Preparation of Alkane

1) Hydrogenation of Alkenes

 Addition of hydrogen to a multiple bond is called hydrogenation. Alkenes can be prepared by the catalytic hydrogenation of alkenes. When a solution of an alkene in ethanol , methnol , or acetic acid is shajen under slightly pressure of hydrogen gas in the presence of a small quantity of finely divided nickle platinum, or palldium, at room temperature , alkenes are converted into alkanes 

 Equation

 

 

 Exothermic reaction

 Although reaction is highly exothermic .

 Catalyst 

 Ni(or Pt or Pd)

 Activation energy 

Activition energy of this reaction is 435kJ/mol.

 Industrial scale

 Production of vegetable ghee by the catalytic hydrogenation of vegetable oil . 

2) Hydrolysis of Grignarc reagent 

A grignard reagent  (alkyl megnesium halides RMgX)
 which is formed when a solution of an alkyl halide in dry ether is allowed to stand over megnesium turning , is a highly reactive species abd reacts readily with water to form an alkanes . 

 Equation

                       RMgX+Mg---------RMgX--------R----H+HOMgX