Chapter 20 Bromination/Debromination of Cholesterol

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Chapter 20 Bromination/Debromination of
Cholesterol
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Purpose

• This reaction involves nucleophilic attack by the
  alkene on bromine, forming a tertiary carbocation
  with bromonium ion character. This ion is
  attacked from the backside by bromide ion to form
  dibromocholesterol in the trans and diaxial
  configuration.
• This reaction is employed in the practical
  purpose of purifying cholesterol.

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Comments

• Follow p. 360, 362 (microscale).
• Follow the lab handout for all experimental
  procedures. Wearing rubber gloves is necessary
  during this lab. You will work with toxic and
  corrosive compounds.
• Calculate yield. Moderate to good yields should
  be achieved.
• (Moles Product / Moles Starting Material) x 100
  Yield
• Answer question 2, p. 364.

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Safety

• Avoid getting the acetic acid and bromine
  solution on skin.
• Be gentle when stirring in a test tube as it is
  easy to punch a stirring rod through the bottom
  of the test tube.
• Filtrate (liquid waste) contains halogenated
  material and must be placed into the halogenated
  waste container.