Question

An organic compound A is widely used as a preservative in Pickles and has molecular formula C2H4O2. This compound reacts with ethanol to form a sweet smelling compound B
(I) Identify the compound A
(2)Write the chemical equation for it's reaction with ethanol to form compound B
(3)How can you get back compound A from compound B
(4)Name the process and the chemical equation for the conversion of B to A

Answer 1

The compound ‘X‘ with molecular formula C2H4O2 is ethanoic acid also called acetic acid.

The compound ‘Y‘ =Ethyl ethanoate ( CH3COO C2H5 )

(ii) Compound X reacts with ethanol to form compound ‗Y‘ which is an ester and has pleasant smell. The reaction is called esterification reaction .

CH3COOH + C2H5OH --------- CH3COO C2H5 + H2O acid

(iii) The compound ‗X‘ can be obtained from ethyl ethanoate by reacting with water in presence of dilute hydrochloric acid acting as catalyst.

CH3COO C2H5 + H2O ----- dil.Hcl-------CH3COOH + C2H5OH

(iv) This process is known is ester hydrolysis (v) Carbon dioxide gas is evolved with effervescence when the compound A reacts with washing soda which is chemically Na2CO3.
2CH3COOH + Na2CO3 -----------------2 CH3COONa + H2O + CO2 The gas can be identified by passing through lime water which turns milky.