Merocyanines Derived from Substituted 4-Hydroxycoumarins. Part II. Determination of Relative Acidity

The relative acidity of different 4-hydroxycoumarins has been determined by two methods: (\(i\)) by extension of the application of Forster's rule to the absorption data of \(p\)-diallrylaminobenzylidene derivatives of different 4-hydroxycoumarins and their sea analogues, (\(ii\)) by the application of Brooker's deviation factor. For evaluation by the second method, the absorption data of oxonols of different 4-hydroxy­coumarins have been collected.