Effect of Added Dimethyl Sulphoxide on the Solvolysis of Cinnamoyl Chloride in Aqueous Acetone and Acetonitrile
Kinetic studies on solvolysis of cinnamoyl chloride in aqueous acetone and acetonitrile with lesser water content shows an order 2.6 with respect to water and it is comparable to that of benzoyl chloride. The relatively greater enthalpy and lesser negative entropy of activation compared to benzoyl chloride favours an S N 2 mechanism for cinnamoyl chloride rather than addition elimination mechanism. A sharp increase in rate observed in presence of small amounts of DMSO is due to its, strong basic and hydrogen bonding character leading to the liberation of strong nucleophile OH-, relatively greater stabilization of transition state than intial state which lowers the enthalpy and free energy of activation, distruction and interpenetration into the solvation shell of water and its direct interaction with the substrate.
p-Chloroacetophenone: A study of enolization kinetics
ABSTRACT The reaction rate of enolization of p-chloroacetophenone has been studied in the presence of amino acids, namely, β-alanine, DL-alanine, L-alanine, and glycine. Maximum reaction rate was observed in the case of β-alanine at 22M concentration. The effects of parameters such as effect of ketone concentration, effect of dielectric constant, effect of catalysts, etc., have been found to exert a significant effect on the reaction rate. The effect of temperature was studied in the range of 313–328 K, and several thermodynamic parameters such as entropy (ΔS≠), enthalpy (ΔH≠), energy of activation (ΔEa), and Gibbs free energy (ΔF≠) were found to be −10.32 e.u., 17.87 cal mol−1, 19.24 kcal mol−1, and 21.20 cal mol−1, respectively. The reaction rate increased from 1.9 to 5.8 min−1 on increasing the percentage of dimethylformamide from 10 to 50% (v/v).
Catalytic removal of tert-butyldimethylsilyl (TBS) ether by PVP-I
Abstract A mild, efficient and rapid protocol the deprotection of alcoholic TBDMS ethers using PVP-1 as catalyst in methanol, the procedure of deprotection of various TBDMS ethers were found to be very convenient, easy work-up, high yielding.