Os(VIII) catalysed oxidation of phenyl styryl ketone and substituted phenyl styryl ketones by periodate: Interactive free energy relationship

Abstract

Kinetics of Os(VIII) catalysed oxidation of phenyl styryl ketone and its substituted analogues by periodate has been investigated in acetic acid + dichloromethane + water medium in the temperature range 298-313 K. The rates are found to be enhanced by electron releasing substituents and retarded by electron withdrawing substituents both in benzaldehyde and acetophenone rings. However, the effect of substituents is more pronounced when they are present in benzaldehyde ring. The magnitude of P_X(Y) value obtained from the slope of Hammett's plot for various substituents in benzaldehyde moiety decreases with the introduction of electron withdrawing groups in acetophenone moiety and vice versa. A linear plot is obtained between P_X(v) and s_y, (substituent constant for substituent in acetophenone moiety) with a slope of 0.36 ± 0.01. The plot of P_y(x) (obtained from Hammett's plot for various substituents in acetophenone moiety) versus s_x (substituent constant for substituent in benzaldehyde moiety) is also linear with a slope of 0.41 ± 0.01. The results have been analysed in terms of interactive free energy relationship.