Chapter 17 Nucleophilic Substitution Reaction of Alkyl Halides

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Chapter 17Nucleophilic Substitution Reaction of
Alkyl Halides
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Purpose

• In this experiment eleven representative alkyl
  halides are treated with sodium iodide in acetone
  and with ethanolic solution of silver nitrate. In
  the first case (I-/acetone) the SN2 reaction is
  favored, while the second system (Ag/EtOH)
  effects the SN1 reaction. In your analysis
  compare reactivity of the given alkyl halides in
  SN2 and SN1 reactions.

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Reaction Mechanism

• SN2 reaction occurs in one smooth step and gives
  the product with the inverted configuration with
  respect to the starting compound (reactant). The
  kinetics of the reaction depends on the
  concentration of both Nu- and alkyl halide. The
  primary factor for the halide reactivity in the
  SN2 reaction is steric hindrance.

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Reaction Mechanism

• SN1 reaction occurs in two discrete steps and
  gives the product as an equimolar mixture of both
  enantiomers because the intermediate is planar.
  The kinetics of the reaction depends only on the
  concentration of halide. The primary factor for
  the halide reactivity in the SN1 reaction is the
  relative stability of the intermediate
  carbocation.

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Comments

• Follow pp. 338-340 (microscale).
• Follow the lab handout for all experimental
  procedures. Wearing rubber gloves is necessary
  during this lab. You will work with harmful and
  toxic compounds.
• Note the starting time when you mix the reagents
  together, and then record the time precipitate
  formed (if formed at all) in a test tube.

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Safety

• Flammable solvents and reagents are used in this
  experiment, keep away from any open flame.
• Organic halides are flammable, and irritating to
  eyes, respiratory system and skin. Harmful by
  inhalation, may cause lung damage if swallowed.
  Do not swallow and inhale, avoid contact with
  skin and eyes.