DE506044C - Process for the preparation of menthol, its isomers or homologues and the corresponding ketones - Google Patents

Description

A process for the preparation of menthol, its isomers or homologues and the corresponding ketones The novel condensation products from domestic or p-cresol and ketones, öderen representation forms the subject of the patent 486 768, can be, without first thermal cleavage is effected by Treating with hydrogen in the presence of hydrogenation catalysts, converting it into the corresponding cyclohexanols (menthol, its isomers and homologues) if the hydrogenation is carried out up to the absorption of 16 atoms. This always results in a small amount of the corresponding ketones (xlenthon), since the reaction does not go completely to the end.

In addition to the usual hydrogenation catalysts, it is advisable to add a catalyst which lowers the thermal decomposition point to such an extent that the temperature most suitable for hydrogen storage is reached. Such catalysts are, for. B. Metallplienolate or compounds capable of forming phenates.

The process also works when a hydrogenation catalyst is used to the goal alone. In this case, however, higher temperatures must be used.

Opposite to win the known method, the menthol or Mentlion from thymol by hydrogenation - furnish that has t '"e process of the present invention has the great advantage that isolation and purification of thymol or its Isorneren and homologues is unnecessary before the Fertighydrierung example. The condensation product of m-cresol and acetone (cf. Patent 486 768) is after the addition of 0.11. Alu'Tlillium-3- "ltfl # 11-6-isopropylene phenolate and 10 /" of a Nli # kellatt-t -Ivsator treated with hydrogen, optionally under pressure, at 180 to igo 'until 16 atoms of hydrogen have been taken up. A mixture of the various stereoisomeric mentholes is obtained in a yield of about 60% of the starting material.

Instead of the aluminum phenolate, magnesium phenolate or Mercury phenolate or the oxides or hydroxides, also carbonates of the above Metals.

For example, (. See Patent 486,768) 2 Starting from the condensation product of p-cresol and acetone, is obtained, after the addition, v on aluminum-4-methyl-6-isopropylenphenolat and BeAandhing with hydrogen until the uptake of 16 Atornen hydrogen, a mixture of stereoisomeric 4-methyl-6-isopropylcyclohexanols in a yield of 60 '/ "of the starting material. Example 3 The condensation product of m-cresol and methyl ethyl ketone (cf. Patent 486768) is treated with hydrogen as described in Example i. From the reaction mixture a mixture of stereoisomeric 3-methyl-1-methopropylcyclohe-.m-anols can be isolated with a yield of 601 ".

Claims (2)

PATENT CLAIMS: i. Process for the preparation of menthol or its isomers and hornologues and the corresponding ketones, characterized in that the condensation products obtainable according to patent 486768 from alkylated phenols and ketones in the presence of catalysts with hydrogen up to the uptake of 16 or 14 atoms of hydrogen treated. 2. The method according to claim i, characterized , characterized in that in addition to the hydrogenation catalysts, catalysts are also used, which lower the decomposition temperature.