Hydrazines and Amines

The oxidation potentials in MeCN for several substituted hydrazines and amines are summarized in Table 11.1. 

In contrast, when hydroxide ion HO- is present, it is more easily oxidized than the amine substrates. In MeCN, in the absence of substrate, HO- is oxidized at +0.7-0.9 V versus SCE. However, with hydrazines and amines present, as in the case of H2NOH [Eq. (11.25)], the N—H bonds are homo-lytically cleaved by the HO product of HO- oxidation. The latter s oxidation potential is shifted by the difference in the HO—H and RN—H bond energies (—AGbf). Thus, the oxidation of PhNHNHPh is shifted by —1.7V when HO-becomes the electron-transfer mediator with PhNH2 the shift is —1.1 V  

TABLE 11.1 Oxidation Potentials for 1-5 mM Hydrazines and Amines in MeCN [0.1 M EtfNiClO ] and in the Presence of an Equivalent of HO- Evaluation of UN—H Bond Energies (—AGBF) 

On the basis of the reduction potential for H20 in MeCN (Chapter 9, H20 H- + HO-), a reasonable estimate of the oxidation potential for HO- in the presence of a free hydrogen atom (H ) can be made  

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Treatment of cotarnine and similar compounds with hydrogen cyanide, alkoxides, mercaptides, hydroxylamine, hydrazine, and amines has been reported to give 1-substituted derivatives of 1,2,3-tetrahydroisoquinoline (171, R = CN, OR, SP, NHOH, NHNH, NHR) (262-265). 

Certain internal chemical treatments employed also need strict control to avoid risks of adverse chemical reaction and resultant corrosion. In particular, nitrogen-containing chemicals such as hydrazine and amines require effective monitoring to limit the concentration of ammonia release into steam because the presence of ammonia may, under certain conditions, cause stress corrosion cracking of copper and brasses. 

The breakdown of internal treatments such as sodium sulfite/sodi-um bisulfite, hydrazine, and amines... 

MAO Inhibitors. MAO is an enzyme which oxidizes a variety of monoamines. Among the substrates of this enzyme are tyramine, tryptamine, 5-hydroxytryptamine, histamine, and short chain aliphatic monoamines ( ). Oxidation of histamine to imidazoleacetaldehyde can be carried out by DAO as well as MAO. is also responsible for the conversion of N -MH, the product of HMT, to N -MIAA. Many MAO inhibitors have been identified they are conventionally divided into hydrazides, hydrazines and amines (44). Some MAO inhibitors, e.g. the hydrazines, are non-selective they also inhibit DAO. 

Pyridine reacts with sodium hydrazide in the presence of hydrazine to yield 2-hydrazinopyridine in the absence of free hydrazine a hydrazo compound is formed (Scheme 88) (64AG(E)342). A difference between hydrazination and amination is the formation of 1,4-adducts which cannot be rearomatized even on heating. This is reflected in the behaviour of quinoline, which gives only a 0.5% yield of a -hydrazino product, whereas 4-methylquino-line is hydrazinated in 76% yield (64AG(E)342). Acridine behaves differently with sodium hydrazide/hydrazine, 9,10-dihydroacridine is formed almost quantitatively, but reaction in the absence of hydrazine yields 9-aminoacridine (65%). An even higher yield of 9-amino-acridine is obtained when sodium Af.AC-dimethylhydrazide is used (Scheme 89). Good evidence for intermediacy of (151) comes from the isolation of (152) on hydrolysis of (151). 

Hydrazines and Amines. These substrates are directly oxidized in a base-free matrix (Me2SO or MeCN) at platinum or glassy-carbon electrodes with the potential determined primarily by the / N—H bond energy, and secondarily by die basicity of the substrate (Figures 11.9 and 11.10) 15,16... 

Dimethoxycarbonylpyrazine heated with hydrazine hydrate in ethanol gave some 5,8-dihydroxypyrazino[2,3-with hydrazines (and amines) has been described in Section 2C(2)(a) (961,1330, 1331). An analogous active ester was prepared from 2-amino-3-carboxy-5-chloro-6-methoxypyrazine and with hydrazine in tetrahydrofuran gave 2-amino-5-chloro-... 

Ammonia, NH3, is used to produce fertilizer, explosives, nitric acid, urea, hydrazine, and amines. 

The enolic /J-diketone 89 with hydrazine and amines produced excellent yields of the pyrazolo derivative 91 and the enamines 92, respectively (Eq. 22).63,64 Similarly, the 3-acetyl compound 93 yielded the corresponding pyrazole when combined with hydrazine,64 and with amines it gave the enaminoketones 94.8-65... 

Nigst, T. A., Antipova, A., Mayr, H. (2012) Nucleophilic Reactivities of Hydrazines and Amines The Futile Search for the a-Effect in Hydrazine Reactivities. Journal of Organic Chemistry, 77, 8142-8155. 

Finally, a direct Mannich-type approach has been developed for the enantioselective synthesis of hydrazines and amines (Scheme 16.40). Thus, by trapping with alkyl diazoacetates some in s/iw-generated acyclic azomethine imines, in the presence of axially chiral dicarboxylic acids, a series of a-diazo-(3-hydrazino esters were obtained with excellent enantioselectivities [86]. 

In 2012, Ohshima and co-workers reported microwave-assisted transamidative deacylation of unactivated amides with a combination of an ammonium salt and ethylene diamine at 50-90°C [105]. In 2014, the same group realized hydrazinolysis of unactivated amide bonds [106]. The reaction proceeded at moderate temperature (50-70°C) to provide M-acyl hydrazines and amines in good yield. They applied the reaction conditions to cleave peptides (Fig. 16). Selective cleavage of the Gly-Phe bonds in two peptides was realized. No epimerization at the a-position of the Phe residue was observed. The site-selectivity was likely caused by both steric and electronic factors. 

Adducts of Halogenogermanes with Ammonia, Hydrazine, and Amines Which Are Stable at Room Temperature... 

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