Nitrous acid esters

Nitrous acid esters 1 can be converted to 3-nitroso alcohols 2 by irradiation with ultraviolet light. This conversion is called the Barton reaction. ... 

Upon the irradiation the nitrous acid ester 1 decomposes to give nitrous oxide (NO) and an alkoxy radical species 3. The latter further reacts by an intramolecular hydrogen abstraction via a cyclic, six-membered transition state 4 to give an intermediate carbon radical species 5, which then reacts with the nitrous oxide to yield the 3-nitroso alcohol 2 ... 

The NO -ion might be formed from the nitrous acid ester if the latter was present as an impurity in the main reactant. Trials carried out with ethyl nitrite and n-butyl nitrite have demonstrated, however, that when these compounds are treated with an excess of hydrazine they do not undergo any chemical reaction accompanied by the formation of the nitrate ion. 

On the basis of the observation that the addition of nitrogen dioxide to compounds with double bonds yields not only nitro compounds, but nitrous acid esters as well (p. 99). Schaarschmidt [38a,39,40] expressed the view that nitrogen dioxide exists in three forms which are in equilibrium. This may be represented in modem symbols in the following way ... 

Hence the formation of nitroso compounds (C-nitroso- and O-nitroso, i.e. nitrous acid esters) is possible. 

Organic nitrates (and nitrites) are simple nitric and nitrous acid esters of alcohols. They differ in their volatility for example, isosorbide dinitrate is solid at room temperature, nitroglycerin is only moderately volatile, whereas amyl nitrate is extremely volatile. These compounds cause a rapid reduction in myocardial oxygen demand followed by rapid relief of symptoms. They are effective in stable and unstable angina, as well as Prinzmetal s or variant angina pectoris. 

Since butyl nitrite is the nitrous acid ester of n-butanol, it is not surprising that it is easily made by bringing nitrous acid into contact with n-butanol in the presence of sulfuric acid catalyst. Nitrous acid is not used directly because it is unstable. Instead it is generated in the reaction flask by allowing excess sulfuric acid to react with sodium nitrite in the mixture. The main precaution taken while running this reaction is to ensure that the temperature of the mixture does not rise above the prescribed limits. 

The third reaction type to be discussed in this section is the Forster reaction. It was discovered by Forster in 1915, as he had obtained (benzoyl)(phenyl)diazomethane (2-diazo-l,2-diphenylethan-l-one, 2.62) by treatment of (Z)- and ( )-benzil monooxime ((Z) = 2.95) with sodium hypochlorite and ammonia (which readily forms chloramine). a-Keto-monoximes like 2.95 are obtained easily from a-methylene-con-taining ketones (e.g., 2.94) by the oximation reaction, i.e., a nitrosation with a nitrous acid ester followed by a C O proton shift (2-41). 

Acetic acid Nitrous acid esters by transesterification... 

Oximinoalcohols from nitrous acid esters Barton reaction s. 15, 315 s. a. Tetrah. Let. 1965, 2497 ... 

In addition, m-cresol is used to produce plant protection agents such as feni-trothion. The manufacturing process involves nitrosation of m-cresol with nitrous acid esters in isopropanol, and subsequent oxidation of the nitroso compounds with nitric acid to yield 4-nitro m-cresol (or its sodium salt), which, when acted upon by 0,0-dimethyl thiophosphoric acid chloride, gives fenitrothion. 

Nitrous acid esters Nitric acid Protection Sulfur... 

N-nitrosourethans 17, 342 urethans 17, 342 Nitrous acid esters s. Alkyl nitrite Nitryl chloride 16,520 1 Nonanol as solvent 16, 728 Nuclei s. Heterocyclics, Isocyclics, Rings Nucleophiles (s. a. C-Hydrogen, active)... 

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