Accomplish the following conversions: (i) Nitrobenzene to benzoic acid (ii) Benzene to m-bromophenol (iii) Benzoic acid to aniline (iv) Aniline to 2,4,6-tribromofluorobenzene (v) Benzyl chloride to 2-phenylethanamine (vi) Chlorobenzene to p-chloroaniline (vii) Aniline to p-bromoaniline (viii) Benzamide to toluene (ix) Aniline to benzyl alcohol.
Nitrobenzene is reduced to aniline using Sn/HCl. Aniline undergoes diazotisation with NaNO₂/HCl at 273-278K to form benzene diazonium chloride. The diazonium salt is hydrolyzed with warm water to give phenol. Phenol is oxidized to benzoic acid using KMnO₄.
Benzene is nitrated with HNO₃/H₂SO₄ to form nitrobenzene. Nitrobenzene is brominated with Br₂/FeBr₃ (bromine goes meta to -NO₂). The nitro group is reduced to amino group using Sn/HCl. The amino group is converted to -OH through diazotisation (NaNO₂/HCl) followed by hydrolysis to give m-bromophenol.
Benzoic acid is converted to benzamide by reaction with NH₃. Benzamide undergoes Hoffmann bromamide reaction with Br₂ + 4NaOH to give aniline.
Aniline is brominated with Br₂/water to form 2,4,6-tribromoaniline. The amino group undergoes diazotisation with NaNO₂/HCl to form diazonium salt. The diazonium salt is treated with HBF₄ and heated to give 2,4,6-tribromofluorobenzene.
Benzyl chloride is treated with ethanolic NaCN to form benzyl cyanide (phenylethanenitrile). Benzyl cyanide is reduced with H₂/Ni to form 2-phenylethanamine.
Chlorobenzene is nitrated with HNO₃/H₂SO₄ to form p-chloronitrobenzene (nitro group goes para to Cl). p-chloronitrobenzene is reduced with Sn/HCl to form p-chloroaniline.
Aniline is acetylated with CH₃COCl to form acetanilide. Acetanilide is brominated with Br₂/FeBr₃ (bromine goes para to -NHCOCH₃). The acetyl group is removed by hydrolysis to form p-bromoaniline.
Benzamide undergoes Hoffmann bromamide reaction with Br₂ + 4NaOH to give aniline. Aniline is converted to benzene through diazotisation (NaNO₂/HCl) followed by treatment with H₃PO₂. Benzene is converted to toluene using Friedel-Crafts alkylation (CH₃Cl/AlCl₃).
Aniline is converted to benzene through diazotisation (NaNO₂/HCl) followed by treatment with H₃PO₂. Benzene is converted to toluene using Friedel-Crafts alkylation (CH₃Cl/AlCl₃). Toluene is oxidized to benzyl alcohol using controlled oxidation.
Explanation
These conversions utilize key reactions from the chapter including Hoffmann bromamide reaction (converts amides to amines), diazotisation (converts aromatic amines to various substituted products), acetylation (protects amino group during electrophilic substitution), and reduction of nitro compounds. Example 9.2 directly shows conversion (v) using ethanolic NaCN followed by reduction. The Hoffmann bromamide reaction is particularly useful for conversions (iii) and (viii). Diazotisation is essential for conversions involving removal or replacement of amino groups.