GB786350A - Novel unsaturated ketones and a process for the manufacture thereof - Google Patents

Abstract

The invention comprises unsaturated ketones having the general formula <FORM:0786350/IV (b)/1> wherein R1 represents an alkyl radical having 2 to 4 carbon atoms and R2 represents the methyl radical or R1 and R2 together with their shared carbon atom form the cyclohexylidene radical, which ketones may be prepared by reacting an alcohol of the general formula <FORM:0786350/IV (b)/2> wherein R1 and R2 are as defined above with a hydrogen halide or a phosphorus halide, condensing the resulting substituted primary allyl halide with an alkali metal derivative of an ester of aceto-acetic acid and subjecting the resulting substituted aceto-acetic ester to a ketonic hydrolysis. The first step may be effected using concentrated aqueous hydrogen chloride or bromide or phosphorus trichloride. The resulting allyl halide may be reacted with the alkali metal aceto-acetic ester derivative in an inert solvent or with an alkali metal alcoholate and an aceto-acetic ester, the alkali metal derivative thereof then being formed in situ. The ketones may be used in perfumes. In examples: (1) aqueous HCl is reacted at below 0 DEG C. with 3,7-dimethyl-nonadien-(1, 6)-ol-(3) yielding 1-chloro-3,7-dimethyl nonadien-(2, 6) which is reacted with ethylaceto acetate and sodium methylate in benzene to form 3-carbethoxy - 6,10 - dimethyl - dodacadien-(5, 9)-one-(2); the latter is treated with KOH in ethanol to form a solution of potassium 6,10-dimethyl-dodecadien - 5, 9) - one - (2) - 3 - carboxylate which on acidifying and heating at 60-70 DEG C. yields 6,10-dimethyl-dodecadien-(5, 9)one-(2); (2) 3,7,9 - trimethyl - decadien - (1, 6) - ol - (3) similarly yields 6,10,12-trimethyl-tridecadien-(5, 9) - one - (2) and (3) 6 - cyclohexylidene - 3 - methyl - hexen - (1) - ol - (3) yields 6 - methyl-9-cyclohexylidene - nonen - (5) - one - (2). 3,7-Dimethyl - nonadien - (1, 6) - ol - (3) may be prepared from 6-methyl-octene-(5)-one-(2) itself obtained from 3-methyl-penten-(1)-ol-(3), by the methods of Specifications 786,349 and 785,086. The other alcohols used as starting materials are prepared similarly.