The presence of intramolecular NH...O=C bonds was proved in N-substituted N'-(2-fluorobenzoyl)thiourea derivatives by analysis of their infrared spectra. The intramolecular vibrational effects bring about a shift of the ν(NH) vibrational band to lower frequencies to the extent that the band gets into a vicinity to the δ(NH) overtone and Fermi resonance occurs between them. In addition, the ν(NH) vibration is also affected by Fermi resonance with the ν(CO) + δ(NH) combination. Double absorption bands were observed in the ν(CO) region for some of the derivatives. Based on perturbation theory applied to three-level interactions and using the Langseth and Lord equations, the band frequencies corrected for Fermi resonance were calculated and the hydrogen bond strength was examined in the compounds studied.
Rate coefficients have been measured for the base-catalysed hydrolysis of a series of (Z)-4-benzylidene-2-(substituted phenyl)-4H-oxazol-5-ones in 70% v/v aqueous dioxan at various temperatures. The enthalpies and entropies of activation, and a Hammett reaction constant for the reaction, have been evaluated. The 1 H and 13 C NMR chemical shifts were assigned, as well as the IR carbonyl stretching frequencies in chloroform, after deconvolution and band separation. Successful correlations between the carbonyl stretching wavenumbers and the 13 C NMR chemical shifts and the rates of the alkaline hydrolysis were found.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.