Adsorption of diphenyl disulfide (DPDS) from CH2Cl2 solutions onto acid zeolites at room temperature generated the "extended" radical cation, DPDS.+. At loadings of 3 wt%, oxidation to DPDS.+ is essentially complete. Upon heating the loaded zeolite to 200°C, the adsorbed DPDS.+ was converted into thianthrenium radical cation (TH.+). Ab initio calculations at the B3LYP and HF levels using the 6-31G* basis set suggest cyclization of a diphenyl disulfide-S,S-dication as a reasonable rate-determining step of the conversion. Non-acidic zeolites devoid of Lewis and Brønsted sites (as determined by the pyridine adsorption-desorption method) failed to generate DPDS.+ to an extent detectable spectroscopically: these results support Lewis and/or Brønsted sites as being responsible for the observed oxidation.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of the Chemical Society. Perkin Transactions 2|
|State||Published - Feb 1999|
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