DE1190933B - Process for the preparation of ionone compounds - Google Patents

Description

Process for the production of ionone compounds Addition to patent: 1,137008 The subject of patent 1137 008 is a process for the preparation of ionone compounds by acidic cyclization of open-chain, conjugated unsaturated ketones of the general formula In the formula, R denotes an aliphatic, cycloaliphatic or araliphatic radical and R 'denotes hydrogen or a methyl group.

It has now been found that, in this process, the compounds of the general formula 1 are completely or partially replaced by cumulatively unsaturated ketones of the general formula in which R and R 'have the meanings given above, can be replaced. Surprisingly, the cumulative unsaturated dienones of the general formula II also result in ionone compounds with a displacement of a double bond, which, as is known, have the structure of an α "B-unsaturated ketone.

Suitable starting materials for the new process are, for. B.

2-methoxy-2,3,6-trimethylundecadien- (6,7) -one- (10), 2-methoxy-2,6-dimethylundecadien- (6,7) -one- (10), 2-n-Butoxy-2,6-dimethylundecadien- (6,7) -one- (10), 2- (fl'-ethoxyethyl) -2,6Mimethylundecadien- (6,7) -one- (10), 2-Benzyloxy-2,6-dimethylundecadien- (6,7) -one- (10), 2- (β'-hydroxyethyl) -2,6-dimethylundecadien- (6,7) -one- (10).

The starting materials are obtained in addition to the conjugated unsaturated starting materials of the process according to patent 1137008 in the reaction of tertiary alkynyl carbinols of the general formula III in which R and R 'have the above meaning, with a fl-keto acid derivative, e.g. B. an acetoacetic acid ester, at elevated temperature under the conditions of the so-called Kimel-Sax reaction.

The mixtures can be implemented immediately using the new process will. But it is also possible to use the pure cumulatively unsaturated dienones, the from the mixtures mentioned by careful distillation or by chromatographic Let adsorption separate, convert to ionone compounds according to the new process.

Claims (1)

The cyclization of the starting materials of the general formula II is carried out under the conditions described in patent 1,137,008. The parts mentioned in the following example are parts by weight. Example 1 500 parts of a ketone mixture in equal parts from 2-methoxy-2,6-dimethylundecadien- (6,7) -one - (10) and 2'-methoxy - 2,6 - dimethylundecadiene46, 8pon410) are diluted with 400 parts of petroleum ether (b.p. 60 to 90 ° C). The mixture is allowed to cool to -12 to -15 ° C. with vigorous stirring Mixture of 1500 parts of concentrated sulfuric acid and 800 parts of petroleum ether run in such a way that the temperature does not rise above -6 ° C. After the inflow has ended The mixture is stirred for a further 30 minutes at 0 to -5 ° C. and then poured to 3000 Parts of ice and 800 parts of n-hexane. The organic layer is separated with 100% Soda solution and then washed with water. After drying over sodium sulfate and distilling off the n-hexane is obtained by fractional distillation 336 Parts of ß-ionon with a bp of 94 to 97 ° C and a refractive index nD20 = 1.5195. The yield corresponds to 78% of theory. Example 2 53 parts of 2-ethoxy-2,6-dimethylundecadien- (6,7) -one- (10) are diluted with 50 parts of benzene and within 30 minutes under strong Stirring introduced into 300 parts of 850% phosphoric acid. The temperature should be 30 ° C not exceed. The mixture is stirred for a further 30 minutes and the reaction mixture is poured on 300 parts of hexane and 300 parts of ice. After working up as in Example 1, one obtains in the distillation 28 parts of α-ionone with a boiling point of 0.1 = 76 to 78 ° C with the refractive index nP = 1.49%. Example 3 In a solution of 25 parts of 2-methoxy-2,3,6-trimethylundecadien- (6,7) -one- (10) and 75 parts of benzene become 10 parts of gaseous form at 0 to 5 ° C. with vigorous stirring Boron trifluoride initiated. The mixture is stirred for a further 30 minutes at 10 to 15 ° C. and poured the mixture then to 100 parts of ice and 100 parts Hexane. One moves on as in Example 1 and obtained by distillation 12 parts of a-iron with a boiling point of 0.05 82 bis 85 ° C; nD20 = 1.4990. Claim: Process for the preparation of ionone compounds by cyclization of open-chain, conjugated unsaturated ketones of the general formula in which R is an aliphatic, cycloaliphatic or araliphatic radical and R 'is hydrogen or a methyl group, in an acidic medium according to Patent 1137008, characterized in that instead of the ketones of the above general formula, unsaturated ketones of the general formula are wholly or partially cumulative in which R and R 'have the meanings given above, used as starting material. Publications considered: German Auslegeschriften No. 1 080 105, 1 095 273, 1109677.