Quiz - Alkyl Halides - SN Reactions 3 | Alkyl Halides - Nucleophilic Substitutions
Organic Chemistry 1 - Quiz - Alkyl Halides - SN Reactions 3
Why do tertiary alkyl halides undergo SN1 reactions?
The neighboring groups of the carbocation are important: electron-donating groups (such as alkyl groups) stabilize a positive charge. The more stable the intermediate carbocation, the faster the SN1 reaction
Which solvent is used for SN1 reactions and why?
- Polar protic solvents (H2O, ROH, RCOOH) favor SN1 reactions because the carbocation intermediates are stabilized by solvation
- Polar aprotic solvents (CH3CN, ROR, DMSO) favor SN2 reactions because the nucleophiles are not well solvated and are therefore more nucleophilic
In an SN2 reaction, what stereochemical outcome is expected after the substitution of a chiral center?
SN2 reactions involve a backside attack by the nucleophile, resulting in inversion of configuration at a chiral center.
What is the stereochemistry of the nitrile produced in the following reaction?
The strong nucleophile -CN with a net negative charge and the polar aprotic solvent CH3CN favor an SN2 process. In this two-step process, a bond is broken then a new bond is formed, and inversion of configuration occurs. The nitrile produced is:
What is the stereochemistry of the alcohol produced in the following reaction?
The strong nucleophile -OH with a net negative charge and the polar aprotic solvent DMSO favor an SN2 process. In this two-step process, a bond is broken then a new bond is formed, and inversion of configuration occurs. The alcohol produced is:
What are the primary factors affecting the rate of SN1 reactions?
In SN1 reactions, the rate is primarily influenced by the concentration of the substrate (alkyl halide): Rate = k [RX]. Higher concentrations of the alkyl halide generally lead to increased reaction rates in SN1 reactions.
Which alkyl bromide would react the fastest in an SN2 reaction?
Steric effects are particularly important in SN2 reactions:
Allylic and benzylic halides undergo SN2 reactions more rapidly than the corresponding simple alkyl halides
Which type of alkyl halide would most likely undergo an SN1 reaction the fastest?
Tertiary alkyl halides are most likely to undergo SN1 reactions the fastest due to the stability of the tertiary carbocation formed as an intermediate.
Which is the order from fastest to slowest for the rates of the SN2 reactions of these following alkyl bromides?
1 is a vinylic halide, 2 is an allylic halide, 3 is secondary alkyl halide
Allylic and benzylic halides undergo SN2 reactions more rapidly than the corresponding simple alkyl halides, whereas vinylic halides do not undergo SN2 reactions
Which of the following is a common leaving group in nucleophilic substitution reactions?
Tosylate ion (TsO-) is a common leaving group in nucleophilic substitution reactions due to its stability after departure from the substrate.