The reduction of carbon-carbon double bonds is generally carried out using hydrogen in the presence of suitable transition metal catalysts such as Pd, Rh, or Raney Nickel. One of the rare alternatives is the use of diimide which is usually generated in situ by e.g.heating arenesulfonyl hydrazides, acidification of azodicarboxylates or from the oxidation of hydrazine. In the latter case a variety of catalytically active species like copper and iron salts or organic molecules such as flavine derivatives are generating the reactive intermediate using molecular oxygen as sole oxidant.Herein, we present an efficient reaction protocol for this hydrogen-free reduction of olefins in a gas-liquid continuous flow regime. Hydrazine hydrate (N2H4 * H2O) and molecular oxygen are efficiently mixed by a segmented flow pattern to in situ generate diimide which subsequently reduces various olefins. The highly efficient mass transfer resulting from the increased surface to volume ratio of the biphasic reaction mixture enables a catalyst-free reaction which undergoes completion in a couple of minutes.

In situ generation of diimide from hydrazine and oxygen: Continuous transfer hydrogenation of olefins

248th National Meeting (2014)

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