Abstract: Competitive reactions of t-BuO. with a series of X-C6H4P (OCH& [X= p-MeO, H, p- C1, and m-CFJ were run to test the importance of polar substituent effects on the rates of such reactions. Rate differences were found to be negligible.(A rate constant for the case X= H of 3.1-3.7 X lo8 Ml sec-l at 65" was estimated.) This is in contrast to the Michaelis-Arbuzov reactions of the same series of ArP (OCH& with CH31 which doubtless have very dipolar ...