Hydrazine hydrate, reaction with diacetylene

In 1967 Matsoyan discovered the reaction of diacetylene with hydrazine hydrate leading to 3(5)-methylpyrazoles (13) (68AKZ998 70AKZ640 71AKZ743 72MI1). 

The reaction of disubstituted diacetylenes with hydrazine hydrate was reported by Darbinyan et al. (70AKZ640). In the first stage the addition of hydrazine to the terminal carbon atom of the diacetylene system is analogous to that of primary amines to diacetylene (69ZC108 69ZC110). With monosubstituted diacetylenes (R = H), hydrazine adds to the terminal triple bond. This leads to the formation of vinylacetylenic hydrazine 22 which cyclizes to dihydropyrazole 23 subjected to further isomerization to the pyrazole 25. It is possible that hydrazine 22 undergoes hydration to the ketone 24 which can easily be cyclized to the pyrazole 25... 

Almost simultaneously, Schroth reported that diacetylene reacts with a hydrazine hydrate solution at 80°C for 4 h to form methylpyrazoles (13) in 80% yield (69ZC108 69ZC110). In the same year, other data concerning the reaction of hydrazine with diacetylene (65°C, EtOH, yield 65%), hexa-2,4-diyne, and 1,4-diphenylbuta-l,3-diyne wCTereported(69JOC999). Later, BASF (93GEP4137011) proposed to carry out the process at 100°C in a polar solvent with a diacetylene concentration of 14-18% in an inert gas. The yield of methypyrazoles was 90% (post-rectification purity 99%). 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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