The chemistry of some derivatives of pyrrolidine green and pyrrolidine violet

Abstract

A comprehensive number of novel, symmetrically or unsymmetrically substitutedtriphenylmethane dyes have been synthesised from their respective leuco-bases or carbinols. The terminal groups and substituents were chosen to give a good variation in structural and electronic properties.
The rates of alkaline hydrolysis of the dyes at various hydroxide ion concentrations, ionic strengths, temperatures and in mixed solvents of varying composition have been investigated with a view to elucidating the mechanism of reaction and the nature of substituent effects.
A complete reaction scheme for the acidic and basic hydrolysis of Pyrrolidine Green is advanced and the associated equilibrium constants have been calculated.
The rate data obtained for some substituted Pyrrolidine·Greens have been used to test the applicability of an isokinetic relationship in the TPM system.
The 4-morpholino-and 4-piperidino-Pyrrolidine Green dyes show enhanced reactivity relative to the other dyes studied and the reasons for this behaviour have been discussed.
The thermodynamic parameters t.Ht and t::S* have been obtained for all the dyes and compared with data from the literature for related dyes.
The effect of substitution and the influence of the tenninal group on the visible spectra of the dyes have been examined in solvents of varying acidity.
The nature of the electrical and/or steric effects in some 2-, 3-, and 4-substituted Pyrrolidine Greens has been examined by the analysis of both kinetic and spectroscopic data using single substituent parameter and multiparameter regression techniques.
Substituent constants and electron donor potentials for a number of nitrogen-containing substituents have been interpolated.
The light fastness of some Pyrrolidine Green derivatives has been measured and the commercial implications assessed.