Prepd by the action of chlorine on acetaldehyde: Krmer, Pinner, Ber. 3, 883 (1870); Pinner, Ann. 179, 24 (1875); on paraldehyde: idem; on crotonaldehyde after saturation with gaseous HCl: High, US 2280290 (1942); Brown, Plump, US 2351000 (1944). From crotonaldehyde and chlorine: Ropp et al., Org. Synth. coll. vol. IV, 130 (1963).