Question

What happens when (any three): (a) Phenyl magnesium bromide is treated with CH\(_3\)CHO followed by hydrolysis.

Hint:

Grignard reagents give alcohols, phenol undergoes electrophilic substitution, and Cu dehydrogenates alcohols to carbonyls.

Answer 1

(a) Grignard reagent reacts with aldehyde: \[ \text{C}_6\text{H}_5\text{MgBr} + \text{CH}_3\text{CHO} \xrightarrow{\text{H}_2\text{O}} \text{C}_6\text{H}_5\text{CH(OH)CH}_3 \] Product: Secondary alcohol (1-phenylethanol) (b) Phenol treated with conc. HNO\(_3\) + H\(_2\)SO\(_4\).
Solution:
\[ \text{Phenol} \xrightarrow{\text{HNO}_3/H_2SO_4} 2,4,6\text{-trinitrophenol (picric acid)} \] (c) Anisole with CH\(_3\)COCl and anhydrous AlCl\(_3\).
Solution:
Friedel–Crafts acylation occurs at para position: \[ \text{Anisole} \xrightarrow{\text{CH}_3\text{COCl}/\text{AlCl}_3} \text{p-methoxyacetophenone} \] (d) Propan-2-ol is heated with Cu at 573 K.
Solution:
Dehydrogenation to form propanone: \[ \text{CH}_3\text{CH(OH)CH}_3 \xrightarrow{\text{Cu}, 573\text{K}} \text{CH}_3\text{COCH}_3 \]