| 摘要 |
A process for the preparation of d,l-menthol by catalytic hydrogenation of aromatic or partly hydrogenated cyclic compounds which have the carbon skeleton of menthol having at least one double bond and are substituted by oxygen in the 3-position relative to the methyl group, with simultaneous rearrangement of optically active or inactive stereoisomers of menthol at elevated temperature and under pressure is described. The hydrogenation, which is to be carried out continuously, is carried out on a fixed bed catalyst which comprises, as active constituents, palladium, ruthenium or rhodium or a mixture of these elements, and comprises alkali metal hydroxides and/or alkali metal sulphates as promoters; the support for this catalyst is doped with a rare earth metal and manganese.
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