The chemistry of some polysubstituted derivatives of di - and triphenylmethane dyes
Several series of disubstituted derivatives of Malachite Green containing chloro, fluoro, methoxy and methyl groups in the phenyl ring have been synthesised and their respective visible absorption spectra compared with that of Malachite Green. In most cases where steric effects are unimportant an additive relationship is found between the electronic effects of the substitüents and the position of the first frequency absorption band. It is noted that the 2,3dichloro derivative produced an anomalous spectral result and an explanation is postulated. The linear relationship between the wavelength of maximum absorption for the x-band of the 3,47 and 3,5-diubstituted derivatives of Malachite Green and the respective Hammett substituent constants has been confirmed except for the 3,4-dimethoxy derivative. The preparation of Crystal Violet and Malachite Green derivatives containing ortho- chioro and fluoro substituents in the dimethylaminophenyl rings has enabled the spectral-changes resulting from the steric and electronic interaction of substituents with the central carbon atom to be examined.
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