Hydrazine and methylhydrazines

As is quite often the case, the hydrolysed form of the oxidant is more reactive than the hexa-aquo species. The stoichiometries suggest dimerisation, rather than secondary oxidation, is the normal fate of the hydrazoyl radical. The variations in ky and k suggest oxidation occurs at the non-protonated nitrogen atom. 

These three reactions require stopped-flow technique for kinetic study. All have a reaction order of two i.e. one in each reactant) with At2 independent of and ionic strength but pH-dependent, indicating both Mn and MnOH to be reactive. A matrix of second order-rate-coefficients (l.mole . sec ) at 25+1 °C is given below 

The mechanisms of all three oxidations involve initial slow one-equivalent oxidation to a radical (NH20-, -NHOCH3 and N02-) followed either by rapid secondary oxidation (of NH20- or N02 ) or by radical dimerisation (-NHOCHs). 

Ce(IV) sulphate oxidation of NH30H shows a stoichiometry depending on the relative initial concentrations, but at low [Ce(IV)]/[NH30H ], the conditions for kinetic experiments, a value of 1.0 is realised for A[Ce(IV)]/A[NH30H ] . The reaction orders with respect to oxidant and substrate are both one but 2 is reduced by addition of sulphate ions, indicating 0(804)3 , the dominant 

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Some reactivity patterns of both the hydrazine and methylhydrazine complexes are given by Singleton and coworkers.5... 

Reactions of hydrazine and methylhydrazine with pyrylium or thiinium salts, e.g. (137), provide major routes to H-1,2-diazepines (138) and l//-l,2-diazepines (139) (76H(4)1509, 80CJC494). 

The radical reaction of hydrazine and methylhydrazine with some a,(3-unsaturated ketones 54 initiated by 2,2-dipenyl-l-picrylhydrazyl (DPPH) is described in [60]. At — 78°C the treatment is practically regioselective and yields pyrazoles 55, while regioisomeric heterocycles 56 are observed in trace amounts (Scheme 2.13). 

Hydrazine and methylhydrazine were determined in aqueous solution at 0.1—50 ppm levels in the form of the corresponding pyrazoles [112] produced by a condensation reaction with 2,4-pentanedione (Scheme 5.11). The pH. of the aqueous solution was adjusted to 6—9 with the aid of 1 N NaOH or 1 N H2S04 and 50 jul of 2,4-pentanedione were added to a 100-ml portion. The mixture was mixed thoroughly and allowed to stand at room temperature for at least 1 h. Samples of 5 (A were analysed on 30% mixture of Amine 220 and Apiezon L (1 5) at 130°C. 

The same authors [42] reported the synthesis of 1 1 complexes between 2,2 -di(4-hydroxyphenyl)propane (13) and several alcohols, primary amines, hydrazine, and methylhydrazine (14). In this context the structure of the complex 13 14, has been elucidated by means of X-ray crystallography (Scheme 4) [43],... 

It is of biochemical interest that hydrazine and methylhydrazine cause mutations on microorganisms, and this can be used to produce biochemically deficient mutants [64ZN(B)151 69MI2 84ZPC1]. 

Harris GW, Atkinson R, Pitts, JN. 1979. Kinetics of the reactions of the OH radical with hydrazine and methylhydrazine. J Phys Chem 83 2557-2559. 

Cyclocondensation of (3 + 2) compounds of type 99 with hydrazine and methylhydrazine leads to pyrazoles (93JHC1159) (Scheme 102). 

Oxidation Reactkns in the Gas Phase.— With a sound theoretical and experimental base established, the direct measurement of reaction temperatures has been applied in the study of oxidation reactions, and a hierarchy of complicity has been revved. Least complex among the systems studied appear to be the explosive oxidations of hydrazine and methylhydrazine. Both appear overwhelmingly thermal in origin ... 

Treatment of 4-methoxy-3-nitrocoumarin 23 with hydrazine hydrate and methylhydrazine in ethanol at room temperature for 3 h gave 1,2-dihydro-5-(2-hydroxyphenyl)-4-nitro-3H-pyrazol-3-one 24a and l,2-dihydro-5-(2-hydroxyphenyl)-2-methyl-4-nitro-3H-pyrazol-3-one 24b in 70 and 51% yields, respectively. 

Reaction of the oxazolo[3,2-b]pyridazinium perchlorates 198 with hydrazine hydrate and methylhydrazine furnish (82CPB1557) hemiperchlo-rates of pyridazinotriazines 199 and pyridazinotriazinium perchlorate 200,... 

Palladium-catalyzed cyclization reactions with aryl halides have been used to synthesize pyrazole derivatives. V-Aryl-lV-(c>-bromobenzyl)hydrazines 26 participated in a palladium-catalyzed intramolecular amination reaction to give 2-aryl-2W-indazoles 27 . Palladium-catalyzed cascade intermolecular queuing-cyclocondensation reaction of o-iodophenol (28) with dimethylallene and aryl hydrazines provided pyrazolyl chromanones 29 <00TL7129>. A novel one-pot synthesis of 3,5-disubstituted-2-pyrazolines 32 has been achieved with an unexpected coupling-isomerization sequence of haloarene 30, propargyl alcohol 31, and methylhydrazine <00ACIE1253>. 

The reaction of 5-aryl-3-(chloromethyl)[l,3,4]oxadiazole-2(3//)-thiones 100 with hydrazine or methylhydrazine yields the corresponding 2,3-dihydro[l,2,4]triazolo[3,4-A][l,3,4]oxadiazole derivatives 102 <1984JCED477>. By analogy, hydrazine and phenylhydrazine convert the [l,2,4]triazole-2(3//)-thiones 101 into 3,7-dihydro-2//-[l,2,4 tria-zolo[4,3-r][ 1,2,4] triazoles 103 <1992PS99, 2002JCCS1035>. Finally, the azole-2(3//)-thiones 101 react with hydroxylamine to form the 3,7-dihydro[l,2,4]triazolo[5,l-d[l,2,4]oxadiazoles 104 (Scheme 8) <1992PS99>. 

Ethyl 3-methyl-5-oxopyrazoline-4-carboxylate and its I-methyl derivative were prepared in the reaction of diethyl acetylmalonate and hydrazine hydrate, and methylhydrazine in acetic acid at 95-100°C for 3 hr in 83% and 95% yields, respectively (89SC2087). 

Toth B Hydrazine, methylhydrazine and methylhydrazine sulfate carcinogenesis in Swiss mice—failure of ammonium hydroxide to interfere in the development of tumors. Int 7 C < er 9 109-118, 1972... 

The availability of o-benzoylbenzenesulfonyl chlorides, prepared by diazotization of o-aminobenzophenones followed by reaction with sulfur dioxide in the presence of cuprous ions, can be exploited in the reaction with hydrazine or methylhydrazine to give 1,2,3-benzothiadiazine 14. Product 14 (R1 = Me) can also be obtained by methylationof 14(R = H) with methyl iodide and sodium hydroxide. The reduced form 15 results from catalytic hydrogenation of 14 (R = H, R2 = H)(68JHC453). Hydra-zobenzene reacts with 2-chlorosulfonylbenzoyl chloride in the presence of triethylamine to give diphenyl derivative 16 (79MI1). 3,1,2-Benzothia-... 

The ene hydrazine 100, prepared from dimedone and methylhydrazine, forms the Michael adduct 101 with dimethyl acetylenedicarboxylate. The adduct is converted into a mixture of pyrrole and pyridone derivatives, 103 and 104, in boiling tetralin. These products arise by a [3.3]sigmatropic shift in the adduct with cleavage of the nitrogen-nitrogen bond to give 102, followed by cyclization and elimination of ammonia and methanol, respectively (equation 42)63. 

High-molecular-weight monoalkylhydrazines (C, and above) can be made from anhydrous hydrazine and alkyl halides in a manner similar to the alkylation of amines. On the other hand, alkylation with the lower halides leads chiefly to di-, tri-, and tetra-substituted hydrazines. Ethylhydrazine has been obtained by alkylation of hydrazine with ethyl sulfate (32%). Methylhydrazine is synthesized by a special variation of this method (54%). ... 

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