Kabushiki Kaisha Ueno Seiyaku Oyo Kenkyujo

Kabushiki Kaisha Ueno Seiyako Oyo Kenkyujo

Kabushiki Kaisha Ueno Seiyaku Oyo K.

Nobutaka Izumichi

Ryuzo Ueno

Masaya Kitayama

Masaharu Kittaka

Hiroyuki Kato

Syungo Nara

The present invention provides a process for preparing crystalline parahydroxybenzoic acid anhydride, comprising the step of precipitating and isolating parahydroxybenzoic acid in an aqueous solvent at a temperature equal to or above the transition temperature of parahydroxybenzoic acid.

Crystalline parahydroxybenzoic acid anhydride and process for preparing the same

Granular product of parahydroxybenzoic acid or its ester which exhibits well suppressed dusting and caking tendency and a process for preparing the product are provided. The granular product of parahydroxybenzoic acid or its ester according to the instant invention has an average particle size of equal to or more than 150 &mgr;m and a hardness of 10-3000 g. The granular product of the invention can be prepared by dry compressing powdery parahydroxybenzoic acid or its ester to give compressed material, pulverizing and classifying the material.

Granule of parahydroxybenzoic acid or parahydroxybenzoic ester and process for producing the same

Granules of 2-hydroxynaphthalene-3-carboxylic acid and method for preparing the same

The present invention provides crystalline 2-hydroxynaphthalene-3-carboxylic acid (BON) characterized in that the average particle size is equal to or more than 157 &mgr;m and the proportion of the particles of which particle size is less than 74 &mgr;m is equal to or less than 14%. The crystalline composition of the present invention can be prepared by a process comprising the step of recrystallizing BON, especially at a high temperature, or by carrying out the acid precipitation step in the method for preparing BON at a high temperature.

Crystal of 2-hydroxynaphthalene-3-carboxylic acid and process for the preparation thereof

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Ashiya, Japan

Nobutaka Izumichi