Rates of Acid-Catalyzed NH Proton Exchange of Enaminones, an 1H NMR Study

Abstract

: 1H NMR spectra of a series of enaminones R-CO-CH=C(NHCH2Ph)-R [1, R=CH3; 2, R=C6H5; 3, R=CF3; 4, R=CH2CH2CH2; 5, R=CH2C(CH3)2CH2], were obtained in the presence of trifluoroacetic acid in CDCl3 or DMSO-d6 at 28 °C. Steric, solvent, electronic and hydrogen bonding effects on the rates of acid-catalyzed NH proton exchanges were investigated. Rate constants were calculated by 1H NMR line shape analysis.

Keywords

• proton exchange reaction
• acid-catalyzed proton exchange
• dynamic nmr spectroscopy
• rate constants
• enaminones