JEE Main & Advanced Chemistry Haloalkanes and Haloarenes / हैलोएल्केन तथा हैलोएरीन्स Tetra-Halides (Carbon tetrachloride, \[CC{{l}_{4}}\])

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.