A spectrophotometric study concering the charge transfer interaction between 2,3-dichloro-5,6-dicyano-1,4-benzoquione (DDQ) and some benzophenoes has been carried out in chloroform at 25°C. Comparision of the spectra of the complexes of 1.2-dimethoxybenzene-DDQ and benzophenone-DDQ is indicative of two kinds of transitions: (i) n→π*, and (ii) π→π* respectively,). Formation constants of the resulting 1:1 molecular complexes were determined by using the Hildebrand method. The values of formation constants are in parallel with the charge density on the oxygen atoms of cabonyl groups. Also steric hindrance of substituents affects the stability of the resulting complexes. The shifts in stretching frequency of carbonyl groups of benzophenones, brought about upon complexation, further supports that donation takes place from oxygens of the carbonyl groups.

Keywords: DDQ, Benzophenones, Charge-transfer complex, spectrophotometry