Methylperoxyl radical

Tertiary peroxyl radicals also produce chemiluminescence although with lower efficiencies. For example, the intensity from cumene autooxidation, where the peroxyl radical is tertiary, is a factor of 10 less than that from ethylbenzene (132). The chemiluminescent mechanism for cumene may be the same as for secondary hydrocarbons because methylperoxy radical combination is involved in the termination step. The primary methylperoxyl radical terminates according to the chemiluminescent reaction just shown for (36), ie, R = H. 

Square brackets around a molecular species indicate atmospheric concentration. The rate constants k times the reactant concentration product refers to the rates of the chemical reactions of the indicated number. The photolytic flux term /l4 refers to the photodissociation rate of N02 in Reaction R14, its value is proportional to solar intensity.]. RO2 stands for an organic peroxyl radical (R is an organic group) that is capable of oxidizing NO to NO2. Hydrocarbons oxidize to form a very large number of different RO2 species the simplest of the family is methylperoxyl radical involved in R5, R6 and R8. 

The formed methyl radical adds dioxygen, and the methylperoxyl radical participates in chain termination ... 

Neta P, Eluie RE, Mosseri S, Shastri LV, Mittal JP, Maruthamuthu P, Steenken S (1989) Rate constants for reduction of substituted methylperoxyl radicals by ascorbate ions and N,N,N, Al -tetrameth-yl-p-phenylenediamine. J Phys Chem 93 4099-4104 Netto LES, Stadtman ER (1996) The iron-catalyzed oxidation of dithiothreitol is a biphasic process hyudrogen peroxide is involved in the initiation of a free-radical chain of reactions. Arch Biochem Biophys 333 233-242... 

Schuchmann H-P, von Sonntag C (1981) Photolysis at 185 nm of dimethyl ether in aqueous solution Involvement of the hydroxymethyl radical. J Photochem 16 289-295 Schuchmann H-P, von Sonntag C (1984) Methylperoxyl radicals a study ofthey-radiolysis of methane in oxygenated aqueous solutions. Z Naturforsch 39b 217—221 Schuchmann MN, von Sonntag C (1977) Radiation chemistry of carbohydrates. Part 14. Hydroxyl radical-induced oxidation of D-glucose in oxygenated aqueous solution. J Chem Soc Perkin Trans 2 1958-1963... 

The chemistry of the methylperoxyl radical (CH3O2) and its products is quite complicated and the kinetics of many of the reactions still are quite tentative. A likely scheme for the degradation of CH3O2 is presented... 

Lipid peroxidation has been implicated in a wide range of tissue injuries, diseases, and even in the aging process. The liver toxicity of carbon tetrachloride (CCI4) is a classic example of the destructive effects of lipid peroxidation. A very small portion of administered carbon tetrachloride is metabolized into trichloromethyl free radical (CCI3) by the action of cytochrome P450 in the liver. This radical reacts rapidly with oxygen and gives rise to the trichloro-methylperoxyl radical... 

The light emission from autoxidizing organic materials can arise from self-reaction of primary or secondary alkylperoxyl or alkoxyl radicals. In the present case, the predominent site of peroxyl radical attack with hydroperoxide formation in PP involves the tertiary centers, so that the chemiluminescence probably arises (1) from primary or methylperoxyl radicals formed from -scission,... 

Continuous emission from NOa 359 and single vibronic level fluorescence from NOa 360 have been reported. The lifetimes of the 2Bl K > 0) states were measured, and the interesting result was obtained that the lifetime of the K = 4, N = 16 1 level was 36 [xs, substantially greater than that of the K = 0 levels. The increase in lifetime is attributed to Renner interaction of the and 2AX components of the linear 2 state. Rotational excitation has been shown to assist in the dissociation of NOa in the 249.1 nm system, but this is minor in extent compared with that observed in the 397.9 nm system. Yields of 0(4)) were reported.361 The photolysis of NOa has been further studied.362 In the report by Harteck et al., a two-photon excitation process was observed when a pulsed ruby laser was used for excitation. Thermal and photochemical reactions of NOa with butyraldehyde,363 other aldehyde-NO systems,364 and methylperoxyl radical-NOx reactions 365 have been discussed. 

FIGURE 7.5 Principal reactions among NO, NO2, and HNO3 in the atmosphere. ROO- represents an organic peroxyl radical, such as the methylperoxyl radical, CHjOO-. 

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