Carbonyl di:isothiocyanate and isothiocyanato-carbonyl isocyanate - obtd. by reaction of carbonyl halide e.g. phosgene or halo:carbonyl isocyanate with ammonium thiocyanate

In a new process for the prodn. of carbonyl psuedohalides of the formula SCN-CO-Y (I) (where Y is isothiocyanate or isocyanato), a carbonyl halide of the formula Hal(1)-CO-Hal (2) (II) (where Hal(1) and Hal(2) are F, Cl or Br and Hal (2) can also be isocyanato) is reacted with ammonium thiocyanate in the presence of an inert polar diluent at below 30 deg.C in such a way that the carbonyl halide (II) is always present in excess. The cpd. isothiocyanate-carbonyl isocyanate (Ia) of the formula SCN-CO-NCO is new and claimed. Also new and claimed is the use of carbonyl diisothiocyanate (Ib) for the prodn. of 5,6-dihydro-6-thioxo -2-(XR1)-1,3,5- thiodiazin-4-one derivs. (II) (where X is O, S or NR2; and R1 and R2 are H, open-chain or cyclic alkyl, aralkyl or aryl) and of 2-thiobuirsts of the formula (R3) (R4)-CO-NH-CS-N(R3)(R4) (III) (where R3 and R4 are H, alkyl, aralkyl or aryl or N(R3) (R4) is a heterocyclic ring). (I) are reactive substances suitable for use as intermediates e.g. pharmaceuticals, plant protection agents and materials protection agents. In particular, (Ib) is useful on intermediate for thiodiazines (II) and thiobuirets (III) useful as pharmaceuticals, microbicides, fungicides and insecticides.