Ethylidene bisformamide, its preparation and use in preparing poly(vinylamine) and salts thereof

Ethylidene bisformamide is prepared by reacting, at elevated temperatures, dry acetaldehyde and formamide in the presence of an acidic catalyst and an ammonia scavenger such as acetic anhydride. The bisformamide is recovered as a bottoms products of high speed low residence time distillation techniques, e.g., wiped film evaporation. The resulting ethylidene bisformamide may be cracked to N-vinylformamide, which monomer is useful in the preparation of active polymers and copolymers, including poly(vinylformamide) which can be hydrolyzed to poly(vinylamine) salts by contact with acid. These amine salts can then be converted to the free amines, which are precursors of polymeric dyes and pharmaceuticals.