A. Olivieri, R. B. Wilson, I. Paul
Jul 19, 1989
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Influential Citations
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Journal
Journal of the American Chemical Society
Abstract
The tautomeric reaction involving a single proton transfer in 1-(phenylazo)-2-naphthol and its 4{prime}-methoxy, ethoxy, and N,N-dimethylamino derivatives has been investigated with variable-temperature solution and high-resolution solid-state {sup 13}C NMR spectroscopy. Crystal structures of the parent unsubstituted compound and the 4{prime}-N,N-dimethylamino derivative have been determined. All of these compounds undergo a fast proton exchange on the NMR time scale between the tautomeric azo and hydrazone forms in both solution and the crystalline phase. Equilibrium compositions in the solid materials are similar to those measured in solution. Crystals of 1-(phenylazo)-2-naphthol are monoclinic, a = 27.875 (7), b = 6.028 (2), c = 14.928 (5) {angstrom}, {beta} = 103.57 (2){degree}, the space group is C2/c with Z = 8, and the structure at 213 K was refined to an R factor of 0.0414 on 1,082 observed reflections. Crystals of 1-((4{prime}-(dimethylamino)phenyl)azo)-2-naphthol are monoclinic, a = 7.604 (1), b = 7.970 (3), c = 24.381 (7) {angstrom}, {beta} = 99.33 (2){degree}, the space group is P2{sub 1}/c with Z = 4, and the structure at 193 K was refined to an R factor of 0.0405 on 1,522 observed reflections.