Near-infrared spectroscopic studies of the hydrogen bonding between thioacetamide and N,N-disubstituted benzamide derivatives in CCl4

The hydrogen bonding interactions between thioacetamide (TA) and several N,N-disubstituted benzamides (N,N-dimethylbenzamide (DMBA), N-methoxy-N-methylbenzamide (MMBA), N,N-diethyl-m-toluamide (DEMT), and N,N-diethyl-2,5-difluorobenzamide (DEDF)) have been studied using near-infrared absorption spectroscopy. Thermodynamic parameters for the interactions between TA and benzamides were determined by analyzing the v(N-H)(35) + amide II combination band of TA. The -Delta H-0 values, indicating the intrinsic strength of hydrogen bonding, are -17.4, -21.6, -21.9 and -20.8 kJ mol(-1) for DMBA, MMBA, DEMT and DEDF, respectively. The results show that the inductive and resonance effects of substituents appear to influence the formation of hydrogen bonds.