question_answer

When phenol is treated with \[{{D}_{2}}S{{O}_{4}}/{{D}_{2}}O.\]some of the hydrogens get exchanged. The final product in this exchange reaction is

A)  

B)  

C)  

D)  

Correct Answer: A

Solution :

 In acidic medium, phenol exists in following resonating structures. Since, o/p positions are electron rich sites, so electrophile will attack on these site, i.e., hydrogen of these sites get exchanged by D (deuterium). Hence, the final product of the reaction is  which is formed as