thiourea in ethanol 20 h; Heating;

in pyridine; ethylene glycol mixing of tetrafluoro-4-thiolpyridine soln., pentafluoropyridine soln. (in waterfree pyridine) and KHS susp. (in ethanediol);

in acetonitrile at 20°C, 2 h, in presence of Na2CO3;