SOLVATION AND METAL-ION EFFECTS ON STRUCTURE AND REACTIVITY OF PHOSPHORYL COMPOUNDS .4. DEALKYLATION OF PHOSPHATE-ESTERS BY THIOPHENOXIDE ION IN METHANOL

Second-order rate constants for the demethylation of three phosphate e sters by thiophenoxide salts, PhS(-)M(+) (M(+) = Me(4)N(+),K+, Na+ Li) in methanol-d(4) at 25 degrees C have been measured. In contrast to the demethylation by iodide salts, metallic counterions do not exhibit any catalytic effects on the demethylation rate. The absence of the c atalysis indicates that the salts react exclusively as ion pairs, in w hich an alkali metal ion is not available for the interactions with th e phosphoryl group in the transition state.