Oxidation and Reduction

1
Oxidation and Reduction

• Recall oxidation-reduction reactions from Chem
  30A. In Chem 30A this was presented with the
  basic Leo says Ger. In organic chemistry,
  oxidation of carbon is said to occur when a
  carbon bonded to a less electronegative atom
  reacts to form a bond to an atom that is more
  electronegative than carbon. Thus, carbon goes
  from having more electron density to having less
  electron density (oxidation). The reverse would
  be reduction.
• When the oxygen content of an organic compound
  increases and the hydrogen decreases the compound
  has been oxidized. The reverse is reduction.
• In the presence of an oxidizing agent primary and
  secondary alcohols can be oxidized to aldehydes
  or carboxylic acids, respectively.
• In the presence of an oxidizing agent aldehydes
  can be oxidized to carboxylic acids.

2
Carbohydrates

• Monosaccharides
• Simple sugars (simplest carbohydrates)
  considered as monomers of polymers known as
  polysaccharides.
• Contain 3-7 carbon atoms
• Have one aldehyde or ketone functional group
  making them aldose or ketose, respectively
• Fischer Projection is drawn with the aldehyde or
  ketone at the top (most oxidized C at the top)
• If the alcohol on the lowest chiral carbon is to
  the right it is called D, to the left it is
  called L
• This DOES NOT tell you which direction the
  compound rotates plane-polarized light. This
  just gives us a way to distinguish between
  carbohydrates that exist as enantiomers. Thus,
  it is best if you do not think of D as standing
  for dextrorotatory and L as standing for
  levorotatory.

3
Mutarotation

• Aldehydes and ketones react with alcohols to form
  hemiacetals and hemiketals, respectively. Five
  and six membered
• rings form.
• In solution, you would find the open chain and
  the two closed ring forms of a monosaccharide.

4
A Look Ahead at Ribose and Deoxyribose