The spectral absorption of certain monoazo dyes -1. The effect of position isomerism on the spectral absorption of methyl derivatives of benzeneazophenol

Quantitative measurements of the spectral absorption of solutions of azoben- zene, benzeneazophenol, and the monoand dimethyl derivatives of benzene- azophenol in alcohol, aqueous hydrochloric acid, and aqueous sodium hydroxide are recorded and their relationships discussed. Although the differences found in the spectral absorption of alcohol solutions or of hydrochloric acid solutions of the position isomers studied are small, marked differences are found in the absorption of 3 per cent aqueous sodium hydroxide solutions.