Quiz - SN Reactions II | Alkyl Halides - Nucleophilic Substitutions

Organic Chemistry 1 - Quiz - SN Reactions II

1

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

2

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
3

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:

4

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:

5

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

6

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