Solid-state and solvent-free synthesis of azines, pyrazoles, and pyridazinones using solid hydrazine

Azines, pyrazoles, and pyridazinones were isolated as the sole products in high yields (>97%) by grinding solid hydrazine (H3N+NHCO2−) with di-carbonyl compounds or by their reaction in the absence of solvent. Neither catalysts nor additives were needed to promote the reactions. The solid-state and solvent-free reactions proceeded under ambient conditions and did not produce any wastes other than water and carbon dioxide. They are operationally easy, environmentally safe, and readily scalable, allowing for highly selective synthesis of compounds containing the hydrazine motif.