Nucleophiles of high reactivity in phosphoryl transfer reactions: .alpha.-effect compounds and fluoride ion

摘要: The second-order rate constants for reactions of hydrogen peroxide, acetohydroxamate, and fluoride anions with phosphorylated pyridine monoanions (H20, 25 OC, ionic strength 1.5) are larger than those "normal" oxygen nucleophiles the same pK, by factors 600-, 160-, 30-fold, respectively. values {-&} = 0.70 0.86 pyridines peroxide smaller predicted a plot against normal nucleophiles; however, they fit (-g Le., enhancements these may reflect an enhanced thermodynamic affinity phosphoryl group that influences stability structure transition state. observed changes in transition-state not from bonding state or weak solvation a-effect nucleophile.