SPECTROSCOPIC INVESTIGATION OF SOME THIO SCHIFF-BASES

Schiff bases of 2-aminothiophenol with some benzaldehyde derivatives h ave been prepared. Tile effect of substitution at the benzal ring on t he band positions of upsilon(C=N) and delta(CH(CH=N)) is investigated; the electron-withdrawing groups lower tile frequency as a result of d ecreased electron density on the C=N linkage while electron-donating g roups exert an opposite effect. Band assignment of the proper absorpti on band is made and correlated with the non-coplanar structure assumed to the Sc!lin base molecules; the effect of substituents is also stud ied. Tile chemical shifts of the different types of protons in the nmr spectra of the prepared Schiff bases are also reported.