Studies in aromatic reactivity

Griffiths, Stephen John (1974) Studies in aromatic reactivity. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (18MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The half-wave potentials of six series of Schiff basese each of nineteen compounds, of the types ArCH=NAr' and ArN=CHAr', where Ar represents an unsubstituted aryl group and Ar' represents a phenyl group substituted in the meta or para positions, have been measured in dimethylformamide, using a mercury pool reference electrode. The effects on the half-wave potentials of changing the substituent in Ar' and of varying the structure of Ar have been investigated. Substituent effects have been examined in terms of the Hammett ϭ-ρ relationship and also in terms of a substituent constant, ϭSB, generated from the data of the Schiff bases (Series B) having the general formula C₆H₅CH=NC₆H₄X. Structural variations in Ar have been studied by adopting Series B as the standard Schiff base series and by generating substituent constants for each structure. -- The values of the reaction constant, ρ, obtained in the present study range from 10.06 to 23.23 and are much larger than ρ values usually obtained in solution. These values are similar in magnitude to ρ values obtained in gas phase reactions. This suggests, in the polarographic reduction of Schiff bases in dimethylformamide, that solvent effects are virtually absent. -- Variations in the half-wave potentials with structure of Ar for the unsubstituted aldehyde fragment of tne molecules have been correlated with quantities derived from the perturbed molecular orbital version of the Huckel molecular orbital theory. Correlations between series of Schiff bases of the type ArCH=NAr' (Ar=C₆H₅, 2-naphthyl, 9-phenanthryl, 9-anthryl) and a' correlation between two series of the type ArN=CHAr' (Ar-C₆H₅, 2-naphthyl) have also been obtained as predicted previously.

Actions (login required)

View Item