ORGANIC CHEMISTRY SUMMARY
Carboxylic Acids
Characteristics
Homologous series with general formula Cn H2n+1 COOH (first series, n = 0, ascending)
They have –COOH functional group (carboxyl group)
All carboxylic acids end with suffix –oic acid
First three members of the series (so that you’d have idea on the next)
- Methanoic acid, HCOOH
- Ethanoic acid, CH 3 COOH
- Propanoic acid, C 2 H5 COOH
PREPARATION OF CARBOXYLIC ACIDS
1. From natural gas
Natural gas is passed over air and catalyst to form ethanoic acid and water.
E.g. production of ethanoic acid from methane
2CH 4 (g) + 2O 2 (g) ---> CH 3 COOH (aq) + 2H 2 O (l)
2. Oxidation
PROPERTIES OF CARBOXYLIC ACIDS
Carboxylic acids are weak acids (partially ionises in water)
Carboxylic acids react with metals to form metal ethanoate (salt) and hydrogen
E.g. Reaction between calcium and ethanoic acid forming calcium ethanoate and hydrogen
Ca )(s) + 2CH3COOH (aq) ---> Ca(CH3COO) 2 (aq) + H2 (g)
Carboxylic acids react with bases to form salt and water (neutralization)
E.g. Ethanoic acid reacts with sodium hydroxide to form sodium ethanoate and water.
CH3COOH (aq) + NaOH (aq) ---> CH3COONa (aq) + H2 O(g)
Carboxylic acids react with carbonates and bicarbonates to form salt, carbon dioxide and hydrogen.
E.g. Ethanoic acid reacts with sodium carbonate to form sodium ethanoate and water.
2CH3COOH (aq) + Na 2 CO3 (aq) ---> 2CH3 COONa (aq) + CO2 (g) + H2O (g)
ESTERIFICATION
Ester is organic compound made from carboxylic acid and alcohol with the removal of one molecule of water.
Sulfuric acid is added as catalyst then heat mixture.
The reaction is reversHYDROLYSISible.
We can add sodium hydroxide and heat mixture to obtain carboxylic acid and alcohol from ester -
LACTONES
Lactones are cyclic esters of hydroxycarboxylic acids, containing a 1-oxacycloalkan-2-one structure, or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring
b. PROTEINS
Proteins have similar linkage to that of a nylon.
Only that their monomers are only amino acids joined together.
formed by condensation polymerisation.
Proteins can be called as polyamide as it has
amide linkage .
Proteins can also be broken down into amino acids by boiling protein with sulfuric acid.
This adds water molecule into the polymer.
c. FATS
Fats have similar linkage to that of a terylene (ester linkage).
Only that their monomers consists of glycerol and fatty acids; different from terylene.
Fats can also be broken down to sodium salts of fatty acids and glycerol by boiling it with an acid or alkali. - This is HYDROLYSIS