The following two questions prompted me to ask this question.
Determine the order of the following compounds according to reactivity in Williamson Ether Synthesis.
a. $\ce{CH3CH2CH2Br}$
b. $\ce{CH2=CHCH2Cl}$Which of these represent the ether($\ce{CH2=CHCH2OC3H7}$) on forming peroxide in air
a. $\ce{CH2=CHCH2OCH(OOH)CH2CH3}$
b. $\ce{CH2=CH-CH(OOH)OC3H7}$
In both the case, I think the question is the relative ease of nucleophilic attack on carbon with $\alpha$-unsaturation. In the former, the bromine is a better leaving group. But, the presence of $\alpha$-unsaturation in the chloro compound, changes the order to b>a. In the latter, the attack of oxygen depends on the most stable electrophilic centre.
My question:-
Is $\alpha$-unsaturation favourable for nucleophilic attack? Relevant factors would be the increased electrophilicity of the carbon attached to the $sp^2$ hybridised ethylinic carbon and the repulsion of the negative nucleophile by the pi electrons.