p-Menthan-3-one → Thymol

Beteiligte Stoffe

Reaktionsschritte

Citronellol (156 g; 1 mole) and 7.8 g of a copper-chromium oxide catalyst (CuO:Cr2O3 = 50:50 by weight; mainly as CuCr2O4 ; less than 200 mesh, a product of Nikki Chemical Co., Ltd.) were charged into a pressure reactor, and reacted at 230° C under a hydrogen pressure of 2 kg/cm2.G. In about 4 hours, the evolution of hydrogen ended. The amount of hydrogen evolved was 24 liters. The catalyst was separated from the reaction product by filtration, and the residue was distilled under reduced pressure to afford 140 g of a fraction having a boiling point of 82° to 90° C/12 mmHg. This fraction was a mixture of menthone and iso-menthone in a ratio of 6:4 by weight. The theoretical yield was 90%. Also, 7.7 g of thymol boiling at 108° to 110° C/12 mmHg was obtained.

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