Question

Give two methods of preparation of acetylene. How does it react with water and Ozone?

Answer 1

Answer:

Two general methods of preparation of acetylene are from calcium carbide and from vicinal dihalides.

Explanation:

Acetylene is the simplest alkyne . It can be prepared using various methods.

1.From calcium carbide: acetylene can be prepared from calcium carbide in a reaction with water.

CaC₂+2H₂O→Ca(OH)₂+C₂H₂

2.from vicinal dihalides: Vicinal dihalides on reaction with alcoholic potassium hydroxide undergoes dehydrohalogenation. One molecule of hydrogen is eliminated and form alkenyl halide which on treating with sodalime gives alkyne.

Acetylene in reaction with water in presence of dilute sulfuric acid and mercuric sulfate forms unstable product which on rearrangement gives acetaldehyde.

Acetylene in reaction with ozone: acetylene undergoes ozonolysis ang gives Acetylene ozonide. Which in presence of Zn undergoes hydrolysis to give glyoxal.

Answer 2

Ozonolysis of acetylene takes place with the help of ozone. It forms acetylene ozonide

Explanation:

Methods of preparation of acetylene:-

1) Acetylene is prepared on large scale by the reaction of calcium carbide and water

$CaO + 3C --- CaC2 + CO$

$CaC2 + H2O ---- Ca(OH)2 + C2H2$

Industrial Preparation:-

2) On a large scale, Acetylene is prepared by the pyrolysis of methane at a very high temperature.

$2CH4 ------- C2H2 + H2$

Acetylene when react with water and Ozone:-

Ozonolysis of acetylene takes place with the help of ozone. It forms acetylene ozonide.