Fig. 3

Carbon-13 NMR spectra for reactions of cyanide and sulfide with methane- and ethanethiol. Spectrum A shows the methanethiol-catalyzed formation of thioformamide at pH 7; spectrum B corresponds to this reaction at pH 11. Spectrum C shows the ethanethiol-catalyzed formation of thioformamide at pH 7; spectrum D shows the reaction at pH 11. The peak corresponding to the carbonyl carbon of thioformamide is highlighted in blue