Nippon Soda Co., Ltd.

Syuichiro Sanpei

Tomoya Hidaka

Minoru Kaeriyama

Toru Kawabe

Masayuki Hanzawa

Yasuyuki Suzuki

A process for producing 4-isopropoxy-4'-hydroxydiphenyl sulfone useful as the developer for leuco dyes to be used in thermosensible papers, which is excellent in productivity, economical efficiency and safety and permits the production of the compounds from constantly available raw materials. This process is improved in productivity and economical efficiency as compared with those of the prior art both by shortening the production time by the use of an isopropyl iodide, which is more reactive than isopropyl bromide which have been used in the prior art.

Industrial process for the production of diphenyl sulfone compounds

A process for producing compounds of general formula (II) useful as the developer for leuco dyes to be used in thermosensible papers, which is excellent in productivity, economical efficiency and safety and permits the production of the compounds from constantly available raw materials. This process is improved in productivity, economical efficiency and safety as compared with those of the prior art both by shortening the production time by the use of, e.g., an alkyl iodide, RI, which is more reactive than alkyl bromides which have been used in the prior art, and by attaining the complete recovery and reuse of iodine by incorporating into the process the iodine recovery step of recovering iodine from the manufacturing wastewater and reacting this iodine with an alcohol to thereby self-produce an alkyl iodide.

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Fukushima, Japan

Syuichiro Sanpei