Aldehydes Ketones Question 127
Question: The enol form of acetone, after treatment with $ D_2O, $ gives
[IIT-JEE (Screening) 1999]
Options:
A) $ CH_3-\overset{OD}{\mathop{\overset{|}{\mathop{C=CH_2}}}} $
B) $ CD_3-\overset{O}{\mathop{\overset{||}{\mathop{C-}}}}CD_3 $
C) $ CH_2=\overset{OH}{\mathop{\overset{|}{\mathop{C-}}}}CH_2D $
D) $ CD_2=\overset{OD}{\mathop{\overset{|}{\mathop{C-}}}}CD $
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Answer:
Correct Answer: B
Solution:
$ \underset{Acetone\text{(ketoform)}}{\mathop{CH_3-\overset{O}{\mathop{\overset{||}{\mathop{C}}}}-CH_3}} $
$ [ \underset{\text{enol form}}{\mathop{CH_3-\overset{OH}{\mathop{\overset{|}{\mathop{C}}}}=CH_2}} ] $ ⇌ $ CH_3-\overset{OD}{\mathop{\overset{|}{\mathop{C}}=}}CH_2 $ ⇌ $ CH_3-\overset{O\ \ \ \ \ \ \ \ \ \ }{\mathop{\overset{||}{\mathop{C}}-CH_2D}} $
$ CH_2=\overset{OH\ \ \ \ \ \ \ }{\mathop{\overset{|}{\mathop{C}}-CH_2D}} $
$ CH_2=\overset{OD\ \ \ \ \ \ \ }{\mathop{\overset{|}{\mathop{C}}-CH_2D}} $ ⇌ $ DCH_2-\overset{O}{\mathop{\overset{||}{\mathop{C}}}}-CH_2D $ ⇌ $ D_3C-\overset{O}{\mathop{\overset{||}{\mathop{C}}}}-CD_3 $ The enol form of acetone on treatment with $ D_2O $ undergoes enolisation, deutration (addition of $ D_2O $ ) and dehydration (removal of $ H_2O $ ). The repeated enolisation, deutration and dehydration ultimately gives $ CD_3.COCD_3(B) $ .
BETA
