Nippon Shokubai Co., Ltd.

Akiko Yamauchi

Hirokatsu Kawakami

Akimasa Watanabe

Kazutaka Otsuki

[Objective] An object is to provide a method for producing a diol by which diols having a favorable color scale and containing a reduced amount of an unsaturated aliphatic hydrocarbon can be produced. [Solution] A method for producing a diol, including a) supplying metaboric acid, a saturated aliphatic hydrocarbon and a reaction gas containing molecular oxygen to a reactor and performing liquid-phase oxidation of the saturated aliphatic hydrocarbon with the reaction gas containing molecular oxygen in the presence of metaboric acid to obtain a reaction liquid containing an oxide, b) esterifying the oxide to obtain a reaction liquid containing a borate compound, c) separating the reaction liquid containing a borate compound into an unreacted saturated aliphatic hydrocarbon and a distillation residue by distillation, d) separating the distillation residue into orthoboric acid and an organic layer by hydrolysis, e) separating the organic layer into an alkali aqueous solution layer and a crude alcohol layer by saponification with an alkali, and f) performing first distillation on the crude alcohol layer to remove a monoalcohol, and then performing second distillation on the residual liquid under conditions of a temperature of lower than 250&#xb0; C. and a residence time of shorter than 60 minutes.

Method for producing diol

The present invention aims to provide a polycarboxylic acid copolymer which is excellent in various properties, in particular dispersibility, and is useful in various uses such as dispersants and admixtures for cement. The present invention also aims to provide a dispersant for cement, an admixture for cement, and a cement composition each containing the above polycarboxylic acid copolymer. The polycarboxylic acid copolymer of the present invention includes a structural unit (I) derived from an unsaturated polyalkylene glycol monomer (a) and a structural unit (II) derived from an unsaturated carboxylic acid monomer (b). The copolymer has a weight average molecular weight (Mw) of 5000 to 25000. The copolymer includes a dimer including two units of the unsaturated polyalkylene glycol monomer (a) bonded to each other, and has an area percentage of the dimer of 7% or higher.

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Osaka, Japan

Akiko Yamauchi