CH3Br + Nu- → CH3Nu + Br- The decreasing order of the rate of the above reaction with the following nucleophiles is: [ Nu = (I) PhO- (II) AcO- (III) HO- (IV) CH3O- ] My answer is IV > III > II > I However the answer is IV > III > I > II I'm having a hard time understanding why PhO- is a better nucleophile than AcO-. Isn't PhO- more stable than AcO- due to the negative charge being delocalized over the entire phenyl ring while for AcO- there is comparatively less delocalization? Also, isn't PhO- bulkier than AcO-? So, it looks to me like there are two factors working against the actual answer. Please help.