Quinaldinium salts

When a quinaldinium salt and 2-unsubstituted thiazolium are condensed together in the presence of a basic agent, the resulting bis-(methylquinoline-2)trimethine cyanine is issued from the cleavage of the thiazolium ring of the anhydrobase (25). It is induced by the -CHj attack of quinaldinium according to a process already described (Scheme 28). 

Quaternary salts, pKa value of, 7] polarographic reduction potentials, 71 Quinaldinium salts, in Mills reaction, 37,45 Quinoline-4)(4-methvlthiazole-2) trimethine cyanine, 62... 

Sawicki et al. (22) showed that terminal ring o- and p-quinones are characterized by a coupling reaction with 1-alkyl quinaldinium salts while inner ring o- and p-quinones do not couple with these salts. The type of dyes formed in the coupling reaction absorb in the 635-775 mp region. Using a modification of Sawicki s procedure, the eluted reference compound, 2,6-dimethoxyquinone, the reaction product at the Rf value of 0.73 and a paper blank were treated with the quinaldinium salt. The three... 

The condensation proceeds via the more reactive quinaldinium salts in which the methyl groups are more activated than in the quinal-dines themselves, and it is therefore necessary to add a catalytic quantity of acid to initiate the reaction.9 The di- and triquinolyl-methanes are separated (a) due to their different basicities by fractional crystallization of their hydrochlorides,1 or (b) by precipitation of the diquinolyl compound as the zinc complex10,11 (see Section V,B,1). 

Recently, quinaldinium salts or 3-ethylrhodanin were proposed as reagents for quinones with a terminal quinoid benzene nucleus. A greater sensitivity is achieved, but the course of the reaction must be followed spectroscopically at 500—800 nm (30). 

N-acoxycyclimmonium salts azidocyclimmonium — azomethinium —, cyclic carbalkoxycyclimmonium — nitrocyclimmonium — phenazinium — pyridinium — quinaldinium — thiazolium —... 

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