¹³C NMR and azomethine ¹H NMR spectra of substituted N‐benzylideneanilines and hammett correlations

Abstract

Twenty-four N-benzylideneanilines (four being new compounds) have been prepared, which are divided conveniently into three series: (I) with 4-substituents, plus one compound with 3-and 4-substituents; (11) with 4'-substituents, plus one compound with 3'-and 4'-substituents; and (111) with 4-and 4'-substituents.Their -C NMR spectra and the 'H N M R absorption of the hydrogen attached to the imidoyl carbon atom have been studied and their Hammett correlations were tested.

NMR Spectroscopy, Hammett Correlations and Biological Activity of Some Schiff Bases Derived from Piperonal

“…Thus, the C-4' chemical shifts are at high field for 4'-iodo (89.71 ppm) and 4'-bromo (118.83 ppm) and practically unchanged for the 4'-chloro compound (130.74 ppm). These values, δC-4', were compared with the corresponding substituted N-benzylidenanilines 9,19 showing small changes except for the 4-chloro derivative.…”

“…We have, for a long time, maintained interest in compounds containing >C=N-X functions and have included some comparisons of >C=O; >C=N and >C=N-X functions [2][3][4][5][6][7][8] . Later, we reported studies on NMR spectroscopy 9 and biological activity of some >C=N-X compounds 10,11 . We have also considered saturation of internal resonance effects in guanidines have also included 4-and 4'-substituted-N-benzylidenanilines 9,10 and N-benzylidene-3,3-diphenyl-propylamines 13 and in both series, 1 H and 13 C-NMR spectra were analysed.…”

“…Later, we reported studies on NMR spectroscopy 9 and biological activity of some >C=N-X compounds 10,11 . We have also considered saturation of internal resonance effects in guanidines have also included 4-and 4'-substituted-N-benzylidenanilines 9,10 and N-benzylidene-3,3-diphenyl-propylamines 13 and in both series, 1 H and 13 C-NMR spectra were analysed. Studies of infra-red and ultra-violet spectra for 3,3-diphenylpropylamine derivatives were also carried out together with preliminary tests of their biological activities.…”

Substituent Effects Using 13c Chemcial Shifts for a Series of Substituted 2-Phenyl-3-(Pyridin-2-Yl)-1,3-Thiazolidin-4-Ones With a Comparison to Similarly Substituted 1,3-Thiazolidin-4-Ones

“…Series 2 has a more limited range of substituents than Series 1, and we have taken the unusual stance of including as many halogens in the series as possible in order to test the robustness of the Hammett and Swain-Lupton correlations; normally only the fluoro group and either the chloro or bromo substituents are used, but not all three halogens due to anomalous outcomes. 9 Tierney et al Typically, we have used Hammett correlations as an initial indicator for the level of effectiveness of the trans of substituent effects (3-6) from the substituent location to site using the relationship shown in Equation 1, w δ 0 is defined as the substituent chemical shift or SCS, σ is the Hammett constant, and ρ is the susceptibility factor for substituent effects in a series. It should be pointed out that the complexity of the…”

Study of the influence of electronic effects on the retention of substitutedN-benzylideneanilines in normal-phase liquid chromatography

“…In experimental studies, NBA have been analyzed by molecular spectroscopy, including UV absorption [13][14][15][16][17][18][19][20], NMR [21][22][23][24][25][26][27][28], and IR [25][26][27][28][29][30][31][32]. X-ray crystallography [12,33,34] of NBA revealed that the aniline ring is twisted out of the C-C=N-C plane at an angle in the range 41 o to 55 o; the benzylidene ring also lies out of the same plane with a smaller and opposite angle in the range 8-14 ~ The transmission of electronic effects arising from the X and Y substituents through the conjugated double bond has been studied intensively [22,30]. It has been shown that substituent X has more influence on the C=N infrared stretching frequency than substituent Y [31].…”