| Cyclopentanone,as an important chemical intermediate,is the raw material of pharmaceutical and perfume industries. It is also widely used in the electronics industry as a solvent because of its good dissolubility of diverse resin. The main work of the paper is the preparation of cyclopentanone from diethyl adipate via cyclization and hydrolysis.The reaction is comprised of the formation of the intermediate 2-ethoxycarbonylcyclopentanone from dieckmann reaction of diethyl adipate and hydrolysis of 2-ethoxycarbonylcyclopentanone to cyclopentanone.The optimum reaction condition of the cyclization was temperature of 95℃, reaction time of 3h, molar ratio of C2H5ONa and diethyl adipate of 1.8:1 and molar ratio of solvent toluene and diethyl adipate of 12:1. Toluene and the product were well separated by distillation and the optimal reflux ratio was 2:1. The small amount of water and ethanol in the toluene fraction resulted in the decline of the reaction activity with the recycling toluene.Cyclopentanone was prepared from 2-ethoxycarbonylcyclopentanone by acid hydrolysis and base hydrolysis. The optimum reaction condition of the acid hydrolysis was the catalyst of hydrochloric acid, temperature of 70℃, reaction time of 3h, molar ratio of hydrochloric acid and 2-ethoxycarbonylcyclopentanone of 1:1. The polymerization reaction of the cyclopentanone in the acidic conditions is the reason for the decline of the yield. The optimum reaction condition of the base hydrolysis was the catalyst of KOH, temperature of 60℃, reaction time of 1h, alkali concentration of 1.5mol/L. The acid decomposition of 2-ethoxycarbonyl- cyclopentanone and the open-loop of cyclopentanone in alkaline conditions leaded to the decline of the yield.For the preparation of cyclopentanone from diethyl adipate via cyclization and hydrolysis, the best conversion of diethyl adipate was 96.5%. The yield of cyclopentanone was 46.3% by cyclization and acid hydrolysis and 53.3% by cyclization and base hydrolysis,respectively.
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