PURPOSE: To obtain the title substances at low cost and in high yield, by the ring- closure of 2-geranyl-1,3-cyclohexanedione in the presence of water and calcium hydroxide.
CONSTITUTION: By the ring-closure of 2-geranyl-1,3-cyclohexanedione having three kinds of isomers of formulas I, II and III, in the presence of water and calcium hydroxide, δ-ketocarboxylic acids of formulas IV, V and VI corresponding to the raw materials are obtained. Less than 500mol of water (preferably 25W200mol) and 0.5W5mol of calcium hydroxide (preferably 0.5W1mol) are used to 1mol of the raw materials. The reaction temperature is 80W150°C (preferably 90W110°C) and the reaction time is 9W12hr. Since δ-ketocarboxylic acids are obtained in the form of calcium salts, they are made free by the addition of a strong acid such as hydrochloric acid or sulfuric acid, and then separated from water layer with ether, etc.
KIHARA NORIAKI
SAEKI KENJI
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