With hydrazine

Reductions of diorgano tellurium dihalides with hydrazine or hydrazine hydrate are carried out in ethanol. Diaryl, alkyl aryl, and dialkyl tellurium dihalides have been reduced in this manner. The isolation of the product is simple because hydrazine is converted to gaseous nitrogen. 

Bis[4-methoxyphenyl] Tellurium 8.3 g (0.02 mol) of bis[4-methoxyphenyl] tellurium dichloride are suspended in a mixture of 150 ml of ethanol and 15 ml of water. The mixture is heated to reflux and 3.2 g (0.1 mol) of hydrazine are added dropwise to the refluxing suspension, vigorous evolution of nitrogen. When further addition of hydrazine does not cause evolution of nitrogen, the mixture is poured into 700 ml of water, and extracted with two iOO-ml portions of diethyl ether. The combined extracts are washed with water, dried, and evaporated. The residue is recrystallized from methanol which is cooled to — 25° yield 5.2 g (77%) m.p. 57°. 

Examples of diorgano tellurium compounds prepared in this manner are  

3- methoxy-2-butyl phenyl tellurium 2-methoxy-2-phenylpropylphenyl tellurium his[2-biphenylyl] tellurium  

4- dimethylaminophenyl 3-nitrophenyl tellurium 4-ethoxyphenyl 2-phenylazophenyl telluriumi 4-ethoxyphenyl 2-(2 -pyridyl)phenyl tellurium his[2- (2 -pyridyl)phenyl] tellurium  

5- cyano-2,3-diphenylpyrazine similarly treated gave 5-carbamoyl-2,3-diphenyl-pyrazine because the intermediate iminoether hydrochloride spontaneously lost ethyl chloride (866). 2,3-Dicyano-5,6-dimethylpyrazine in dioxane with ethanolic hydrogen chloride gave 2-cyano-3-(C-ethoxy-C-iminomethyl)-5,6-dimethylpyrazine hydrochloride (1044), which hydrolyzed in boiling water to 2-cyano-3-ethoxy-carbonyl-5,6-dimethylpyrazine (1044). 

Iminoethers were also prepared from 2-amino-3-cyanopyrazine with ethanolic hydrogen chloride (792, 1218) [the product with guanidine and sodium methoxide in methanol formed 2-amino-3-(C-guanidino-C-iminomethyl)pyrazine (878, 1218)] from 2,6-diamino-3-chloro-5-cyanopyrazine with ethanolic hydrogen chloride at 0 (the product heated with ethanol gave 2,6-diamino-3-chloro-5-triethoxymethyl-pyrazine) (1432) from 2-amino-5-chloro-3-cyanopyrazine the product with 

2- amino-2-imidazoline hydrochloride and sodium methoxide gave 2-amino-5-chloro- 

3- [A -(2 -imidazolin-2 -yl)amidino]pyrazine (59) (877)) and from 2,6-diamino-3-chloro-5-cyanopyrazine [the product heated with dimethylamine in ethanol at 40° gave 2,6-diamino-3-chloro-5-(A(,A -dimethylamidino)pyrazine] (1361). 2-Chloro- 

6- cyanopyrazine with methanol and triethylamine gave 2-methoxy-6-(C-imino-C-methoxymethyl)pyrazine, and a similar reaction was observed in ethanol (985) 2-amino-3,5-dicyano-6-methoxypyrazine with sodium methoxide gave 2-amino-5 -cyano-3-(C-imino-C-methoxymethyl)-6-methoxypyrazine (484). 

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Acid hjdrazides from esters. Meth and ethyl esters react with hydrazine to give acid hydrazides ... 

The independent preparation of potassium phthabmide (from a solution of phthalimide in absolute ethanol and potassium hydroxide in 75 per cent, ethanol) may be avoided in many cases by boiling phthalimide with the halide in the presence of anhydrous potassium carbonate. The N-substituted phthalimide (I) is frequently cleav with difficulty this is often facilitated by reaction with hydrazine hydrate to give an intermediate product, which is easily decomposed by hydrochloric acid to 3deld the insoluble hydrazide of phthaUc acid (II) and the primary amine (III) ... 

This method cannot be applied to polynitro amines, since these are so weakly basic that they can be diazotised only under special conditions in strongly acidic solutions. In such cases use may, however, be made of the mobility oonfared upon halogen atoms by the presence of nitro groups in the orlko and para positions. Thus the valuable reagent 2 4-dinitrophenylhydrazine is readily prepared by the condensation of 2 4-dinitrochlorobenzene with hydrazine ... 

The reaction represented is that with hydrazine solution, produced from hydrazine sulphate and sodium acetate in the presence of aqueous alcohol. Excellent results are also obtained by interaction of the commercially available 60-64 per cent, hydrazine solution with a solution of 2 4 dinitrochloro-benzene in triethylene glycol or in diethylene glycol at about 20°. 

Azines, Aldehydes react with hydrazine to yield azines the reaction cannot usually be arrested at the hydrazone stage. This reaction may be illustrated by the preparation of bevzalazine from benzaldehyde ... 

Girard s reagent T is carbohydrazidomethyltrimethylammonium chloride (I) and is prepared by the reaction of the quaternary ammonium salt formed from ethyl chloroacetate and trimethylamine with hydrazine hydrate in alco-hoUc solution ... 

A cousin to this reduction is one using stannous chloride (a.k.a. SnCb, a.k.a. Tin chloride) which is done exactly as the calcium one except that about lOOg of SnCb is used in place of the Mg or Ca and the addition occurs at room temperature and the solution is stirred for one hour rather than 15 minutes. Some very good reductions that operate almost exclusively at room temperature with no pressure and give almost 100% yields are to follow. The only reason Strike did not detail these methods is that some of the chemicals involved are a little less common than Strike is used to but all are available to the public. These alternatives include acetlylacetone and triethylamine [73], propanedithlol and trieth-ylamine [74], triphenylphosphine [75], NaBH4 with phase transfer catalyst [76], H2S and pyridine [77], and palladium hydrox-ide/carbon with hydrazine [78], stannous chloride dihydrate [85]. 

The problem of the synthesis of highly substituted olefins from ketones according to this principle was solved by D.H.R. Barton. The ketones are first connected to azines by hydrazine and secondly treated with hydrogen sulfide to yield 1,3,4-thiadiazolidines. In this heterocycle the substituents of the prospective olefin are too far from each other to produce problems. Mild oxidation of the hydrazine nitrogens produces d -l,3,4-thiadiazolines. The decisive step of carbon-carbon bond formation is achieved in a thermal reaction a nitrogen molecule is cleaved off and the biradical formed recombines immediately since its two reactive centers are hold together by the sulfur atom. The thiirane (episulfide) can be finally desulfurized by phosphines or phosphites, and the desired olefin is formed. With very large substituents the 1,3,4-thiadiazolidines do not form with hydrazine. In such cases, however, direct thiadiazoline formation from thiones and diazo compounds is often possible, or a thermal reaction between alkylideneazinophosphoranes and thiones may be successful (D.H.R. Barton, 1972, 1974, 1975). 

Thiazolyloxy)propanediol-1.2-acetonide (198) has been prepared from 4-Br-thiazole (197) (Scheme 101) (440). Thiazolopyridazines (199) or thiazolooxazines (200) can be obtained from the 4-alkoxyderivalives (201) by treatment with hydrazine or hydroxylamine, respectively (Scheme 102) (441). 

The diesters may react with hydrazine in acidic medium to give 4.7-dioxo-4.5,6.7-tetrahydro[4.5,d]azolopyridazine (Scheme 28) (107). The... 

Thiazolecarboxylic acid hydrazides are prepared by the same general methods used to prepare amides, that is, by treating acids, esters, amides, anhydrides, or acid halides with hydrazine or substitued hydrazines. For example, see Scheme 21 (92). The dihydrazides are obtained in the same way (88). With diethyl 2-chloro-4,5-thiazoledicarboxylate this reaction gives the mono hydr azide monoester of 2-hydrazine-4,5-... 

Acetaldehyde can be isolated and identified by the characteristic melting points of the crystalline compounds formed with hydrazines, semicarbazides, etc these derivatives of aldehydes can be separated by paper and column chromatography (104,113). Acetaldehyde has been separated quantitatively from other carbonyl compounds on an ion-exchange resin in the bisulfite form the aldehyde is then eluted from the column with a solution of sodium chloride (114). In larger quantities, acetaldehyde may be isolated by passing the vapor into ether, then saturating with dry ammonia acetaldehyde—ammonia crystallizes from the solution. Reactions with bisulfite, hydrazines, oximes, semicarb azides, and 5,5-dimethyl-1,3-cyclohexanedione [126-81 -8] (dimedone) have also been used to isolate acetaldehyde from various solutions. 

Hydrazine as Nucleophile. Reaction of hydrazine and carbon dioxide or carbon disulfide gives, respectively, hydrazinecarboxyhc acid [471-31-8], NH2NHCOOH, and hydrazinecarbodithioic acid [471-32-9], NH2NHCSSH, in the form of the hydrazinium salts. These compounds are useful starting materials for further synthesis. For example, if carbon disulfide reacts with hydrazine in basic medium with an alkyl haUde, an alkyl dithiocarbazate ester is obtained in a one-step reaction ... 

Branched-chain alkenes react with hydrazine under acidic conditions to give the corresponding alkyl hydrazine. For example, isobutylene bubbled through an aqueous solution of hydrazine and HCl gives /-butyUiydrazine in reasonably good yields (64). 

The reactor effluent, containing 1—2% hydrazine, ammonia, sodium chloride, and water, is preheated and sent to the ammonia recovery system, which consists of two columns. In the first column, ammonia goes overhead under pressure and recycles to the anhydrous ammonia storage tank. In the second column, some water and final traces of ammonia are removed overhead. The bottoms from this column, consisting of water, sodium chloride, and hydrazine, are sent to an evaporating crystallizer where sodium chloride (and the slight excess of sodium hydroxide) is removed from the system as a soHd. Vapors from the crystallizer flow to the hydrate column where water is removed overhead. The bottom stream from this column is close to the hydrazine—water azeotrope composition. Standard materials of constmction may be used for handling chlorine, caustic, and sodium hypochlorite. For all surfaces in contact with hydrazine, however, the preferred material of constmction is 304 L stainless steel. 

Concern for personnel exposure to hydrazine has led to several innovations in packaging to minimize direct contact with hydrazine, eg, Olin s E-Z dmm systems. Carbohydrazide was introduced into this market for the same reason it is a soHd derivative of hydrazine, considered safer to handle because of its low vapor pressure. It hydrolyzes to release free hydrazine at elevated temperatures in the boiler. It is, however, fairly expensive and contributes to dissolved soHds (carbonates) in the water (193). In field tests, catalyzed hydrazine outperformed both hydrazine and carbohydrazide when the feedwater oxygen and iron levels were critical (194). A pubUshed comparison is available (195) of these and other proposed oxygen scavengers, eg, diethyUiydroxylarnine, ydroquinone, methyethylketoxime, and isoascorbic acid. 

Automobile safety air bags use sodium azide [26628-22-8] NaN, for gas generation. It can be made from hydrazine by refluxing ethyl or Abutyl nitrite with hydrazine hydrate and sodium hydroxide in alcohol (209,210) ... 

Reactions with Amines and Amides. Hydroxybenzaldehydes undergo the normal reactions with aUphatic and aromatic primary amines to form imines and Schiff bases reaction with hydroxylamine gives an oxime, reaction with hydrazines gives hydrazones, and reactions with semicarbazide give semicarbazones. The reaction of 4-hydroxybenzaldehyde with hydroxylamine hydrochloride is a convenient method for the preparation of 4-cyanophenol (52,53). 

Nitric acid may be precipitated by nitron [2218-94-2] (4,5-dihydro-l,4-diphenyl-3,5-phenylimino-l,2,4-triazole). The yellow precipitate maybe seen at dilutions as low as 1 60,000 at 25°C or 1 80,000 at 0°C. To prevent nitrous acid from interfering with the test results, it may be removed by treating the solution with hydrazine sulfate, sodium azide, or sulfamic acid. 

Several methods are available to supplement the phenol alkylations described above. Primary alkylphenols can be produced using the more traditional Friedel-Crafts reaction. Thus an -butylphenol can be synthesized direcdy from a butyl haUde, phenol, and mild Lewis acid catalyst. Alternatively, butyryl chloride can be used to acylate phenol producing a butyrophenone. Reduction with hydrazine (a Wolff-Kishner reduction) generates butylphenol. 

If 7 Rg, a mixture of the two isomeric pyrazoles is obtained. An excellent method to prepare pyrazole [288-13-1] consists in treating 1,1,3,3-tetramethoxypropane (masked malondialdehyde) with hydrazine (eq. 2). 

Silver Azide. Silver a2ide, AgN, is prepared by treating an aqueous solution of silver nitrate with hydrazine (qv) or hydrazoic acid. It is shock-sensitive and decomposes violendy when heated. 

Miscellaneous Reactions. Aromatic sulfonic acid derivatives can be nitrated using nitric acid [52583-42-3] HNO, ia H2SO4 (19). Sultones may be treated with hydrazine derivatives to give the corresponding ring-opened sulfonic acid (20). 

Pyridazinecarbohydrazides are prepared in the normal way from an ester or acid chloride and hydrazine or a substituted hydrazine, generally in good yields. Pyridazines with two ortho alkoxycarbonyl groups give cyclic hydrazides with hydrazine, which are pyridazinopyridazines. 

Cyanopyridazines add ammonia, primary and secondary amines and hydroxylamine to give amidines or amidoximes. Substituted amides, thioamides and carboximidates can be also prepared. With hydrazine, 3-pyridazinylcarbohydrazide imide is formed and addition of methylmagnesium iodide with subsequent hydrolysis of the imine affords the corresponding pyridazinyl methyl ketone. 

It is customary to perform the condensation of 1,4-dicarbonyl compounds with hydrazines in the presence of mineral acid to avoid the formation of A-aminopyrroles. Contrary to early claims that 4,5-dihydropyridazines are formed <07CB4598), these compounds are now regarded as 1,4-dihydro derivatives 81CB564). 

In a similar manner, phthalazine or its alkyl- or aryl-substituted derivatives are obtainable from 1,2-diacylarenes (Scheme 76). Phthalaldehydic acid and its analogs are transformed by hydrazines into the corresponding phthalazin-l(2//)-ones. Phthalazin-l(2iT)-one itself is prepared from naphthalene by oxidation, subsequent treatment with hydrazine and decarboxylation as shown in Scheme 77 (55YZ1423,64FRP1335759). 4-Substituted phthalazin-l(2iT)-ones are prepared in a similar way from 2-acylbenzoic acids. 3-Hydroxyphthalides,... 

Phthalic anhydride and diethyl phthalate are easily converted with hydrazine into 4-hydroxyphthalazin-l(2/f)-one. Its substituted derivatives have been prepared using substituted hydrazines, substituted phthalic anhydrides, or diesters or disodium salts of substituted phthalic acids (Scheme 81). However, condensation of phenylhydrazine with phthalic anhydride gives only a small amount of the corresponding phthalazine, the main product being 2-anilinophthalimide. This can be rearranged in the presence of base into the phthalazine derivative. For the preparation of 2,3-disubstituted derivatives, 1,2-disub-stituted hydrazines are reacted with the appropriate phthalic anhydrides or phthaloyl chlorides. Derivatives of 4-amino- or 4-hydrazino-phthalazin-l(2iT)-one have been prepared either from the corresponding monothiophthalimide and 3-aminoisoindolin-3-one (1S4) or from ethyl 2-cyanobenzoate (155) and hydrazine hydrate (Scheme 82). Similarly,... 

AK(30)26l). 2-Acetoxyfuran-3(2i/)-ones react with hydrazine to give 3,6-disubstituted-4-ethoxycarbonylpyridazin-4(li/)-ones (184) as the main product, but with mono-substituted hydrazines in addition to these pyridazines anhydro-5-hydroxypyridazinium hydroxide (185) derivatives and some pyrazole derivatives are also formed (Scheme 102) (79JOC3053). The... 

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