Hydrazine, as reducing agent

Fig. 38. Gold plating thickness vs. time curves at various cyanide concentrations for substrate-catalyzed gold deposition with hydrazine as reducing agent (C. D. lacovangelo et al., 1991 [167]).

A. Fijrst, R. C. Berlo u. S. Hooton, Chem. Rev. 65, 51 (1965) Hydrazin as reducing agent for organic compounds. 

In the case of noble metals, several protocols have been described to produce metal nanosized particles by chemical reduction in microemulsions. Pileni and co-workers synthesized metallic particles of Ag," Cu," Co" (and other materials) by reduction of the corresponding salts in w/o microemulsions using borohydride or hydrazine as reducing agents. They also showed a correlation between the structure of the mesophase in the surfactant system with the size and shape of the formation of metallic particle. 

Pyrroline-N-oxides (12) are sometimes isolated when using zinc-ammonium chloride (19,20), iron-sulfuric acid (14) or hydrazine-Raney nickel (21) as reducing agents. During the reduction, dimerization has been often observed (22). 

BW-755C and its congeners can be considered as reducing agents either because they are dihydroaromatic compounds, or because of the presence of a hydrazine moiety, which is easily oxidized. In the latter vein, the amid-razone CBS-1114 (100) inhibited platelet CO and 12-LO, the release of 5-LO products from human or rabbit neutrophils (1-10 /M), and leukocyte... 

Of the various methods of estimation which are based on the use of hydrazine salts as reducing agents the following appears to be one of the most satisfactory 8 The tellurium, present either as a derivative of the dioxide or as a tellurate, is dissolved in hydrochloric acid and boiled. Sulphurous acid and hydrazine hydrochloride are added, and on continued boiling the tellurium is precipitated as such and may be collected,... 

Tellurium, potassium hydroxide, water, phenylacetylene, a trialkylmethylammonium chloride as phase-transfer catalyst, either tin(IJ) chloride or hydrazine hydrate as reducing agent and toluene as the organic solvent upon heating at approximately 100 for six hours produced Z,Z-bis[2-phenylvinyl ditellurium in low yields. Polytelluride radical anions were postulated as intermediates2 3. 

A comparison of anodic polarization curves for various reducing agents shows that the reducing power in a base electrolyte containing sulfite, thiosulfate, and ammonium chloride at pH 6.0 and at 60 °C decreases in the order ascorbate > thiourea > hydrazine. These polarization curves are reproduced in Fig. 41, which demonstrates that hydroxylamine and formaldehyde are not useful as reducing agents in this system. 

Nafion 117 membranes were electroless coated with Pt from a solution ofH2PtCl6 and hydrazine (N2H4) as reducing agent.58 The coated membrane was used to make an MEA of proton exchange membrane fuel cell which was tested at 60°C in a saturated H2/O2 system. The maximum current density of about 80 mA/cm2 at 0.3 V was obtained in this system. 

N2H4, SnCl2, and ascorbic acid are employed as reducing agents. A mixture containing ammonium molybdate, hydrazine, and H2SO4 in suitable proportions, is conveniently used in the determination of As. 

II. A note on the substitution of ferrous sulfate for hydrazine sulfate as reducing agent. /. Biol. Chem. 181, 195 (1949). 

In recent years several lines of research have been directed at the preparation of catalysts with improved selectivity. Colloids [7-9] were reported to furnish remarkably selective catalyst systems for the hydrogenation of chloronitroarenes. Reusable Pd complexes on different supports have been described for the selective hydrogenation of nitroaromatic compounds in the presence of C=0 [10] and C-Cl functionality [11]. Progress has also been reported in the use of chemoselective transfer hydrogenation systems, most notably with iron hydroxide catalysts in combination with hydrazine hydrate as reducing agent [12]. 

---