The ultraviolet spectra of O-(2,4-dinitrophenyl)oximes and 2,4-dinitrophenylhydrazones: transmission of electronic effects through O and NH groups

Abstract

The λ_max values in the ultraviolet spectra of 61 pairs of 2,4-dinitrophenylhydrazones (DNP) and O-(2,4-dinitrophenyl)oximes (DNO) were compared. The λ_max(DNP)–λ_max(DNO)=Δλ values are 61 ± 1 mµ for aliphatic carbonyl compounds, 69 ± 1 mµ for aromatic aldehydes and ketones, and 71 ± 1 mµ for diaryl ketones. Deviations were found for several ortho substituents or for para substituents having strong +M effect. The factors determining the constancy and the deviations of the Δλ values are discussed.