CARBENIUM ION CARBINOL EQUILIBRATION FOR BASIC TRIARYLMETHANE DYES - RELATIVE REACTIVITIES OF DYES IN AQ SOLUTIONS

Equilibria and kinetics of carbenium ion-to-carbinol base reactions fo r a set of selected basic triarylmethane dyes in aq. buffer solutions of low ionic strength have been measured spectrophotometrically. Relat ive reactivities of the dyes towards nucleophilic attack by hydroxide ion, on the basis of both equilibrium constant and forward rate consta nt of the reaction, have been found to follow the same order: malachit e green (MG) > brilliant green (BG)>> Victoria pure blue BO(VB)> methy l violet (MV) congruent-to crystal violet (CV)> ethyl violet (EV). A f airly good correlation between electrophilicities of the dyes and sigm a(R)+ parameters of their 4-alkylamino substituents has been obtained.