Reduction of Hydrazines

The twelve-membered cyclo-dipeptide glidobamine will be synthesized using the reductive cleavage of the nitrogen, nitrogen bond in a hydrazine derivative as a key step [76]. 

As mentioned at the beginning of this chapter the retro aidol and the retro Mannich reaction can be used for ring expansion of proper substituted bicyclic systems. 

Ring Expansion by Cleavage of the Zero Bridge in Bicycles 

---

Calculate the reaction enthalpy for the reduction of hydrazine to ammonia, N2H4(1) + H2(g) - 2 NH3(g), from the following data ... 

Scheme VIII/23. Reduction of hydrazine derivatives as a method of ring enlargement.

Coucouvanis, D., Mosier, P.E. Malinak, S. Laughlin, L. Demadis, K.D. (1995) Catalytic reduction of hydrazine and acetylene to ammonia and ethylene and stoichiometric reduction of CN to ammonia and methane by Fe/M/S clusters (M =Mo, V) with structural features similar to those of the Fe/Mo/S site in nitrogenase, Plant Sci. Biotechnol. Agric. (Nitrogen Fixation Fundamentals and Applications) 27, 137-42. 

VFe3S4X3] (X = Cl, Br, and I), (Me4N)2[TpVFeS4Cl3], and (Me4N)[(NH3)-(bipy)Fe3S4Cl3]. A study of the catalytic reduction of hydrazine (a nitrogenase substrate) to ammonia in the presence of an external source of electrons and protons shows that the rate of reduction decreases as the number of labile solvent molecules coordinated to the V atom decreases but does not depend on the nature of the atom attached to the Fe atoms. 

Reduction of hydrazines. Monosubstituted hydrazines are converted into hydrocarbons by reaction with the reagent under phase-transfer conditions (equation I). Yields are poor to moderate (6-40%) for aryihydrazines, but often fairiy high for heterocyclic substrates (7-95%). 

Wolfrom, M L, Bernsmann, J, Horton, D, Synthesis of amino sugars by reduction of hydrazine derivatives. 5-Amino-3,6-anhydro-5-deoxy-L-idosederivatives,7. Org. Chem., 27,4505-4509,1967. 

Teiranitromethane in crude trinitrotoluene may be estimated by reduction of hydrazine in alkaline sdution to nitrogen... 

Reactions of hydrazine (N2Hs ), phenylhydrazine (N2H4Ph ) at pH 2.8 and azide (Nj-) at pH 5.3 with [Ru (HL)(H20)] and [Ru "L(H20)] (where L = ethylenediamminetetraacetate) were studied by voltammetry and spectrophotometry at 25 °C. The resultant complexes were electrolyzed in the presence of nitrogenous ligands in excess by constant potential coulometry at Hg-pool electrode. The turnover rates for the formation of ammonia and/or amine and the catalytic efficiency of these nitrogenous compounds were reported. An appropriate mechanism for the catalytic reduction of hydrazines and azide were proposed. 

A solution hydrazine (100 mM) in 0.2 M CH3COONa buffer containing 1 mM of [Ru "(HL)(H20)] was electrolyzed at -0.05 V vs SCE in order to estimate the catalytic activity of Ru -EDTA through its hydrazinium complexes for the reduction of hydrazine to ammonia. As expected, hydrazine was only reduced to NH3 justifying the first step as a multi-electron reduction wave. The plot of moles of NH3 produced per mole of complex vs the electrolysis time was linear (Figure 4a). From the slope of the plot, the turnover rate was calculated tmd found to be 18.4 moles of ammonia per mole of catalyst per hour. While phenylhydrazine was electrolyzed under identical conditions at -0.200 V vs SCE, it reduced to equimolar ratio of ammonia and aniline The plot of moles of ammonia produced per mole of catalyst (Figure 4b) was linear and the turnover number was found to be 5.98. In both cases, 100% coulombic efficiency was observed. 

Cubane clusters that contain a VFe3S4 core and catecholate or multicarboxylate ligands homogeneously catalyze the reduction of hydrazine to ammonia and that of acetylene to ethylene... 

Synthesis of Amino Sugars by Reduction of Hydrazine Derivatives. 2-Amino-2-deoxy-L-lyxose (L-Lyxosamine) Hydrochloride, D. Horton, M. L. Wolfrom, and A. Thompson,/. Org. Chem., 26, 5069-5074 (1961). 

The study of MoFe3S4 cubane clusters (Section 8.22.2.3.5) has not yielded N2 adducts, although some iron-sulfur and molybdenum-iron-sulfur clusters may be catalysts for the electrolytic reduction of N2. Coucouvanis and co-workers have discovered that a number of Mo/Fe cubanes catalyze the reduction of hydrazines and diazenes to ammonia and/or amines. ... 

Peng and Guarr " and Trollund et al. reported on the electrocatalytic oxidation of hydrazine at a GCE modified with CoTAPc polymer, with a well-defined catalytic peak at -0.30 Table 7.8. The central Co(II) metal was found to act as the electronic receptor for hydrazine ". H2TAPC on GCE or conducting glass electrodes has also shown catalytic activity towards the oxidation of hydrazine. Ebadi reported on the use of a dimeric (RuPc)2 complex for the electrocatalytic reduction of hydrazine to nitrogen in basic media. The mechanism for this process may be similar to that reported below for hydroxylamine. The potentials for the oxidation of hydrazine on FeTSPc and CoTSPc are similar. Table 7.8. 

The reduction of hydrazine derivatives has not been widely exploited for the preparation of amines, but might be useful in certain cases. Benzhydrazide can be alkylated on the terminal nitrogen atom hydrogenolysis then gives the amine (reaction 92)... 

---