Frank Tschwatschal

NMR-SPEKTROSKOPISCHE UNTERSUCHUNGEN AN DERIVATEN DES 2,4-DICHLORPHENOXYESSIGSAUREHYDRAZIDS

SummaryDerivatives of 2,4-dichlorphenoxyacetyl-hydrazides were prepared by reaction of the hydrazides with different aldehydes. NMR-spectroscopic investigations of these compounds show the existence of rotamers resulting from a nitrogen-carbonyl bond rotation. Contrary to substituted dithiocarbacinic acid derivatives noE/Z-isomerism relative to the C=N double bond could be demonstrated. In order to prove the structures we utilized chemical shift differences in the1H-,13C- and15N-NMR-spectra, NH and CH coupling constants and NOE-difference measurements. The barriers of rotation were determined by NMR-measurements at various temperatures and line shape analysis using the computer program D-NMR 3.

NMR-spektroskopische Untersuchungen zurE/Z-Isomerie von substituierten Dithiocarbazinsäurederivaten

SummaryNMR-spectroscopic investigations of substituted dithiocarbacinic acid derivatives show the existence of configurational isomers relative to the C=N double bond, but no tautomerism. We applied chemical shift differences in the1H-,13C- and15N-NMR-spectra, N - H and C - H coupling constants and NOE difference measurements in the solvents CDCl3,DMSO-d6 and partly CD3OD in order to discriminate between the isomers and to determine the configurational composition. Compounds4 and5 exist asE-isomers in all solvents, compounds1, 2 and3 as a mixture ofE/Z-isomers. InDMSO-d6 theE-form is the preferred isomer.