The title compound (1) is converted into an unusual chlorophenacyl disulphide (2) through a crystal structure controlled Chlorination-oxidation reaction. ... Organic gas-solid reactions are interesting from both mechan- istic and stereochemical viewpoints. Recent work has shown that topochemical control plays an important role in determin- ing the course and outcome of these reactions.1-7 We report here a novel chlorination-oxidation of the title compound. ...