Question

In each case tell which sn2 reaction will proceed faster. 1. the displacement on 2-bromopropane by (a) ch3ch2o- or (b) cn-. 2. the displacement by oh- on (a) h2c=chbr or (b) h2c=chch2br. submit answertry another version2 item attempts remaining

Answer 1

The displacement on 2-bromopropane will likely proceed faster with CH3CH2O- because of the degree of nucleophilicity; this group is likely more nucleophilic than a CN group, as even though the triple bond would make it more reactive it is still relying heavily on the effects of induction in justifying its reactivity.

The displacement for number 2 would occur SIGNIFICANTLY quicker on the H2C=CHCH2Br due to its position. The alternative has Bromine in a vinylic position to the double bond making an SN2 reaction nearly impossible (sp2 hybridized centers don’t react well with SN2 and have a poor intermediate while allylic SN2s are stabilized by resonance).

Hope this helps!