Steric factors affecting hydrogen-bonding between amide groups

Abstract

The infra-red spectra of aseries of N-monosubstituted amides R · CONH · R′[R or R′ CH 3, C 2H 5, CH(CH 3) 2, C(CH 3) 3] in carbon tetrachloride solution have been recorded in the region 3600 cm −1 −2800 cm −1. The shift in the NH stretching frequency on hydrogen—bonding (Δν  ν monomeric — ν associated) has been found to be proportional to the estimated area ( B) of the association band, and to the width at half-height (ν 1 2 ) of this band. B was also found to be proportional to the concentration ratio ϱ= C associated C monomeric In a series of secondary amides where R  R′  n-C 3H 7 to n-C 6H 13 inclusive, Δν, ν 1 2 , and B were essentially constant.