What is the effect of leaving group and solvent on the reaction rate of #S_N2# reaction?

1 Answer
Oct 16, 2015

Greater rate: Better leaving group & polar aprotic solvent .


#S_(N2)# is a bimolecular molecule and the reaction rate depends on the alkyl halide and the nucleophile.

#S_(N2)# has a concerted mechanism which means that it occurs in one step which is itself the rate determining step:


Effect of leaving group:
The better the leaving group the faster the reaction and therefore greater reaction rate.

Effect of solvent:
#S_(N2)# favours polar aprotic solvents.
Polar aprotic solvents do not affect the strength of the nucleophile (#S_(N2)# favours strong nucleophiles), therefore, the reaction will proceed at a faster rate.