FIELD: as a semifinished product in organic synthesis. SUBSTANCE: Reagent 1: a gaseous mixture of isocyanic acid and ammonia. Reagent: C5-C8 tertiary cyclic amine or an amide of the formula: NR1R2R3 wherein R1,R2 end R3 are linear or branched lower alkyl, phenyl, phenyl lower alkyl or cyclic or linear ester of the general formula: R1-O-/R4-O/n-R2 wherein n is 0 or 1; R1 end R2 are linear or branched lower alkyl or phenyl, or R1 end R2 together are C2-C4-alkylene; R4 is lower alkyl. Reaction conditions: reagent 2 is passed into reagent 1 at 250-600 C at an isocyanic acid to reagent 2 molar ratio of 1:0.0 to 1:3; the resulting gaseous reaction mixture is added to an inert organic diluent and cooled from -70 C to room temperature. EFFECT: improved process for preparing isocyanic acid in stable form ready for use.
