Sn1 Sn2 E1 And E2 Reaction MDCAT Quiz reactions are among the basic kinds of organic reactions that MDCAT students must learn very well. The mechanisms involved here are nucleophilic substitution (SN1 and SN2) and elimination (E1 and E2), with each having different characteristics and conditions.
SN1 (Unimolecular Nucleophilic Substitution): In this reaction, the rate-determining step is the formation of a carbocation intermediate after the leaving group departs. This reaction usually occurs with tertiary alkyl halides in polar protic solvents. The rate depends only on the substrate concentration.
SN2 (Bimolecular Nucleophilic Substitution): In this case, the nucleophile attacks the carbon center at the same time as the leaving group departs, forming a transition state. This reaction occurs predominantly with primary alkyl halides and in polar aprotic solvents. The reaction is stereospecific, meaning it inverts the configuration of the carbon center.
E1 (Unimolecular Elimination): Like SN1, this reaction proceeds through the formation of a carbocation intermediate, followed by the elimination of a proton (H⁺) and a leaving group. E1 reactions are usually in competition with SN1 reactions and take place with tertiary alkyl halides in polar protic solvents.
E2 (Bimolecular Elimination): During this reaction, the base abstracts a proton from the carbon adjacent to the one bearing the leaving group; simultaneously, the leaving group is eliminated, and an alkene is formed. This reaction occurs in a single step and is favored with strong bases and secondary/tertiary alkyl halides in polar aprotic solvents.
Quiz: Test Your Knowledge of SN1, SN2, E1, and E2 Reactions
Our MDCAT Quiz on SN1, SN2, E1, and E2 reactions will help you solidify your understanding of these important mechanisms. The quiz includes questions on identifying the conditions that favor each reaction type, understanding their mechanisms, and predicting the products. Practicing this quiz will have you well-prepared for any related questions in the MDCAT exam.
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Free Flashcard: Important Facts about SN1, SN2, E1 and E2 reactions
Our Free Flashcard set on SN1, SN2, E1, and E2 reactions summarizes the key points about each reaction mechanism. These flashcards include information on the reaction steps, factors affecting the reaction rates, and the type of products formed. They are an excellent tool for quick review and reinforcement of your knowledge before the MDCAT exam.
Which reaction mechanism involves the formation of a carbocation?
SN1
Which of the following mechanisms is favored by a strong nucleophile?
SN2
What is the rate-determining step in an E1 mechanism?
Departure of leaving group
What type of alkyl halide undergoes SN1 reaction most readily?
Tertiary alkyl halide
Which of the following reactions is bimolecular in the rate-determining step?
SN2
What type of alkyl halide favors the E2 mechanism?
Secondary or tertiary
Which mechanism involves a single-step process without the formation of an intermediate?
SN2
Which reaction mechanism is favored by a polar aprotic solvent?
SN2
What is the product when a tertiary alkyl halide undergoes an E1 reaction?
Alkene
What is the result of an SN1 reaction with a weak nucleophile?
Alcohol
Which reaction mechanism is typically favored by a bulky base like t-butoxide?
E2
What happens when a primary alkyl halide undergoes an E2 reaction with a strong base?
Alkene
In an E1 reaction, what is the first step?
Departure of leaving group
Which reaction mechanism involves the formation of a transition state?
SN2
What is the major product of an E2 reaction with a strong base?
Alkene
What type of mechanism does a tertiary alkyl halide undergo when it reacts with a weak nucleophile in a polar protic solvent?
SN1
Which of the following reactions proceeds through a carbocation intermediate?
E1
What is the result when a secondary alkyl halide undergoes an E1 reaction?
Alkene
Which mechanism requires the presence of a good leaving group?
E2
What is the product of a reaction when a primary alkyl halide undergoes an E2 reaction with a strong base?
Alkene
Which reaction mechanism is favored by a strong nucleophile in a polar aprotic solvent?
SN2
What is the rate-determining step in an SN2 reaction?
Attack of nucleophile
Which of the following reactions is a two-step process?
E1
Which reaction mechanism is favored by a strong, bulky base like potassium tert-butoxide?
E2
In an SN1 reaction, which factor affects the reaction rate the most?
Stability of the carbocation
Which of the following mechanisms is favored by a polar protic solvent?
SN1
Which reaction involves the simultaneous removal of a leaving group and a proton?
E2
Which reaction mechanism involves a single nucleophile and a leaving group?
SN2
Which reaction mechanism results in the inversion of configuration at the chiral center?
SN2
What is the major product when a primary alkyl halide undergoes an SN2 reaction?
Alcohol
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