# JEE Main & Advanced Chemistry Haloalkanes and Haloarenes Tetra-Halides (Carbon tetrachloride, $CC{{l}_{4}}$)

## Tetra-Halides (Carbon tetrachloride, $CC{{l}_{4}}$)

Category : JEE Main & Advanced

It is the most important tetrahalogen derivative of methane.

(1) Manufacture

(i) From methane :

$C{{H}_{4}}+4C{{l}_{2}}\xrightarrow{400{}^\circ C}CC{{l}_{4}}+4HCl$

(ii) From carbon disulphide :

$C{{S}_{2}}+3C{{l}_{2}}\xrightarrow{Fe/{{I}_{2}}/AlC{{l}_{3}}}CC{{l}_{4}}+\underset{\text{monochloride}}{\mathop{\underset{\text{Sulphur}}{\mathop{{{S}_{2}}C{{l}_{2}}}}\,}}\,$

${{S}_{2}}C{{l}_{2}}$ further reacts with $C{{S}_{2}}$ to form more of carbon tetrachloride.

$C{{S}_{2}}+2{{S}_{2}}C{{l}_{2}}\xrightarrow{{}}CC{{l}_{4}}+6S$

Carbon tetrachloride is separated out by fractional distillation. It is washed with sodium hydroxide and then distilled to get a pure sample.

(iii) From propane :

${{C}_{3}}{{H}_{8}}+9C{{l}_{2}}\underset{\text{70-100}}{\mathop{\xrightarrow{\text{400}{}^\circ C}}}\,\underset{\text{(Liquid)}}{\mathop{\underset{\text{Carbon}\,\text{tetrachloride}}{\mathop{CC{{l}_{4}}}}\,}}\,+\underset{\text{(Solid)}}{\mathop{\underset{\text{Hexachloroethane}}{\mathop{{{C}_{2}}C{{l}_{6}}}}\,}}\,+8HCl$

(2) Physical properties

(i) It is a colourless liquid having characteristic smell.

(ii) It is non-inflammable and poisonous. It has boiling point ${{77}^{o}}C$.

(iii) It is insoluble in water but soluble in organic solvents.

(iv) It is an excellent solvent for oils, fats, waxes and greases.

(3) Chemical properties : Carbon tetrachloride is less reactive and inert to most organic reagents. However, the following reactions are observed.

(i) Reaction with steam (Oxidation) :

$CC{{l}_{4}}+{{H}_{2}}O\xrightarrow{500{}^\circ C}\underset{\text{Phosgene (Carbonyl chloride)}}{\mathop{COC{{l}_{2}}}}\,+2HCl$

(ii) Reduction :

$CC{{l}_{4}}+2H\xrightarrow{Fe/{{H}_{2}}O}CHC{{l}_{3}}+HCl$

(iii) Hydrolysis :

$CC{{l}_{4}}+4KOH\xrightarrow{-4KCl}\underset{\text{Unstable}}{\mathop{[C{{(OH)}_{4}}]}}\,$$\xrightarrow{-2{{H}_{2}}O}C{{O}_{2}}\xrightarrow{2KOH}{{K}_{2}}C{{O}_{3}}+{{H}_{2}}O$

(iv) Reaction with phenol (Reimer-tiemann reaction) :

(4) Uses

(i) It is used as a fire extinguisher under the name pyrene. The dense vapours form a protective layer on the burning objects and prevent the oxygen or air to come in contact with the burning objects.

(ii) It is used as a solvent for fats, oils, waxes and greases, resins, iodine etc.

(iii) It finds use in medicine as helmenthicide for elimination of hook worms.

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