Nitrogen-15 nuclear magnetic resonance spectroscopy. Differential rates of NH proton-exchange reactions of hydrazine-carbothioamide and 4-methylhydrazine-carbothioamide in dimethyl sulfoxide

✍ Scribed by Issa Yavari; John D. Roberts

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 344 KB
• Volume: 14
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270140115

✦ Synopsis

Abstract

The proton‐coupled nitrogen‐15 NMR spectra of hydrazinecarbothioamide and 4‐methylhydrazinecarbothioamide have been taken at the natural‐abundance level in neutral, basic and acidic solutions at 25°C. The NH proton‐exchange reactions of the hydrazino‐NH~2~ groups in both compounds were found to be very rapid in the presence of acid, but quite slow in the presence of base. The hydrazino‐NH protons of hydrazinecarbothioamide exhange six times and 200 times faster than the amide protons in the presence of either base or acid, respectively. Similarly, acid‐ and base‐catalyzed NH proton exchanges of the hydrazino‐NH group of 4‐methylhydrazinecarbothioamide were found to be two to three orders of magnitude faster than those of N‐methylamido protons. These results can be rationalized by consideration of the effect of the lone pair on the hydrazinoNH~2~ group on the reactivity of the adjacent NH group.