Aldehydes and Ketones

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Naming Aldehydes

The parent chain is the longest chain that includes the aldehyde group. It's name is made by replacing the ending -e of parent alkane name with -al. The numbering of the chain always starts with the carbon of the aldehyde group being 1. For example: (parent chain will be bold for visual clarity) 
H
|
C=O
|
H
methanal
 
CH3
|
C=O
|
H
ethanal
 
CH3CH2
   |
   C=O
   |
   H
propanal
 
   CH3
   |
CH3CH
   |
   C=O
   |
   H
2-methylpropanal

Naming Ketones

In naming ketones, the parent chain includes the carbonyl group and is numbered so that the carbonyl location is the lowest number. The number of the location must be part of the name whenever there would be an uncertainty. For example: (parent chain will be bold for visual clarity) 
CH3
|
C=O
|
CH3
propanone (acetone)
 
CH3CH2
   |
   C=O
   |
   CH2CH2CH3
3-hexanone
 
   CH3
   |
CH3CH
   |
   C=O
   |
   CH2CH2CH3
2-methyl-3-hexanone

Hydrogenation of Aldehydes and Ketones

Just like the double bond in alkenes, aldehydes and ketones also add hydrogen by breaking the double bond under roughly the same conditions--metal catalyst, heat, and pressure. For example: 
CH3             CH3
|               |
C=O + H-H ==> H-C-O-H or CH3CH2OH
|               |
H               H
ethanal + hydrogen ==> ethanol

CH3             CH3         OH
|               |           |
C=O + H-H ==> H-C-O-H or CH3CHCH3
|               |
CH3             CH3
propanone + hydrogen ==> 2-propanol

Oxidation of Aldehydes

Aldehydes are the most easily oxidized of all organic compounds, though ketones resist oxidation strongly. They can also be slowly oxidized by oxygen in the air. In this example, potassium dichromate, together with hydrogen sulfate, easily oxidizes ethanal to ethanoic acid: 
3CH3CHO + K2Cr2O7 + 4H2SO4 ==> 3CH3COOH + Cr2(SO4)3 + K2SO4 + 4H2O
ethanal                        ethanoic
                                 acid
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