| 摘要 |
<p>Menthol isomers are produced by catalytically isomerising verbenone with metal (pref. Ni or Pd) catalysts, opt. in the presence of aldehyde (pref. HCHO) and in the same vessel hydrogenating the isomerisate. Both isomerisation and hydrogenation are pref. carried out at 150-300 degrees C. The procedure gives in high yield a dl-menthol mixture of 56% menthol, 30% neo-menthol and 20% neo-isomenthol; the n-menthol can be separated off by conventional techniques (pref. fractional distillation) and the remaining siomer mixture re-isomerised and again fractionated.</p> |
