Substituted-cyclic-and polymeric thiourea cpds by

N,N'-disubstituted aliphatic thiourea cpds., cyclic thiorea cpds. and polythioureas are made by reacting aliphatic amines, diamines or the corresponding urea cpds. with CS2 in the liquid phase at 60-250 deg.C (pref. 90-180 deg.C). The reaction may be carried out in the melt or in a solvent, opt. under pressure, using a slight excess of CS2. May be carried out in a counter-flow reactor, whereby a soln. of the amine or urea cpd. is fed in at the top and the CS2 (pref. in a diluent such as N2, CO2, etc.) at the bottom. The H2S or COS formed during the reacting are removed from the top of the reactor. Alternatively, the CS2 and the amine soln. may be added simultaneously and continuously to a reaction vessel until the concn. of thiourea cpd. in the mixt. has reached a predetermined level, when the mixt. is removed and the solvent evaporated off. In many cases products are sufficiently pure to be used directly, but if necessary they can be recrystallised from alcohol/water.