How is N,N'-Diphenylimidoformamide (CAS: 622-15-1) typically synthesized?

N,N'-Diphenylimidoformamide is typically synthesized by the reaction of phthalimide with anhydrous ammonia followed by formylation using a formamide-formamide mixed solvent. This process involves a multi-step transformation where the phthalimide reacts with ammonia to form phthalimide amidinium chloride, which then undergoes formylation to produce the final product. The yield is around 70-80%, and the method is selective and efficient.