Hydrocarbons(Ethyne For Grade 10 students)

 Properties of Alkynes

Physical Properties

Like alkenes, alkynes are unsaturated hydrocarbons. The first three members of this class are gases, next eight members are liquids and higher numbers are solids. Alkynes are non polar and dissolve readily in organic solvents. Alkynes are reactive compounds due presence of pi bonds and undergo addition reactions.

Chemical Properties

1. Addition of Halogens

Alkynes add two molecules of halogens.

Self Assessment

 Solution 

Reaction with KMnO4

Alkynes do not react with very dilute alkaline aqueous solution of KMnO4. However, they are oxidized by strong alkaline solution of KMnO4 to produce oxalic acid. First four hydroxyl groups are added across the triple bond.

Uses of Ethyne

Ethyne is used

a. in oxy-acetylene torch for welding and cutting metals.

b. for ripening of fruits

c. for the manufacture of polyvinyl acetate(PVA), polyvinyl chloride (PVC), polyvinyl ethers and rubber.

Self Assessment 

Complete the following reaction

Solution