Alcohol, phenol & ether MCQs for NEET — Chemistry Questions with Answers

(b) CH₃CH=CH₂ $\stackrel{{\mathrm{B}}_2{\mathrm{H}}_6}{\to }$(CH₃CH₂CH₂)₃B 

                        $\stackrel{{\mathrm{H}}_2{\mathrm{O}}_2}{\to }$CH₃CH₂CH₂OH + H₃BO₃;

The process is called hydroboration.

(c) ${\mathrm{CH}}_2={\mathrm{CH}}_2 + \mathrm{HBr} \stackrel{ }{\to } {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Br} \stackrel{\mathrm{HOH}}{\to } {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH} \underset{+ {\mathrm{I}}_2 \left(\mathrm{excess}\right)}{\overset{{\mathrm{Na}}_2{\mathrm{CO}}_3}{\to }} \mathrm{Iodoform}$

The given reaction sequence involves: 1) Conversion of phenol to benzene using Zn dust (reduction). 2) Friedel-Crafts acylation of benzene with acetyl chloride (CH3COCl) using anhydrous AlCl3 catalyst to give acetophenone. 3) Oxidation of acetophenone with alkaline KMnO4 to give benzoic acid (Z).

The NCERT text specifies that phenol is commercially produced synthetically, and lists methods like from haloarenes, benzenesulphonic acid, diazonium salts, and cumene. Production from Grignard reagents is used for alcohols, not typically for industrial phenol synthesis.

The NCERT text states, 'Most of the worldwide production of phenol is from cumene.' Cumene is isopropylbenzene, which is oxidized to cumene hydroperoxide and then converted to phenol and acetone.

The NCERT text mentions, 'It is converted to phenol and acetone by treating it with dilute acid. Acetone, a by-product of this reaction, is also obtained in large quantities by this method.'

The NCERT text states: 'Diazonium salts are hydrolysed to phenols by warming with water or by treating with dilute acids.'

The NCERT text describes this method: 'Chlorobenzene is fused with NaOH at 623K and 320 atmospheric pressure. Phenol is obtained by acidification of sodium phenoxide so produced'.

The NCERT text says: 'Benzene is sulphonated with oleum and benzene sulphonic acid so formed is converted to sodium phenoxide on heating with molten sodium hydroxide. Acidification of the sodium salt gives phenol.'