CARBOXYLIC
ACIDS
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Carboxylic acids are compounds which contain a
Carbonyl group (
) attached to a hydroxyl group
(OH).i.e.
Carboxylic acid -COOH group
Or
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When naming carboxylic acids the first step is to select
the longest chain containing maximum number of carbon
atoms.
If you have something substituted into the hydrocarbon
chain, the carbon in the –CO-OH group counts as the
number 1 carbon.
In each case, the name is derived by replacing the “e“ of
alkanes by “anoic acid”. e.g.
Methane becomes methanoic acid.
Ethane becomes ethanoic acid.
Propane becomes propanoic acid.
Write the names of the following according to IUPAC system
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By Oxidation of alkenes:
Alkenes are oxidized to acids by heating them with solutions of
potassium permanganate (KMnO 4) or potassium dichromate
(K 2Cr 2O 7).
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Hydrolysis of nitriles:
The hydrolysis of nitriles, which are organic molecules containing a
cyano group, leads to carboxylic acid formation.
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The boiling points of carboxylic acids are higher than
alcohols and alkanes of similar size.
In a pure carboxylic acid, hydrogen bonding can occur
between two molecules of acid to produce a dimer.
The carboxylic acids with up to four carbon atoms will
mix with water in any proportion. The solubility of the
bigger acids decreases very rapidly with increase in the
molecular size.
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With carbonates:
When a carboxylic acid reacts with carbonates, a salt is
formed together with carbon dioxide and water.
With ammonia:
If a solution of ethanoic acid and a solution of
ammonia are mixed together, it will produce a
colourless solution of ammonium ethanoate.
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Acetic acid (a carboxylic acid) is used as vinegar and
as coagulant in the manufacture of rubber.
Some carboxylic acids such as sodium salts of some
organic acids are used as preservatives.
Carboxylic acids are used for the preparation of many
drugs such as aspirin, phenacetin etc.