Reduction of carbonyl compounds

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Reduction of carbonyl compounds
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Introduction

• -Reduction is defined in chemistry as loss of
  oxygen, gain of hydrogen or gain of electrons
• -Carbonyl group is consisting of a carbon (C) and
  an oxygen (O) atom connected by a double bond.

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Introduction

• The difference between the electronegativities of
  carbon and oxygen is large enough to make the CO
  bond moderately polar.

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Carbonyl compounds
Ester Carboxylic acid ketone aldehyde Compound
Structure
RCOOR' RCOOH RCOR' RCHO General formula
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1\ Reduction of aldehydes and ketones
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1\ Reduction of aldehydes and ketones

• e.g.1
• e.g.2

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2\ Reduction of carboxylic acids

• Most reductions of carboxylic acids lead to the
  formation of primary alcohols.
• These reductions are normally carried out using a
  strong reducing agent, such as lithium aluminum
  hydride (LiAlH4).

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2\ Reduction of carboxylic acids

• Examples

(1 alcohol)
(1 alcohol)
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3\ Reduction of esters

• A pair of alcohols ( with at least one being 1ry
  ) results from the reduction of an ester.
• They can be reduced by LiAlH4, NaBH4

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3\ Reduction of esters

• Example

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Reduction of benzaldehyde
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Reduction of benzaldehyde

• Procedure
• 1- dissolve 13.5g of KOH in 13ml of H2O then add
  it in ice bath.
• 2-add the solution in glass bottle and add 15ml
  of benzaldehyde, close the bottle and shake will,
  then leave it for 24h.
• 3-after 24h, add 50ml of H2O and shake until the
  solution dissolve.

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Reduction of benzaldehyde

• 4- transfer the solution to separating funnel,
  wash the remain with 15ml of ether and add it to
  the solution.
• 5-shake the solution in the separating funnle to
  separate benzyl alcohol, collect the ether layer,
  and repeat the process twice more (each with 12ml
  ether).
• (keep the aqueous layer)

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Reduction of benzaldehyde

• 6-pass the collected solution (ether layer) in to
  ordinary funnel lined with filter paper and
  saturated sodium sulphate powder.
• 7- add 5ml of 10 sodium carbonate and separate
  it , then wash it with 5ml H2O.
• 8-leave to dry, then collect the powder and
  calculate the of benzyl alcohol.

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Reduction of benzaldehyde

• 9- to the aqueous layer add 40ml conc HCl , 40ml
  of H2O and 50g of ice.
• 10-filter the benzoic acid by vacum filtration.
• 11-wight the powder and calculate the of
  benzoic acid.

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• Thank you