PHOTOCHEMISTRY OF 2,3-DIMETHYL-2,3-DIPHENYLBUTANE - C-C HOMOLYSIS AND PROTONATION-INDUCED SIDE-CHAIN FRAGMENTATION

• Type: Article in International Scientific Journal
• Date: 1992

Authors

Faria, JL (Author) FEUP; Steenken, S (Author) Other

Journal

Title: Journal of Physical Chemistry

Vol. 96

Pages: 10869-10874

ISSN: 0022-3654

Publisher: American Chemical Society

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Other information

Authenticus ID: P-008-NYA

DOI: 10.1021/j100205a049

Abstract (EN): In dichloromethane upon 248-nm (or 254-nm) irradiation, 2,3-dimethyl-2,3-diphenylbutane (bicumene) undergoes homolysis of the central C-C bond to yield two ¿,¿-dimethylbenzyl (cumyl) radicals (¿hom = 0.18). In 2,2,2-trifluoroethanol (TFE), this reaction is less efficient (¿hom < 0.02), but a new process is observed, i.e., biphotonic ionization followed by C-C fragmentation of the resulting radical cation leading to the cumyl radical and the cumyl cation. The latter reacts with TFE to give cumyl trifluoroethyl ether. In the more acidic solvent 1,1,1,3,3,3-hexafluoroisopropyl alcohol, the electronically excited state of bicumene is efficiently protonated by the solvent to yield a cyclohexadienyl-type carbocation which undergoes side-chain fragmentation to produce cumyl cation, which was directly observed by its UV absorption and whose electrophilic reactivity was characterized. Photoprotonation followed by side-chain fragmentation was also observed with ß-phenylalkanols which give rise to the aliphatic oxo compounds derived from the ß-carbon of the side chain. © 1992 American Chemical Society.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6