Mitsubishi Gas Chemical Company, Inc.

Youichi Kyuuko

Toshio Hidaka

Makoto Takagawa

Kazuo Tanaka

Norio Fushimi

Atsushi Okamoto

Akifumi Iida

Kazunari Yamamoto

The present invention provides an industrially available method for efficiently producing high-purity S-(&#x2212;)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid excellent in solid-liquid separability from an S-(&#x2212;)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid ester, and also provides products obtained by the method. Under a temperature condition of 50-80&#xb0; C. in an aqueous solvent, (A) an S-(&#x2212;)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid ester represented by the general formula (1) is hydrolyzed under a basic condition for 1-3 hours; then (B) the insoluble matters contained in the reaction solution resulting from the hydrolysis are removed; and (C) an acid is added to the resulting solution to effect crystallization; provided that R in the general formula (1) represents an alkyl or aryl group. 

Method of producing S-(&#x2212;)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid and product obtained by the method

The invention provides a process for producing a chroman compound represented by formula (1), characterized in that the process includes allowing a phenol, an unsaturated compound, and a formaldehyde to react in the absence of catalyst and in the presence of water in an amount by mole 1 to 10 times that of the phenol. According to the present invention, a high-purity chroman compound can be produced in the absence of catalyst and under mild conditions. In addition, the invention provides an industrial means for producing the compound, without using a large amount of an acid or a base serving as a reaction promoter or a catalyst, which would otherwise cause side reactions, apparatus corrosion, etc.

Process for producing chroman compound

5-Tolyl-pent-2-ene is cyclized in liquid phase in the present of an aliphatic hydrocarbon to produce the corresponding dimethyltetralin. The use of the aliphatic hydrocarbon effectively prevents a side reaction such as dimerization of 5-tolyl-pent-2-ene to provide dimethyltetralin in a high yield. Also, 5-tolyl-pent-2-ene is cyclized in liquid phase or vapor phase in the presence of a catalyst comprising a carrier supporting sulfate ions to produce the corresponding dimethyltetralin. The catalyst supporting sulfate ions shows a high catalytic activity event at low temperatures. Therefore, the cyclization of 5-tolyl-pent-2-ene is conducted in a wide temperature range from low temperatures to high temperatures.

Process for producing dimethyltetralin

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Niigata, Japan

Youichi Kyuuko