Process for preparing hydrazodicarbonamide via ketimines

A process for preparing hydrazodicarbonamide of formula (I)

• comprising
• (a) reacting an aliphatic ketone of formula (II)
• wherein
• R1, R2, and R3 are identical or different and are each substituted or unsubstituted alkyl, and
• R4 is hydrogen, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl, or
• R1 together with R2 or R4 form an alkylene chain,
• with ammonia under pressure to form a ketimine of formula (III)
• wherein
• R1, R2, R3 and R4 are as defined above,
• (b) oxidizing the ketimine of formula (III) with oxygen in the presence of a salt of Cr, Mn, Fe, Co, Ni, Tl, Pb, Cu or Ag as catalyst to form a ketazine of formula (IV)
• wherein
• R1, R2, R3 and R4 are as defined above, and
• (c) reacting the ketazine of formula (IV) with urea and water in the presence of a catalyst.