Category : JEE Main & Advanced
(1) Source of Arenes
Source of arenes is coal. It contains benzene, xylene, naphthalene etc. Arenes are obtained by destructive distillation of coal.
(2) Distillation of coal
(3) Distillation of coal tar : Arenes are isolated by fractional distillation of coal tar,
Name of the fraction | Temperature range (K) | Main constituents |
Light oil (or crude oil) fraction | Upto 443 | Benzene, toluene, xylene |
Middle oil fraction (Carbolic oil) | 443-503 | Phenol, naphthalene, pyridine |
Heavy oil fraction (Creosote oil) | 503-543 | Naphthalene, naphthol and cresol |
Green oil (Anthracene oil) | 543-633 | Anthracene, phenanthrene |
Pitch (left as residue) | Non-volatile | Carbon |
(4) Isolation of benzene
\[\text{Light}\,\text{oil}\xrightarrow{\text{cold }{{H}_{2}}S{{O}_{4}}}\begin{matrix}\underset{\text{ }\!\![\!\!\text{ Like pyridene }\!\!]\!\!\text{ }}{\mathop{\text{Basic impurities removed }}}\, \\\end{matrix}\xrightarrow{NaOH}\]
\[\underset{\text{ }\!\![\!\!\text{ Acidic impurities }\!\!]\!\!\text{ }}{\mathop{\begin{matrix} \text{Phenols removed} \\ \end{matrix}}}\,\xrightarrow{\text{distillation}}\begin{matrix} \underset{\text{Toluene (383 }K\text{)}\,\,\,\,\,\,\,\,\,\,}{\mathop{\text{Benzene (255-257}K\text{)}}}\,\text{ } \\ \end{matrix}\]
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