58634-64-3Relevant academic research and scientific papers
Deuterium Isotope Effects and the Bunnet w Factor in Elimination Reactions of 4-Alkoxyimino-5,6-dihydro-6-alkoxyaminopyrimidin-2(1H)-one in Strong Acid Media
Atkins, Paul J.,Palling, David J.,Poon, Nai L.,Hall, C. Dennis
, p. 1107 - 1112 (2007/10/02)
Rate coefficients for the elimination of hydroxylamines from 4-alkoxyimino-5,6-dihydro-6-alkoxyaminopyrimidin-2(1H)-ones (1a) show maxima at H0 values of -1.8 (for O-benzylhydroxylamine) and -0.8 (for hydroxylamine) in a variety of mineral acids.The hitherto unknown values of H0 for trifluoromethanesulphonic acid are reported and this acid also gives a rate maximum at -1.8 for the elimination of O-benzylhydroxylamine from (1a; R2 = Bz).Bunnett w values for these eliminations fall in the range 6.0-16.0 (dependent upon the acid) implying that water is involved as a proton transfer agent.In contrast, eliminations in formic acid show low and variable w values and formate ion is involved as the proton transfer agent which explains the lack of a rate maximum in this acid.Deuterium isotope effects reveal a highly stereoselective elimination and support the proposal of an E1cB (irreversible) mechanism.The inhibition of elimination by the 5-fluoro-substituent is probably due to destabilisation of the intermediate carbanion by the lone pair electrons on fluorine.
