13C nuclear magnetic resonance study of π-polarization in 3- and 4-substituted benzamides and N-chlorobenzamides

Michael De Rosa, Keith Brown, Mary McCoy, Kevin Ong, Kimberley Sanford

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

The substituent effect on the carbonyl carbon [C(α)] 13C chemical shift in 3- and 4-substituted benzamides and N-chlorobenzamides has been studied in (CD3)2SO. Chlorine shields the carbonyl carbon. A cross correlation was carried out for C(α) and the carbonyl carbon in N-chlorobenzamides is less sensitive to substituents than in the benzamides. The dual substituent parameter method indicated a significant diminution in the π-polarization effect (ρ1) in N-chlorobenzamides compared to benzamides. This is in contrast to other carbonyl systems where ρ1 has been found to be essentially independent of the substituent attached to the carbonyl carbon. It is concluded that π-polarization in benzamide and its derivatives is more sensitive to the substituent attached to the carbonyl carbon than in the other classes of aromatic carbonyl compounds studied to date.

Original languageEnglish (US)
Pages (from-to)1787-1790
Number of pages4
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number10
StatePublished - Dec 1 1993

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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