title: Electrophilicity of 5-benzylidene-1,3-dimethylbarbituric and -thiobarbituric acids.
abstract: The kinetics of reactions of acceptor-stabilized carbanions 2a-m with benzylidenebarbituric and -thiobarbituric acids 1a-e has been determined in a dimethyl sulfoxide solution at 20 degrees C. Second-order rate constants were employed to determine the electrophilicity parameters E of the benzylidenebarbituric and -thiobarbituric acids 1a-e according to the correlation equation log k(20 degrees C) = s(N + E). With E parameters in the range of -10.4 to -13.9, the electrophilicities of 1a-e are comparable to those of analogously substituted benzylidenemalononitriles.
authors.affiliation: Department Chemie und Biochemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377, München, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Seeliger
authors.forename: Stefan T A
authors.initials: ST
authors.lastname: Berger
authors.forename: Grygoriy Y
authors.initials: GY
authors.lastname: Remennikov
authors.forename: Kurt
authors.initials: K
authors.lastname: Polborn
authors.forename: Herbert
authors.initials: H
authors.lastname: Mayr