IV. Researches on the hydrocarbons of the series C n H 2 n +2 .—No. V

Abstract

Oxidation Products . In a former communication I have shortly described the action of different oxidizing agents upon some of the saturated hydrocarbons; the following paper contains some further results which I have since then obtained. One of the most striking properties of these compounds is, that they are with the greatest difficulty acted upon by any oxidizing substance in the cold. On heating them, however, a reaction sets in, and either they are completely burnt up to carbonic dioxide and water, or other oxidation products besides those two are formed in comparatively small quantities; thus chromic acid produces some acetic acid. Fuming nitric acid, which in the cold shows no action whatever, even if left in contact with one of these hydrocarbons for months, acts rather violently on gently heating; acid of the specific gravity 1.4 acts in a similar way, and produces the same products, but the reaction is much less violent. The apparatus which I used consisted of a glass flask of about one litre capacity, the narrow neck of which was several feet in length, and surrounded by a wider tube through which cold water flowed. The hydrocarbons treated in this way were hexylhydride and octylhydride (from petroleum), and diamyl. They were heated with the acid as long as red fumes were evolved; the liquid left in the flask was then distilled in a retort, until the unaltered hydrocarbon together with the greater part of the diluted nitric acid had passed over. The syrupy residue was heated in a steam-bath as long as nitric acid vapours escaped. A thick syrupy mass was left, from which, on cooling, a crystallized acid was deposited; on adding water these crystals dissolved, whilst a thick yellowish oil separated. This oil is insoluble in water, but somewhat soluble in the aqueous solution of the crystalline acid, which therefore cannot be obtained quite free from the oily substance by recrystallization only; but this may be effected by washing the crystals with cold ether, which dissolves very little of them, whilst the oil itself is very soluble. The acid obtained from octylhydride and that from diamyl melted at 180° C., and showed all the characteristic reactions of succinic acid; that from hexylhydride, from which I obtained only a very small quantity, could not be completely freed from the yellow oil, and therefore did not show a definite melting-point; it began to fuse at about 120°, and became perfectly liquid at 150°; it exhibited, however, all the reactions of succinic acid; and the following analyses, although they do not agree very well, yet show that it was this compound. From the acids the calcium and the silver-salt were prepared by neutralizing the aqueous solution with calcium carbonate and concentrating the filtered solution by boiling, when the salt separated in microscopic needles. Calcium succinate obtained in this way has the formula C 4 H 4 CaO 4 + H 2 O; the quantities of water and calcium found agree with this composition. The water was determined by drying the salt at 180° C., and the calcium by heating the dried salt over the blowpipe until the residue had a constant weight.