Synthesis Of Dichlorohydrin From Glycerol

Dichlorohydrin(DCH) is an intermediate for produce epichlorohydrin. The traditional methods include allyl chloride route and allyl acetate route. The energy consumption and sullage produced in the former method are excessive. In the latter method, flow technics and equipments are complex and costly.Glycerol, as a byproduct of biodiesel, is increasingly available. Under the atmospheric or higher pressure, glycerol can be chlorinated with hydrogen chloride or hydrochloric acid to synthesize DCH, especially 1,3-DCH, by adopting catalysts such as carboxylic acids, carboxylic acids anhydride, esters of organic acids, nitriles and so on. The cost, energy consumption and contamination in the glycerol route is lower than the traditional methods. This technique has been used in the modern industry.In the experiments, the nature of products can be determined depending on gas chromatography analysis associated with mass spectrometry. Internal standard method can be carried out for the quantitative analysis of products and the relative error is less than 2%.In the experiments, catalysts such as carboxylic acids A , B , C,D, E , F and acetonitrile,ZnCl2, SnCl2 etc., are studied. ZnCl2 and SnCl2 have scarcely any effects on the reaction. A acid, B acid and C acid affect the process markedly. But they are prone to be stripped to the collected solution due to their lower boiling points. E acid and F acid have not enough catalysis for application although their losses are lower. Acetonitrile brings on white thick solution containing much solid which is difficult to dispose. D acid has not only enough catalysis, but also can be left largely in the reactor due to its higher boiling point. So, D acid is a perfect catalyst.In the experiments design of orthogonal array by using D acid as catalyst, the better parameters for the reaction are found. Yields of total DCH can reach 88.74%. But the quantity of HCl flow and losses of catalyst are excessive.Based on the experiments design of orthogonal array, the parameters of the optimized experiment are controlled according to the different phases of the reaction. The oil outside reactor is controlled gradually from low to high temperature. Accordingly, the quantity of HCl flow is reduced. Yields of total DCH can reach 91.16%. What is more important is that D acid losses are reduced and the color of products is pellucid. In addition, the losses of material and energy are less than the experiments design of orthogonal array.