"Versatility of Zeolites as Catalysts for Ring or Side-Chain Aromatic Chlorinations by Sulfuryl Chloride"

Lionel Delaude and Pierre Laszlo

          source: Journal of Organic Chemistry
            year: 1990
          volume: 55
      first page: 5260
       last page: 5269
             doi: 10.1021/jo00305a023

Abstract Zeolites catalyze chlorination of aromatics by sulfuryl chloride SO₂Cl₂. It is possible by an appropriate choice of the catalyst to effect at will, with very high selectivity, either the ring or the side-chain chlorination. Zeolite ZF520 is the choice catalyst for the former, because of its high Brønsted acidity. Zeolite NaX (13X) is a fine catalyst for the latter, free-radical chlorination; the reaction is best effected in the presence of a light source; the catalyst can be re-used many times with no loss in activity. Both reaction modes, the ionic (ring chlorination) and the radical (side-chain substitution), are likely to occur outside of the channel network in the microporous solid. The effects of various experimental factors -such as the nature of the solvent, the reaction time and temperature, the Brønsted acidity of the solid support, the presence of radical inhibitors, the quantity of catalysts- were investigated. The procedures resulting from this study are very easy to implement in practice and are quite effective.

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