What are haloarenes? Write their two main substitution reactions. Write formula and uses of Freon.

Haloarenes are the hydrocarbons in which one or more hydrogen atoms have been replaced with halogen atoms. The haloarenes are derived from aromatic hydrocarbons. Halogenation: In the above Reaction Of Haloarenes when a haloarene comes in the vicinity of chlorine in the presence of ferric chloride as solvent, then the chlorine molecule develops a polarity within itself and the chlorine with a slightly positive charge acts as electrophile (electron seeking) and attacks the electron rich ortho and para position of haloarene. Both ortho and para compounds are formed out of which para isomer is the major product and ortho isomer is the minor product. Nitration: In this reaction, first NO 2 is formed from nitric acid which is initiated by the presence of sulphuric acid; NO 2 has an electrophilic centre over nitrogen due to the presence of two electronegative oxygen atoms in the molecule. The NO 2 attacks the electron rich ortho and para positions, out of which we get para isomer as the main product and ortho isomer as the minor product. Freons, CFCl 3 are chlorofluorocarbon compounds that contains only carbon, chlorine, and fluorine, produced as a volatile derivative of methane, ethane and propane. Freons are also used as: Aerosol propellants. Foam-blowing agents. Solvents. Glass chillers. Polymer intermediates.

Complete the following reaction: CH 3 - CH 2 - CHBr 2 → KOH aq A → ∆ B .

Elimination reaction will take place since potassium hydroxide is a strong base so, it will eliminate bromine from the 1,2 dibromopropane. Therefore, propan-1,2-diol (A) is formed. On further heating, the gem-diol is highly unstable which produces propanal, having an aldehyde. i.e., compound B is propanal. The reaction will be, CH 3 - CH 2 - CHBr 2 → KOH aq CH 3 - CH 2 - CH OH 2 → ∆ CH 3 - CH 2 - CHO .

Write the uses of freon. What is its impact on environment?

Freons are used as: Aerosol propellants. Foam-blowing agents. Solvents. Glass chillers. Polymer intermediates. Freon has been described as one of the most significant environmental pollutants. As it moves throughout the air, its chemical ingredients cause a depletion of the ozone layer. Depletion increases the ultraviolet radiation that reaches the Earth's surface, resulting in serious risks to human health.

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