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Published September 1, 1954 | public
Journal Article

Orientation in Aromatic Nitration Reactions

Abstract

The isotope dilution method has been employed to determine isomer distributions in the nitration of chloro-, bromo- and iodobenzenes and the relative reactivity of iodobenzene with respect to benzene. For nitration at 25º, the following isomer distributions were found: chlorobenzene, ortho 29.6 ± 1.7%, meta 0.9 ± 0.0%, and para 69.5 ± 1.7%; bromobenzene, ortho 36.5 ± 1.7%, meta 1.2 ± 0.l%, and para 62.4 ± 2.8%; iodobenzene, ortho 38.3 ± 2.0%, meta 1.8 ± 0.3%, and para 59.7 ± 2.0%. The reactivity of iodobenzene relative to benzene at 25º was 0.13 in acetic anhydride and 0.22 in nitromethane. The degree of correlation of the nitration reactivities of benzene derivatives with Hammett σ-constants is discussed. Deviations from the Hammett relationship are interpreted in terms of important contributions of transition-state resonance.

Additional Information

© 1954 American Chemical Society. Received March 8, 1954. Supported in part by the joint program of the Office of Naval Research and the U. S. Atomic Energy Commission; also supported in part by a grant from the van't Hoff Fund of the Koninklijke Ned. Akademie van Wetenschappen. Presented before the Division of Organic Chemistry at the New York meeting of the American Chemical Society, September 13, 1954.

Additional details

Created:
August 19, 2023
Modified:
October 25, 2023