Page 16 - 10-Chem-12 Hydrocarbon
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12. Hydrocarbon eLearn.Punjab
This reaction is used to identify the unsaturation of alkynes.
12.3.2.2 Oxidation with KMnO4 .
Ethyne is oxidized by alkaline KMnO4. And four hydroxyl groups add to the triple bond,
such as:
This intermediate product eliminates water molecules to form
glyoxal, which is further oxidized to form oxalic acid.
Uses of Acetylene
(i) Acetylene produces oxy-acetylene flame with oxygen. It is a highly exothermic
reaction. Heat released is used for welding purposes.
(ii) Acetylene is used to prepare other chemicals, such as alcohols, acetaldehyde and
acids.
(iii) It is used for the ripening of fruits.
(iv) It is used for the manufacturing of polymer products like polyvinyl chloride, polyvinyl
acetate and synthetic rubber like neoprene.
(v) It is polymerized to form benzene, which is used as raw material to form a variety
of organic compounds.
Test i. Why the alkynes are called acetylenes?
yourself 12.4 ii. How is tetrabromoethane prepared from acetylene?
iii. How can you prepare acetylene from tetrachloroethane?
iv. What is the difference between glycol and glyoxal?
v. Write the formula of oxalic acid.
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