22439-61-8Relevant articles and documents
Photochemistry and photophysics of halogen-substituted dibenzothiophene oxides
Nag, Mrinmoy,Jenks, William S.
, p. 8177 - 8182 (2007/10/03)
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.
Hydrodesulfurization of Alkyldibenzothiophenes over a NiMo/Al2O3 Catalyst: Kinetics and Mechanism
Meille, Valerie,Schulz, Emmanuelle,Lemaire, Marc,Vrinat, Michel
, p. 29 - 36 (2007/10/03)
The transformation mechanism of dibenzothiophene, 4-methyldibenzothiophene, 4,6-dimethyldibenzothiophene, and 2,8-dimethyldibenzothiophene has been studied in a batch reactor over an industrial NiMo/Al2O3 hydrotreating catalyst at 573 K under 5 MPa of hydrogen pressure. A detailed mechanistic study including competitive catalytic experiments proved that the adsorption of the most refractory molecules at the catalyst surface was not the rate-determining step for their transformation. Our results imply that the hydrodesulfurization of these compounds occurs on one single type of sites by a flat adsorption, leading to a preliminary partial hydrogenation of one aromatic ring. Variations in reactivities of the dibenzothiophene derivatives were thus explained by different reaction rates for the C-S bond scission due to steric hindrance generated by the methyl substitution near the sulfur atom.
