Free radical methylation

TABLE m-33. FREE-RADICAL METHYLATION IN ACIDIC MEDIUM OF AL-KYLTHIAZOLE (197)... 

UV spectra, 5, 517 bromination, 5, 540 dipole moment, 5, 523 free radical alkylation, 5, 543 free radical methylation, 5, 544 IR spectra, 5, 518, 519 irradiation, 5, 543 mass spectra, 5, 519 metabolism, 1, 234 monoprotonated tautomerism, 5, 509 oxidation, 5, 539 1-oxides... 

Hypoxanthine, 7-ethyl-synthesis, 5, 584 Hypoxanthine, 1-methyl-deuterium-hydrogen exchange, 5, 527 synthesis, 5, 594 Hypoxanthine, 2-methyl-methylation, 5, 532 synthesis, 5, 587 Hypoxanthine, 3-methyl-free radical methylation, 5, 544 irradiation, 5, 543 synthesis, 5, 584 Hypoxanthine, 8-methyl-synthesis, 5, 584 Hypoxanthine, 9-methyl-methylation, 5, 532... 

M. Gomberg Ann Arbor, USA generation of the free radicals, methyl and ethyl ... 

Fig. 22. Apparatus for the detection of organic free radicals. Methyl radicals are formed in the heated zone and react with the lead mirror downstream to form volatile tetramethyllead (199).

Table 22 Free Radical Methylation of some Purines (79joci4so) ...

Table 23 Rate Constants for Free Radical Methylation of Purines <79JOCi45o) ...

The same authors have examined the free radical methylation of several "nucleosides in the presence of r-butyl peracetate and shown that C-methylation occurs at pH 1-4 but at pH 4-10 there is increasing iV-methylation (80JOC2373) as the electron availability on these atoms builds up. C-Methylation is proposed to proceed via an addition mechanism and iV-methylation via a radical extraction of hydrogen from NH followed by reaction with a methyl radical. Implications of these reactions in radical oncogenesis are discussed. 

In contrast to the shift of the sulfur monomer/polymer floor temperature to higher temperatures, recent work from our laboratory shows that nanoconfinement shifts equilibrium in free radical methyl methacrylate (MMA) polymerization towards monomer [93]. Results are shown in Fig. 11.9 again for MMA polymerized by 0.5 wt% AIBN, where the equilibrium conversion is plotted versus temperature. Conversions at low reaction temperatures are less than 100 % due to the effect of vitrification (i.e., the reaction cannot reach equilibrium because the reaction mixture turns to a glass and the reaction stops prior to 100 % conversion being reached). As the reaction temperature approaches and rises above the glass transition of the neat polymer (Tg p 110 °C), vitrification effects disappear and the conversion reaches the maximum value of 1.0. At higher temperatures, conversion again decreases. 

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