Aldehydes and Ketones

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• Aldehydes and Ketones

- Both aldehydes and ketones contain carbonyl
group CO.
- The difference between aldehyde and ketone was
found to be

• In aldehyde CO attach with H and R i.e

• In ketone CO attach with two R

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General formulae of aldehyde and ketones
Nomenclature of Aldehydes and Ketones

• I) IUPAC
• A) Aldehyde
• 1- ??? ??? ??? alkane ???????? ??? e ??
  alkane ????? al

e.g. Methane Methanal
Ethane Ethanal
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• 2 - ??? ?????? CHO ???? ????? ?? ???
  ??????? ??? ???? ?????
• 3- ?? ???? ???? ???? ??? ????? ??????? ??????
  ?????? ???????? ?????? 1
• Examples

4- ? ???? ?????? ??????? ???
??? ??? ??? alkene???????? ??? e ?? alkene
????? al
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5- ?? ???? ?????? ??????? ???
??? ??? ??? alkyne ???????? ??? e ?? alkyne
????? al
Examples

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• 2) Common name
• ??? ???? ??? ????? ?????? ??? ???? oic ?
  ???????? ? aldehyde
• Examples

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• B) Iupac nomenclature of ketones
• ??? ??? ??? alkane ???????? ??? e ?? alkane ?????
  one

Example Propane Propanone
2 - ??? ????? ?????? ?? ????? ???? ???? ? CO
??? ?????
Common system of ketones -???? ????? alkyl ???
CO ?? ???? ???? ketone ?? ???????.
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• ??? ??????? ???? ??? ?????

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• Preparation of aldehydes ketones
• From acid chloride

• This method is called Rosemund reduction.
• ?????? ????? Pd-BaSO4 catalyst ??? ???? ????????
  ??? ????? ald. ??? ????? ald. ??? ????.

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(2) From geminal dihalide ?? ???? ??????? ???
??? ??? ???????
Question convert toluene to benzaldehyde Answer
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(3) Partial decarboxylation of salt of acids
Question Show how could you prepare the
following
by above method, we use two molecules

• To prepare

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Question Show how could you prepare the following

• ??????? ??????? ?????? ?????? ??????? ??? ??????
  ?? ????? ??????

Example conversion of
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(4) From nitrile a- Aldehyde
b- Ketone
Methods have been studied
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(5) Oxidation of alcohols a- Aldehyde From
oxidation of primary alcohol.
b- Ketone From oxidation of secondary alcohol.
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(6) Ozonolysis of alkene
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(7) Hydration of alkyne
Only other alkyne except acetylene will give
ketone
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Synthesis of aromatic ketones via Friedel-Crafts
acylation E.g. Acetophenone
For benzophenone
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• Synthesis of benzaldehyde
• Gattermann-Koch aldehyde synthesis

b) Gattermann aldehyde synthesis
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Chemical reactions of aldehydes Ketones A-Type
I of reaction (Addition reaction)

• ????? ??? ????????? ??? ????? H ???? O ?????
  ?????? ? C
• Examples of this addition is addition of HCN, H2,
  RMgX, HOH, NaSO3H

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• Some observations
• ???? ???? ????? HCN ???? ??? aldehyde ??
  ketone ??????? ?? cyanohydrin.
• ???? ??? ????????? ????? HCN ??????

• ???? ???? ????? NaSO3H ???? ??? aldehyde ??
  ketone ??????? ?? bisulphite.
• ????? NaSO3H ??? ??? ??? Aldehydes ?? methyl
  Ketones ( )

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E.g. these ketones does not add NaSO3H

• ???? ????? H2O ??? ???? ? ???? H2O ????? ?????
  Aldehyde ?????? ? ??? ???? ??? ??? ????? H2O
  ????? ???

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• Special cases of addition reactions
• Benzoin condensation

b) Formation of hemiacetals and acetals
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• B-Type II of reaction addition reaction followed
  by loss of H2O
• e.g. (Condensation with amines)
• ?? Ald. Or Ketones ?????? ??amines ????????
  ??????? ?????? ???? H2O

Examples
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C-Type III of reaction (Base catalyzed
reaction) 1- Aldol condensation - It occurs
between two aldehydes or two ketones containing
a-Hydrogen..
Mechanism
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- Other example
Mechanism
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• In case of mixture of acetaldehyde and acetone ,
  we obtain four products

Mechanism of formation of crotanaldehyde
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Mechanism of formation of Mestyl oxide
Mechanism of formation of 3-methyl-2-butenal
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Mechanism of formation of 3-penten-2-one
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• 2- Cannizaro reaction
• - It occurs between two aldehydes with no
  a-hydrogen in presence of base to
  give an alc. and an acid.

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Question Show the effect of NaOH on acetaldehyde
and benzaldehyde
3- Clasien condensation
4- Perkin condensation
D-Type IV of reaction (Different types of
reaction)
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Oxidation of aldehyde ketones

• Aldehydes can also oxidized by Tollens reagent
  Ag(NH3)2OH.

• Ketones are difficult for oxidation

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• Haloform reaction
• It occurs with aldehyde or ketones containing

• The only aldehyde gives Iodoform reaction is
  acetaldehyde

) only can give iodoform only for example

• Methyl ketones (

• These ketones cannot give iodoform because they
  do not have

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Examples of iodoform equation
Mechanism
?????? ????? ????? ?????????? ????? ?? ald. ??
ketone ??? ??? ?? ??? ??? ????? ?????.
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Reduction of aldehydes Ketones 1- Reduction
by catalytic hydrogen It converts aldehyde or
ketone to alcohol.
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• 2- Reduction to hydrocarbon
• ?? ????? ald. ?? ketone ??? alkane.

For examples
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a- Clemmensen reduction
b- Walf-Kishner reduction
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3- Reduction with sod. Borohydride (NaBH4)
4- Reduction with Mg
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• Replacement of oxygen by halogen
• PCl3, PCl5 or SOCl2 convert CO into

Example

• PCl3, PCl5 or SOCl2 convert OH to -Cl

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The reaction of aldehyde or ketones with PCl3,
PCl5 or SOCl2, can be used to convert aldehyde or
ketones alkyne as follow e.g. conversion of
acetone to propyne
Halogenation of a-carbon
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• In case of aromatic aldehyde or ketones.
• In absence of Fe or FeCl3 catalyst
• In this case the reaction occur at a-carbon to
  CO or in H of CHO

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b) In absence of Fe or FeCl3 catalyst
Aldehydes and ketones are m- directing group, so
orient halogen in m- position
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• Polymerization reaction
• Only aldehydes can polymerize
• Examples
• a) Polymerization of formaldehyde in presence
  of water

B )Polymerization of formaldehyde and acetaldehyd
of presence of H2SO4
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