question_answer

Which one of the following compounds cannot show tautomerism?

A)  \[C{{H}_{3}}-\underset{O}{\mathop{\underset{\mathbf{||}}{\mathop{C}}\,}}\,-C{{H}_{3}}\]   

B)  \[C{{H}_{2}}=CH-OH\]

C)                                

D)  

E)  

Correct Answer: D

Solution :

                 \[C{{H}_{3}}-\underset{\text{keto}\,\text{form}}{\mathop{\underset{O}{\mathop{\underset{\mathbf{||}}{\mathop{C}}\,}}\,}}\,-C{{H}_{3}}\] \[C{{H}_{3}}-\underset{\text{enol}\,\,\text{form}}{\mathop{\underset{OH}{\mathop{\underset{\mathbf{|}}{\mathop{CH}}\,}}\,}}\,=C{{H}_{2}}\]  \[\underset{\text{enol}\,\text{form}}{\mathop{C{{H}_{2}}=CH-OH}}\,\] \[\underset{\text{keto}\,\text{form}}{\mathop{\underset{H}{\mathop{\underset{\mathbf{|}}{\mathop{C{{H}_{3}}-C=O}}\,}}\,}}\,\]