Thermodynamic analysis of synthesis of cyclopentanol from cyclopentene and comparison with experimental data

Abstract

Cyclopentanol is a very important chemical intermediate, which has been widely used in the chemical industry, and could be prepared from cyclopentene by two steps: an initial addition-esterification reaction of cyclopentene with acetic acid and the subsequent transesterification reaction with methanol. However, so far, no direct theoretical or experimental work has been reported on this process. In this work, we have carried out the thermodynamic calculation of the indirect process and also validated the thermodynamic prediction through experimental work. The liquid heat capacities of cyclopentanol and cyclopentyl acetate were estimated using the Ruzicka-Domalski group contribution method, the standard enthalpy of formation and standard entropy of gaseous cyclopentyl acetate by the Yoneda group contribution method, the standard vaporization enthalpy of cyclopentyl acetate by the Ducros group contribution method. The enthalpy changes, free energy changes, equilibrium constant and equilibrium conversion of the addition-esterification and transesterification reactions were calculated according to the principles of chemical thermodynamics in the temperature range from 273.15 to 373.15 K. The results showed that both the addition-esterification reaction and transesterification reaction were exothermic, the free energy changes increased with a rise on temperature, which indicated that low temperature was favorable for the reactions in the temperature range from 273.15 to 373.15 K. The optimal addition-esterification reaction conditions were a temperature range from 333.15 to 353.15 K, molar ratios of acetic acid to cyclopentene in the range from 2:1 to 3:1. For the transesterification reaction, the ideal temperature ranges from 323.15 to 343.15 K, with a molar ratio of methanol to cyclopentyl acetate in the range from 3:1 to 4:1. These thermodynamic calculation results for the addition-esterification reaction of cyclopentene and acetic acid experiments results are in good agreement with the experimental results.