Sumitomo Chemical Company, Limited

Yoshitaka Nishida

Tamio Shirafuji

Kiyomi Sakai

Kensen Okusako

A process for producing coumarin or a derivative thereof, which process comprises dehydrogenation of 3,4-dihydrocoumarin or a derivative thereof in the presence of a palladium catalyst by heating under reduced pressure.

Process for producing coumarin and derivatives thereof

A process for producing coumarin and a derivative thereof represented by formula (2): ##STR1## wherein R.sub.1 to R.sub.4 each represents a hydrogen atom, a methyl group, or an ethyl group, provided that at least two of R.sub.1 to R.sub.4 each represents a hydrogen atom, the process comprising the step of heating a 3-(2-cyclohexanoyl)propionic acid ester represented by formula (1): ##STR2## wherein R.sub.1 to R.sub.4 are as defined above and R.sub.5 represents an alkyl group having from 1 to 4 carbon atoms, in the presence of a palladium catalyst, thereby to allow the ester of formula (1) to undergo cyclization and dehydrogenation reactions, the latter stage of the reactions, in which the conversion of the 3-(2-cyclohexanoyl) propionic acid ester used as a starting material has reached about 80% or more, being conducted at a higher temperature than that for the former stage of the reactions.

Process for producing coumarin and derivative thereof

A process for producing 3,4-dihydrocoumarin comprising cyclization and dehydrogenation of a 3-(2-cyclohexanoyl)propionic acid ester, in which a reaction mixture obtained by the cyclization and dehydrogenation is washed with an alkali to reduce the dihydrocinnamic acid content of the reaction mixture to 1% by weight or less and/or previously distilling the reaction mixture to remove high-boiling substances, and then subjected to rectification to recover 3,4-dihydrocoumarin. The thus obtained 3,4-dihydrocoumarin has high purity and high quality sufficient for use as a perfume as it is.

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Ehime, Japan

Yoshitaka Nishida