GB451594A - Improvements relating to the production of nitriles - Google Patents

Abstract

Aliphatic nitriles are manufactured by passing a fatty acid containing at least 8, preferably at least 12 carbon atoms per molecule and free from hydroxy groups, or a functional derivative thereof, in the vapour phase together with ammonia over a dehydrating catalyst at 320--420 DEG C., preferably at 330--380 DEG C. Suitable starting materials are lauric, palmitic, stearic, oleic, linoleic and montanic acids, or mixtures thereof, e.g. those obtainable by saponifying fats, oils or waxes, e.g. coco-fat, palm kernel fat, linseed oil, tallow, train oil, beeswax or montan wax, carboxylic acids or mixtures thereof obtainable by oxidizing hard or soft paraffin wax, paraffin oil or mineral oil, also the amides of the acids, their esters with monovalent, preferably aliphatic, or polyvalent alcohols of low molecular weight, e.g. their methyl, ethyl, isopropyl, butyl and glycerol esters, or anhydrides, e.g. lauric anhydride or the mixed stearic-acetic anhydride. The reaction may be effected under ordinary, increased or reduced pressure, and advantageously with the addition of inert gaseous or vaporous diluents, e.g. hydrogen, nitrogen, carbon dioxide, air, or the vapours of methanol, acetic acid, nitriles or hydrocarbons. The materials treated may be vaporized in a separate chamber or in the reaction chamber. The nitriles are preferably treated before distillation or before further use with an acid or alkaline agent or an oxidizing agent, e.g. dilute hydrochloric acid, sulphuric acid, acetic acid, dilute alkali lye, potassium permanganate solution or hydrogen peroxide, in order to deodorize them. The products may be converted by hydrogenation into the corresponding amines. In examples: (1) the vapours of the mixture of acids obtainable by saponifying palm kernel fat are passed with ammonia and nitrogen over aluminium phosphate at 340--350 DEG C.; (2) the vapours of the acids obtainable by saponifying coco-fat are passed with ammonia over bauxite at 350--370 DEG C.; (3) hardened palm kernel fat is saponified with alkali and the acids are liberated from the soaps and passed with ammonia over silica gel at 360 DEG C.; (4) a vaporous mixture of stearic acid and cyclohexane is passed with ammonia over bauxite at 370--375 DEG C.; (5) oleic acid is vaporized in a current of superheated ammonia and the mixture is passed over aluminium oxide, partly dehydrated by heating, at 380--390 DEG C.; (6) oleic acid methyl ester is vaporized in the presence of ammonia and a little hydrogen, and the mixture is passed over silica gel at 370 DEG C.; a mixture of the methyl esters of the acids of coco-fat or of the acids obtainable by oxidation of paraffinic hydrocarbons of high molecular weight, e.g. paraffin wax, may be similarly treated; (7) palm kernel fat is vaporized and passed with ammonia and nitrogen over bauxite at 380 DEG C.; (8) molten coco-fatty acid is injected with ammonia into a high pressure apparatus containing kaolin and hydrated alumina at 350 DEG C.; (9) the acid mixture obtained by catalytic oxidation of paraffin wax is similarly treated at 360 DEG C.; (10) molten stearic acid and liquid ammonia are injected into a high pressure apparatus containing bauxite at 320 DEG C.; (11) coco-fatty acid and ammonia are passed in at the top of a vertical reaction vessel containing alumina and kaolin at 375 DEG C.; (12) lauric acid amide is vaporized in a stream of ammonia and the mixture is passed over aluminium oxide at 350--400 DEG C.; (13) stearic acid, preheated to 150 DEG C. and mixed with a little nitrogen, is evaporated by passing over plates in a chamber heated to 400--420 DEG C. to which preheated ammonia is supplied, and the resulting mixture is passed over bauxite at 400--420 DEG C.; (14) coconut oil, preheated to 100 DEG C., is passed with air and a gaseous diluent into the top of a evaporator filled with Raschig rings, into the bottom of which ammonia is supplied, whereby amides are produced and are passed over bauxite at 350--400 DEG C. Specification 416,631 is referred to.