Bicarbonate Ion → 4-Hydroxy-3,5,5-Trimethylcyclohex-2-Enone

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Reaction Steps

The process of the present invention is relatively simple technically. Inexpensive commercial chemicals are used as reagents. For example, formic acid and 30% hydrogen peroxide solution are placed in a stirred apparatus in a molar ratio of from about 1:1 to about 5:1 in a temperature range between 0° C. and 100° C., and about 0.5 to 2.5 moles, preferably 1 mole of beta-isophorone is added slowly. The formic acid/hydrogen peroxide mixture may also be added to the beta-isophorone. Gentle cooling may be used to remove the heat of reaction, depending on the selected temperature conditions and batch size. After completing the reaction and allowing the reaction to stand, the batch, which has become homogeneous, is neutralized with a suitable base, such as for example an alkali or alkaline earth metal hydroxide, oxide, carbonate or bicarbonate. A preferred base is sodium bicarbonate. The upper phase that forms is separated, dried, and distilled under vacuum. After the separation of back-isomerized alpha-isophorone, 4-hydroxyisophorone is obtained as a distillate. The alpha-isophorone distilled off in the forerun can be recycled to the process after reisomerization according to DE-OS 37 35 211.

Provenance & Evidence