Nitrogen-15 NMR Studies on Hydrazines. 2— Substituent Effect Analysis in ortho–Substituted Phenylhydrazines and Anilines

✍ Scribed by Elisabetta Mezzina; Domenico Spinelli; Stefano Chimichi; Vincenzo Frenna; Liliana Lamartina

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 458 KB
• Volume: 34
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/(sici)1097-458x(199612)34:12<1019::aid-omr19>3.0.co;2-f

✦ Synopsis

N and 13C NMR spectra of some ortho-substituted phenylhydrazines were measured at natural isotope abundance in DMSO-d, solutions. The substituent present exerts a larger effect on the chemical shift of the nitrogen atom directly bound to the aromatic ring (N-1), the second one (N-2) showing an attenuated trend of similar sign. Contrary to what observed for para and metu isomers, the cross-correlation between N-1 and N-2 SCS values of ortho-substituted phenylhydrazines is not satisfactory ; on the other hand, N-1 SCSs show a reasonably good linear regression with the q -constants. As expected, no correlation was found between N-1 and C-1 or H-1 SCS values. Correlations between 13C and "N chemical shifts of the title compounds with those of ortho-substituted anilines and of monosubstituted benzenes are also reported. Multiparameter regression analysis carried out on a large range of ortho-substituted anilines gave satisfactory results in the TSP treatment of C-1 and C-2 chemical shifts. Onebond ' 5N-'H coupling constants of ortho-substituted phenylhydrazines and ortho-substituted anilines well correlate with oP-constants.