Intra- and inter-molecular hydrogen-atom abstraction of photoexcited 1,4-dimethylanthraquinone

✍ Scribed by Nakayama Toshihiro; Honma Chisako; Miki Sadao; Kumao Hamanoue

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 454 KB
• Volume: 213
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)89164-d

✦ Synopsis

Steady-state (366 nm) and nanosecond laser (347.2 nm) photolyses of the title compound in benzene, ethanol and EPA at room temperature and 77 K reveal that both the lowest excited singlet and triplet states cause the intramolecular hydrogen-atom abstraction yielding the excited singlet and triplet biradicals, respectively, followed by the final formation of 9-hydroxy-4-methyl-1,l O-anthraquinone-1 -methide (HMAQM) In contrast, 3 13 nm steady-state photolysis in ethanol or EPA at room temperature yields 1,4dimethyl-9,10-anthrahydroquinone (DMAQH,), although HMAQM is still produced in EPA at 77 K. The formation of DMAQHl is tentatively interpreted in terms of the temperature-dependent intermolecular hydrogen-atom abstraction from ethanol by the third excited singlet state of DMAQ yielding the semiquinone radical.