Which of the following can exhibit keto-enol tautomerism?

Question

Which of the following can exhibit keto-enol tautomerism? (A)  H- underset beginsmallmatrix | | O endsmallmatrix mathopC -H  (B)  (CH3)3C- underset beginsmallmatrix | | O endsmallmatrix mathopC -H  (C)  CH3- overset beginsmallmatrix O | | endsmallmatrix mathopC -H  (D)  CCl3- underset beginsmallmatrix | | O endsmallmatrix mathopC -H

Tardigrade Admin · Accepted Answer

Tautomerism is a special kind of functional isomerism in which the isomers exist in dynamic equilibrium with each other. It arises due to migration of hydrogen atom from one polyvalent atom to the other within the same molecule. The isomers thus obtained are called tautomers. Thus, HCHO, text CCl3CHO and (CH3)3CCHO do not show tautomerism due to the absence of α - hydrogen atom w.r.t carbonyl (>C=O) group while CH3CHO shows tautomerism as underset beginsmallmatrix (acetaldehyde) keto text form endsmallmatrix mathopCH3- overset beginsmallmatrix O | | endsmallmatrix mathopC -H underset beginsmallmatrix (vinyl text alcohol) enolic text form endsmallmatrix mathopCH2= overset beginsmallmatrix O-H | | endsmallmatrix mathopC -H

Q. Which of the following can exhibit keto-enol tautomerism?

$H - ∣ ∣ O C - H$

$(C H_{3})_{3} C - ∣ ∣ O C - H$

$C H_{3} - C O ∣ ∣ - H$

$CC l_{3} - ∣ ∣ O C - H$

Q. Which of the following can exhibit keto-enol tautomerism?

H−∣∣O​C​−H

(CH3​)3​C−∣∣O​C​−H

CH3​−CO∣∣​−H

CCl3​−∣∣O​C​−H

$H - ∣ ∣ O C - H$

$(C H_{3})_{3} C - ∣ ∣ O C - H$

$C H_{3} - C O ∣ ∣ - H$

$CC l_{3} - ∣ ∣ O C - H$