Vol. 3, Issue 5 (2019)
Solvent effect and kinetics on ethyl benzoate in aqueous solvent system
Author(s): Anil Kr Singh, Arjuman Bano
Abstract: Rate constant for the base catalyzed hydrolysis of ethyl benzoate is determined volumetrically in methanol-water mixture for the composition varying from 30 to 70% (v/v) at different temperature ranging from 200 C to 400 C. The initial slow but sharp decrease in rate with gradual addition organic co- solvent in the reaction media and with increasing temperature of reaction has been explained on the basis of salvation and desolvation of first and transition state to a different extent. The Iso-composition activation energy(EC) energy for same solution decreases as methanol content is increases while Iso- Dielectric activation energy(ED) with increase as the dielectric constant of the solvent increases. The trends of variation of numbers of water molecule associated with activated complex increases with increasing temperature from 200 C to 400 C tells about the fact that in the presence of the protic solvent(methanol) in reaction media, the bimolecular mechanistic path of reaction changed to unimolecular. The enhancement in DG* with simultaneous decrease in (DH*) and (DS*) values of the reaction concluded that the reaction is enthalpy stimulating and entropy control.