Hydrazine hydrate method

Dialkyl Ditellurium (Hydrazine Hydrate Method)1 6.35 g (50 mmol) tellurium is added to a stirred solution of 3.0 g sodium hydroxide (75 mmol) in 20 ml deoxygenated water. The mixture is cooled in a water bath. Hydrazine hydrate (100%, 2.5 g, 200 mmol) is added to the stirred suspension over 30 min. Stirring is continued for an additional hour at 20°. The alkyl halide (50 mmol) is then added dropwise over a period of 2-3 h. During the addition the temperature is maintained at 15 to 20". The end point of the alkylation is reached when the color of the solution changes from dark-brown to nearly colorless. The mixture is extracted with diethyl ether. The organic layer is washed with water, dried with anhydrous sodium sulfate, filtered, and the filtrate distilled to remove the solvent. The residue is distilled under reduced pressure. 

The hydrazine hydrate method was found to give transaminated products, whereas the ammonium hydroxide treatment results in low yields (14). Furthermore, the half-life of cleavage of the benzoyl group from dC with ammonium hydroxide at room temperature is 2 h (27). Consequently, the benzoyl group is not completely removed by a 2-h ammonium hydroxide treatment, which may also lead to transaminated side products. If longer ammonium hydroxide treatments are used, unacceptable levels of backbone cleavage can occur. 

Method 2. Drop 10 g. of hydrazine hydrate (85 per cent, aqueous solution see Section 11,49,Id) into a hot solution of 35 g. of benzil (Section IV,126) in 70 ml. of alcohol with stirring. When about three-fourths of the hydrazine hydrate has been introduced, the product begins to separate. After all the reagent has been added, heat the solution under reflux for 5 minutes, cool to 0°, filter at the pump, and wash twice with 20 ml. portions of alcohol. The yield of benzil monohydrazone, m.p. 149-151° (decomp.), is almost quantitative. 

Indazoles can also be prepared by the [CCC + NN] method. For instance indazolones have been obtained rather simply by the action of hydrazine hydrate on 2-halobenzoic esters (78S633). 

Most of these compounds, for instance pyrazole itself, are today commercially available, so there is only a minor interest in detailing the experimental procedures used. The best way to prepare pyrazole is the Protopopova method (Section 4.04.3.3.2) and a modification using hydrazine hydrate instead of a hydrazine salt has recently been patented (80GEP2922591). 

Phenylsemicarbazide has been obtained by the action of hydrazine hydrate on diphenylurea, phenylurethane,i phenyl isocyanate, or the potassium salt of dibenzohydroxamic acid. For its preparation, Curtius method of treating phenylurea with hydrazine liydratc is better Ilian either the older method of... 

One of the most dramatic developments in the chemistry of N2 during the past 30 years was the discovery by A. D. Allen and C. V. Senoff in 1965 that dinitrogen complexes such as [Ru(NH3)5(N2)1 could readily be prepared from aqueous RUCI3 using hydrazine hydrate in aqueous solution. Since that time virtually all transition metals have been found to give dinitrogen complexes and several hundred such compounds are now characterized.Three general preparative methods are available ... 

One year later, Tietze and co-workers (97BMC1303) presented a general and straightforward method for the synthesis of diverse polymer-bound -keto esters starting from acid chlorides and Meldrum s acid. One such resin-bound y3-keto ester, 43, was treated with hydrazine hydrate in THF to afford resin-ffee N-2-unsubstituted pyrazolone 44 in 84% yield (Scheme 13). In the same paper, the synthesis of a large number of 4,5-disubstituted 2-phenyl-2,4-dihydro-37/-pyrazol-3-ones was reported. 

There are two methods for the introduction of a hydroxyalkyl group at position 5 of the pyrazol-3-one ring. Schmidt and Zimmer converted furanediones 258a-k into arylmethylenepyrazol-3-reaction with hydrazine hydrate or methylhydrazine (83Jmechanism proposed for the reaction involves nucleophilic attack of the hydrazine on the ketone carbonyl, followed by attack on the ester carbonyl and ring opening of the... 

Method A Tetrabutylammonium perchlorate (8.5 g, 25 mmol) was added to a solution containing DMF (49.5 mL) and hydrazine hydrate (0.5 tnL). To this solution was added green Pc2Lu (50 mg, 4.1 x 10 2 mmol). This mixture was stirred for 4 h. The blue-green of the starting solution rapidly became dark blue. Filtration and rapid evaporation under vacuum yielded 7 as a microcrystalline powder. 

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. 

A useful method for obtaining indazoles in high yields involves treatment of ortho-azido phenyl ketones or aldehydes with hydrazine hydrate. When this reaction was applied to 3-azido-2-formylselenophene, selenolo[3,2-c] pyrazole (111) was obtained in low yield. The yield could not be improved when the amino derivative was prepared as an intermediate142 (Scheme 13). 2-Dialkylamino-5-formylselenophenes react with diazonium salts under deformylation conditions to give azo dyes (Eq. 39).143 Another nitrogen-containing derivative of selenophene is compound U2.144 ... 

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]. 

Recently a method for increasing the yield of (I) about 10% using 2.5% hydrazine hydrate was described (CA 69,36323w(1968)). 

For the replacement of oxygen by hydrogen in ketones and aldehydes the method of Kishner and Wolff is used as often as is that of Clemmensen. In the former method the hydrazone or semicarbazone of the carbonyl compound is heated for several hours—preferably in the presence of hydrazine hydrate—in a sealed tube or autoclave with sodium ethoxide at about 160°. The explanation of the reaction is that, under the catalytic influence of the ethoxide, the hydrazone is transformed into a diimine which then decomposes in the same way as does phenyldiimine (p. 286) ... 

Frankel and Klager have reported using the Mannich reaction for the condensation of 2,2-dinitroalkanols with ammonia and hydrazine. This method was used to synthesize 2,2,6,6-tetranitro-4-azaheptane (100%) and bis(2,2-dinitropropyl)hydrazine (162) (73%) from the reaction of 2,2-dinitropropanol (25) with ammonia and hydrazine hydrate respectively. This work was later extended to using polynitroaliphatic amines and diamines. " ... 

Recently, a completely new four-component heterocyclization of pyranopyrazoles 193 has been designed (09RCB2362,09JCO914) (Scheme 73). It consists in the simultaneous mixing of aldehydes 28, MN 27b, ketoesters 36, and hydrazine hydrate. Domino-type heterocyclization proceeds very regioselectively, probably, via formation of a pyrazolone 194 and UN 30in situ. The method is very facile and facilitates preparation of a broad variety of pyranopyrazoles 193. 

The condensation of a pyridazine-2,3-dicarboxylic acid derivative with hydrazine remains a favored method for the formation of pyridazino[4,5-f]pyridazines. In the examples generalized in Scheme 5, the presence of an excess of hydrazine hydrate results in formation of the bis(acylhydrazide), which undergoes cyclization in dimethylformamide (DME) to give the 8-hydrazinopyridazino[4,5-f]pyridazine <200181861, 2004JHC647>. 

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