Contributions towards the history of caproic and œnanthylic acids / by J.S. Brazier and G. Grossleth.

  • Brazier, James S. (James Smith)
Date:
[1851?]
Catalogue details

Licence: Public Domain Mark

Credit: Contributions towards the history of caproic and œnanthylic acids / by J.S. Brazier and G. Grossleth. Source: Wellcome Collection.

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    the commercial cyanide of potassium. This substance, which is now manufactured in this country by hundredweights, is invariably pre¬ pared by Liebig’s process, the success of which, as is well known, ac¬ tually depends upon the simultaneous formation of the cyanate. In the first place, we attempted to purify the crude cyanide pre¬ viously to its conversion into caproic acid; but after having ascer¬ tained the nature of the impurities, we at once subjected the crude product collected between 130° and 150° to the action of the alkali. The products of decomposition furnished by the cyanide and cyanate are so opposite in their chemical character—the one yielding a strong acid, caproic acid, the other a powerful base, amylamine or valera- mine, while the fusel-oil present remains unaltered—that the sepa¬ ration, after decomposition follows as a matter of course, whilst se¬ paration by fractional distillation before the action, would have been a tedious and nevertheless imperfect operation. The conversion of the cyanide of amyl may be effected by an aqueous solution of potassa: we found, however, that the operation succeeds much better with a solution of the alkali in alcohol. The mixture, when boiled in a flask connected with a condenser in such a manner as to induce the liquid to return to the alkali, readily changes into a pasty mass, while torrents of ammonia are evolved. After half an hour’s ebullition, the mixture is introduced into a re¬ tort and subjected to distillation, when a small quantity of ammonia, alcohol, amylamine, and fusel-oil distil over, a solution of caproate of potassa remaining behind, which usually solidifies on cooling into a semi-crystalline mass. The distillate was mixed with some hydrochloric acid, and sub¬ jected once more to distillation ; it began to boil at about 78° C. (1720,4 F.), the first product consisting of alcohol; the boiling-point rose gradually to 131° C. (2670,8 F.), at which temperature pure fusel- oil distilled over, a syrupy mass remaining behind, containing chiefly hydrochlorate of amylamine, and from which an additional quantity of fusel-oil was separated by addition of water. The dilute solution, when boiled for some time, in order to drive off fusel-oil, which was still mechanically adhering, and distilled with potassa, yielded a con¬ siderable quantity of pure amylamine. The production of this base under these circumstances is, as we have mentioned, due to the de¬ composition of the cyanate and cyanurate of amyl: these substances as Wurtz has shown, assimilating the elements of water, are split up into carbonic acid and amylamine. In several operations, the pro¬ duction of the latter base nearly equalled the quantity of caproic acid obtained, which shows how much cyanate is present in many kinds of commercial cyanide of potassium. With respect to the pro¬ perties of amylamine, we have scarcely to add anything to Wurtz’s description; however, as we had a considerable quantity of the sub¬ stance at our disposal, we determined its boiling-point with accuracy.