig. 3), which have a very brilliant, glassy lustre. The prism ~ ( 1 1 0 ) is always dominant, but gives poor results on measurement owing to the presence of vicinal faces and of striations parallel to the c-axis; the forms p(Ol1) and ~(101) are next in size, ~(101) being usually rather the larger, and give very brilliant reflections, so that the measurements obtained from them may be relied upon.The pinacoid ~(001) is very small and frequently absent.l4@ KIPPING: DERIVATIVES OF CAMPHORIC ACID. PART III. Fro. 3.. Crystal line System, - Or thorhombic. a : b : c = 1.4654 : 1 : 0.9501. '' Forms observed.-c(001), p(110), q(O11), r(101). The following angular measurements were obtained. Angle. cr=001 : 101 rr=lOl : i o i rr=lOl : 101 pq=llO : 011 pr-Oll : 101 Tp=101 : 110 qq=Oll: 01 1 qp=Oll : Oil cq=OOl : O t l pp=110 : 110 pp=110 : 110 Number of measure- ments. 9 29 25 34 29 31 16 14 15 37 24 Limits.35O17'- 35"59' 71 12- 71 26 108 34-108 48 70 41 - 70 56 55 49- 56 15 53 5 - 5324 86 52- 87 20 92 37- 93 11 46 1- 4654 110 47-111 58 68 20- 69 13 Mean. 35"41' 71 19 108 40 70 49 56 59 53 15 87 4 92 55 46 21 111 26 68 47 Calculated . 35"39'30" - 108 4 1 8 56 57 53 14 87 8 92 62 46 26 111 23 68 37 - '6 The plane c(OO1) is the optic axial plane, and an optic axis emerges obliquely through each face of the form ~ ( 1 1 0 ) ; the double refraction is strong and the optic axial dispersion slight. After melting, the substance solidifies readily, and is thus obtained in large individual flakes, which are often marked by stris crossing each other at about 60°, and cracked across their longest dimension on cooling; the flakes are frequently perpendicular t o an optically negative bisectrix of a large axial angle." Methy lie r- Blromocamphana te, COOMe * C,H,,Br<C? - 0 9 This ethereal salt is conveniently prepared by passing hydrogen chloride into a solution of the acid in methylic aleohol and thenHIPPING: DERIVATIVES OF CAMPIIORIC ACID.PART IJI. 141 evaporating at the ordinary temperature ; the product, which is slowly deposited in felted needles, can be purified by recrystallisation from a mixture of ether and chloroform. 0.1662 gave 0.27'77 GO, and 0.0832 H,O. C,,H1513r0, requires C = 45.36 ; H = 5.15 per cent. Methylic r-bromocamphsnate crystallises from ether and from most other solvents in long, transparent needles melting a t 87-88O ; it is very readily soluble in cold chloroform, methylic alcohol, and boiling ether, but comparatively sparingly soluble in light petroleum.Massive crystals are easily obtained from a solution in a mixture of ethel: and chloroform, and a specimen of the compound thus obtained was examined by Mr. W. J. Pope, whose report is now given. '( The crystals of methylic bromocamphanate are transparent ortho- rhombic plates or prisms, possessing a high lustre (Fig. 4) j the habit of the crystals varies cousiderably, those of prismatic habit are lengthened in the direction of the axis-a, and somewhat flattened in that of the 6-axis, the dominant forms being ~ ( 1 0 0 ) and ~ ( 1 0 1 ) ; the tabular crystals are flattened on two parallel faces of the form ~ ( 1 0 1 ) . Very good results are obtained on measuring the crystals, Cz45.57 ; H-5.56, FIG.4. (' Crystalline System.-Orthorhombic. cc : 6 : c = 1.0977 : 1 : 0.6561. '' Forms observed.-a(lOO), 6(OlO), p(llO), ~ ( 1 0 1 ) . ( I The following angular measurements were obtained. Angle. ap=lOO : 110 p b = l l O : 010 ar= 100 : _lo1 r r = l O l : 101 pr= 110 : 101 Nnmber of n~easnre- nients. 18 12 24 16 7 Limits. 4 7 "3 4'-4 7 "4 7 ' 42 12-42 27 59 0--59 23 61 31 -61 50 69 39 -69 52 Mean. 47"40' 42 18 59 8 61 42 69 45 Calculated. - 42"PO' 61 44 69 47 - VOL. LXXV. I,142 KIPPINQ: DERIVATIVES OF CAMPHORIC ACID. PART 111. ‘( There is a poor conchoidal cleavage parallel to b(010), and the axis-b is the acute bisectrix; the optic axial plane is c(OOl), and the double refraction is positive in sign, and strong. The optic axial angle is fairly large and the optic axial dispersion is slight.‘ I The substance solidifies readily after melting on a microscope slide under a cover slip, giving large, individual flakes ; most of these are nearly perpendicular to an optically negative bisectrix of a very large optic axial angle, and these are full of symmetrically arranged egg- shaped bubbles and of intersecting striations. A few fragments are usually to be observed which show no bubbles or stria ; these are nearly perpendicular to the optically positive bisectrix of a fairly large optic axial angle. This modification is doubtless identical with the crystals measured above.” Methylic r-bromocamphanate is slowly attacked by concentrated aqueous ammonia at ordinary temperatures, and is thereby converted into a crystalline substance, which, judging by its melting point and other ordinary properties, is identical with the Ir-bromocamphanamide produced by the action of aqueous ammonia on m-dibromocamphoric anhydride. This compound may now be described.GO nBromo-w- camphanamide, NH,. CO*C,H,,Br< I 0‘ When finely divided ?rw-dibromocamphoric anhydride is left in contact with concentrated aqueous ammonia a t ordinary temperatures, i t slowly changes into a rather more bulky mass of small prisms, but without passing into solution to any noticeable extent ; after keeping the mixture for about two days, the product is separated by filtration from the ammoniacal solution, which contains a small quantity of a readily soluble, crystalline, ammonium salt, washed with cold water, and recrystallised from dilute methylic alcohol.The substance obtained in this way is the amide of r-bromo-w-camphanic acid, and an analysis of it gave the following result. 0.1678 gave 0-2671 CO, and 0.0796 H,O. C = 43.41 ; H = 5.27. C1,H,,O,BrN requires C = 43.47 ; H = 5.07 per cent. The natnre of this compound is further established by the fact already mentioned, namely, that it is formed on treating methylic n-bromocamphanate with aqueous ammonia, and also by its behaviour on hydrolysis ; when boiled for a short time with concentrated hydro- chloric acid, it is converted into a crystalline acid, which melts at 176-177’, and has all the properties of .rr-bromocamphanic acid. T-Bromo-w-camphanamide crystallises from most solvents in lustrous, transparent needles or prisms melting at 161-162’ ; it is very readilyRIPPING: DERIVATIVES OF CABWHORIC ACID, PART 111.143 soluble in cold chloroform, acetone, ethylic acetate, metic acid, and most other solvents, and it also dissolves freely in boiling water, but it is insoluble, or nearly so, in a cold dilute solution of sodium car- bonate. It seems to be dimorphous, as the transparent crystals deposited from dilute methylic alcohol become opaque a t about 140' when slowly heated, and do so a t even lower temperatures when the tube containing them is rubbed gently. Porrnation of r-Bromocamphanic Acid from r-Bromo-~o-chlorocamphoric Anhydride.-It was stated in the introduction that r-bromo-w-chloro- camphoric anhydride is decomposed b7 boiling water, giving hydrogen chloride, and an acid identical with the r- bromo-w-camphanic acid, prepared in a similar manner from rrw-dibromocamphoric anhydride ; this statement rests on the following experimental evidence.When bropochlorocamphoric anhydride is boiled for some hours with diluted acetic acid, and the filtered solution then allowed to cool, a substance crystallising in colourless prisms is deposited ; this com- pound, after having been purified, melted at 176-1 77', and in appear- ance and other properties seemed to be identical with r-bromo- camphanic acid. The great similarity between dibromo- and bromo- chloro-camphoric anhydrides, however, if repeated in the case of the bromo- and chloro-camphanic acids, might render the distinction between the two latter a matter of some difficulty ; for this reason, it was necessary to make the following analysis, the results of which show that the decomposition product of the bromochloro-anhydride is really a rr-bromocamphanic acid.0.15'72 gave 0.2521 CO, and 0.0679 H,O. C = 43.74 ; H = 4.80. C,,H,,Br04 requires C = 43.32 j H = 4.69 per cent. Nydroxy-cis-r-camp~unic Acid. It has been shown in earlier papers that cis-a-camphanic acid is slowly oxidised by potassium permanganate in alkaline solution, being converted into a hydroxy-cis-r-camphanic acid, which is the lactone of a dihydroxycamphoric acid ; this hydroxy-acid can be obtained in various ways from dibromocamphoric anhydride and its derivatives. When, for example, dibromocamphoric anhydride is boiled for some time with alcoholic potash, or fused with potash at a moderate temperature, both the bromine atoms are removed, and hydroxy-cis- r-camphanic acid can be isolated from the product by methods which it is unnecessary to describe. Again, when r-bromocamphanic acid is heated with silver nitrate in aqueous solution, silver bromide is rapidly deposited, and an acid having all the properties of hydroxy- citm-camphanic acid can be obtained from the solution. A number of experiments were made in the hope of isolating a L 2144 RIPPING AND HILL : a-KETOTETRAH'YDRONAPH!FHALENE. dihydroxycamphoric acid, or the corresponding dilactone ; for this purpose, the dibromo-anhydride, dibromo-acid, and r-bromocamphanic acid, were separately treated with aqueous silver nitrate under various conditions ; in nearly every case the product seemed to be a mixture of two or three organic compounds, and it was not easily separable into its components by fractional crystallisation or by other methods ; hydroxy-cis-n-camphanic acid was isolated in almost every instance, and also a crystalline substance, which fro-m its melting point and other properties was found t o be identical with the y-lactone of hydroxycamphotricarboxylic acid. Further, in several experiments, small quantities of an oily product were obtained; this substance, when purified, was only sparingly soluble in boiling water (the other two products are readily soluble), and apparently insoluble in cold dilute sodium carbonate ; it was vigorously attacked by hot concen- trated nitric acid, being converted into the y-lactone of camphotricarb- oxylic acid. These observations seem to show the existence of a dilactoae of dihydroxycamphoric acid amongst the products of the action of silver nitrate on the bromo- and dibromo-compounds in question. Hydroxy-cis-n-camphanic acid is prepared far more easily by one of these methods than by the oxidation of cis-n-camphanic acid, and its investigation, as well as that of some of the other compounds related to it, is being continued ; the crystals of this acid, obtained from an acetone solution, are of large size and suitable for goniometric examination. UNIVERSITY COLLEGE, NOTTINOHAM.

ISSN:0368-1645    

DOI:10.1039/CT8997500125

出版商:RSC    

年代:1899

数据来源: RSC

摘要:

144 RIPPING AND HILL : a-KETOTETRAH'YDRONAPH!FHALENE. XVII.-a-Ketotetrah ydronaphthalene. By FREDERIC STANLEY KIPPING, Ph.D., D.Sc., F.R.S., and ALFRED HILL. THE conversion of phenylpropionic chloride into a-hydrindone by the action of aluminium chloride under the conditions described by one of us in a previous communication (Kipping, Trans., 1894, 65, 680) is an example of intramolecular condensation by which an open- is converted into a closed-carbon chain ; the reaction also provides by far the most convenient method yet known for the preparation of a-hydrindone, as, with due care, the yield is invariably very good, and phenylpropionic chloride itself can be obtained without any difficulty in almost unlimited quantity; this method of preparation was, there- fore, made use of i n later investigations of the derivatives of a-hydrin- done (Kipping and Revis, Trans., 1897, 71, 238).KIPPINO AND HILL : d-KETOT~RAETPDRONAPHTEALENE. 146 That such a reaction would be capable of more general application WW, of course, extremely probable, but until quite recently no oppor- tunity offered itself of putting this view to the test of experiment ; now, however, the reaction is being tried with various substances, and in the present paper some of the first results of this work are described.Taking the well-known synthesis of a-naphthol from phenyl-py- crotonic acid by Fittig and Erdmann as an indication of the ease with which intramolecular condensation may occur in the case of a benzene derivative containing a suitable unsaturated side chain, it seemed very probable that a similar change might be brought about in the case of phenylbutyric acid, if the chloride of this acid were treated with aluminium chloride in a suitable manner ; if so, the analogy between phenylpropionic and phenylbutyric acid would be complete, the one giving a-hydrindone, the other a-ke tot e t rah y dronaph thalene.')'';H2 + HCl I " j C H 2 - 1,) /"TiH2 )CH, - COG1 co Experiments showed that a-ketotetrahydronaphthalene is, in fact, formed by the action of aluminium chloride on phenylbutyric chloride under the conditions described below, but, so far, satisfactory yields have not been obtained, owing probably to the readiness with which the ketone, when once formed, undergoes further condensation of the ordinary type ; a sufficient quantity of this substance, however, has been obtained t o enable us to study its properties in some measure, and to prepare from it various crystalline derivatives. a-Ketotetrahydronaphthalene is isomeric with, and closely related to, the P-keto-compound, which was first prepared by Bamberger and Lodter (Ber., 1893, !B, 1833) by the action of alkalis on " tetrahydro- naphthylene chlorhydrin '' (2 :, 3-~hlorhydroxytetrahydronaphthalene), and afterwards examined by Bamberger and Voss (Bey., 1894, 2'7, 1547).As far as can be judged, the two compounds resemble one another very closely in properties, and both show the ordinary general reactions of ketones ; the semicarbazone, oxime, hydrazone, and para- bromhydrazone of the a-keto-compound are described in this paper, the oxime and hydrazone of the P-ketone having been previously prepared by Bamberger and Voss (Zoc.cit.). That the substance we describe as a-ketotetrahydronaphthalene really has this constitution is shown, not only by its method of formation and ketonic properties, but also by the fact that it can be indirectly converted into a base which seoms to be identical with ac-tetrahydro- Phenylbutyric chloride, a- Ketotetrahydronaphthalene.146 KIPPING AND HILL : a-KETOTETRAHYDRONAPHTHALENE. a-naphthylamine; this base was first obtained by Bamberger and Bammann (Ber., 1889, 22, 951) by reducing tetrahydro-1 : 5-naphthyl- enediamine with sodium and amylic alcohol, and then eliminating the amido-group combined with the unrecluced aromatic nucleus. NH, CII, CH, CH, \/\/ \/\/ /\/'\C€€.> - /\/\C€€., /\/\cH, I I 'UH, I I ICH, CO I 1 iCHi CH-NH, \/\/ CH-NH, 1 : 5-Tetrah~dro1rapI1tbyl- Tetraliydro-a iiaphthyl- a-Iietotetrahyclro- eiiediamiiie. smine.naphthalene. The conversion of a-ketotetrahydronaphthalene into this base was accomplished by first preparing the oxime, and then reducing the latter with sodium amalgam in acetic acid solution. The study of this interesting ketone is being continued. A portion of the expense incurred in this and in two earlier inves- tigations of a similar kind (Kipping, Trans., 1894, 65, 6SO; Kipping and Revis, Trans., 1897, '71, 338) has keen met by a grant kindly awarded by the Government Grant Committee of the Royal Society. Ex P E R I 31 EN TA L. P~epcwc~tion of Phen?/Zbut?/~*ic Acid-The preparation of a large quantity of phenylbutyric acid by the method which we employed is not a very easy task, but we were unable to find any process which appeared to be more suitzlble, recorded in the literature.Starting with benzaldehyde, anhydrous sodium succinate, and acetic anhydride, me first prepared the mixture of phenyl-py-crotonic and phenylparaconic acids under the conditions laid down by J a p e (AnnoZen, 1883, 216, 97), but instead of then separating these two compounds by dissolving out the phenyl-py-crotonic acid with carbon bisulphide, we submitted the dried mixture directly to dry distillation under reduced pressure (about 30 mm.), whereby, as J a p e has already shown (Zoc. cit.), the phenylpsrsconic acid is decomposed into phenyl-/3y-crotonic acid and carbonic anhydride, a small quantity of phenylbutyrolactone being also formed from the phenyl-py-crotonic acid by an intramolecular change.The distillate, which solidifies on cooling to a brown, pasty, crystalline mass, was spread on porous earthenware to separate the phenylbutyrolactone and other oily impurities, and afterwards recrystallised from hot carbon bisulpliide, froin which the phenyl-py-crotonic acid was deposited in almost colourless needles; the last portions of this acid generally contain a little benzoic acid, this compound being always present in the original condensation product in large quantities; it is bestKIPPINU AND HILL : a-ICETOTETRAHYDRONAPHTHALENE. 147 removed by heating the mixture on a water-bath, the residue being again crystallised from carbon bisulphide. The phenyl-py-crotonic acid was thus obtained in colourless needles melting sharply at 86', but the yield was always very poor, owing to the formation of tarry matter in the original condensation process.For the conversion of this unsaturated compound into phenylbutyric acid, the pure acid was reduced with sodium amalgam in alkaline solution, and after precipitating with hydrochloric acid and filtering, the rest of the product was extracted with ether, and the whole purified by recrystallisation from this solvent ; the acid then melted at 47-48O as stated by J a p e (Zoc. cit.). We did not experience any difficulty in reducing the phenyl-By-crotonic acid at ordinary tempera- tures, although, according to Jayne, prolonged treatment and warming are necessary.Phenpllbutyric chloride, C,H,~CH2*CH,*CH,*COCI, is easily prepared by treating the dry, powdered acid with a slight excess of the theoreti- cal quantity of phosphorus pentachloride at ordinary temperatures, a vigorous action immediately setting in ; instead of separating the product from the phosphorus oxychloride by fractional distillation under reduced pressure, as in the case of phenylpropionic chloride (Trans., lS91,65,484), we merely heated the oil on a water-bath under diminished pressure until the oxychloride had volatilised, using the residual phenylbutyric chloride, which is sufficiently free from impurity, for the subsequent experiments. Phenylbutyric chloride, as thus obtained, is a yellowish, mobile liquid, having a slight, but not very unpleasant, odour ; when poured into water, it rapidly solidifies to crystals, which are only very slowly decomposed by cold water, and which do not immediately dissolve in a cold dilute solution of sodium carbonate.Actioib of Alunzinium Chloride on Plmplbutyric Chloride. Experiments were made in order to ascertain the conditions under which the conversion of phenylbutyric chloride into a-ketotetrahydro- naphthalene could be accomplished, and we commenced by employing very much the same method as in the case of a-hydrindone, the acid chloride, mixed with about four times its weight of light petroleum (b. p. 40-60°), being treated with its own weight of anhydrous alu- minium chloride. Under these conditions, however, only a very slight reaction, if any, occurred, and even after heating on the water- bath during 30-40 minutes, the phenylbutyric chloride was found t o be unchanged ; on employing as diluent a sample of light petroleum boiling at 60-80°, the reaction was almost as sluggish as before, but with petroleum boiling at 100-110' a vigorous evolution of hydrogen148 KIPPING AND HILL : a-KETOTETRAHYDRONAPHTHALENE. chloride set in on heating, and in a short time the reaction abruptly ceased.An examination of the product from this last experiment showed that the yield of ketone was extremely small, most of the acid chloride having been converted into a pale brown resin. For this reason, a smaller proportion of aluminium chloride was employed in the later experiments, and the results appeared to be distinctly better.The most satisfactory yield, so far, has been obtained by working in the following manner. Phenylbutyric chloride (5 parts) is dissolved in light petroleum (25 parts) boiling at 100-1 lo”, aluminium chloride (4 parts) is added, and the mixture is rapidly heated on a boiling water bath in a flask provided with reflux condenser ; after a very short time, hydrogen chloride is very rapidly evolved, and during this reaction the flask is repeatedly and vigorously shaken. At the end of about 10 minutes, or when the evolution of gas suddenly ceases, the contents of the flask are cooled and water carefully added; finally, the mixture is submitted to distillation in steam. The petroleum which passes over first contains only a smallquantity of the ketone, the rest distilling over slowly with the steam and leaving in the flask a brown, oily, non-volatile substance, which, on cooling, solidifies to a brittle resin; the ketone is isolated bp evaporating the petroleum and by extracting the aqueous portion of the distillate with ether.The a-ketotetrahydronaphthalene obtained in this way as a pale yellow oil is probably slightly impure, and is further treated in the manner described below ; the yield is by no means satisfactory, being at t h s most only about 10 per cent. of the theoretical, but it is probable that, as in the case of a-hydrindone, further experiments will lead to the discovery of some slight modification of the process which will give much better results. The principal product of the reaction is the brown, brittle resin, referred to above ; this substance is probably formed from a-ketotetra- hydronaphthalene by a condensation process similar t o that which occurs in the case of “anhydrobishydrindone,” or by the further action of phenylbutyric chloride on the ketone in presence of aluminium chloride. To obtain some information on this point, some of the resinous substance was oxidised with nitric acid, and it wag found to be ultimately converted into phthalic acid; this fact Heems to justify the above assumptions, and to indicate that if this secondary reaction could be prevented the yield of the ketone would be as good as in the case of a-hydrindone.Wheu working with small quantities of a-ketotetrahydronaphthalene, the best method of purification is doubtless the following, The crudeKIPPING AND HILL : a-KETOTETRBHYDRONAPHTHALENE. 149 oil is converted into its sparingly soluble semicarbazone in the manner described later, and after recrystallisation it is heated in a small Wurtz flask with rather more moderately-concentrated hydrochloric acid than is required t o combine with the semicarbazide; the semi- carbazone is thus decomposed with regeneration of the ketone, which can be distilled off in a current of steam and extracted with ether.The addition of a little acetic acid, in which the semicarbazone is readily soluble, hastecs the reaction. In this operation, there is no appreciable charring if the pure semicarbazone be employed, and the decomposition appears to be normal, as expressed by the following equation, C1,H,,:N*NH*CO*NH, + H20 = C,,H,,O + NH,*NH*CO*NH,.a-Ketotetrahydronaphthalene is a colourless, mobile, highly refrac- tive liquid. It does not crystallise when kept for some days at ordinary temperatures, or when cooled to Oo, whereas the correspond- ing @ketone solidifies when cooled, and melts again at 1 8 O (Bamberger and Voss, Zoc. cit.); il; does not seem probable that this difference in behaviour is due to the presence of impurity in the a-ketone, as the process just given appears to be a very satisfactory method of purifi- cation. a-Ketotetrahydronaphthalene is specifically heavier than water at 15*, and is moderately easily volatile in steam. It has only a faint odour, recalling that of camphor, but when warmed it has 5t distinct odoiir of peppermint.It shows many of the ordinary reactions of a ketone, and yields crystalline products with hydroxylamine, phenyl hydrazine, kc.; it does not appear to dissolve in, or to combine with, sodium hydrogen sulphite in aqueous solution, although the P-ketone forms a crystalline additive product with this reagent, The ketone itself mas not snalysed, as its composition is established by its method of formation and properties, and by the analysis of the semicarbazone. When the crude ketone, obtained by the method described above, is heated with semicarbazide hydrochloride and sodium acetate in aqueous alcoholic solution, the separation of an almost colourless, crystalline compound soon commences, and the reaction is completed by warming on the water-bath during about 2 hours; the hot solution is then diluted with water, allowed to cool, and the product separated by filtration, and washed well with cold water.When purified by recrystallisation from hot alcohol and dried over sulphuric acid, i t gave the following result.150 KIPPINCI AND HILL : a-ICETOTETRABYDRONAPHTEALENE. 0.1640 gave 0.3885 GO, and 0.0968 H,O. C = 64.6 ; H = 6.6. CllH13N,0 requires c' = 65.0 ; H = 6.4 per cent. a-Ketotetrahydronaphthalene semicarbazone crystallises from alcohol in long, transparent needles or prisms, usually forming aggregates of a rosette-like form ; these crystals are distinctly yellow, their colour being almost as intense as that of quinone, but when in a fine state of division the substance appears almost colourless.The melting point is not very definite, for when heated moderately quickly the finely-divided sub- stance melts at about 217', but larger crystals only sinter at this temperature, and do not liquefy completely until about 2209 when effervescence sets in and the substance darkens slightly ; on heating more strongly, a large quantity of gas is disengaged and a yellow liquid remains. The semicarbazone is comparatively sparingly soluble in boiling chloroform and ethylic acetate, and apparently insoluble in water ; it dissolves fairly easily in boiling alcohol and boiling acetone, and also in warm acetic acid, but i t seems to be decomposed on boiling its acetic acid solution. As stated above, this compound may be con- veniently employed in the purification of the ketone, as the latter is immediately regenerated on warming the semicarbazone with hydro- chloric acid ; it also affords the best means of detecting and identifying the ketone, the phenylhydrazone being far less suitable for such purposes.a - K e t o t e t r a j ~ ~ d ~ o ~ ~ a i ~ ~ t j ~ ~ ~ n ~ Pilenp?hpdvaxone, C,,€€,,:N*NHPh. This compound is easily obtained by treating the purified ketone with phenylhydrazine acetate in dilute acetic acid solution in the usual manner, combination taking place spontaneously ; after warm- ing gently, water is added, and the product, which is precipitated as a thick, yellow oil, is washed well with cold water, and then dissolved in methylic alcohol. From this solution, the hgdrazone separates, on spontaneous evaporation, in a crystalline condition, but if the warm solution be rapidly cooled, the compound is generally deposited as an oil.The crystals obtained from methylic alcohol and other solvents are massive, transparent, almost colourless six-sided and rhomboidal plates melting a t 84-85', a t the same time effervescing and decom- posing; they are readily soluble in most of the ordinary organic solvents, and dissolve comparatively easily even in boiling light pet- roleum, separating again, on cooling, in lustrous, transparent prisms, The hydrazone is very unstable, and soon decomposes on exposure to light and air ; its behaviour towards hydrochloric acid seems to be similar to that of the parabromo-derivative described below.KLPPINO AND HILL : a-KETOTETRAHYDRONAPHTHALENE. 151 a- Ke t ote t mlbgdronaph t Acc Zene Pccrccbromophe n9II~3drcczo12e, C,,H,,:N*NH* C6H,Br.The preparation of this substance from the purified ketone and parabromophenylhydrazine is carried out exactly as described in the case of the preceding compound, interaction taking place very readily ; the almost colourless, oily product, which is precipitated on the addi- tion of water, crystallises immediately when treated with a little methylic alcohol, and is easily purified with the aid of this solvent, from which i t separates, on cooling, in long, colourless prisms, or in massive, transparent crystals. It melts a t 117-llS", when heated fairly quickly from about 1 loo, effervescing and decomposing, and i t is readily soluble in cold ether, ethylic acetate, acetic acid, and benzene; i t also dissolves in boiling light petroleum, but, on cooling, separates again almost com- pletely in nodular aggregates of needles. It is more stable than the hydrazone, and does not change colour when exposed t o light and air during several days.Attempts to regenerate the ketone by distilling the parabrom- hydrazone with moderately concentrated hydrochloric acid were not successful ; under these conditions, the bromhydrszone is converted into a crystalline compound, which is probably produced by a change analogous to that which occiirs in the formation of '' benzyleneindol " from the phenylhydrazone of a-hydrindone (compare Hausmann, Be?*., 1889, 22, 2019 ; Kipping, Trans., 1894, 65, 494). a- h~etotetra~~ldront?btha Zeneoxime, C,,H,,: NOH. On gently heating a solution of the purified ketone in dilute methylic alcohol with hydroxylamine hydrochloride and excess of potash, the separation of a crystalline compound soon commences, if the alcohol be sufficiently dilute, and on allowing the solution to evaporate on the water-bath, most of the product is deposited in colourless plates.It is easily purified by recrystallisation from dilute methylic alcohol, the lustrous, transparent, well-defined rhomboidal crystals thus obtained generally exceeding 10 mm. in diameter. It melts at 102.5-103.5° without decomposing, and is very readily soluble in cold ether, chloroform, mcthylic alcohol, and most other solvents ; i t also dissolves freely in cold concentrated potash, but i t is insoluble, or nearly so, in water.152 KIPPING AND HILL : ~-KETOTETRAHYDRONAPHTHALENE.Convemion of a- Ket otetrahydronapht ha Zene into Tetrahydro-a- nuphth y lamine. Alhhough the method of formation of the ketone described above and the analysis of its semicarbazone left little room to doubt that it had the constitution assigned to it, we thought it would be inter- esting t o t r y and convert it into one of the tetraliydronaphthalene derivatives of known constitution ; for this purpose, experiments were made with the object of converting the oxime into the tetrahydro-a- naphthylamine described by Bamberger and Bammann (Ber., 1889, 22, 951). Attempts to reduce the oxime with sodium and moist &,her were not successful ; even after employing a large excess of sodium, a portion of the ethereal solution gave, on evaporation, crystals of the un- changed oxime, and a basic substance appeared not to have been formed ; we, therefore, tried the action of sodium amalgam in warm dilute acetic acid solution, and found that reduction took place very readily.After using the amalgam in considerable excess of the theoretical quantity, the acid solution was submitted to distillation with steam, but as no unchanged oxime passed over, the solution was rendered strongly alkaline with potash, and again submitted to steam distillation. A colourless, strongly basic oil, which was only moderately soluble in water, then collected in the receiver. This aqueous distillate, having been mixed with excess of hydrochloric acid and evaporated almost to dryness on the water-bath, left a consider- able quantity of a salt which crystallised in needles or prisms, and was very readily soluble in water ; the yield seemed to be practically theoretical. I n order t o prove that this salt was the hydrochloride of tetra- hydro-a-naphthylamine, a portion of it was roughly dried at looo, and then heated for a few minutes with excess of acetic anhydride; on subsequently cooling and adding water, the cccetyl derivative of the base separated in colourless needles. Bamberger aud Baminann (Zoc.cit.) describe this ace tyl derivative as crystallising from very dilute alcohol in felted masses of needles, and they give 148-149' as its melting point. The compound we obtained had these and all other properties mentioned by Bamberger and Bammann, except that it melted at 144-145', and its melting point underwent no change on recrystallisation.As, therefore, there was this considerable difference in melting point, which is diflicult to account for, further evidence as to the identity of our base was desirable. For this reason, we prepared the platinochloride, a salt which isPURDIE & PITKEATELY: PRODUCTION OF ACTIVE ACIDS, ETC. 153 immediately precipitated in yelIow plates or prisms on the addition of platinic chloride to a solution of the hydrochloride of the base. This compound crystallised from water in long, flat, orange-yellow prisms, was readily soluble in hot water and cold methylic alcohol, and melted immediately at 140' when suddenly heated, thus indicating that it contained water of crystallisation ; these properties agreed with those assigned to the platinochloride of tetrahydro-a-naphth ylamine by Bamberger and Bammann, and our salt, like theirs, melted at 190°, decomposing and effervescing; t h a temperature at which the salt melts and decomposes varies, however, within very wide limits, according to the rate of heating, and on heating quickly the tempera- ture can be raised to about 197' before liquefaction and decomposition ensue. An analysis was, therefore, necessary to confirm the supposed identity of the two compounds. 0.4543 salt, dried over sulphuric acid, lost 0.0232 at looo. H,O = 5.1. 0.4311 anhydrous salt gave 0.1224 platinum. Calculated for (C,oHl,N),,H2PtC16 + 2H,O, H,O = 4.87 per cent. Calculated for (C,oHl,N)2,H,PtC16, Pt = 27.6 per cent. On ignition, the salt gave off fumes having a strong odour of Pt = 28.4. naphthalene. UNIVERSITY COLLEGE, NOTT I N o IJ A M.

ISSN:0368-1645    

DOI:10.1039/CT8997500144

出版商:RSC    

年代:1899

数据来源: RSC

摘要:

PURDIE & PITKEATELY: PRODUCTION OF ACTIVE ACIDS, ETC. 153 XVII1.-Production of Optically Active Mono- and Di-alkyloxysuccinic Acids j-onz Malic and Taj-taric A cids. By THONAS PURDIE, F.R.S., and WILLIAM PITBEATHLY, B.Sc., Berry Scholar in Science. IT has been shown in previous papers (Trans., 1898, 73, 287, 862) that the high optical activity of the ethereal malates and lactates, prepared from the respective silver salts, is due to the production of small quantities of the more active alkyloxy-derivatives, and Rodger and Brame (Trans., 1898, 73, 306) were consequently inclined to attribute the abnormally high rotation of the ethereal tartrates, which they prepared from silver tartrate, to a similar cause. On hydrolysing specimens of methylic tartrate, on the other hand, which had been prepared by this and by the commoner methods, they found that the products showed practically the same rotation, which sug-154 PURDIE AND PITKEATHLY : PRODUCTION OF OPTICALLY gested the possibility that the ethereal salts from the two different sources might be isomeric.The object of the present research was to obtain further evidence of the production of alkyloxy-derivatives in the interaction of the silver salts of hydroxy-acids with alkyl iodides, and t o find a modifi- cation of the reaction which might serve as tt practical method for their preparation. We have, accordingly, made further experiments on the production of alkyloxysuccinates from silver malate, and, Mr. Brame having kindly left us to continue his work, we have examined the product of the action of isopropylic iodide on silver tartrate for di-isopropoxysuccinic acid.We find that this compound is actually produced, and conclude, therefore, that a similar reaction occurs, although probably to a smaller extent, when other alkyl iodides are used. We find further that the ethereal malstes and tartrates can be readily alkylated by means of alkyl iodide in the presence of silver oxide, the reaction furnishing a convenient method of preparing the optically active mono- and di-alkyloxysuccinic acids from malic and tartaric acid respectively. The ethereal di-alkyloxysuccinates are highly active compounds, and their presence even in small quantity would account for the abnormally high rotation of the ethereal tartrates prepared from silver tartrate. Observations made on the metallic salts of diethoxysuccinic acid also explain the apparently anomalous results obtained by Rodger and Brame in the hydrolysis of methy lic tartrate.Action of AZkyZ Iodides on SiZvei* 3hZate. I n former experiments with ethylic iodide (Zoc. cit,), the crude distilled product of the reaction had always nearly the same rotation, - 14' ( I = 1). We now find that, by modifying the conditions, a somewhat more active liquid is obtained, although in no case is the proportion of ethoxysuccinate produced large enough to admit of its being separated from the malate. Thus, by adding the iodide (3 mols.) gradually to the silver malate (1 mol.), the treatment being otherwise the same as before, a product mas obtained which, without fractional distillation, gave the rotation -15.31O.Even when 2 mols. of iodide only were used and benzene added to moderate the action, con- ditions which should be unfavourable to the hydroxyl group being attacked, the ethovysuccinate was formed as before, the ethereal salt obtained showing a rotation almost identical with that just quoted. I n attempting to prepare isobutylic malate by the silver salt method (Trans,, 1896, 69, 824), the product was found t o consist mainly of free acid, which, however, mas not further examined at the time; as it seemed possible that this result might be due to theACTIVE MONO- AND DI-ALKYLOXYSUCCINIC ACIDS, ETC. 15.5 formation of isobutoxysuccinic acid, we have investigated the reaction more closely. The method employed was the same as bRfore, but the free organic acid was removed from the product before distillation by allowing it to stand over potassium carbonate.I n an experiment in which 92 grams of malate were added gradually to 167 grams of iodide, the yield of ethereal salt amounted to only 5 grams, and in another experiment, in which the order of mixture mas reversed, the yield was still less. The free organic acid, which was isolated as in a previous similar case (Trans., 1898, 73, 299), gave, on heating with a solution of barium hydroxide, n large quantity OC barium malate ; when dried at 160", it was found to contain 50.89 per cent. of barium, the calculated number being 50.93. The filtrate from this, on evaporation, left a less granular and more soluble salt, which analysis showed to be barium isobutoxysuccinate contaminated with some malate.Great difficulty was experienced in freeing the isobutoxy- succinic acid from malic acid. We found, finally, that although both barium salts are precipitated on boiling their aqueous solutions, the isobutoxysuccinate differs from the malate in redissolving readily when the solution cools, which enabled us to obtain the isobutoxy- succinate as a flocculent powder approximately free from malate. The results of the combustion of the substance, dried a t 160°, were as f ollowsl' I. C = 28-93. H = 4.08 ; Ba = 4 N 1 per cent. C8H,,05Ra requires C = 29.54 ; H = 3.69 ; Ba = 42.16 per cent. 11. C=29.03. H=4*05; Ba=43*36 ,, ,, In very dilute aqueous solutions (c=0.(1132) at 13', the salt showed the specific rotation -21.4'.The silver salt could not be obtained by precipitation. The sodium salt, prepared from the barium salt, gave in aqueous solution the specific rotation - 27.8" (c = 1.888), and, on analysis, was found to contain 19-46 per cent. of sodium, instead of the calculated number, 19.66. The rotations quoted are much higher than those of the corresponding malates, and are such as butoxysuccinates might be expected to exhibit. The 5 grams of ethereal salt, mentioned above, contained a small proportion of isobutylic isobutoxysuccinate. This mas evident from its high observed rotation, - 15.28' in a 100 mm. tube, that of the corresponding malate being only - 11.60' (Zeit. physikal. Chena., 1895), 17, 249), and was confirmed by the detection of barium isobutoxy- succinate in the product of hydrolysis. The quantity of substance was too small to admit of its being purified, but it showed a specific rotation nearly the same as that quoted above, namely, - 20.81' at 10' for c = 1.538.These observations show that the reaction between isobutylic iodide and silver malate does not follow the normal course,156 PURDIE AND PITKEATHLY: PRODUCTION OF OPTICALLY but that the main product is free malic acid, produced probably by the decomposition of the iodide into isobutylene and haloid acid, and that a considerable quantity of isobutoxysuccinic acid is also formed. Mr. J. C. Irvine mas good enough to examine for us the action of secondary butylic iodide on silver malate, in the hope that this iodide, like isopropylic iodide, would yield a larger proportion of the alkyloxy- acid.He obtained from the product only a small quantity of a very soluble barium salt of wax-like appearance which, although it could not be obtained quite pure, was evidently a barium butoxysuccinate. On combustion, it gave results approximating t o the calculated numbers, and its specific rotation in dilute aqueous solution, - 20*97", was practically the same as that of the isobutoxysuccinate. Action of Igoprop$ic Iodide on Silver Tartrate. Isopropylic iodide was used in this experiment, previous results having shown that it is more prone than other iodides to the reaction by which the alkyloxy-acid is produced. Sixty-seven grams of silver tartrate (1 mol.) were gradually added to 134 grams of the iodide (about 4 mols.) previously diluted with an equal volume of benzene, and the mixture was treated as in previous similar experiments. After distilling off the benz- ene and unaltered iodide, and shaking the residual liquid with a solution of sodium carbonate, a small quantity of an oily, ethereal salt remained, which, as it mas too dark coloured for polarimetric observation, was diluted with an equal bulk of alcohol and then examined in a 100 mm.tube, The observed rotation, about + 2 5 O , showed t h a t the substance was far more active than any of the ethereal tartrates. A crude, syrupy acid, obtained from this by hydrolysis with potassium hydroxide, acidifying with sulphnric acid, and extracting with ether, showed the specific rotation +%lo in about a 10 per cent.solution, an activity much exceeding that of tartaric acid. The barium and magnesium salts did not crystnllise ; the calcium salt was very soluble i n cold water, but was precipitated as a crystalline powder on boiling its aqueous solution. Estimations of calcium in the salt, dried at 130°, gave the results 14.77 and 14-89 per cent., the calculated percentage for calcium di-isopropoxysuccinate being 14.70. The production of the alkyloxy-compound in the reactions, which have been described in this and previous papers, appears t o be due t o some of the ethereal salt of the hydroxy-acid, which is-formed in the first instance, reacting further with alkylic iodide and unaltered silver salt with the formation of silver iodide, ethereal salt of the alkyloxy- acid, and free hydroxy-acid, which is always present in the product.The free alkyloxy-acid or its acid alkyl salt, which also frequently results from the reaction, may be produced from the normal alkylACTIVE MONO- AND DI-ALKYLOXYSUCCINIC ACIDS, ETC. 157 salt by water accidentally present, or by a reaction suoh as the following, in the case, for example, of silver malate and ethylic iodide, Consideration of the reaction in question suggested that the alkyla- tion would probably be much more complete if the ethereal salt of the hydroxy-acid was first prepared and then treated with alkyl iodide in the presence of silver oxide, or other metallic oxide of a similar nature. Ethylic malate, ethylic iodide, and lead oxide gave a negative result, but the product obtained by heating the malate and iodide with mercuric oxide yielded, on distillation in a vacuum, an ethereal salt much more active than the original malate, the rotation having risen from - 1 1 .8 O to - 3 0 * 7 O ( I = 1). A mixture of ethylic malate and ivopropylic iodide reacted very vigorously with silver oxide, and gave an ethereal salt showing the rotation - 30.5'. As these results indi- cated that the expected reaction had occurred, the action of ethylic iodide on ethylic malate and on ethylic tartrate in presence of silver oxide was examined in detail. OH* C,H3(COOAg)2 + 2EtI = OEt* C,H,(COOEt)*COOH + 2AgI. Pyepc6mtion of Etkgh'c Ethom~succinnte from EtJqliC Afcdute. The materials used were 52 grams of ethylic malate, the rotation of which was a= - 1 1 * 8 3 O (I= 1, t = 6O), 86 grams of ethylic iodide, and 64 grams of dry silver oxide, these proportions being chosen on the assumption that the reaction occurs in accordance with the equation OH*C,H,(COOEt), + 2EtI + Ag,O = OEt*C,H,(COOEt), + EtOH + 2AgI.The mixture, which underwent an energetic reaction on being gently warmed, mas afterwards heated for some time on a water-bath, then diluted with benzene, filtered," and distilled under reduced pressure, when it yielded 43 grams of a liquid having a nearly constant boiling point, and showing the rotation - 4 1 . 2 1 O in a 100 mm. tube at 6'. Assuming that the liquid consisted of only ethylic ethoxysuccinate and malate, the rotation indicated the presence of about 60 per cent. of the former compound. To remove the malate, the mixture was shaken repeatedly with a cold 10 per cent.aqueous solution of potassium hydroxide until the residual oil was reduced to about one-half its original weight. The oil, after being washed with mnt,er and dried with calcium chloride, mas found on distillation to boil at the same temperature as ethylic cl-ethoxysuc- cinate formerly prepared (Trans., 1895, 67, 972), namely, at 124O under a pressure of 10 mm., and its analysis gave the following results agreeing with the composition of that substance. * The silver rcsi(1iies froin these and the sncceeding espcriments were. black aild their composition reinairis to be esamiued. VOL. LXXV. 31158 PURDIE AND PITKEATHLY : PRODUCTION OF OPTICALLY Found : I. C-54-63 ; H =8*68 per cent. 11. C=54*79 ; H-8.44 ,, ,, Calculated : C-55.05; H=8*26 per cent.A determination of the specific rotation of the liquid at 6' gave the following result : a= - 58.85', E = 1, d 6'/4'= 1*0501, hence [.ID = - 5 4 ~ 1 4 ~ . The specific rotation of ethylic cl-ethoxysuccinate from the active acid, which was obtained by resolution of the racemoid com- pound (loc. cit., p. 979), was + 55.48'. The somewhat lower rotation now found is accounted for by the substance being contaminated with some ethylic fumarate, produced probably in the preparation of the ethylic malate. The specific rotation of an aqueous solution of I-ethoxysuccinic acid, which was obtained by hydrolysing the ethylic salt, acidifying the product and extracting it with ether, was found to be - 31.14' ( c = 8.0588, t = 7'), a number about 3' lower than that previously found, the discrepancy here being greater than in the Case of the ethylic salts owing to the fumaric acid being chiefly con- tained in the crystallised portion of the acid which was used in the determination. For further comparison of the acids from the two sources, observations were made on the acid ammonium salt which could be free'd by crystallisation from fumarate. A determination of the specific rotation of the hydrated salt in aqueous solution at 8" gave the following result : a = - 6*00', I= 2, c = 10.0288, hence [a]= = - 29.91'.The value formerly found for similar concentration at 17' was 28.46'. To obtain evidence of the purity of the compound, a silver salt was made from it, and analysed with the following result.Found : C = lS.90 ; H = 2.37 ; Ag = 57.76 and 57-69 per cent. C,H,O,Ag, requires C = 19.15 ; H = 2.1 3 ; Ag = 57.45 per cent. The yield of alkyloxysuccinic acid by the process which has been described would probably be increased by employing a larger propor- tion of alkyl iodide and silver oxide, in order to allow €or the loss which is doubtless entailed by their partial direct interaction. Pyepurcction of Etlhylic d-D,iet?boxysuccinate fvom EtAylic Tartrate. Attempts have been frequently made to alkylate the alcoholic hydroxyl groups of tartaric acid, but without success. Perkin (Trans., 1867, 20, 155), by the action of ethylic iodide on ethylic monosodio- tartrate, obtained an oil which he thought was probably ethylic mon- ethyltartrate, but the later researches of Lassar Cohn (Bes.., 1887,20, 2003), Mulder (Rec.T?w. Clhim., 1889, 8, 361) and Freundler (Bull. Xoc. (%xh2., 1894, 11, 308) have shown that neithei- the sodium nor potassium derivatives of ethylic tartrate react in the usual way with alkyl iodides. The ethylic diethoxysuccinate which Michael andACTIVE MONO- AND DI-UKYLOXYSUCCINIC ACIDS, ETC. 159 Bucher (Bey., 1896,20, 1792) found to be one of the products of the action of sodium ethoxide on ethylic dibromosuccinate and on ethylic acetylenedicarboxylate, was shown by these authors to be the unsym- metrical compound. The proportions of ethylic iodide and silver oxide employed in our experiments were 6 mols. of the iodide and 3 mols. of the oxide to 1 mol. of the tartrate, that is to say, an excess of one-half over the calculated quantity, assuming the reaction to proceed in the sense indicated in the case of ethylic malate.On adding the oxide to the mixture of iodide with tartrate, the reaction set in spontaneously, and became so violent that it had to be moderated by cooling. The liquid. product, obtained as described under et hylic ethoxysuccinate, was about equal in quantity to the tartrate employed, its boiling point was nearly constant, and its observed rotation varied in different preparations from +83*5O to +92*5O in a 100 mm. tube. As the percentage numbers found, on analysis, were somewhat lower than those calculated for ethylic diethoxysuccinate, and as it proved impossible to purify the substance either by fractional distillation or by shaking with water, which we expected would remove unaltered ethylic tartrate, if present, we had to resort to the method of partial hydrolysis by shaking with a 10 per cent.aqueous solution of potassium hydroxide. The p~ocess entailed a considerable loss of material, but the residual oil, on redistillation (b. p. 149-151' at 15 mm.), had increased in rotation to +97*5', and on analysis gave results in agreement with the calculated numbers. Found : I. C = 54.99 ; H = 8.71 per cent. 11. C=54*87 ; H=8*67 ,, ,, Calculated for C12H,,06 : C = 54.96 ; H = 5.40 per cent. The specific rotation of the liquid a t 18' was as follows : a = + 97-52", I = 1, d 1So!4O = 1.0460, hence [a], = + 93.23'. The ethereal salt of lower activity, which was removed by the partial hydrolysis, gave an uncrystallisable acid, which me intend to examine further.d-Diethoxysuccinic acid, which was obtained from the ethylic salt in the same manner as the monethoxy-acid, is sparingly soluble in benzene, readily soluble in ether, alcohol, chloroform, and water, from which it crystallises in long prisms melting a t 126-128O. The results of the analysis of the substance, dried at loo', were as follows, Found : I. C = 46.86 ; H = 7.04 per cent. 11. C=46*81 ; H=6.90 ,, ,, Calculated for C,H,,06 : c' = 46.60 ; H = 6.80 per cent. The acid showed the following specific rotations in aqueous soh- M 2160 PURDIE AND PITKEATHLY : PRODUCTION OF ACIDS, ETC. tions at 20' : U = + 6.73, c = 10.1488, l= 1, hence [ + 66.31' ; a= +2*70', c-4.0595, I= 1, hence [a]== + 66.51'.The silver salt is soluble in water, and does not decompose much on evaporating the solution. An estimation of silver in the salt gave the result; 51-01 per-cent., the calculated number being 51.43. The acid potassiunz and acid anzmoniunz salts are crystalline. The normal sodium salt, in aqueous solution at 17', showed the specific rotation + 41.11' (c= 3.138) ; the residue left on evaporating the solution, dried at 120°, was found to contain 18.35 per cent. of sodium instead of the calculated number, 18.40. The ccclciuwz salt is very soluble, and was not obtained in the crystalline state. The bnviunz salt, which is characteristic, is sparingly soluble in cold water, a,nd crystallises readily in large, glassy prisms, contniuiiig apparently 4H,O, which is lost at 120-139O.Analysis of the anhydrous salt gave the following resul ta. Pwnd : C = 27.78 ; H = 3.77 ; Ba = 39.94 and 40.12 per cent. An aqueous solution of the salt at 16' had the specific rotation Ethglic d-diethoxysuccinate is also obtained by the direct action of ethylic iodide and silver oxide on tartaric acid, but the yield is smaller than when the alkyl t,artrate is used as the starting point. From 17 grams of tartaric acid me obtained in this way 12 grams of an ethereal oil having the same boiling point, and the same observed rotation, + 85', as the crude ethylic diethoxysuccinate prepared from e t h y lic tartrate. The optical effect of t'he replacement of the alcoholic hydrogen of tartaric acid by alkyl mdicles is of the same nature as that which attends a similar substitution in lactic and malic acids ; the sign of rotation, defined in the case of lactic acid as that of its salts, remains unchanged ; a st,riking rise of activity, observable more particularly in the free acids and the ethereal salts, is produced, and the specific rotation of the acids in aqueous solutions of varying concentration becomes mare constant.Thus, in passing from tartaric t o diethoxy- succinic acid the molecular rotation of the ethylic salt is raised from + 15.8' to + 244*3', and that of the free acid at similar concentration from + 20.6' to + 136.6". The ionic rotation, however, does not ex- perience a proportional rise, the result being that, whilst in the case of the three hydroxy-acids mentioned the molecdar rotations of the alkali salts in dilute solution greatly exceed those of the free acids, these rotations become nearly equal in the citw of the dkyloxypro- pionic compounds, and the order of their value is reversed in the case of the mono- aud di-alkyloxysuccinic compounds. Calculated : C = 28.15 ; H = 3.52 ; Bn = 40.15 ,, ,, + 26 25' (C == 1.8092).CROSSLEY AND LE SUEUR : CONSTITUTION OF FATTY ACIDS. 161 Our observations furnish a satisfactory explanation of the apparently anomalous results obtained by Rodger and Brame, which have been already referred to, An admixture of 6 per cent. of ethylic d-di ethoxysuccinate would suffice to account for the high rotation of the ethylic tartrate which they prepared by the silver salt method, but the difference between the rotations of the products of hydrolysis of such a mixture and of pure ethylic tartrate respectively would not, under the conditions of the experiment described by them, amount to more than O*1-0*2ro.* The action of alkyl iodides and silver oxide on the alkyl salts of optically active hgdroxy-acids furnishes a general method of obtaining the active alkyloxy-acids. We have used the method with success for the preparation of alkyloxypropionic and alkyloxyphenylacetic acids from active lactic and mandelic acids, and we are a t present studying the application of the alkylating agent to the a-lkyl tartrates in general and to other compounds. UKITI%D c'OLtICGE OF ST. SALVATOR AND ST. LRONAItD, C'SIVERSITP O F ST. ANl>ItEWS.

ISSN:0368-1645    

DOI:10.1039/CT8997500153

出版商:RSC    

年代:1899

数据来源: RSC

摘要:

CROSSLEY AND LE SUEUR : CONSTITUTION OF FATTY ACIDS. 161 SIX. -De t eq- 11 1 i~za t io I I of the Comt i t ti tio 11 o j E’ut t y Acids. Pwt I. By ARTHUR WILLIAN CROSSLEY and HENRY RONDEL LE SUEUR. SOME short time ago one of us, in conjunction with Professor Perkin (Trans., 1898, ’73, l), described an investigation of a complicated mixture of fatty acids derived from the fusion of camphoric acid with alkalis; as the difficulties encountered in identifying some of the fatty acids were very great, it was considered desirable to t r y and devise a method for the determination of the constitution of such acids, and the object of this paper is to give a short account of experiments which have been carried out in this direction. So far as our present experiments go, we think they may be described as satisfactory, and altbough the method may not be an infallible one, i t seems likely to prove of considerable importance as a means of establishing the constitution of organic acids.The method of procedure which was suggested to us by Professor Perkin is the following. Starting with n fatty acid, X*CH,* CH,* COOH, this is first converted into the ethylic salt of the monobromo-deriva- tive by Volhard’s process (Annalen, 1887, 242, 61) ; from the work of * The experiment referred to was made on the methylic tartrates, but this would not niaterially alter the result as stated above.162 CROSSLEY AND LE SUEUR: DETERMINATION OF THE Acid employed. Auwers and Bernhardi (Ber., 1891, 24, 3209) and others, there can be n; doubt that;, under these conditions, the bromine atom takes up the a-position, yielding the substance X* CH,* CHBr*COOEt.The brom-ethereal salt is then treated with quinoline or diethylaniline (compare Weinig, Annalen, 1894, 280, 253), whereby the elements of hydrobromic acid are removed, and the ethylic salt of an unsatu- rated acid of the acrylic series, X*CH:CH* COOEt, is produced. The free acid obtained from this salt by hydrolysis is then oxidised, first with potassium permanganate, giving rise to the corresponding dihydroxy-acid, X* CH(OH)*CH(OH)*COOH, and then with chromic acid, when the molecule is broken down a t the position occupied by the double bond in the unsaturated acid, giving X*COOH and GOOH* COOH. The result is, therefore, the production of oxalic acid and a fatty acid (or ketone) containing two carbon atoms less than the original acid, and as the number of isomerides decreases greatly Eith loss of two carbon atoms, the possibility of identification is much enhanced.We have carried out this process with three acids, namely, valeric, iso-valeric, and iso-butylacetic acids, as we considered that the oxidation products of the acids of the acrylic series corresponding with these fatty acids would be typical examples of what might be expected to be met with in actual determinations. Thus valeric acid gives ethylacrylic acid, and this, on oxidation, propionic acid (normal acid) ; iso-valeric acid gives dimethylacrylic acid, which then yields acetone (ketone) ; and iso-butylacetic acid gives iso-propylacrylic acid, and, on oxidation, iso-butyric acid (iso-acid).I n all cases we have been careful to note the yields of substances obtained in the various stages, and there is here appended a tabulated list of results. The numbers express the percentage yields, and are referred, in the case of the unsaturated ethereal salt and acid, to the amounts theoretically obtainable from the brom-ethereal salt employed ; and in the case of the " acid or ketone produced on oxidation," to the amounts theoretically obtainable from the unsaturated acid used. With the three acids mentioned, the method works well. Broin- Unsaturated Unsaturated Acid or ketone produced on oxidation. acid. ethereal ethereal salt. salt. Valeric ac id.. ,. . . . . , . . &o-Valeric acid.. .. . . . iso-Butylacetic acid. 97 3 52.0 41 -0 53'0 - 80.0 55-60 47.0 93.0 70 '0 61 -0 60.0 The poor yield of unsaturated ethereal salt obtained from ethylic bromovalerate is accmnted for by the fact that there is also pro-CONSTITUTION OF FATTY ACIDS.PART I. 163 duced a considerable quantity of some substance of higher boiling point, which is at present under investigation ; and the comparatively small amount of the solid dimethylacrylic acid obtained from its ethylic salt is due to the fact that an oily substance is produced at the same time (see page 164). I n no case was oxalic acid identified in the products of the reaction, nor could it be expected to resist the action of the strong oxidising agents employed, We have experimented with both quinoline and diethylaniline, using them as reagents for the elimination of the elements of hydro- bromic acid, and find that, with the lower fatty acids, the one gives quite as good results as the other, but with the higher fatty acids diethylaniline is to be preferred.For example, in the case of ethylic bromisobutylncetate, the 42 per cent. yield of ethylic isopropyl acrylate, obtained when using quinoline, was increased to 70 per cent. by employing diethylaniline. Quinoline always gives rise to tarry products, which are not easy or agreeable t o work with, whereas diethylaniline does not ; in the latter case, however, the substances require to be heated together for a much longer time, and it is very difficult toeliminate the last traces of hydrobromic acid. As, hom- ever, the Unsaturated ethereal salts are subsequently heated with alcoholic potash, the latter objection is of no great moment.We intend to further test the efficacy of the method by trying it on other acids, such as ( ( 4 ) stearic acid, and from preliminary experi- ments already made with this acid, it seems highly probable that the various reactions will take place as expected, The insolubility of the hydroxylated higher fatty acids in water may render the oxidation with chromic acid a difficult operation, in which case it will be of interest to see whether fusion with potash will serve a similar purpose. ( b ) It will be noticed that, among the acids examined, none contain alkyl groups in the a-position. I n such a case, as, for example, ethyl- isopropylscrglic acid, quite a new point is raised.This acid, %,H,*cH(C, H,)*COOH, still contains one a-hydrogen atom, and should, therefore, yield an a-brom-ethereal salt in the usual manner; but when the latter is treated with quinoline, there are two possible ways in which hydro- bromic acid may be eliminated (compare Perkin, Trans., 1896, 69, 1466), giving rise to (CH,),CH*$* COOH (CH,),C:y* COOH or 7% CH3 YH CH3 Dimethyl-a-ethylacrylic acid. 1iethyl.a-isopropylacrylic acid. The study of the oxidation products of the unsaturated acid or acids produced would, therefore, be of special importance.165 CROSSLEY AND LE SUEUR: DETERMINATION OF THE ( c ) The method may also prove to be applicable in the case of di- basic acids, and me propose to t r y it on pimelic (isopropylsuccinic) aoid. EXPERIMENT A L. Acetone from Isovaleric Acid.Instead of starting with isovaleric acid, the ethylic salt of a-brom- isovalerate supplied by Kahlbaum was employed, which, on distillation, boiled constantly at 185-186', and a bromine determination gave the following numbers. 0.2514 gave 0.2375 AgBr. C,H,Br-COOC,€15 requires Br = 38.28 per cent. Treatment of Et?qlic a- Bi*omisovaZerccte with Quinoline. -Wei nig (An- nalen, 1894,280,253) has shown that diethylaniline may be used instead of alcoholic potash for the elimination of the elements of hydrobromic acid, and later Perkin and Goodwin (this Journal, 1896, 69, 1470) described experiments in which they employed quinoline for the preparation of dimethylacrylic acid from etb ylic a-bromisovalerate. We have followed their instructions exactly, using 50 grams (1 mol.) of the brom-ethereal salt and 70 grams (2 mols.) of freshly distilled coal-tar quinoline ; on fractionating the product, it was found to distil between 153' and 155' as a colourless oil of penetrating odour.The yield is 80 per cent. of the theoretical. This ethereal salt is readily saponified by alcoholic potash, and the dimethyZccrp!ic mid formed 1 oils constantly a t a temperature of 114O under a pressure of 40 min. On standing, the distillate solidifies almost completely to rz mass of needle-shaped crystals, which, after being freed from the mother liquor by spreading on a porous plate and recrystallisation from light petroleum (b. p. 60-80°), melted at 68*5-69', and gave the follomiiig results on analysis. Br = 38.50. 0.1047 gixve 0,3296 CO, and 0.0744 H,O.C = 59.80 ; H = 7.90. C,HSO, requires C = 60.00 ; H = 8.00 per cent. The yield of pure acid is from 55-60 per cent. of the theoretical obtainable from the brom-ethereal salt employed. On extracting the porous plate just mentioned with ether, a small amount of an oily liquid was obtained which showed no signs of solidifying even after long st.anding, and which was not further investigated. Perkiii and Goodwin (loc. cit.) also mention this oily bye-product. Tyeatment of EthyZic a-Bro?&sovuZerccta with Dietl~yZuniZine.-In using quinoline for the elimination of the elements of hydrobromic acid, there is always a considerable quantity of tarry matter formed, and in later experiments we found that diethylaniline could be used withCONSTITUTION OF FATTY ACIDS.PART I. 165 advantage instead of quinoline ; the yield of unsaturated ethereal salt is considerably increased, and no tarry products are produced, although the mixture requires t o be heated for a,much longer period. The yield of e thylic dimethylacry late as obtained in the experiments just described is good, but we thought it of sufficient interest t o t r y the effect of diethylnniline on ethylic a-bromisovalerate. The process was carried out exactly as described on page 166. There is, however, in this case, no particular advantage t o be de- rived, for the yield of ethylic dimethylacrylate is no higher than when quinoline is employed. O.ciddion of Dinzetlqlacrylic Acid with Potassium Pemzangctnate.- Ten grams of dimethylacrylic acid were aeutralised with potassium hydroxide and dissolved in 600 C.C.of water ; the whole was stirred with a turbine, and maintained at O'throughout the operation ; ft rapid current of carbonic anhydride was then passed in, and a cold solution of 12 grams of potassi~im permanganate in 400 C.C. of water gradually added from a tap funnel. After standing overnight, the liquid was filtered from precipitated manganese dioxide, and evaporated to a small bulk; no attempt was made to isolate tohe dihydroxy-acid produced, but the liquid was a t once submitted to the process of :- Oxidation with Potassium Diclwonznte and S'ul$uric Acid.-For this purpose, the evaporated liquid was placed iu a flask connected with a condenser, and, after warming to 70" on the wnter-bath, a solution of 30 grams of potassium dichromate in dilute sulphuric acid was slowly run in, the heating continued for eight hours, and the whole steam distilled.The distillate, which was slightly acid to litmus paper, was carefully neutralised with potassium hydroxide, and again steam dis- tilled ; on adding an alcoholic solution of parabromophenylhydrazine to the distillate, there was ail immediate and copious precipitate, which was collected and dried on a porous plate, After recrystallisation from light petroleum (b. p. SO-loo'), it was obtained as beautiful, shining scales melting at 94'. Bromine determinations gave the following results. I. 0.2886 gave 0.2314 AgBr. Br = 34.09. 11. 0.1226 ,, 0*099S AgBr. Br = 34-58, (CH,),C:N*NH* C,H,Br requires BF = 35-24 per cent.Although the figures obtained are not so good as might be desired, there can be no doubt that this substance is the parabromophenyl- hydrazine compound of acetone (compare Neufeld, Annalen, 1888, 248, 96), the ease with which it undergoes decomposition accounting for the lowness of bromine found. The parabromophenylhydrztzine compound obtained weighed 10*7 grams, whereas the amount theoretically obtainable from 10 grams of166 CROSSLEY AND LE SUEUR: DETERMINATION OF THE dimethylacrylic acid is 32.7 grams ; this is a 47 per cent. yield of the substance. The residue from the steam distillation was examined for oxalic acid, after removing the chromium by the use of sulphurous acid and then boiling with excess of sodium carbonate. No traces of the acid were found, nor is this to be wondered at, as, when produced, it would at once be further oxidised to carbonic anhydride and water, in presence of the strong oxidising agent employed. This remark also applies to the other oxidations mentioned in this paper ; in no case was any oxalic acid detect,ed.P.r.opiowic Acicljiiwn V d e y i c Acid. P.r.epcwatio.12 of VaZeTic AciL-Tbis acid was prepared by the eon- densation of ethylic sodiomnlonate and normal propylic iodide, and, after saponification, heating the propylmalonic acid so formed. It boiled constantly between 184' and 185" (uncorr.). Bro?hcction of Yaleric Acid.-Forty-four grams of valeric acid mere brominated with 135 grams of dry bromine and 4.5 grams of amorphous phosphorus in the usual manner, the product slowly poured into three times its volume of absolute alcohol, and the ethylic a-bromovalerate extracted with ether and distilled under diminished pressure.It boils constantly a t a temperature of 110" (40 mm.), and is obtained in nearly theoretical amount (97.5 per cent.). Treatment of Ethyllic a-B~*o,uovtcllemte with Diethy1aniline.-Seventy- six grams (1 iiiol.) of the brom-ethereal salt, and 115 grams (2 mols.) of diethylaniline, were heated in two portions i n LL flask attached to an air condenser and containing a thermometer, so that the temperature of reaction could be noted ; this begins at about 1 7 5 O , and the thermometer rises rapidly to 190-200°, at which temperature the whole was maintained for 6 hours. The product, when cold, was poured into excess of dilute hydrochloric acid, and extracted with ether, kc., but as it was found to contain bromine, it was again heated with diethylaniline (1 mol.) for 16 hours at 190-200".After ex- tracting in the manner just described, the ethereal solution was dried over calcium chloride, the ether distilled off, and the liquid residue fractionated ; by this means, 24 grams of ethylic ethylacrylate were obtained boiling at 155-160'. This is only a 52 per cent. yield, which is accounted for by the fact that 12 grams of some substance of higher boiling point (270-280O) mas also produced, the nature of which is at present under investigation. Ethylic ethylacrylate is readily saponified by alcoholic potash, yield- ing ethylacrylic acid as a colourless, oily liquid, with pungent, charac- teristic odour, boiling a t 195-1 97" under atmospheric pressure, andCONSTITUTION OF FATTY ACIDS.PART I. 16'7 ahowiug no signs of solidification even when cooled to - 14". The yield of pure acid is 41 per cent. of the amount theoreticidly obtain- able from the ethylic bromovalerate employed. A portion of the acid was converted into the silver salt and anal y sed. 0.3510 gave 0.1834 Ag. Ag=52*25. Oxidation of EtlqZacr92ic Acid.-Fourteen grams of the acid were oxidised exactly as described on page 165, firstly, with 16 grams of potassium permanganate, and then with a solution of 45 grams of potassium dichromate dissolved in dilute sulphuric acid ; the mixture mas distilled in a current of steam, and the distillate, after neutralisation with potassium hydroxide, was evaporated to complete dryness, finally on the water-bath.The fatty acids obtained on distilling the residue with concentrated sulphuric acid were dried by standing for some time in contact with concentrated sulphiiric acid, and then fractionally distilled. Eventually, nearly the whole of the acids boiled between 137' and 143O, and a portion boiling a t 140° was converted into the silver salt and analgsed. C5H,0,Ag requires Ag = 52.17 per cent. 0.1914, on ignition, gave 0.1144 Ag. 0.2386 gave 0.1744 GO,, 0.0640 H20, and 0.1420 Ag. C,H,COOAg requires C = 19.S9 ; H = 8.76 ; Ag = 59.66 per cent. The fraction boiling between 137" and 1433 was then converted into the anilide by heating for 24 hours with twice its volume of pure aniline, and the solid product was repeatedly crystallised from light petroleum (b.p. 80-loo'), from which it separates in white, glist,en- ing plates melting at 102-103" (compare Crossley and Perkin, Trans., 1898, 73, 34). 0.1814 gave 15.2 C.C. moist nitrogen a t 21Oand 762 mm. N = 9.56. C,H,*CO *NH* C,H, requires N = 9-39 per cent. These data prove conclusively that the acid produced by oxidising ethylacrylic acid j n the manner described is propionic acid. The amount of propionic acid obtained was 5.5 grams, which corresponds with a 53 per cent. yield of the amount theoretically obtainable from the ethylacrylic acid used. Ag=59*77. c! = 19.92 ; H = 2.97 ; Ag = 59.51. Isobuty~ic Acid from hobuty~ncet~c Acid. Preparation of Isobutylacetic Acid-This acid was prepared by the condensation of ethylic sodiomczlonate with is0 butylic bromide, and168 CROSSLEY AND LE SUEUR : CONSTITUTION OF FATTY ACIDS.subsequent distillation of the product, after saponification with alco- holic potash. Bronzincction of hobutykccetic Acid.-Fi fty-two grams of the acid, 4.8 grams of amorphous phosphorus, and 140 grams of dry bromine were treated in the usual manner. Etlbylic a-bromisobzctylucetate was obtained as ft colourless, pleasant smelling liquid boiling a t 115' under a pressure of 43 min. The acid boiled at 198-200'. 0.1530 gave 0.1295 AgBr. Br= 36.01. C,H,,Br* COOC,H, requires Br = 35.87 per cent. The yield of the ethylic salt was 93 per cent. of the theoretical. Yrentnzeizt of Ethy lie Bro miso butylacetccte with Quiizo line or D lethyl- aniline.-Eighty-five grams of the bromethylic salt mere treated in two portions with quinoline exactly as described on page 164, and the unsaturated et hered salt was distilled, when 32 grams were obtained boiling a t 16S-169O a t the ordinary pressure.As this is only 42 per cent. of the amount theoretically obtainable, the effect of diethyl- aniline on tlie broni-ethereal salt mas tried, when the yield was in- creased to 70 per cent. It was, however, found exceedingly difficult to get rid of the last traces of halogen ; and even after a third treat- ment with diethylaniline, tlie substance did not give good results on analysis. I. 0.1040 gave 0.2526 CO, and 0.0966 €&O. C = 66.93 ; H = 10.31, Possibly this is due to the presence of traces of halogen. 11. 0.15'70 ,, 0.3890 CO, ,, 0.1416 H,O.C=66*36 ; H= 10.03. C,H,* COOC,H, requires C, = 67.60 ; H = 9.86 per cent. Perkin and Goodwin (Trans., 18'36, 69, 14'71) found that ethylic dimethylacrylate, prepared in a similar manner, did not give good results on analysis, but no explanation of the fact is offered. When hydrolysed with alcoholic potash, the oily, unpleasant smell- ing liquid boiling a t 169' is converted into isop~*o~~~lcc~~yZ~c m i d , which is a colourless, oily liquid of exceedingly unpleasant odour, boiling a t 133' (50 mm.) ; it does not solidify when cooled to - 15'. The yield is 61 per cent, of that theoretically obtainable. The silver salt is a white, amorphous, insoluble precipitate. On analysis, i t gave the following numbers. 0.2536 gave, on ignition, 0.1233, Ag. C,H,O,Ag requires Ag = 48.77 per cent. Oziclation of Isopopylucrylic Acid.-Twenty grams of the acid were oxidised with 30 grams of potnssiuiii permanganate, and afterwards with 60 grams of potassium dichromate dissolved in dilute sulphuric acid, and worked up exactly as already described on page 165; after careful fractionation of the acid, the portion boiling at 153-154' mas converted into the silver salt and analysed. Ag = 48.58.DOOTSON : DERIVATIVES OF ACETONE DICARBOXYLlC! ACID. 169 0.2044, on ignition, gave 0.1134 Ag. 0.2154 gave 0.1900 CO,, 0.0682 H,O, and 0.1198 Ag. C,,H,* COOAg requires C= 24.61 ; H = 3.59 ; Ag = 55-38 per cent. The remainder of the acid (b. p. 152-158") was converted into the nnilide which crystallised from light petroleum (b. p. S0-lOO0) in glistening, feathery needles melting at 104-105" (compare Trans., 1898, 73, 34). Ag = 55.47. C = 24.10 ; H = 3.52 ; Ag = 55.61. 0,1296 gave 10 C.C. moist nitrogen a t 80" anti 762 mm. N=S*84. C,H,*CO*NH* C,H, requires N = 8-59 per cent. The acid (50 per cent. yield) produced by the oxidation of isopropyl- acrylic acid was, therefore, isobutyric acid, and the oxidation had taken place in the manner expected. CHEMICAL LABORATORY, ST. THOMAS'S HOSPITAL.

ISSN:0368-1645    

DOI:10.1039/CT8997500161

出版商:RSC    

年代:1899

数据来源: RSC

摘要:

DOOTSON : DERIVATIVES OF ACETONE DICARBOXYLlC ACID. 169 XX-Some HulogeiA Dc&xxtiz*cs o f Acetone Diccwb- oxylic Acid. Pco-t I, By FREDERICK W. DOOTSON, &LA. THE extremely reactive nature of the hydrogen atoms of acetone- dicarboxylic acid, CO(CH,* COOH),, has already been shown by a long series of experiments, but, so far, no attempt to replace them by halogens has been recorded. This is the more remarkable, since halogen substitution products could not fail to lend themselves to reactions which would yield derivatives not easily obtainable by other means. The present papel‘ is intended as a preliminary note of investigations undertaken in this direction. Acetonedicarboxylic acid in aqneous solution reacts readily with chlorine and bromine, evolving carbon dioxide, aiid yielding an oil which attacks the eyes, and which, froin its general properties, is probably a mixture of the halide derivatives of acetone.The inter- action of these halogens with the ethylic salt, however, proceeds smoothly and with but little decomposition, yielding ultimately ethylic tetrahalideacetonedicnrboxylate. Etlylic tetrncl~lorcicetoiaedicc6~~bo:~~~kcte is easily obt ained by passing a stream of dry chlorine into ethylic acetonedicnrboxylate ; the latter, prepared by the action of hydrogen chloride on an alcoholic solution of the acid (Annalen, 189 1,261, ly’i), is sufficiently good for the purpose vithout further purification. Hydrogen chloride is freely evolved,170 DOOTSON : SOME HALOGEN DERIVATIVES OF and the liquid becomes hot ; the operation is continued until chlorine is no longer absorbed, when the contents of the flask are found to have increased in weight by about 65 per cent., the reaction as it approaches completion being facilitated by heating on the water-bath. The heavy, pale yellow, oily product is fractionated under reduced pressure, when the greater part of the liquid distils over between 180" and 183' (16 mm.pressure) ; this fraction is nearly pure ethylic tetrachloracetonedicarboxylste. A readier method of purification is found in fractional crystallisation. On cooling in a freezing mixture, a nearly solid mass is obtained which, after being drained by the aid of the filter pump, is strongly pressed between folds of bibulous paper ; the crystals thus obtained are practically pure.Ethylic tetrachloracetonedicarboxylnte is very soluble in ether, benzene, alcohol, chloroform, carbon bisulphide, and light petroleum, but insoluble in water. On recrystallisation from alcohol, it is obtained in large, lustrous, colourless, rectangular plates or leaves, which melt constantly at 30-30.5" (uncorr.). 0.3660 gave 0,4220 CO, and 0.0947 H,O. H = 2.87 ; C=31*44. C,H,oC1,O, requires C = 31.81 j H = 2.34 ; C1= 41.68 per cent. Since all the hydrogen atoms of the acid radicle have been dis- placed by chlorine, the constitution of this substance is without doubt represented by the formula CO(CCl,* C'OOC,H,),. So far this ethereal salt has resisted all attempts to saponify it, Cold, dilute aqueous potash seems to be without action ; aqueous soda or potash, on warming, liberates alcohol, but the acid at the same time decomposes with the formation of oxalic acid, recognised by the insolubility of the calcium salt in acetic acid, by a melting point determination (104' uncorr.), and by a titration of the crystallised acid.Sodium ethoxide in alcoholic solution behaves in a similar manner, whilst water, hydrochloric acid, and hydrobromic acid at 2003 are without appreciable effect. Action of AZcolt,oZic Potash.-If a cold alcoholic solution of potash be slowly poured into an alcoholic solution of the ethylic salt, the contents of the flask being kept cold, no potassium chloride separates, but after a short time a copious crop of colourless crystals is obtained ; these are exceedingly soluble in water, but only slightly so in alcohol.An analysis showed them to be the potassium salt of cZichZm*omocZonic acid (Conrad and Briickner, Ber., 1891, 24, 2993). The following numbers were obtained on analysis, 0.3455 ,, 0.5860 AgCI. C1= 41.87. 0.229'7 give 0.1587 I<,SO,. I< = 30.98. 0.2159 ,, 0.2480 A@. C1= 28.42. CCl,(COOK), requires K = 31-32 ; C1= 28.42 per cent.ACETONE DICARBOXYLIC ACID. PART I. 171 The mother liquor from these crystals was diluted, acidified, and extracted with ether, and the ethereal solution washed with water, dried over calcium chloride, and evaporated, when a liquid with a strongly acid reaction was left. A consideration of the action of ammonia on ethylic tetrachloracetonedicarboxylate, described below, leaves no room for doubt that this liquid is dichloracetic acid.Hence the reaction that takes place is represented by the equation OC(CC1,COOC2Ha)z + 3KOH = CCl,(COOK), + CHCI,. COOK + 2C,H,* OH. Action of Aqueous A9)tntonicc. --Ethylic t etrachlorace tonedicarb- oxylate dissolves readily in aqueous ammonia with evolution of heat, and, on standing, a bulky crop of large, colourless crystals separates, these, on being recrystallised several times from hot water, are obtained in thin, rhombic leaves or plates, which melt constantly at 204-205' (uncorr.), are very soluble in alcohol and hot water, and moderately in ether, light petroleum, and benzene. From the melt- ing point, although this is somewhat higher than that found by Conrad and Bruckner (Zoc. cit.), and on analysis, this substance was identified as dicl~lo~~onzulon~i~ii~e.0,2083 gave 0.1596 CO, and 0.0472 H20. C= 20.89 ; H=2*61. 0.1464 ,, 20.4 C.C. nitrogen at 18" and 768 mm. X= 16.57. 0.1470 ,, 21.1 C.C. ,, 19.5' and 750 mm. N== 16.58. CCl,(CONH2)2requiresC:=21*08; H=2*35;N= 16.40; C'1=41*42percent. The mother liquor from the dichloromalonamide, on concentration, yielded a crop of crystals which, after recrystallisation from hot water, were obtained in short, thick, colourless needles with ill-defined ends ; these crystals, which are very soluble in alcohol and hot water, and moderately so in cold water, melted sharply a t 98-99' (uncorr.). This, together with a nitrogen determination, was sufficient to identify them as dichlorncetccnticle (Ilantzsch and Zeckendorf, Bell., 1887, 20, 1309). 0.1684 ,, 0,2740 AgC11.C1= 41.75. 0.2000 gave 19.5 C.C. nitrogen at 1 7 O and 762 mm. CHUl,CONH, requires N = 1 1 *06 per cent. From these results, it follows that the intmachion of ethylic tetra- chloracetonedicarboxylate and ammonia must be represented by the following equation. N = 11.35. CO(CCl,COOC,H,), + 3NH, = CCl,(CONH,), + CHCl,* CONH, + 2C,H,* OH. From the above experiments, it appears that tetrachloracetone- dicarboxylic acid, if capable of existence at all, must be a very172 YOUNG : ACTION OF CHLOROSULPHONIC ACID ON THE unstable compound towards alkalis, and that the displacement of hydrogen atoms by chlorine exercises a remarkably modifying influence on the nature of the products of decomposition, whilst the chlorine atoms themselves show an unexpected degree of stability.An attempt to obtain condensation products by the interaction of the dipotassium derivative of ethylic acetonedicarboxylate and ethylic tetrachloracetonedicnrboxylate in alcoholic solution was unsuccessful, there being no separation of potassium chloride evenafter long-continued boiling. The action of bromine on ethylic acetonedicarboxylate is very similar to that of chlorine, hydrogen bromide being freely evolved and the liquid remaining almost colourless. After adding excess of bromine and heating for some time on the water-bath, the contents of the flask were shaken with dilute sodium c.zrbonste solution until the colour was discharged, extracted with ether, and the ethereal solution mashed several times with small quantities of water. After drying and evaporating the ether, a pale yellow oil was left, which became very viscid in a freezing mixture, but could not be obtained crystalline. The reactions of this oil, although not identical with, are very similar to those of ethylic tetrschloracetonedicarboxylnte, and will be described in a future communication. USIVICRSITT CHEMICAL LABORATOXY, CAYBHIDGE.

ISSN:0368-1645    

DOI:10.1039/CT8997500169

出版商:RSC    

年代:1899

数据来源: RSC