Reactivities of Several Nucleophiles toward 4-Methylbenzyne in Very Hot Water

Article abstract of DOI:10.1021/jo01298a007

By means of competition experiments, the relative rates of reaction of several nucleophiles with 4-methylbenzyne in aqueous solution at temperatures up to 318 deg C have been determined.The relative nucleophilicities vs. chloride ion are as follows: PhS^-, 46; I^-, 6.2; piperidine, 3.0; Br^-, 1.7; aniline, 1.3; Cl^-, (1.0); PhO^-, 1.0; ammonia, 0.55; F^-, 0.20.For all but PhS^-, piperidine, and iodide, the p/m product ratio is 0.83+/-0.02.In the cases of PhS^- and piperidine a competing mechanism of ipso substitution, probably involving catalysis by copper ions, caused the observed p/m ratios to be high and variable.Our experimental design precluded determination of the p/m ratio for iodide ion.Because of chemical complications, only rough estimates could be made of the nucleophilicities of nitrite and benzenesulfinate ions.