Photochemistry and Photophysics of Halogen-Substituted Dibenzothiophene Oxides1

Dibenzothiophene-5-oxide (DBTO) cleanly produces dibenzothiophene (DBT) on direct photolysis, but with very low quantum yield. A proposed mechanism involves scission of the S−O bond which is coupled to an intersystem crossing step, thus producing the sulfide and O(3P) via a unimolecular pathway. To...

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Bibliographic Details
Published in:Journal of organic chemistry 2004-11, Vol.69 (24), p.8177-8182
Main Authors: Nag, Mrinmoy, Jenks, William S
Format: Article
Language:English
Online Access:Get full text
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Summary:Dibenzothiophene-5-oxide (DBTO) cleanly produces dibenzothiophene (DBT) on direct photolysis, but with very low quantum yield. A proposed mechanism involves scission of the S−O bond which is coupled to an intersystem crossing step, thus producing the sulfide and O(3P) via a unimolecular pathway. To test this hypothesis, heavy atom substituted DBTOs were prepared and photolyzed. Iodo-, bromo-, and chloro-substituted DBTOs show higher quantum yields for deoxygenation than does the parent molecule, in the order consistent with an intersystem crossing-related heavy atom effect. 2-Iododibenzothiophene also undergoes photochemical deiodination. Phosphorescence data are consistent with heavy-atom assisted intersystem crossing.
ISSN:0022-3263
1520-6904
DOI:10.1021/jo0490346