Improvements relating to the synthesis of the beta - ionylidène acetaldehyde

摘要

An a ,b -unsaturated aldehyde is prepared by reacting together an a ,b -unsaturated alcohol, a primary aromatic amine, and a ketone in the presence of either an aluminium alkoxide or a p magnesium alkoxide in order to produce a Schiffs base, and thereafter hydrolysing the Schiffs base to the a ,b -unsaturated aldehyde. Before hydrolysis the Schiffs base may be isolated. Specified are: alcohols: b -ionylidene ethanol, Vitamin A, and cinnamyl alcohol; ketones: diethyl-, dibutyl-, and methyl ethyl ketone, benzophenone, acetophenone, cyclohexanone, and fluorenone; amines: aniline, a - or b -naphthylamine, o-, m- or p-toluidine, and xylidines. In examples: (1) b -ionylidene ethanol is refluxed with aniline, diethyl ketone and aluminium ter-butoxide. The product is reacted with dilute HCl to give b -ionylidene acetaldehyde. In a similar manner, (11) Vitamin A and (12) cinnamyl alcohol are reacted to give the corresponding anils which are hydrolysed with hydrochloric acid to the aldehydes. The b -ionylidene acetaldehyde obtained in (1) may be reacted with acetone in the presence of aluminium isopropoxide to yield the "C18 ketone". Other examples, some for comparison purposes, show the use as amine in place of the aniline in (1) of (3) naphthylamine, (4) 4-amino-1,3-dimethyl-benzene, (5) o-toluidine, (6) diphenylamine, (7) n-butylamine, (8) cyclohexylamine, (99) ethylene diamine, and (10) pyridine, and in (2) no amine is employed.