Collect. Czech. Chem. Commun. 1989, 54, 2715-2720

Reactivity of nucleophiles in dimethyl sulfoxide and its comparison with nucleophilic reactivity in protic medium

Vítězslav Zima, Oldřich Pytela, Jaromír Kaválek and Miroslav Večeřa

Department of Organic Chemistry, Institute of Chemical Technology, 532 10 Pardubice


Reactions of 2,4-dinitrophenyl acetate and 2,4-dinitrofluorobenzene as model substrates with 12 nucleophiles have been studied in dimethyl sulfoxide. The rate constants obtained have been discussed with regard to the nucleophilic reactivity differences in dimethyl sulfoxide and protic solvents inclusive of the different manifestation of the charge of nucleophiles. The applicability of an earlier-suggested correlation equation to the data obtained has been verified. The reaction medium markedly affects the reactivity of nucleophiles, the effect of charge being substantially greater in aprotic solvents (electrostatic interaction) than in protic ones (solvation). In spite of these differences the correlation with application of an empirical nucleophilicity scale suggested earlier is satisfactory, the regression coefficients obtained reflect changes in the nature of medium.