Question

Write an only two methods for preparation of actilyn

Answer 1

Methods of Preparation of Alkynes

Methods of Preparation of Alkynes

Acetylene itself is formed from the reaction of the inorganic compound calcium carbide with water. 

CaC2 + 2 H2O → Ca(OH)2 + HC≡CH

This method was once an important industrial process for the manufacture of acetylene. However, the method has now been replaced by a process in which methane is pyrolyzed in a flow system with short contact time.


This reaction is endothermic at ordinary temperatures, but is thermodynamically favored at high temperatures.

Laboratory Methods of Preparation of Alkynes:

1.   Dehydrohalogenation of vic-Dihalides or gem-Dihalides



2.   Dehalogenation of vic-Tetrahalogen Compounds



This reaction has the drawback that the halogen compound is itself prepared by halogen addition to alkynes.

3.   Alkyl Substitution in Acetylene; Acidity of  

There is a fair amount of variety possible using this method. Acetylene itself may be alkylated either once to make a terminal alkyne or twice to make an internal alkyne. 

Since acetylide ions are highly basic, competing elimination is a common side reaction.

The products of such an elimination reaction are an alkene (from the alkyl halide) and an alkyne.