Hydrocarbon Derivatives
Aldehydes and Ketones (“the Carbonyl Functional Group”)
C/ Aldehydes
General Formula : R—COH or
Naming Aldeyhydes: use the suffix “-al” at the end of the hydrocarbon parent chain name. Since the
functional group always occurs at one of the molecule’s ends, a number is not usually needed for it (still
will require numbers to identify alkyl groups).
Examples :
D/ Ketones
O
General Formula : R—C—R
Naming Ketones: use the suffix “-one” at the end of the hydrocarbon parent chain name. In addition,
since the functional group occurs within the hydrocarbon chain(s), a number will be required to denote
the location of the functional group.
Examples :
Properties of Aldehydes and Ketones
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Due to the polarity of the carbonyl group, (polar bonds but especially the lone pairs on the oxygen
atom) aldehydes and ketones have higher m.p. and b.p. than ethers of similar hydrocarbon chain
length;
The m.p. and b.p. of aldehydes and ketones are lower than similar length alcohol molecules.
There is more hydrogen bonding occurring between alcohol molecules than with aldehydes and
ketones;
Shorter-chain aldehydes and ketones are more soluble in water than longer-chain molecules;
The relatively greater strength of the carbon-oxygen double bond (stronger than a carbon-carbon
double bond) makes aldehydes and ketones less reactive than alkenes of similar size.
Reactions Involving Aldehydes and Ketones
1)
10 alcohol  aldehyde (controlled oxidation) Common Oxidizing Agent : MnO4 –(aq) or H2O2(aq),
but usually shown in the reaction as (O*)
2)
20 alcohol  ketone (controlled oxidation)
3)
Aldehyde  10 alcohol and Ketone  20 alcohol - through a Hydrogenation Reaction (add
H2(g)). Special condition – Platinum metal (Pt)