Woodward's rules
Rules predicting maximum absorption wavelengths / From Wikipedia, the free encyclopedia
This article is about rules related to spectroscopy. For rules related to pericyclic reactions, see Woodward–Hoffmann rules.
Woodward's rules, named after Robert Burns Woodward and also known as Woodward–Fieser rules (for Louis Fieser) are several sets of empirically derived rules which attempt to predict the wavelength of the absorption maximum (λmax) in an ultraviolet–visible spectrum of a given compound. Inputs used in the calculation are the type of chromophores present, the auxochromes (substituents on the chromophores, and solvent.[1][2] Examples are conjugated carbonyl compounds,[3][4][5] conjugated dienes,[3][6] and polyenes.[3][5]