Prototropic reactions of 2-carbonyl-substituted fluorenes in the ground and first excited singlet states

✍ Scribed by Ramasamy Manoharan; Sneh K. Dogra

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 979 KB
• Volume: 50
• Category: Article
• ISSN: 1010-6030
• DOI: 10.1016/1010-6030(89)80020-6

✦ Synopsis

The spectral characteristics of 2_fluorenaldehyde, 2-acetylfluorene and 2-benzoylfluorene have been studied in different solvents and at various acid concentrations. This study has shown that nr* may be the lowest energy transition in non-polar and aprotic solvents but that OTT* is the lowest energy transition in water. The carbonyl group attains more planarity with respect to the fluorene moiety on excitation. The prototropic equilibrium follows the benzophenone acidity scale rather than Hammett's acidity scale. A medium effect is also observed during the protonation of the species. Contrary to literature reports at H, -8 the dication species are formed by protonating the carbonyl group and the fluorene ring at position 7.