Hydrazine hydrate reductions

An enamine (formed in situ) reacts with a neighbouring amino group (also formed in situ by sodium borohydride-nickei boride-hydrazine hydrate reduction of a nitro group) to give a high yield of the precursor of a biologically important indole. 

The classical procedure for the Wolff-Kishner reduction—i.e. the decomposition of the hydrazone in an autoclave at 200 °C—has been replaced almost completely by the modified procedure after Huang-Minlon The isolation of the intermediate is not necessary with this variant instead the aldehyde or ketone is heated with excess hydrazine hydrate in diethyleneglycol as solvent and in the presence of alkali hydroxide for several hours under reflux. A further improvement of the reaction conditions is the use of potassium tcrt-butoxide as base and dimethyl sulfoxide (DMSO) as solvent the reaction can then proceed already at room temperature. ... 

Dinitroarenes containing substituents such as hydroxyl or amino groups are reduced with 3 mol equiv of hydrazine hydrate in the presence of Raney nickel to afford selectively a compound in which only one nitro group is reduced. In general, the main product is derived by reduction of the more hindered nitro function. For example,... 

To 1,400 ml of an approximately 50% water/triglycol solution of the potassium salt of cheno-deoxycholic acid, obtained by the Wolff-Kishner reduction (using hydrazine hydrate and potassium hydroxide) from 50 g of 7-acetyl-12-ketochenodeoxycholic acid, 220 ml of dilute hydrochloric acid is added to bring the pH to 2. The solution is stirred and the crude cheno-deoxycholic acid precipitates. The precipitate is recovered and dried to constant weight at about 60°C. About 36 g of the crude chenodeoxycholic acid, melting in the range of 126°-129°C, is obtained. 

Diphenylbutadiene (16, 28) In yields of 50 per cent by reduction of 0-bro-mostyrene with hydrazine hydrate in the presence of a palladium catalyst and alco-... 

Hydrazine hydrate, in preparation of sulfonylhydrazides, 40, 93, OS in reduction of 2-nitrofiuorene to 2-aminofluorene, 40, 5 in Wolff-Kishner reduction, 43, 34 Hydrazines, asymmetrically substituted by N-aminatiou of amines by hydroxylamine-O-sulfonic acid, 43,2... 

Nitro compounds can be further reduced to hydrazo compounds with zinc and sodium hydroxide, with hydrazine hydrate and Raney nickel,or with LiAlH4 mixed with a metal chloride such as TiCU or VCl3. The reduction has also been accomplished electrochemically. 

Suhtnicion nickel powders luive been synthesized successfully from aqueous NiCh at various tempmatuTKi and times with ethanol-water solvent by using the conventional and ultrasonic chemical reduction method. The reductive condition was prepared by flie dissolution of hydrazine hydrate into basic solution. The samples synthesized in various conditions weae claractsiz by the m ins of an X-ray diffractometry (XRD), a scanning electron microscopy (SEM), a thermo-gravimetry (TG) and an X-ray photoelectron spectroscopy (XPS). It was found that the samples obtained by the ultrasonic method were more smoothly spherical in shape, smaller in size and narrower in particle size distribution, compared to the conventional one. 

The spherical fine nickel powders have been prepared fiom aqueous NiCU and hydrazine hydrate at various temperatures wife ethanol-water solvent by the conventional and ultrasonic hydrothermal reduction method. The induction time decreased wife inrareasing fee reaction temperature in both fee method, but was relatively shorter in fee ultrasonic mefeod. Compared to the conventional one, the surface morphology and particle size of fee sample obtained by the ultrasonic method was much smooth and regular in spherical shape and was much small, respectively. Therefore, the tap density of the sample obtained by fee ultrasonic mefeod was relatively higher than feat obtained by fee conventional one. 

The deoxygenation of aldehydes and ketones to the corresponding hydrocarbons via the hydrazones is known as the Wolff-Kishner reduction.28 Various modifications of the original protocols have been suggested. One of the most useful is the Huang-Minlon modification, which substituted hydrazine hydrate as a safer and less expensive replacement of anhydrous hydrazine. In addition, diethylene glycol together with sodium hydroxide was used to increase the reaction... 

Diaminobiuret has been prepared only from N-tricarboxylic ester and hydrazine hydrate.1 Ethyl hydrazinecarboxylate has been prepared by reduction of nitrourethan electrolytically2 or with zinc dust and acetic acid,3 and by the action of hydrazine hydrate on diethyl carbonate,4 6 ethyl chlorocarbonate,6 and N-tricarboxylic ester.1... 

The use of hydrazine hydrate in anhydrous methanol with 5% palladium on charcoal under an inert atmosphere gave excellent results for the reduction of l-benzyl-4-nitroimidazole (72 R1 = CH2Ph, R2 = H) with compound (71 R1 = CH2Ph, R2 = H) being isolated as its hydrochloride salt (96%) (74JMC1168). 

Finally, the amino metabolites of the NMs have been synthesized by researchers and used as standards. These synthesis methods include reduction of NMs with hydrogen in the presence of Pd/charcoal to form the amino metabolites [ 15,16,23] or reaction of NMs with hydrazine hydrate and Raney nickel [ 14,23]. A metabolite of HHCB, HHCB-lactone, has also been synthesized and used as a standard [17]. 

Starting from the known isothiocyanate 351 <1998JHC29>, the cyclization of the semicarbazide 352, obtained from compound 351, by condensation with hydrazine hydrate, gives thione 353, whose nitrosation and reduction... 

Phenylhydrazine has been prepared by the reduction of benzene diazonium salts with sulfites 1 by the reduction of benzene diazonium chloride with stannous chloride 2 by the reduction of benzene diazonium hydrate with zinc or sulfur dioxide 3 by the reduction of sodium benzene diazotate with sodium stannite 4 by the reduction of diazoamino benzene 5 by the reduction of nitrosophenyl hydroxylamine or its methyl ether 6 and by the action of hydrazine hydrate on phenol.7... 

Abstract Starting with tetracyanodibenzo(l,4,7,10-tetrathia-(12-crown-4)) (1) and 4-nitro-l,2-dicyanobenzene (2), nitro-substituted dimeric phthalocyanine (3) was synthesized. In the second step, using hydrazine hydrate as a reductant, amine-substituted dimeric phthalocyanine (4) was synthesized from nitro-substituted dimeric phthalocyanine. Stractmres of all synthesized compounds were determined by elemental analyses, UV/vis, H-NMR and IR spectroscopy. 

Peripheral nitro substituents on the Pc offer a number of possibilities to obtain reactive binding sites, such as reduction to an amine. For this purpose, hydrazine hydrate is used as the reductant. 

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