Substitution & Elimination
Supplemental Instruction
Iowa State University
Leader:
Course:
Instructor:
Date:
Chelsea
Chem 231
Jeffries-El
3/24/10
Consider the reaction:
CH3CH2Br + CH3OH  CH3CH2-OCH3
What type of reaction is this? (SN1, SN2, E1, or E2)
SN2
What is the substrate?
CH3CH2Br
What is the nucleophile?
CH3OH
What is added to the substrate (might be different than the nucleophile)? CH3OWhat is the leaving group? BrWhat happens to the reaction rate if…
1. The substrate is changed to CH3Br? increases
2. The substrate is changed to (CH3)2CH2Br? decreases
3. The leaving group is changed to Cl-? decreases
4. The leaving group is changed to I-? increases
5. The nucleophile is changed to NaOCH3? increases
6. The concentration of CH3OH is doubled? increases
7. The concentration of CH3CH2Br is halved? decreases
8. Both 6 and 7 happen at the same time? Stays the same
Which of these 8 will change the overall product of the reaction? (only 1 & 2)
What are the products of these substitution reactions? Are they SN1 or SN2?
CH3CH2OH + PBr3  CH3CH2Br (SN2)
CH3CH2CH2CH2Br + NaCN  CH3CH2CH2CH2CN + NaBr (SN2)
CH3Br + NaOC(CH3)3  CH3OC(CH3)3 + NaBr (SN2)
CH3CH2CH2I + NaN3  CH3CH2CH2N3 + NaI (SN2)
CH3CH2I + NaSH  CH3CH2SH + NaI (SN2)
CH3CH2CHCH3 + CH3OH  subst. product (inverted stereochem) & 2 elim. Products
Br
(SN2 & E2)
CH3Br + NaOCOCH3  CH3OCOCH3 + NaBr (SN2)
What are the products of these elimination reactions?
(CH3)3CBr + NaOCH3  CH2=C(CH3)2 (E2)
CH3CH2CHCH3 + CH3OH  subst. product (inverted stereochem) & 2 elim. Products
Br
(SN2 & E2)