Benzene and Alkyl Benzene - Result Question 52
52. Answer the following with suitable equation wherever applicable
essential
(i) How can you prepare benzene from benzene?
(ii) How will you convert toluene to $m$-nitrobenzoic acid?
(1987, 2M)
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Solution:
(i) Lime is heated with coke at high temperature to form calcium carbide, which is then hydrolysed to form acetylene. This acetylene on passing red hot tube polymerises to form benzene :
$ \underset{\text { Lime }}{\mathrm{CaO}}+\underset{\text { Coke }}{3 \mathrm{C}} \xrightarrow{2000^{\circ} \mathrm{C}} \mathrm{CaC}_2+\mathrm{CO} \uparrow $
$ \begin{alignedat} & \mathrm{CaC}_2+2 \mathrm{H}_2 \mathrm{O} \longrightarrow \mathrm{Ca}(\mathrm{OH})_2+\underset{\text { Acetylene }}{\mathrm{C}_2 \mathrm{H}_2} \\ & 3 \mathrm{C}_2 \mathrm{H}_2 \xrightarrow[\Delta]{\mathrm{Cu}} \underset{\substack{\mathrm{C}_6 \mathrm{H}_6 \}}{} \text { Benzene }}}{\mathrm{Cl}} \\ \end{aligned} $
(ii) $-\mathrm{CH}_3$ in toluene is ortho/para directing group, first oxidised to $-COOH$ in order to make it meta directing and then nitrated.
BETA
