Study On The Conditions For Preparation Of Epichlorohydrin From Glycerol

Epichlorohydrin played an important role in organic raw materials and fine chemicals, which was used in chemical industry widely.In this paper,direct preparation of dichloropropanol from glycerol and hydrochloric acid gas was carried out in a single step, then dichloropropanol can be converted to epichlorohydrin by cyclization.Through analyzing the factors of the reaction,found the optimum conditions.The structure of these compounds were identified by means of GC/MS,IR and ¹H-NMR,the results were introduced as follows.(1) The chlorination of glycerol catalyzed by carboxylic acid catalysts and its derivatives, heteropolyacid catalysts and solid acid catalysts was studied.The optimum conditions of the reaction were described as follows,when H₃PW₁₂O₄₀ was used as catalyst was 2.3 g, calcinations temperature of catalyst was 300℃,n(HCl):n(glycerol)=2.5:1,the reaction temperature was 110℃,the yield of dichloropropanol was up to 97.8%.The yield of dichloropropanol was increased by 9.2%compared with carboxylic acid catalysts and its derivatives and the yield was increased by 4.3%compared with solid acid catalysts.The main factors were their different catalytic mechanisms and their acid strengths.(2) The cyclization of dichloropropanol catalyzed by Ca(OH)₂ NaOH,KOH and solid superbase catalysts was studied.It was found that,the yield of epichlorohydrin was increased by 5.5%compared with Ca(OH)₂ catalyst,the results were influenced by their basicity and conditions.