From nitrite esters

Table 3. Synthesis of ort/io-Substituted Fluoroaromatics from Nitrite Esters, Boron Trifluoride, and Hydrogen Fluoride [26]...

A recent patent application disclosed a method for making polyurethanes made from nitrite esters and di/poly-isocyanates with the help of UV-irradiation for use as coatings. The application disclosed polymerizable and curable compositions and processes of polymerizing and curing polyurethanes involving an isocyante compound and a nitrite ester compound. Irradiation of the nitrite ester compound with UV generates an active hydrogen compound by the Barton nitrite photolysis reaction that reacts with an isocyanate compound to produce and/or crosslink a polyurethane. 

The reactants are fed separately iato a stUl, from which the product is continuously removed by distillation (qv) (31). Isopropyl nitrate is a valuable engiae-starter fuel and can be used ia explosives (see Explosives and propellants) (32). The nitrite ester, isopropyl nitrite, can be prepared from the reaction of isopropyl alcohol and either nitrosyl chloride or nitrous acid at ambient temperature (33). The ester is used as a jet engine propellant (30). 

Cycloalkoxy radical intermediates are readily generated from a parent alcohol by various methods (e.g., nitrite ester photolysis, hypohalite thermolysis, lead tetraacetate oxidation) (83MI1). Once formed, reactive cycloalkoxy radicals undergo /3-scission to produce a carbonyl compound and a new carbon-centered radical. 

Figure 8, Photolytic generation of nitrogen dioxide and an aryl nitrite ester from a nitro compound, as formulated by Lippert and Kelm (27),...

Diazo esters can also be prepared from glycine esters by treatment with nitrous acid [966] or with alkyl nitrites. Further methods include the oxidation of hydrazones, oximes (Forster reaction), and semicarbazones, the base-induced... 

Nitrite ions can also be produced from nitrate esters by reducing the latter with zinc in acidic solutions [33] (Eq. (7)) ... 

The second class of benzo-fused heterocycles accessible from benzofuroxans are benzimidazole oxides. In this case only one carbon from the co-reactant is incorporated in the product. With primary nitroalkanes 2-substituted l-hydroxybenzimidazole-3-oxides (46) are formed via displacement of nitrite, and / -sulfones behave similarly. The nitrile group of a-cyanoacetamides is likewise eliminated to alford 2-amide derivatives (46 R = CONRjX and the corresponding esters are formed in addition to the expected quinoxaline dioxides from acetoacetate esters. Under similar conditions secondary nitroalkyl compounds afford 2,2-disubstituted 2//-benzimidazole-1,3-dioxides (47). Benzimidazoles can also result from reaction of benzofuroxans with phosphorus ylides <86T3631>, nitrones (85H(23)1625>, and diazo compounds <75TL3577>. 

Figure 1. Postulated formation of a-dialkylamino nitrite esters (I) from immo-nium ion donors and their fragmentation to nitrosamines...

Peroxynitrite is an important cytotoxin that results in vivo from the direct reaction of superoxide and nitric oxide. There are several methods to synthesize peroxynitrite, including the solid-state photolysis of KNOs, the ozonation of sodium azide, or the alkaline reaction of nitrite esters with hydrogen peroxide. Perhaps the most common peroxynitrite synthesis involves treating an acidified solution of hydrogen peroxide with nitrite, followed by an immediate quench with base. Although this synthesis is facile, quick, and affordable, it results in... 

A variation of this procedure is the nitrosation of a phenol such as thymol in an alcohol solution with hydrochloric acid and sodium nitrite. This procedure is said to avoid the evolution of oxides of nitrogen, since it may involve the intermediate formation of ethyl nitrite as the nitrosating agent [31]. However, from the safety standpoint, the oxides of nitrogen and nitrite esters must be considered hazardous. 

A reaction which has some resemblance to this nitroso decarboxylation is the pyrolytic or photolytic decarboxylation of fluorinated nitrites (Eqs. 24 and 25) [63]. The nitroso compounds derived from these nitrite esters appear... 

The minor products frequendy formed in deaminations may result from such side reactions as reaction of the intermediate cation with nucleophiles, for example, acetate or chloride ions,49,30 present in low concentration. Nitrite ions can give rise to nitrite esters or ni-troalkanes 50,51 the former are probably hydrolyzed prior to or during processing of the products.52 Some alkenes have been reported to react with nitrous acid or related nitrosating agents.19,58 Enol ethers would be expected to be more nucleophilic than simple alkenes, and it has been found that D-glucal reacts with nitrous acid under the conditions of deamination.54... 

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