The Photodecomposition Of Cl Basic Green 4.

The decomposition of Malachite Green, CI Basic Green 4, by carbon arc light source has been studied in aqueous solution and on sulfoethyl and carboxymethyl ethers of cellulose. A mechanism for the photochemical decomposition has been proposed for both the solution and cellulose substrates. The decomposition products isolated from the aqueous solution studies included benzaphenone, 4-methylaminobenzophenone, 4-dimethylaminobenzophenone and p-dimethylaminophenol. Evidence for the formation of both ketones was also found in cellulose substrate reaction products. Chromatographic, infrared and mass spectra analyses were used to identify the decomposition products. The fact that the decomposition products were similar from both the solution and fiber substrate studies is taken as evidence for an analogous decomposition mechanism leading to their formation. The pKa of the anionic dye site on the fiber substrate directly influenced the fading rate of Malachite Green. [ABSTRACT FROM AUTHOR]