Reduction of carbonyl compounds. Introduction -Reduction is defined in chemistry as loss of oxygen,...
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Transcript of Reduction of carbonyl compounds. Introduction -Reduction is defined in chemistry as loss of oxygen,...
![Page 1: Reduction of carbonyl compounds. Introduction -Reduction is defined in chemistry as loss of oxygen, gain of hydrogen or gain of electrons -Carbonyl group.](https://reader030.fdocuments.net/reader030/viewer/2022032612/56649f045503460f94c1902b/html5/thumbnails/1.jpg)
Reduction of carbonyl Reduction of carbonyl compoundscompounds
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IntroductionIntroduction
-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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IntroductionIntroduction
The difference between the electronegativities of carbon and oxygen is large enough to make the C=O bond moderately polar.
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Carbonyl compoundsCarbonyl compoundsCompoun
daldehydeketoneCarboxyli
c acidEster
Structure
General formula
RCHORCOR'RCOOHRCOOR'
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1\ 1\ Reduction of aldehydes and Reduction of aldehydes and ketonesketones
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e.g.1:
e.g.2:
CH3-CH + H2 CH3CH2OHPt
O
CH3-C-CH3 + H2 CH3-CH-CH3Pt
O OH
1\ 1\ Reduction of aldehydes and Reduction of aldehydes and ketonesketones
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22 \ \Reduction of carboxylic Reduction of carboxylic acidsacids
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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Examples:
22 \ \Reduction of carboxylic Reduction of carboxylic acidsacids
(1° alcohol)
(1° alcohol)
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33 \ \Reduction of estersReduction 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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Example:
33 \ \Reduction of estersReduction of esters
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Reduction of Reduction of benzaldehydebenzaldehyde
CHO
+ KOH
CH2OH
H+
COOK
H
COOH
2
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Reduction of Reduction of benzaldehydebenzaldehydeProcedure:
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 Reduction of benzaldehydebenzaldehyde
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 Reduction of benzaldehydebenzaldehyde
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 Reduction of benzaldehydebenzaldehyde
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