Methylhydrazine complex

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

Scheme 4 shows in a general manner cyclocondensations considered to involve reaction mechanisms in which nucleophilic heteroatoms condense with electrophilic carbonyl groups in a 1,3-relationship to each other. The standard method of preparation of pyrazoles involves such condensations (see Chapter 4.04). With hydrazine itself the question of regiospecificity in the condensation does not occur. However, with a monosubstituted hydrazine such as methylhydrazine and 4,4-dimethoxybutan-2-one (105) two products were obtained the 1,3-dimethylpyrazole (106) and the 1,5-dimethylpyrazole (107). Although Scheme 4 represents this type of reaction as a relatively straightforward process, it is considerably more complex and an appreciable effort has been expended on its study (77BSF1163). Details of these reactions and the possible variations of the procedure may be found in Chapter 4.04. 

The formation of malonaldehyde induced by the Fenton reaction (Fe2+ plus H202 in excess) has been studied using the N-methylhydrazine assay (Matsu-fuji and Shibamoto 2004). Under such conditions, the yield of malonaldehyde is much lower (2 x 10"5 mol per mol Fe2+ 1 x 10 4 when Fe2+ is complexed by EDTA) than in the radiolytic system discussed above. The reasons for these differences are not yet known. 

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],... 

Scheme 4 Preparation of the complex 13 14 between 2,2 -di(4-hydroxyphenyl)propane (11) and methylhydrazine (12).

Although the cyclic dimers are connected by additional H-bonds, the authors did not observe a super-tetrahedral network. Notably, a 2 1 alcohol-amine complex 14 15, was also observed [41] between 4-methoxyphenol (15) and methylhydrazine (14) (Scheme 5). Thus, a dimer formed by a primary amine and a secondary amine in such cases does not have the general requisites to generate a supramolecular architecture. 

Scheme 5 Preparation of the complex 14 15 between 4-methoxyphenol (15) and methylhydrazine (14).

Fig. 6. Marcus relation Free energies of activation as a function of the driving force (terms (A) + (B) in text) corrected for electrostatic work terms (cyano complexes reaction with hydrazine ( ) methylhydrazine (O) 1,2-dimethylhydrazine ( ). Adapted with permission from Dennis et al. (52). Copyright 1987, American Chemical Society.

Other silylhydrazines behave similarly to 6, although the NMR spectra are sometimes more complex. The anion of bis(tert-butyldimethylsi-lyl)methylhydrazine shows three singlets at room temperature for the... 

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 ... 

Several other products of hepatic DMN metabolism in vitro have been identified (160). Microsomal metabolites of DMN were formaldehyde, formic acid, methylamine and -methylhydrazine. When pH 5 enzymes were added to the medium, A -methylhydroxylamine and AT,A -dimethylhydrazine were also produced. These results indicate that DMN metabolism is complex and suggest that other pathways could be involved in activation of DMN. 

Reactions of Co-ordinated Ligands. The topic of the attack of pyridine at co-ordinated ethene and co-ordinated dienes in appropriate platinum(ii) complexes has already been alluded to in an earlier section. " The reaction of c -[PtCl2(p-tolyl isocyanide) 2] with methylhydrazine in dichloromethane, which gives a carbene complex, follows a two-term rate law of this type shown in equation (1). As usual the term is assigned to a solvolytic path, but here the term is attributed to bimolecular attack of the hydrazine at the co-ordinated isocyanide. There is some discussion... 

A feature of transition metal cluster complexes is that they can undergo electron transfer reactions to give mixed-valence clusters. A second feature of these complexes is that, in addition to homometallic clusters, heterometallic cluster complexes can be prepared that have two or more different metals within the cluster core. Examples of such complexes for which emission has been observed are (DENC)3Cu 2Cu°Co(NS)2CU and (DENC)3Cu3M(NS)CU [DENC = iV,A -diethyl-nicotinamide NS = 5-methylhydrazine-carbodithioate Schiff base M = Co(II), Ni(II), Cu(n), Zn(n)]. For these complexes the emission maxima and lifetimes are shown in Table The emission from all the complexes is centered on the... 

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