1-Heteroarylsulphonyl-2-imino-imidazolidines

An imidazolidine compound of the formula I ##EQU16## in which Het is a thienyl radical,

• R.sub.1 denotes an alkyl group with at most 12 carbon atoms, an alkenyl group with 3 to 5 carbon atoms, a cycloalkyl, lower alkyl-cycloalkyl, cycloalkenyl or lower alkyl-cycloalkenyl group, each of which of at most 7 carbon atoms, or 7 to 9 carbon atoms,
• R.sub.2 denotes hydrogen, or the methyl or ethyl group,
• X denotes hydrogen, halogen up to atomic number 35, an alkyl group which is or is not interrupted by 1 or by 2 non-adjacent oxygen or sulphur atoms and contains a total of at most 7 carbon atoms, or the hydroxyl group, the amino group or an alkanamido group with at most 4 carbon atoms, and
• Y has the meaning of X or denotes a radical of the partial formula Ia or Ib ##EQU17## in which m denotes 2 or 3,
• Z denotes oxygen,
• R.sub.3 denotes hydrogen or the methyl group,
• R.sub.4 denotes an alkyl or chloroalkyl group with at most 7 carbon atoms, an alkenyl group with 2 to 5 carbon atoms, a cycloalkyl, lower alkyl-cycloalkyl, cycloalkenyl or lower-cycloalkenyl group, each of which with a total of at most 8 carbon atoms, a phenyl group, a phenylalkyl group of 7 to 10 carbon atoms or a phenylalkenyl group of 8 to 10 carbon atoms, whereby the phenyl group present as R.sub.4 or as a part of R.sub.4 is unsubstituted or substituted by one to three substituents selected from the group consisting of halogen up to atomic number 35, trifluoromethyl, alkyl with at most 4 carbon atoms, hydroxy, alkoxy with at most 2 carbon atoms and alkylthio with at most 2 carbon atoms,
• and the pharmaceutically acceptable addition salt of the compound of formula I with inorganic or organic acids.