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

Answer 1

Ella Allen

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:

#R=k[R-X][Nu^-]#

Effect of leaving group: A higher reaction rate and a faster reaction occur when a leaving group performs better.

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.

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Answer 2

Madison Anderson

The leaving group and solvent both affect the reaction rate of SN2 reactions. A good leaving group increases the rate by stabilizing the transition state, while a polar aprotic solvent enhances the reaction rate by solvating the nucleophile and reducing its reactivity with the substrate.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.