Abstract: A process for removing trioxane from a liquid mixture containing trioxane, water and formaldehyde, which includes distilling the liquid mixture in a first distillation stage at a low pressure, distilling the resulting distillate in a second distillation stage at a higher pressure and taking off trioxane as bottom product.

Abstract: The invention relates to a process for the preparation of acesulfam salts by reaction of salts of amidosulfonic acid with diketene to give a salt of acetoacetamidosulfonic acid (I), ring closure by the action of at least about an equivalent amount of SO.sub.3, at least this ring closure reaction being carried out in the presence of a halogenated, aliphatic hydrocarbon as an inert solvent, treatment of the cyclization product with water and conversion of the resulting acesulfam-H (II) into the form of a non-toxic salt, which comprises, in the work-up by distillation of the resulting crude solvent, after removal of water and low-boilers and recovery of solvent sufficiently pure for reuse in the preparation of compounds (I) and/or (II), directly returning :he remaining, solvent-containing distillation residue, without further purification, into the system downstream of the reaction vessel for carrying out the ring closure reaction.