Preparation method of 1, 3-propanediol

The invention relates to a preparation method of 1, 3-propanediol, belonging to the field of synthesis of chemical products. The preparation method of 1, 3-propanediol comprises the following steps: (1) synthesizing 1-bromo-3-chloropropane: enabling 3-chloro-1-propene, hydrogen bromide and benzoyl peroxide to react according to the molar ratio of 1: 1: (0.001-0.03) to obtain 1-bromo-3-chloropropane; (2) synthesizing 1, 3-propanediol: enabling 1-bromo-3-chloropropane, sodium hydroxide and water to react according to the molar ratio of 1: (1.9-2.5): (4-15) under the conditions that the reaction pressure is not more than 0.5MPa and the reaction temperature is 120-140 DEG C. According to the preparation method provided by the invention, although bromine is taken as a reaction raw material, bromine can be recycled, the production of three wastes is low, and the obtained product has the advantages of low cost and high benefits and can completely realize large-tonnage production.