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methods of preparations of alkanes
General Methods of Preparation of Alkanes:

(i)   Decarboxylation:
 Decarboxylation means removal of CO2 from molecules having - COOH gp.
   The decarboxylation of sodium formate yields
 methane.

(ii) Wurtz reaction:
  A solution of alkyl halide in ether on heating with sodium gives alkane.
 

(iii)   By the reduction of alkyl halides:
  Alkyl halides on reduction with nascent hydrogen form alkanes.

(iv)    By hydrogenation of alkenes : Sabatier and senderen's method :
 Alkenes and alkynes on catatlytic hydrogenation give alkanes.
           
(v)  Kolbe's electrolysis method:
            Alkanes are formed, on electrolysis of concentrated aqueous solution of sodium or potassium salt of saturated mono carboxylic acids

(vi)  By Grignard reagents:
         Grignard reagent on double decomposition with water or with other compounds having active H (the hydrogen attached on O, N, F or triple bonded carbon atom are known as active hydrogen) give alkane.

(vii)  By reduction of alcohols, aldehydes, ketones or fatty acids and their derivatives:
          The reduction of either of the above in presence of red P & HI gives corresponding alkane.

(viii)  By Reduction of Carbonyl compounds
            The reduction of carbonyl compounds by amalgamated zinc and conc. HCI also yields alkanes. This is Clemmensen reduction.


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