Hydrazine hydrate applications

An interesting application of this synthetic methodology is the conversion of 265 into 266 upon reflux with hydrazine hydrate (Equation 35) <2004ZNB1132>. 

All technical processes for the synthesis of hydrazine yield either hydrazine in aqueous solution or hydrazine hydrate. Most applications can use hydrazine hydrate, but for some applications, for example, rocket propulsion, anhydrous hydrazine is necessary. The water can be removed by a chemical reaction followed by distillation or by azeotropic distillation with an auxiliary fluid. As water binding chemicals, calcium carbide, sodium hydroxide, calcium oxide, calcium hydride, barium oxide, barium hydroxide, and barium pemitride Ba3N4 have been used. The use of sodium or calcium metal and sodium amide is best avoided because of the formation of explosive hydrazides. Starting from hydrazine hydrate (64% hydrazine), sodium hydroxide is generally used... 

There are a few applications of the Wharton reaction in acyclic systems. For example, treating an acyclic a, -epoxy ketone (Scheme 19) with hydrazine hydrate at 0 °C affords the expected product, but as a l l-( ) ( mixture. However, the major product (60%) in this particular case is the bicyclic alcohol that arises via cyclization of the intermediate vinyl radical (or anion) on the endocyclic carbon-carbon double bond. 

Hydrazine is commercially available as aqueous solutions and, in smaller quantities, in the form of salts. Hydrazine forms a high boiling point azeotrope with water, whose composition is close to a 1 1 molar ratio, corresponding to 64% hydrazine. This solution is known as hydrazine hydrate . The capacity statistics in table 1.4-1 relate to hydrazine hydrate . Anhydrous hydrazine is only produced in very small quantities for special applications in satellite technology. 

The method is also applicable to Ar-oxides. Thus, dimethyl pyridine-3,4-dicarboxylate 1-oxide and hydrazine hydrate are refluxed in methanol to give pyrido[3,4-t/]pyridazine-l,4(2//,3//)-dione 6-oxide in 22% yield.45... 

Various 3-substituted aminoquinoxaline-2-thiones have been prepared from quinoxaline-2,3-dithione. For example, treatment of the dithione with methylamine yields 3-methylaminoquinoxaline-2-thione, and the corresponding reaction with hydrazine hydrate yields 3-hydrazino-quinoxaline-2-thione. The latter compound is also obtained by treatment of 2,3-dichloroquinoxaline with thiourea and then with hydrazine hydrate. When 2-chloroquinoxaline 1-oxide is heated with thiourea in methanol at room temperature, an unidentified solid m.p. 184-185° is obtained alkaline hydrolysis of methanol-soluble products gives quinoxaline-2-thione in 41% yield. A method of some general applicability is illustrated by the preparation of the thioxo compound 4 from o-anilinoaniline (3). °... 

Ytterbium(III) triflate in methanol is an efficient catalyst for cleaving methoxy-acetates (e.g., 23 - 24). The methoxyacetate protecting group was introduced 30 years ago (C.B. Reese and J.C.M. Stewart, Tetrahedron Lett., 1968,4723) but has found little application so far, due to difficulties associated with its removal. Efficient, selective anomeric deacetylation of peracetylated reducing disaccharides has been achieved with hydrazine hydrate (1.2 equivalent) in acetonitrile. It has been observed that the BF3.Et20-catalysed glycosidation of several pento- and hexo-pyranose peracetates with simple alcohols is accompanied by selective deacetylation at the 2-position. ... 

The formulations of Astrolite explosives usually include anhydrous hydrazine, a strong reducing substance, thus the mixture of which with air is prone to explosion and combustion. Plus, anhydrous hydrazine is expensive and toxic. Consequently, other combustible substances such as hydrazine hydrate and fatty acids have been employed to substitute anhydrous hydrazine, affording excellent results in practical applications. 

A method of almost universal applicability for the deoxygenation of carbonyl compounds is the Wolff-Kishner reduction While the earlier reductions were carried out in two steps on the derived hydrazone or semicarbazone derivatives, the Huang-Minlon modification is a single-pot operation. In this procedure, the carbonyl compound and hydrazine (hydrate or anhydrous) are heated (180-220 °C) in the presence of a base and a proton source. Sodium or potassium hydroxide, potassium-t-butoxide and other alkoxides are the frequently used bases and ethylene glycol or its oligomers are used as the solvent and proton source. Over the years, several modifications of this procedure have been used to cater to the specific needs of a given substrate. The Wolff-Kishner reaction works well with both aldehydes and ketones and remains the most routinely used procedure for the preparation of alkanes from carbonyl compounds (Table 9). This method is equally suitable for the synthesis of polycyclic and hindered alkanes. 

Zhang F, Zhang H, Ren J, Qu C (2010) PTFE based composite anion exchange membranes thermally induced in situ polymerization and direct hydrazine hydrate fuel cell application. J Mater Chem 20 8139-8146. doi 10.1039/c0jm0131 Ik... 

The reaction of hydrazine with chloroform and base to yield diazomethane was reported by Staudinger some sixty years ago but remained of limited utility. The application of 18-crown-6 mediated phase transfer catalysis to this reaction has made it a preparatively useful method. By this method, hydrazine hydrate can be conveniently converted to diazomethane in almost 50% yield (see Eq. 3.11) [16]. 

Condensation of 2-24 with hydrazine hydrate and hydroxylamine hydrochloride was carried out. The pyrrole-fused heterocycles pyrrolo[3,2-ii]pyridazine 2-27 and pyrrolo[2,3-c]pyridinone 2-28 were generated in high isolated yields, respectively (Scheme 2.16). These further applications of 2-24 demonstrate that the two carbonyl groups on the pyrrole ring of 2-24 are useful for the preparation of other valuable pyrrole-fused A -heterocyclic compounds [59, 60]. 

This was accomplished via a novel quinoxalinone-benzimidazole rearrangement of 3-arylacylidene-3,4-dihydroquinoxalin-2(l/f)-ones on exposure to hydrazine hydrate and phenylhydrazine. The reaction is readily applicable to large-scale synthesis. 

In 2012, by taking advantage of the high reactivity of allenic ketones, a highly efficient synthesis of substituted pyrazole (31 and 32) via the reaction of 1,2-allenic ketones 29 with hydrazine hydrate under mild conditions has been reported by Guo, Fan and co-workers (Scheme 7.15) [70]. As an application, this methodology provides a highly efficient route to 5-(5-methyl-pyrazol-3-yl)-2 -deoxycytidine. 

Schulz et al. [497] described a series of poly(oxadiazoles) for potential LED applications. Some of their structures have been depicted earlier in Fig. 12-21. These were prepared by a one-step polycondensation of the aromatic dicarboxylic acids with hydrazine hydrate in polyphosphoric acid, which acted as a solvent as well as dehydration agent. 

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