Methyl nitrite, photolysis

Atkinson, R W. P. L. Carter, A. M. Winer, and J. N. Pitts, Jr., An Experimental Protocol for the Determination of OH Radical Rate Constants with Organics Using Methyl Nitrite Photolysis as an OH Radical Source, J. Air Pollut. Control Assoc., 31, 1090-1092 (1981). 

Napier and Norrish (1965, 1967) identified HNO spectroscopically in flash photolyses of methyl nitrite as the intermediate product and from the kinetics of its appearance concluded that process (I) was the major primary process involved in methyl nitrite photolysis. McGraw and Johnston (1969) also studied the HNO formation and decay in methyl nitrite photolyses at 366 nm. Direct detection of the methoxy radical formed in methyl nitrite photolyses at 266 nm was reported by Sanders et al. (1980) using laser-excited fluorescence (Ohbayashi et al., 1977 Inoue et al., 1979). All current evidence suggests that the occurrence of processes (I) and (II) rationalize well the theoretical and experimental results available today < in is probably near zero. 

The photolysis of methyl nitrite at low temperature in an argon matrix was studied157. The products include formaldehyde, and nitroxyl HNO which also reacts to form N2O and water. The 355-nm photodissociation of gaseous methyl nitrite has been studied by monitoring the nascent NO product using a two-photon laser-induced fluorescence... 

The most common sources of OH used for relative rate studies include the photolysis of HONO (e.g., see Cox, 1975) or alternatively methyl nitrite (CH3ONO) in air in the presence of NO (Atkinson et al., 1981) ... 

Other applications of nitrite photolysis include the functionalisation of the i4a-methyl group of the lanosterol skeleton by irradiation of the nitrite of a, y a-alcohol [20], attack on C(i9> by irradiation of 5a-halo-6ji mtrito derivatives [2X,22] or nitrites of 2/ alcohols [23], intramolecular addition of a 20 alkoxy radical to a Ai -double bond [24], and some reactions involving radical-induced fragmentation of adjacent C-C bonds [23]. A comprehensive review by Nussbaum and Robinson [26] surveys the wide variety of reaction paths open to alkoxy radicals generated by photolysis of nitrites. 

Support for this type of cleavage is the observation that the yield of CH2O is unaffected by the addition of NO and the identification of the species HNO in flash photolysis experiments . Photolyses in argon matrices at 20° K produced HNO and cw-methylnitrite, and it was suggested that the latter was the intermediate postulated by Hirschlaff and Norrish . However, later experiments demonstrated that methyl nitrite is a major product of the continuous photolysis, and the following mechanism was suggested ... 

Methyl radicals were indeed detected at short delay times in flash photolysis , and ESR studies have demonstrated the presence of CHj and NO2 radicals . In addition, large yields of CH are formed in the photolysis, presumably by abstraction reactions of CHj . Recently, experiments by kinetic flash photolysis have shown that the primary step leads to C-N cleavage and that the formation of methyl nitrite is explained by step (b). In contrast to previous results the... 

The photolysis of methyl nitrite indicates that the process... 

In the flash photolysis of methyl nitrite, NO was observed at short delay times ... 

For all the experiments, hydroxyl radicals were produced by ftie photolysis of methyl nitrite around 365 nm ... 

Alkyl halides (RX X = Cl, I) are an important source of halogens in the atmosphere. The major tropospheric sinks of these compounds are photolysis (RBr, RI) and reaction with OH radicals. In the case of alkyl iodides (RI) relative kinetic studies of their OH reactions in photoreactors are complicated by fast reactions with the 0( P) atoms generated by the photochemical OH radical sources. Figure 1 below shows a In-ln plot of the kinetic data from an experiment performed in a large photoreactor to determine the OH rate coefficient for the reaction OH + CH3CH2CH2I relative to OH + ethene using the photolysis of methyl nitrite (CH3ONO) as the OH radical source. A recent example of the implementation of the relative kinetic technique for the determination of OH radical rate coefficients in a photoreactor can be found in Olariu et al. (2000). 

Methyl nitrite is the first member of this class of organic compounds, and photolysis is its only important loss process ... 

The near-u.v. photolysis of methyl nitrite yields methoxy radicals [equation (10)] with a quantum yield of unity. Reaction rate constants of CH3O with Oj... 

Heicklen has studied the photolysis of methyl nitrite,which gives methoxyl radicals ... 

The gas-phase reactions of PAHs with OH and NO3 radicals generated in situ via photolysis of methyl nitrite were followed by ESI-MS. Naphthalene and dg-labeled naphthalene were used as PAH components [443]. 

Section 12.5. in Part A describes some additional reactions that are of synthetic value and involve intramolecular hydrogen abstraction at unactivated groups. Of particular value is the nitrite photolysis method developed by Barton, which has been important in the functionalization of methyl groups in steroids. 

Excimer laser photolysis of ethyl nitrite was studied at 248 and 351 nm as a function of O2 pressure (Zellner). In contrast to methyl nitrite, the photolysis produced not only C2H5O radicals but also methyl radicals with high yield. This study indicates that photolysis of higher alkyl nitrites is not an appropriate source for the laboratory generation of alkoxy radicals. 

Relative rate experiments were carried out in a 50 litre FEP Teflon reaction chamber. The chamber was surrounded by blacklamps and sunlamps. Temperature was maintained at 298 K. Hydroxyl radicals were produced by photolysis of methyl nitrite in air with NO added or by the dark reaction of hydrazine with O3. The generated OH radicals react with the substrate compound, RH, and the reference compound, REF ... 

Masamune and co-workers oxidized the angular methyl group of 31 using the nitrite photolysis reaction this facilitated the synthesis of rishitin. ... 

Photolysis of Methyl Nitrite in the Presence of Nitric Oxide, Nitrogen Dioxide, and Oxygen, J. Amer. Chem. Soc. (1973) 7. 

Gray, J.A. and Style, D.W.G., Photolysis of methyl nitrite, Trans. Faraday Soc., 48, 1137, 1952. Steacie, E.W.R. and Show, G.T., The homogeneous unimolecular decomposition of gaseous alkyl nitrites. II. The decomposition of ethyl nitrite, /. Chem. Phys., 2, 345, 1934. 

The atmospheric lifetime of methyl nitrite with respect to reaction with OH radicals is estimated to be around 1 month. Methyl nitrite is dissociated quite rapidly by solar radiation, as it absorbs strongly in the actinic region the lifetime for photodissociation with an overhead Sun is about 8 1 min. (see table IX-M-1). Because of this rapid photolysis, other reactions such as with OH radicals are considered to be of minor importance as loss processes for this species from the atmosphere. 

Figure IX-H-4. Photolysis frequencies for methyl nitrite versus solar zenith angle as calculated for a clear day in the lower troposphere with a vertical ozone column of 350 DU. The total quantum yield of photodecomposition was taken as either 1.0 or 0.78, independent of wavelength. 

Brown, H.W., and GC. Pimentel (1958), Photolysis of nihomethane and of methyl nitrite in an argon matrix infrared detection of nitroxyL HNO, J. Chem. Phys., 29, 883-888. 

---