Organic Chemistry : Help with Substitution Reactions
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Example Questions
Example Question #51 :Organic Concepts
What is the product of the reaction shown?
This reaction is an example of a nucleophilic substitution on a secondary alkyl halide. The nucleophile in this case is cyanide (
Note: when nucleophilic substitution is performed using a nucleophile that contains carbon (Grignard reagents, acetylide reagents, cyanide, etc.) it is often easy to incorrectly count the number of carbons in the final product.
Example Question #52 :Organic Concepts
Which of these molecules would have a faster SN2 reaction?
Neither would react.
1-iodobutane
1-bromobutane
他们会the same rate.
1-iodobutane
Example Question #53 :Organic Concepts
Which of these would undergo a faster SN2 reaction?
2-bromobutane
They would react at the same rate.
1-bromopropane
Neither would undergo the reaction.
1-bromopropane
There would be more steric hindrance for a nucleophile in the 2-bromobutane because the leaving group, bromine, is located on a secondary carbon atom. A secondary carbon atom is attached to two other carbon atoms. The leaving group on the 1-propane is located on a primary carbon atom, which is attached to only one other carbon atom.
Example Question #54 :Organic Concepts
What is the rate law for this equation?
rate = k[R-Leaving Group]2
rate = k[R-Leaving Group]
rate = k[Nucleophile]2
rate = k[Nucleophile][R-Leaving Group]
rate = k[R-Leaving Group]
This reaction would occur using an SN1 mechanism because the leaving group is attached to a tertiary carbon, a carbon atom with three of the carbon atoms attached to it. The rate laws for SN1 mechanisms do not depend on the nucleophile concentration. The slow-step occurs unimolecularly within the molecule with the leaving group.
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