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How is phenol isolated from coal tar?

Answer»

SOLUTION :Middle oil `(170-230^(@)C)` contains mainly phenols napthalene and traces of pyridine. Its cooled Napthalene crystallises. It is removed by filtration. Crude phenol is washed with dilure `H_(2)SO_(4)` then treated with sodium hydroxide solution. Sodium phenate formed in aqueous solution is separated, acidified to get phenol.
`C_(6)H_(5)OH+NaOHtoC_(6)H_(5)ONa+H_(2)O`
`C_(6)H_(5)ONa+HCl toC_(6)H_(5)OH+NaCl`
(For acidification `CO_(2)` or `H_(2)SO_(4)` can be USED)


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