Mitsubishi Gas Chemical Company, Inc.

Hidechika Wakabayashi

Yasuo Sugihara

Akira Hosomi

Hisashi Sakaitani

Tadashi Shimomura

Toshiaki Kozaki

Toru Takahashi

Osamu Kondo

Akitoshi Sugio

Toshio Komatsu

Chiharu Nishizawa

Masaru Sakamoto

Mitsuzo Arii

Hiromitsu Nagashima

Teruo Takeuchi

Masafumi Shimpo

Kazuharu Ogasawara

Futoshi Nakaya

Tomio Fujioka

Yoshihiro Tsurumi

Rieko Sano

Yasunobu Shigaki

Toshio Matsuzaki

Disclosed is a process for preparing a water-soluble tricarboxypolysaccharide which includes the step of oxidizing an &agr;-bonding type polysaccharide with a ruthenium compound and an oxidizing agent. The water-soluble tricarboxypolysaccharide, having a high carboxyl group content, can easily and inexpensively be prepared in a high yield without any problem of a post-treatment after the reaction, and thus the present invention is desirable as an industrial preparation process of the water-soluble tricarboxpolysaccharide.

Process for preparing water-soluble tricarboxypolysaccharide

There is herein disclosed a process for preparing a carboxypolysaccharide by oxidizing a polysaccharide with a combination of a transition metal compound and an oxidizing agent, said process comprising the step of separating the transition metal from a reaction mixture with a chelating agent. According to the present invention, the transition metal can be removed to a low concentration of less than 100 ppm from an aqueous solution including the transition metal and the tricarboxypolysaccharide. The process of the present invention is important to reduce the loss of a transition metal catalyst such as the ruthenium catalyst and to industrially manufacture a purified tricarboxypolysaccharide.

Process for preparing carboxypolysaccharide

In a process of producing a carboxypolysaccharide by oxidizing a polysaccharide in the presence of a ruthenium compound and an oxidizing agent, the expensive ruthenium is easily and efficiently recovered. Ruthenium dissolved in a reaction mixture after the oxidation of the polysaccharide is converted, after or without being subjected to a heat. treatment, to high oxidation sate, which is then recovered by the extraction with a water-insoluble organic solvent. The recovered ruthenium is reduced to low oxidation state and reused in a subsequent production of the carboxypolysaccharide.

Process for producing carboxypolysaccharide

A food-preserving agent comprising an oxygen absorbent and a compound represented by the following structural formula (I): ##STR1## , wherein n is an integer of 2 to 4 and X is H or CH.sub.3, can remove generated acetaldehyde effective, thereby preserving food without any fear of disagreeable odor for a long duration.

Food-preserving agent

A chemically and physically stable humidity sensor including a porous sintered body and electrodes, which is formed by bringing a humidity sensor including a porous sintered body and electrodes into contact with a solution of a polyurethane resin.

Humidity sensor

There are disclosed an oxygen absorbent comprising boron or a reducing boron compound, an alkaline substance and a carrier, an oxygen absorbent parcel formed by enclosing said oxygen absorbent in a permeable packaging parcel, a food package and a package of a metallic or electronic product or part containing said oxygen absorbent parcel.

Oxygen absorbent

A humidity-sensing component composition includes a metallic oxide and a chalcogen oxyacid salt represented by a general formula A.sub.x B.sub.y O.sub.z where A is one of an alkali metal and an alkaline earth metal, B is one of sulphur, selenium, and tellurium, O is oxygen, x is 1 to 2, y 1 to 5, and z 2 to 7. The chalcogen oxyacid salt is blended by an amount of 0.01 to 99.99 mol % in the metallic oxide with the sum of the metallic oxide and the chalcogen oxyacid salt as a reference. The metallic oxide and the chalcogen oxyacid salt are sintered under an atmosphere of molecular oxygen.

Humidity-sensing component composition

Peroxidase, which is an enzyme having a catalytic effect on oxidation by hydrogen peroxide and known to be found in vegetables such as horseradish or Japanese radish, is produced according to a biological process using a microorganism belonging to the genus Myrothecium and capable of producing a peroxidase, for example, Myrothecium gramineum 38-3, 46-2 and 283-2, and Myrothecium verrucaria IFO 6113 and IFO 6133.

Process for production of peroxidase

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Tokyo, Japan

Hidechika Wakabayashi