Nitrosyl chloride, photolysis

Photolytic. Photodegrades under simulated atmospheric conditions to phosgene and nitrosyl chloride. Photolysis of nitrosyl chloride yields chlorine and nitrous oxide (Moilanen et al., 1978 Woodrow et ah, 1983). When aqueous solution of chloropicrin (10 M) is exposed to artificial UV light (X <300 nm), protons, carbon dioxide, hydrochloric and nitric acids are formed (Castro and Belser, 1981). 

A procedure for intramolecular functionalization of alcohols has been developed in studies carried out primarily with steroid derivatives. The alcohol is converted to a nitrite ester by reaction with nitrosyl chloride. Photolysis effects... 

The nitrites aie most conveniently prepared from the corresponding alcohols by treatment with nitrosyl chloride in pyridine. The crude nitrites can be precipitated by addition of water and recrystallized from appropriate solvents. However nitrites prepared from carbinols in which the adjacent carbon is substituted by halogen, free or esterified hydroxyl or a carbonyl function are very readily hydrolyzed and must be recrystallized with great care. In general the photolysis gives higher yields if purified and dried nitrites are used which do not contain acids or pyridine, although occasionally the addition of small amounts of pyridine is recommended in order to prevent hydrolysis of the nitrite. Traces of acids do in fact catalyze the thermal decomposition of secondary nitrites to equimolar amounts of alcohol and ketone. ... 

Nevertheless, there are a few reactions which satisfy the stringent criteria considered above, two of which have been studied as possible energy storage reactions. One of these is the photolysis of nitrosyl chloride (24)... 

Basco, N., and R. G. W. Norrish Vibrationally excited nitric oxide produced in the flash photolysis of nitrosyl chloride. Nature [London] 189, 455 (1961). 

Marcus, R. J., and H. G. Wohlers Flow systems in the solar furnace and the photolysis of nitrosyl chloride. Solar Energy 5, 121 (1961). 

Neuwirth, 0. SThe photolysis of nitrosyl chloride and the storage of solar energy. J. physic. Chem. 63, 17 (1959). 

Wayne, R. P. Photolysis of nitrosyl chloride by ultra-violet radiation. Nature [London] 203, 516 (1964). 

Barton reaction In the Barton reaction " a methyl group in the 7 -position to an OH group is converted into an oxime group. For example, corticosterone acetate (2.45) on reaction with nitrosyl chloride (NOCl) in pyridine forms its 1 l -nitrite 2.46, which on photolysis in toluene gives aldosterone acetate oxime (2.47) in 21% yield. Treatment of 2.47 with nitrous acid (HNO2) gives aldosterone acetate (2.48) (Scheme 2.40). 

Cyclopropanoxyl radicals were generated by thermal and photochemical decomposition of cyclopropyl nitrites.The nitrites were prepared from cyclopropanols and nitrosyl chloride in pyridine, and they decomposed at low temperatures often below room temperature. A mixture of -bromo and jS-nitroso ketones was formed from the photolysis of pentamethylcyclo-propyl nitrite (19) in bromotrichloromethane. " ... 

In a novel interconversion, the phosphine sulphide 192 reacts with nitrosyl chloride to give the phosphinothioic cyanate 193 which, when irradiated, isomerizes to the iso-cyanate. Two unusual reactions (equations 10 and 11) result from the photolysis of derivatives of (diazomethyl)phosphonothioic diamide derivatives. Yet a further unusual reaction is experienced by the monoanion 194 when irradiated in MeOH, and which is thought to proceed with the cyclization of the carbene intermediate to give an oxaphos-phirane, methanolysis of which results in ring opening with phosphorus arbon bond fission . ... 

If such a reaction is possible under atmospheric conditions (at highly concentrated particle interfaces), the subsequent step would be the formation of nitrosyl chloride NOCl, an important species in gas phase chemistry. The likely importance of this pathway lies in the photolysis of NOCl gaining Cl radicals ... 

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