Comparison of methods for the preparation of ethyl 6,8-dichlorooctanoate

Ethyl 6,8-dichlorooctanoate is an important organic intermediate for the synthesis of lipoic acid, which is a powerful antioxidant with a promising domestic and international market.

The first method is carry out chlorination reaction (crude yield about 88%) when pyridine does acid binding agent with 6-hydroxyl-8-chloroctanoic acid ethyl ester and chlorination reagent and thionyl chloride and prepare.

The smell is awful for pyridine owing to adding acid binding agent pyridine when reaction for the method, operating environment is very severe, add water to carry out terminating reaction when reaction terminates, and washing removing impurity with water, and pyridine is after having adsorbed hydrogen chloride gas, the pyridine hydrochloride of formation is soluble in water, result in substantial amounts of nitrogenous effluent, add the intractability of industrial wastewater, do not meet the requirement that cleaning produces, do not meet the needs that modern industrialization produces.

The second method is carry out chlorination reaction with 6-hydroxyl-8-chloroctanoic acid ethyl ester and chlorination reagent and solid phosgene when DMF (DMF) does acid binding agent to prepare.

The method is with N, dinethylformamide (DMF) is catalyst, in organic solvent with solid phosgene generation chlorination reaction, in chlorination reaction process, DMF and hydrogen chloride gas form DMF hydrochlorate, and chlorination liquid is put in water after terminating by reaction again, washes DMF hydrochlorate with water, producing a large amount of containing DMF hydrochlorate production waste, the hydrochlorate production waste containing DMF enters back into recycle section and adjusts PH to reclaim to neutrality。Due in DMF containing substantial amounts of water, in removal process DMF easily decompose cannot recovery, create substantial amounts of nitrogenous effluent, add the intractability of industrial wastewater, production cost is high, does not meet the requirement that cleaning produces, and does not meet the needs that modern industrialization produces.

You may like