Problem: Which of the following multistep reaction pathways will give a higher yield and why?#1 (CH3)2CH(CH2)2Br  (CH3)2CH(CH2)2CN  (CH3)2CH(CH2)2COOH#2CH3(CH2)2CHCH3Br  CH3(CH2)2CHCH3CN   CH3(CH2)2CHCH3COOHa) Pathway #1, because there is much less steric hindrance for primary substrates than for secondary substrates in the SN2 reaction, which is the first mechanism in each of the two pathways. b) Pathway #2, because there is much steric hindrance for secondary substrates than for primary substrates in the SN2 reaction, which is the first mechanism in each of the pathways.c) Both pathways will give the same yield.

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FREE Expert Solution

Nucleophile Strength:              SN1 =   WEAK               SN2 = STRONG

Leaving Group Substitution:    SN = 3° > 2°                 SN2 = 0° > 1° > 2°

KCN or CN- as nucleophile will be considered as strong (since its negatively charged)

For 1 → 1° leaving group 

For 2 → 1° leaving group 

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Problem Details

Which of the following multistep reaction pathways will give a higher yield and why?

#1 

(CH3)2CH(CH2)2Br  (CH3)2CH(CH2)2CN  (CH3)2CH(CH2)2COOH

#2

CH3(CH2)2CHCH3Br  CH3(CH2)2CHCH3CN   CH3(CH2)2CHCH3COOH



a) Pathway #1, because there is much less steric hindrance for primary substrates than for secondary substrates in the SN2 reaction, which is the first mechanism in each of the two pathways. 

b) Pathway #2, because there is much steric hindrance for secondary substrates than for primary substrates in the SN2 reaction, which is the first mechanism in each of the pathways.

c) Both pathways will give the same yield.

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