- Discovery and development of a commercial synthesis of azafenidin
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A commercial synthesis of the DuPont herbicide azafenidin is described. Discovery of a novel synthesis of the triazolinone ring system and a practical, environmentally benign process to 5-cyanovaleramide were critical breakthroughs in enabling azafenidin to be manufactured at an acceptable cost. The process began with the selective hydrolysis of DuPont's nylon intermediate, adiponitrile, to 5-cyanovaleramide. This was converted via Hofmann rearrangement and Pinner-type cyclization to afford the key amidine carboxylate intermediate containing both carbon atoms of the triazolinone ring. The preservation of all six carbon atoms of adiponitrile set up a 2 + 3 cyclocondensation with arylhydrazines, which replaced a costly 4 + 1 cyclocondensation of an amidrazone with phosgene or a phosgene surrogate used in the original route. This new triazolinone process was optimized to afford the commercial product in a highly efficient and economical fashion.
- Shapiro, Rafael,DiCosimo, Robert,Hennessey, Susan M.,Stieglitz, Barry,Campopiano, Onorato,Chiang, George C.
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p. 593 - 598
(2013/09/07)
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- Process for preparing arylhydrazines
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The present invention relates to a process for preparing arylhydrazines of the formula R1R2R3Ar-NH-NH2 (I) by reacting an arylhydrazinedisulfonate of the formula in which R1, R2, and R3 are identical or different and are H, C1-C4-alkyl, C1-C4-alkoxy, halogen or OH, Ar is phenyl or naphthyl, M1 and M2 are identical or different and are H, NH4, an alkali metal or +E,fra 1/2+EE alkaline earth metal and R1, R2, R3 and Ar in the formulae (I) and (II) have the same meaning, with water and an inorganic acid at from 0 to 100 DEG C. in the presence of an inert organic solvent to give the corresponding arylhydrazine salt and treating the arylhydrazine salt with a base.
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