Nitrogen diazene

Intramolecular chalcogen interactions may also stabilize reactive functional groups enabling the isolation of otherwise unstable species or their use as transient intermediates, especially in the case of selenium and tellurium. For example, tellurium(II) compounds of the type ArTeCl are unstable with respect to disproportionation in the absence of such interactions. The diazene derivative 15.23 is stabilized by a Te N interaction. Presumably, intramolecular coordination hinders the disproportionation process. Other derivatives of the type RTeX that are stabilized by a Te N interaction include 8-(dimethylamino)-l-(naphthyl)tellurium bromide, 2-(bromotelluro)-A-(p-tolyl)benzylamine, and 2-[(dimethylammo)methyl]phenyltellunum iodide. Intramolecular donation from a nitrogen donor can also be used to stabilize the Se-I functionality in related compounds." ... 

Likewise, thermolysis of 4-azidophenyl methyl ketone in methanol yields 5-acetyl-2-methoxy-3//-azepine (60%), compared to only an 8% yield from the photolytic reaction.78 119 The thermolysis of phenyl azide in refluxing cyclohexanol yields no 3H-azepine, only diphenyl-diazene (10%) and aniline (30%).74 In contrast, thermolysis of methyl 2-azidobenzoate in cyclohexanol furnishes a mixture of methyl 2-(cyclohexyloxy)-3//-azepine-3-carboxylate (20 % bp 127°C/0.1 Torr) and methyl 2-aminobenzoate (60%). Thermolysis of the azido ester in methanol under nitrogen in an autoclave at 150 C yields a 7 10 mixture (by 1HNMR spectroscopy) of the amino ester and methyl 2-methoxy-3//-azepine-3-carboxylate, which proved to be difficult to separate, and much tar.74 The acidic medium179 is probably responsible for the failure of methyl 2-azidoberjzoate to yield a 3//-azepine when thermolyzed in 3-methoxyphenol aniline (40%) is the major product.74... 

A good example of a concerted cheletropic elimination is the reaction of 3-pyrroline with IV-nitrohydroxylamine, which gives rise the the diazene 21, which then undergoes elimination of nitrogen. 

Rice, F. O. et al., J. Amer. Chem. Soc., 1957, 79, 1880-1881 This blue solid (a cyclic dimer of diazene, 93.3% of nitrogen), obtained by freezing out at — 195°C the pyrolysis products of hydrogen azide, is extremely explosive above this temperature. An explosion at — 125°C destroyed the apparatus. 

Butadiene can be obtained by thermal extrusion of a nitrogen molecule from a cyclic diazene (equation 80)128. However, this reaction has found only limited synthetic applications. 

Diimide diimine, diazene), N2H2 or HN=NH, is an ephemeral species which results from decomposition with acids of potassium azodicarboxylate [264, 265] from thermal decomposition of anthracene-9,10-diimine [266, 267], and of hydrazine [268,269] and its derivatives [270]. Although this species has not been isolated, its transient existence has been proven by mass spectroscopy and by its reactions in which it hydrogenates organic compounds with concomitant evolution of nitrogen [271]. 

Hydrazines with at least one hydrogen substituent on nitrogen are oxidised in aqueous solution to the substituted diazene. Oxidation takes place in both acid and basic solution. Phenylhydraziiie is oxidised by inorganic reagents such as iodine buffered by sodium hydrogen carbonate to form benzenediazonium ion. The latter combines with the substrate to form the isolated product [140]. 1,1-Disubstituted... 

Azoadamantane exposed to 2 mol equivalents of T CIO4 at room temperature rapidly and quantitatively evolved nitrogen, and thianthrene and products derived from the adamantyl cation were obtained. Equations (38)-(40) (AA, azo-adamantane Ad, adamantane) make clear why 2 mol equivalents of the radical oxidant are required (85JA2561). The comparable interaction of T with phenylazotriphenylmethane and di-ter/-butyl diazene, using a 2 1 ratio of radical cation to substrate, also leads to the formation of thianthrene and nitrogen (85PS111). 

The characteristics of the HERON transition states for both steps in the thermal decomposition of Ai,Ai -diacyl-Ai,A -diaIkoxyhydrazines facilitate the synthesis of esters. Notably, the alkoxyl group migrations in the internal 8 2 displacement of the 1,1-diazene in the first step, and nitrogen in the second step, do not involve a tetrahedral alkoxide intermediate and both Barton and coworkers and Glover and have utilized... 

The electrochemistry of dinitrogen bridging two porphyrin ligated ruthenium centers has been studied as a possible route to fixed nitrogen [45 -47]. Diazene stabilized by bonding to two iron centers in a FeS system has been advanced as a structural model of a plausible intermediate in biological nitrogen fixation [48-50]. 

According to this mechanism, most of the nitrogen in the hydrazine would form N2, which would not have been detected in this system. The diazene HN=NH would be expected to react with OH radicals ... 

Davis and Goddard calculated that the heat of formation (298 K) of singlet H2NN is 90.1 kcal/mol. This value is only 14 kcal/mol below that of molecular nitrogen and two hydrogen atoms, and is 54 kcal/mol above A//f(298 K) for frani-diimide determined experimentally by Willis et al. The relative energies of 1,1- and frani-1,2-diazene have been calculated by several methods these studies have been reviewed by Parsons and Dykstra. It was found using the... 

Azo or diazene compounds possess the —N=N— grouping. Aliphatic azo compounds of the type R—N=N—H appear to be highly unstable and decompose to R—H and nitrogen. Derivatives of the type R—N=N—R are much more stable and can be prepared as mentioned above by oxidation of the corresponding hydrazines. Aromatic azo compounds are available in considerable profusion from diazo coupling reactions (Section 23-IOC) and are of commercial importance as dyes and coloring materials. 

We shall find that this reaction is again a rather special anomaly, needing special treatment, but there are straightforward 6-electron cheletropic reactions, such as the irreversible extrusion of nitrogen from the diazene 2.176, and the easy loss of carbon monoxide from norbornadienone 2.177. 

Nitrogen-bound diazeniumdiolates (IV-diazeniumdiolates or 1-amino-substituted diazen-l-ium-l,2-diolates) spontaneously produce NO under physiological conditions.34 This class of NO donors is synthesized by exposing polyamine precursors to high pressures of NO (Scheme 9.1). 

Little is known of the stabiity of diazene in solution. In general the species is generated in situ and its presence is shown by the hydrogenation of carbon-carbon multiple bonds. Direct detection has so far proved unsuccessful (193). Despite this, the formation of diazene has been invoked in several studies (besides those in nitrogen fixation). 

The reaction of phenyllithium with [(Tj5-C5H5)Mn(CO)2N2] is unique (305) [Eq. (27)]. It has been proposed that the phenyl anion attacks the a-nitrogen atom, and subsequent protonation of the /3-nitrogen gives the diazene product. 

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