Which of the following is the correct order of decreasing SN2 reactivity?

Question

Which of the following is the correct order of decreasing SN2 reactivity? (A) R2CH X > R3C X > RCH2 X (B) RCH2 X > R3C X > R2CH X (C) RCH2 X > R2CH X > R3C X (D) R3C X > R2CH X > RCH2 X (X is a halogen)

Tardigrade Admin · Accepted Answer

In SN2 mechanism transition state is pentavelent. For bulky alkyl group it will have sterical hinderance and smaller alkyl group will favour the SN2 mechanism. So the decreasing order of reactivity of alkyl halides is RCH2X > R2CHX > R3CX

Q. Which of the following is the correct order of decreasing $S_{N} 2$ reactivity?

$R_{2} C H X > R_{3} CX > RC H_{2} X$

$RC H_{2} X > R_{3} CX > R_{2} C H X$

$RC H_{2} X > R_{2} C H X > R_{3} CX$

$R_{3} CX > R_{2} C H X > RC H_{2} X (X$ is a halogen)

In $S_{N^{2}}$ mechanism transition state is pentavelent. For bulky alkyl group it will have sterical hinderance and smaller alkyl group will favour the $S_{N^{2}}$ mechanism. So the decreasing order of reactivity of alkyl halides is $RC H_{2} X > R_{2} C H X > R_{3} CX$

Q. Which of the following is the correct order of decreasing SN​2 reactivity?

R2​CHX>R3​CX>RCH2​X

RCH2​X>R3​CX>R2​CHX

RCH2​X>R2​CHX>R3​CX

R3​CX>R2​CHX>RCH2​X(X is a halogen)