question_answer

Phenol on reaction with a mixture of cone. \[HN{{O}_{3}}\]and conc. \[{{H}_{2}}S{{O}_{4}}\]produces a compound. What is the degree of unsaturation present in the compound and nature of compound?

A)  5, acidic                              

B)  7, basic

C)  6, neutral                           

D)  7, acidic

Correct Answer: D

Solution :

 This problem includes conceptual mixing of electrophilic substitution  reaction,  degree of unsaturation and acidic/basic nature. Electrophilic Substitution Reaction Phenol undergo electrophilic substitution reaction on reaction with a mixture of cone. \[HN{{O}_{3}}\]and cone. \[{{H}_{2}}S{{O}_{4}}\](known as nitrating mixture). This reaction produces nitro compound and on successive nitration it produces trinitro phenol. conc.\[HN{{O}_{3}}+conc.{{H}_{2}}S{{O}_{4}}\xrightarrow{{}}N{{\overset{+}{\mathop{O}}\,}_{2}}\] Molecular formula\[={{C}_{8}}{{H}_{3}}{{N}_{3}}{{O}_{7}}\] Degree of unsaturation = \[(C+1)-\frac{H}{2}+\frac{N}{2}\]                 \[=(6+1)-\frac{3}{2}+\frac{3}{2}=7-0=7\] Nature of compound The compound is acidic in nature due to presence of three strong electron withdrawing groups\[(N{{O}_{2}})\].