in acetonitrile on boiling;;

R. Appel, W. Senkpiel, Angew. Chem. 70 (1958) 572; trap-to-trap distillation;

in neat (no solvent) byproducts: HF; leading a stream of F2 (dild. with N2) through FSO2NH2 (35 h, 30 - 40 ml/min), heating to max. 50°C, condensing the product in two traps(cooled with dry ice) arranged behind the reaction vessel; combining the product from the traps, fractionated condensation;