Sumitomo Chemical Company, Limited

Kenzi Takuma

Yukio Suzuki

Masahiro Hayashi

Tomoyuki Kusaba

Akiko Kakimizu

The method for producing the benzyl bromide derivatives of the formula: ##STR1## wherein R.sub.1 represents a C.sub.1 to C.sub.5 alkyl group, which comprises reacting a 2-methylphenylacetic acid derivative of the formula: ##STR2## wherein R.sub.1 represents the same meaning above, with bromine in the presence of an alkali metal salt. In case that R.sup.1 is an ethyl or isopropyl group, the recrystallization of the above reaction product from aliphatic hydrocarbon solution gives the benzyl bromide derivatives efficiently and in high purity.

Method for producing benzyl bromide derivatives

A method for preparing a mixture of stereoisomers of .alpha.-cyano-3-phenoxybenzyl isovalerate ester derivatives, which is rich is an enantiomer pair of a compound having an (S)-configuration on both the acid and alcohol moieties and an enantiomer thereof having an (R)-configuration on both the acid and alcohol moieties.

Method for preparing a mixture of stereoisomers of

A crystal of an enantiomer pair of stereoisomers of .alpha.-cyano-3-phenoxybenzyl 2-(4-chlorophenyl)isovalerate (general name: fenvalerate) comprising (S)-.alpha.-cyano-3-phenoxybenzyl (S)-2-(4-chlorophenyl)isovalerate and an enantiomer thereof, which has the crystal characteristics as specified in the specification, is disclosed. A process for preparing the enantiomer pair or the fenvalerate rich in the enantiomer pair by depositing the above-described crystal from a solution of a racemate of fenvalerate is also disclosed. A process for preparing the enantiomer pair by depositing the crystal from a solution of the fenvalerate rich in the enantiomer pair is further disclosed.

Crystal of enantiomer pair of phenylacetic acid ester derivative and

A method for preparing an optically active carboxylic acid ester of the formula (I): ##STR1## wherein X is a hydrogen atom or a fluorine atom, and * indicates an asymmetric carbon atom, which is an A.alpha.-isomer having an (S)-configuration on both the acid and alcohol moieties, or rich in said A.alpha.-isomer, which method comprises crystallizing said A.alpha.-isomer from a solution of an A-isomer of the formula (I) having an (S)-configuration on the acid moiety in the presence of a crystal that is of substantially pure A.alpha.-isomer and in the presence or absence of a basic catalyst.

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Nara, Japan

Kenzi Takuma