Influence of structural factors on the kinetics and regioselectivity of the reaction of aryloxiranes with arenesulfonic acids

Abstract

dioxane and diglyme at 265 K has been studied. The non-additive structural effects led to isoparametricity phenomenon: at the isoparametric point with respect to the constant s X of substituent X, the rate of the process does not depend on the structure of Y.Despite the great interest in the chemistry of oxiranes, both in recent decades and at the present day (see, for example, [1-4]), some important aspects of the reactions of oxirane substrates have been little studied. In the first place this is concerned with the study of quantitative regularities, including the mutual influence of structures, media, temperature, and other internal and external factors on the rate and regioselectivity of the interaction of oxiranes with various reagents. Knowledge of these rules permits the development of the quantitative theory of the processes of opening of the oxirane ring.The objective of the present work was the investigation of the concurrent influence of the substituents X and Y on the rate and regioselectivity of the reaction of aryloxiranes XC 6 H 4(3) CH(O)CH 2 (X = H, 3-Br, 4-Br, 4-NO 2 , 3,5-(NO 2 ) 2 ) with arenesulfonic acids YC 6 H 4 SO 3 H (Y = 4-OCH 3 , 4-CH 3 , H, 4-Cl, 3-NO 2 ) in mixture of equal volumes of dioxane and dimethyl ethyleneglycol (diglyme) at 265 K:It had been shown previously [5] that the products of reaction (1) with participation of 4-nitrophenyloxirane are primary alcohols -2-arylsulfonate-2-(4-nitrophenyl)ethanols 4-NO 2 C 6 H 4 CH(OSO 2 C 6 H 4 Y)CH 2 OH (a-opening of the oxirane ring). The same type of 2,2-disubstituted derivatives of ethanol are formed by the reaction of 4-nitrophenyloxirane and aryloxiranes with less electron-accepting substituents with benzoic acids [6] and also with HNO 3 [1]. In addition, in the case of aryloxiranes with X substituents which are stronger electron-acceptors than 4-NO 2 , for example 3,5-(NO 2 ) 2 , a change in regioselectivity of the process was observed: it was established recently [7] that the products of reaction (1) are secondary alcohols XC 6 H 3 CH(OH)CH 2 OSO 2 C 6 H 4 Y (b-opening of the oxirane ring).