Carboxylic Acids Presentation Unit A2 1 - Periodic Trends and Further Organic, Physical and Inorganic Chemistry

Carboxylic acids can form hydrogen bonds with water molecules. Two carboxylic acid molecules can also form hydrogen bonds to each
This gives them high solubility in water, since the polar OH H other to form a dimer, giving carboxylic acids high melting points.
group forms hydrogen bonds with water molecules.
S Carboxylic acids
j
O H O
--
O3 H O are weak acids,
they only
partially ionise
H in water.


O H---O
S
O H- O
..




H -
-




Carboxylic acids with phosphorus pentachloride, PCl5 Carboxylic acids and ammonia, NH3

CH3COOH + PCl5 CH3COCl + POCl3 + HCl Carboxylic Acids CH COOH
3
+ NH
3
NH COONH
3 4
Ethanoic Ethanoyl
acid chloride O Ethanoic Ammonium
acid ethanoate
During this reaction there are misty fumes of HCl
(gas) and the reaction is vigorous with heat Reaction releases heat, all observations are colourless.
produced.
OH
To test for HCl, use a glass rod dipped in conc. Carboxyl group
ammonia held in the gas, if HCl, white smoke -anoic acid or -enoic acid if an alkene
appears. group is present



O O O O


+ NaOH + H2O + Na2CO3 + H2O + CO2


OH O Na OH O Na
Sodium Sodium Water Carbon
Ethanoic acid Sodium hydroxide Sodium propanoate (salt) Water Ethanoic acid carbonate ethanoate dioxide