Notes on lesson on Haloalkanes and Haloarenes |

Haloalkanes and Haloarenes


Physical and chemical property of Haloarenes

Haloarenes are colourless liquid or crystalline solids.Haloarenes are the non-polar compound which cannot form the hydrogen bond with water molecules. As a result, there are insoluble in water but soluble in organic solvents.Among the isomeric haloarenes para isomer due to its symmetrical structure,fits more property in its crystal lattice than O-and M isomer. Hence, P-haloarenes have the highest Melting point.

Analysis of Haloalkanes and Haloarenes

In this test, the halo compound under test is warmed with aqueous or alcoholic KOH solution. The solution is then acidified with dill. HNO3 followed by adding of AgNO3 solution.Formation of white precipitate soluble in ammonium hydroxide shows the presence of chlorine element in the compound.

General method of preparation of Iodoethane

$$\underbrace{CH_3-CH_3}_{Ethane}+I_2\xrightarrow{HIO_3}\underbrace{CH_3-CH_2-I}_{Iodoethane}+HI$$ $$\underbrace{CH_3-CH_3-I}_{Iodoetnane}\xrightarrow{alc.NaOH}\underbrace{CH_2=CH_2}_{Ethene}+H_2O+NaI$$