Daicel Chemical Industries, Ltd.

Mamoru Endo

Tadayuki Mitani

Takashi Hiramoto

Masayoshi Hinenoya

The present invention provides (1) a process for producing a colorless aromatic acid anhydride having a high purity in a high yield by reacting an aromatic carboxylic acid having a carboxyl group bonded to the aromatic nucleus with a lower aliphatic acid anhydride in the presence of at least one metal ion selected from the group consisting of ions of metals of Groups, I, II, III, V, VII and VIII of the periodic table and (2) a process for producing an acid anhydride by an exchange reaction of an organic carboxylic acid anhydride and a carboxylic acid in the presence of at least 5 ppm of at least one metal ion selected from the group consisting of Co, Ni, Mn, Fe, Li, Na, K, Mg, Ca, Cu, Zn, Al, Ti and V ions.

Process for producing carboxylic acid anhydrides

A process for producing glyoxylic acid is disclosed which comprises oxidizing glyoxal with an aqueous oxidizing agent composition obtained from nitric acid and a nonoxidizing strong acid present in a concentration of 6 to 40 wt. % in the reaction mixture. Preferably, the nonoxidizing strong acid is hydrochloric acid and the reaction is carried out while nitric acid is gradually added to the reaction mixture so that the concentration of said nitric acid in said reaction mixture does not exceed 1 wt. % during the reaction.

Process for producing glyoxylic acid

A process for the preparation of glyoxylic acid is disclosed which comprises reacting an aqueous solution of glyoxal with chlorine. The reaction is preferably carried out under pressure, under the condition that the hydrochloric acid concentration in the aqueous solution of glyoxal is 1 to 15%. The reaction can be carried out in the presence of a catalytically effective amount of bromine as a catalyst.

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Arai, Japan

Mamoru Endo