Solvent and Substituent Effects on Proton and Carbon-13 NMR Parameters of some Mono- and N, N'-Di-substituted Thioureas and Ureas PDF

Keywords

carbon 13, protons, chemistry

Abstract

The proton and carbon-13 NMR spectra for a number of mono- and N, N'-Di-substituted thioureas; RNHC(S)NHR', R ≠ R' or R = R' = H, ethyl, cyclohexyl, phenyl and 1-naphthyl and some analogous ureas; RNHC(O)NHR' (or comparison), have been recorded. Substituent effects (R and R') on the 1H chemical shifts for H-NR (or R') group of the N, N'-disubstituted thiourea were elucidated. Determination of 1H data for EtNHC(S)NHPh in a range of solvents reveals from the ẟ value of H-NEt and H-NPh is almost always shifted downfield as the donor number (DN) of the solvent increases. The 13C chemical shifts of carbon atoms for 1-naphthyl group (those other than C-1, C-9 and C-10 were deduced by comparison with known 1-substituted naphthalene. Solvent effects on 13C chemical shifts for some thiourea compounds were also checked by changing from donor solvent (DMSO-d6) to inert solvent (CDCl3)