Carbon-13 nuclear magnetic resonance studies of aromatic compounds: comparison of hydrogen bonding effects in phenols, anilides, and anilines

Abstract

Two- and three-bond ¹³C n.m.r. coupling constants to ¹H are reported for ring-substituted phenols, anilides, and anilines, plus limited data for thiophenols. The magnitude of the three-bond coupling constants to the phenolic hydroxy were rather insensitive to structural variations designed to alter the geometry of the coupled nuclei and raises the question of the exact geometric dependence of ³J on geometry. For acetanilides, the difference in magnitude between ³J_anti and ³J_syn is small. For anilines, the data are not suggestive of a geometric relationship. Thiophenols are similar to phenols. The influence of substitution on coupling constants between ring carbons and hydrogens is discussed briefly. Chemical shifts are reported for 16-ortho-substituted aromatic compounds.