NEET AIPMT SOLVED PAPER MAINS 2010

  • question_answer
    Among the following four compounds
    A. Phenol                           
    B. Methyl phenol
    C. meta-nitrophenol      
    D. para nitrophenol the acidity order is

    A)  \[D>C>A>B\]   

    B) \[C>D>A>B\]

    C) \[A>D>C>B\]    

    D) \[B>A>C>D\]

    Correct Answer: A

    Solution :

    An electron withdrawing group (-1 showing group like \[-N{{O}_{2}},-CN)\] stabilises the phenoxide ion, thus when present, increases the acidity of phenol. On the other hand electron releasing groups (+I showing group like \[-C{{H}_{3}}-{{C}_{2}}{{H}_{5}}),\] when present, decrease the acidity of phenol by destabilizing peroxide ion. Hence, the correct order of acidity of given compounds is \[\underset{\text{(D)}}{\mathop{\text{p-nitrophenol}}}\,>\underset{\text{(C)}}{\mathop{\text{m-nitrophenol}}}\,>\underset{\text{(B)}}{\mathop{\underset{\text{methyal}\,\text{phenol}}{\mathop{\underset{\text{(A)}}{\mathop{\text{phenol}}}\,}}\,}}\,\] (due to intermolecular H-bonding)


You need to login to perform this action.
You will be redirected in 3 sec spinner