Abstract
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 of oxygen nucleophiles of the same pK, by factors of 600-, 160-, and 30-fold, respectively. The values of {-&} = 0.70 and 0.86 for reactions of phosphorylated pyridines with hydrogen peroxide and fluoride anions are smaller than predicted by a plot of {-&} against the pK, of normal oxygen nucleophiles; however, they fit a plot of (-g Le., the rate enhancements for these nucleophiles may reflect an enhanced thermodynamic affinity for the phosphoryl group that influences the stability and structure of the transition state. The observed changes in transition-state structure are not predicted for rate enhancements from hydrogen bonding in the transition state or from weak solvation of the a-effect nucleophile.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
