Method for producing diol

Abstract

[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° C. and a residence time of shorter than 60 minutes.