2-Phosphatoalkyl radicals

Table 6.6. Approximate rate constants of phosphate release from some a-methoxy-p-phosphatoalkyl radicals. (Behrens et al. 1978)...

Schuchmann MN, Schuchmann H-P, von Sonntag C (1989) The pJCa value of the O2CH2CO2H radical the Taft a constant of the -CH2O2 group. J Phys Chem 93 5320-5323 Schuchmann MN, Scholes ML, Zegota H, von Sonntag C (1995) Reaction of hydroxyl radicals with alkyl phosphates and the oxidation of phosphatoalkyl radicals by nitrocompounds. Int J Radiat Biol 68 121-131... 

Oxidation of a-phosphatoalkyl radicals by TNM leads first to an adduct which subsequently decays thereby releasing NF (Schuchmann et al. 1995). Nitroaro-matic sensistizers form also adducts albeit more slowly than TNM. Oxidation of a-phosphatoalkyl radicals by Fe(CN)63- is only moderately fast. 

The radicals derived from 2-deoxyribose (ribose) upon Oil-attack yield 37% (23%) PNAP-", and it has been concluded that ET only occurs from the C(l ) radicals (Michaels et al. 1976). With CH20H/CH20- the rate of reaction with PNAP is only fast with the anion, CH20 (Adams and Willson 1973). Whether the radicals formed at the other sites in 2-deoxyribose and ribose give (slowly) rise to adducts cannot be deduced from the reported data. Yet, the fact that PNAP enhances the yield of free phosphate in the radiolysis of GMP (Greenstock et al. 1973a) is an indication that such adducts are likely to be formed, but the rate of reaction is very slow with a-phosphatoalkyl radicals (< 5 x 107 dm3 mol 1 s 1 Schuchmann et al. 1995). 

In a-hydroxy-P-phosphatoalkyl radicals, phosphate elimination and hydroxyl proton loss may occur in a concerted manner. In the glycerol phosphates, the elimination occurs within a few microseconds [27, 41, 42]. This type of reaction plays a role in the nucleobase-radical-induced strand breakage of poly(U) [cf. reaction (17)]. In this reaction, a radical at C(2 ) 17 is generated. In DNA, strand... 

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