(v) Elimination Reaction (Mechanism expressed in end of this chapter)
(a) Decarboxylation by soda lime [ NaOH + CaO] [Only applicable on acids & their derivatives ] removal

of CO2

gas means COOH is replaced by -H. Here CaO is porous responsible to absorb CO₂gas.

Methods to prepare higher to lower alkanes and vice versa

NaOH + CaO has no selective decarboxylation. So all the –COOH are removed in molecule.

(b) Dehydroyhalogenation -
H X is removed using alcoholic KOH or strong bases as reagent.

In this case CH₃CH = CHCH₃
is the major product. According to Saytzeff's rule more the alkyl groups are attached to the doubly bonded carbon atoms, more is the stability of alkene. The hydrogen is taken out from the neighbouring carbon atom or the

, by strong bases like alkoxides of metal.

(c) Dehalogenation
removal of halogen (- X₂) by Zn dust.