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Effect of carbonyl substituents on the barrier to rotation in N-ethyl-N-methylamides

✍ Scribed by Helio G. Bonacorso; Miguel S. B. Caro; Nilo Zanatta; Marcos A. P. Martins

Publisher
John Wiley and Sons
Year
1993
Tongue
English
Weight
450 KB
Volume
31
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

The barriers to rotation about the C(O)N bond for 13 α‐alkyl‐ and α‐halo‐substituted N‐theyl‐N‐methylamides were determined by ^1^H NMR spectroscopy at coalescence temperature. Plots of Gibbs free energy (Δ__G__°) and Gibbs energy of activation (Δ__G__‡) values against Charton's electronic and steric parameters of the α‐carbonyl groups allows the conclusion that both the isomeric preference and the barrier to rotation about the C(O)N bond of the N‐ethyl‐N‐methylamides depend mainly on the steric effect of the α‐carbonyl group.

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