STUDIES IN THE POLYOXYPHENOL SERIES: VII. THE OXIDATION OF VANILLIN WITH SODIUM CHLORITE AND CHLORINE DIOXIDE

Vanillin almost instantly reduced 1.2 to 1.5 moles of aqueous chlorine dioxide at 20 °C. or 5 °C. and any pH between 1.2 and 6.5, and a white crystalline substance with the composition of a dihydroxyvanillin, C7H5O4(OCH3), was isolated in roughly 25% yield independently of the pH. When oxidized with aqueous sodium chlorite at 20 °C. and pH 0.5, these crystals gave another crystalline substance with the composition of a dihydroxyvanillic acid, C7H5O5(OCH3). Although both these substances decomposed readily to red oils and then to brown powders free of methoxyl groups, seven well characterized derivatives were prepared. The results showed that the substances were unsaturated, monohydroxy, diketone tautomers of a dihydroxyvanillin and the corresponding dihydroxyvanillic acid, but precise structures could not be assigned. Parallel oxidations of vanillin with aqueous sodium chlorite at 20 °C. and pH 6 proceeded at a negligible rate, but near pH 5 a reaction that often seemed autocatalytic produced about 19% of 5-chlorovanillin. At pH 4 the aldehyde C7H5O4(OCH3) was isolated in 19% yield; at pH 1 this aldehyde (15%) was mixed with 7.7% of the corresponding acid C7H5O5(OCH3), but at pH 0.5 the latter alone was produced (28%). Chlorine dioxide and sodium chlorite therefore differed markedly in their oxidizing action and in the effect of pH upon it. When acting on vanillin, both oxidants also produced deep red, unstable oils with quinone-like properties and often containing chlorine.

IX. On parasulphide of phenyl and parasulphobenzine

When sulphide of phenyl, C 6 H 5 C 6 H 5 }S, was passed several times in succession through an iron tube filled with nails and heated to low redness, a considerable amount of carbonaceous matter was deposited, and a portion of the sulphide was converted into an isomeric compound, which I propose to call Parasulphide of Phenyl. In order to obtain this substance from the dark-coloured distillate which collected in the receiver when sulphide of phenyl was submitted to the action of heat in the manner above described, it was transferred to a copper retort and distilled. The clear dark-yellow oil was then cooled for several hours in a freezing-mixture, when a considerable quantity of a white crystalline substance separated in nodules; this is freed from undecomposed sulphide of phenyl by thoroughly draining it on a vacuum filter. It can readily be purified by repeated crystallization from boiling alcohol, in which it is rather soluble.

IX. On benzoline, a new organic salt-base from bitter almond oil

When pure oil of bitter almonds is left some days in contact with a strong solution of ammonia, at the ordinary temperature of the air, it is slowly, but in the end completely converted into a white crystalline substance, insoluble in water, but readily soluble in hot alcohol. The solidification of the oil is complete, and there is no secondary product. This substance was examined by M. Laurent, who conferred upon it the name of hydrobenzamide , and assigned to it the formula C 42 H 18 N 2 ; it is generated by the union of the elements of two equivalents of ammonia with those of three equivalents of hydruret of benzoyle, and the separation of six equivalents of water. 3 eq. bitter almond oil . C 42 H 18 O 6 2 eq. ammonia...... H 6 N 2 / C 42 H 24 N 2 O 6 }= { Hydrobenzamide C 42 H 18 N 2 6 eq. water... H 6 O 6 / C 42 H 24 N 2 O 6 Acids decompose hydrobenzamide immediately, with separation of bitter almond oil and formation of salt of ammonia; with alkalies the case is different, solution of potash, even at a boiling heat, occasioning, as remarked by M. Laurent, no perceptible change. I found however that when the boiling was prolonged for some hours, a change was induced resembling that undergone by furfurolamide under similar circumstances. A few brownish crystalline flocks appear in the solution, and after cooling, the cake of resin-like substance is found harder and less fusible than hydrobenzamide which has been melted and left to solidify. This change is unaccompanied by any notable alteration of weight, although a faint odour of bitter almond oil is disengaged during the whole course of the ebullition. The new substance is an organic salt-base, having the same composition as hydrobenzamide itself; it might perhaps with propriety be called benzoline .