Give the reactions involved in the preparation of propane from the following :
(i) CH3—CH = CH2
(ii) CH3 CH2 CH2 Cl
(iii) CH3 CH2 CH2 COO– Na+
(i) Propene can be converted to propane by hydrogenation that is addition of H2 in the presence of Ni/Pd catalyst.
CH3—CH = CH2→ CH3CH2CH3
(propene) (propane)
(ii) Alkyl halides (except fluorides) on reduction with zinc and dilute hydrochloric acid give alkanes.
CH3 CH2 CH2 Cl → CH3CH2CH3 + HCl
(propane)
(iii) Sodium salts of carboxylic acids on heating with soda lime (mixture of sodium hydroxide and calcium oxide) give alkanes containing one carbon atom less than the carboxylic acid. This process of elimination of carbon dioxide from a carboxylic acid is known as decarboxylation.
CH3 CH2 CH2 COO– Na+ + NaOH → CH3CH2CH3
(propane)