Acetone, a ketone, reacts with appropriate bases to form a type of carbanion kno
ID: 482826 • Letter: A
Question
Acetone, a ketone, reacts with appropriate bases to form a type of carbanion known as an enoloate.
a. Circle the base(s) shown below that would permit this equilibrium lie far to the right with Keq > 100. (See Image)
b. Draw a box around the one compound above that would be the least favorable for this reaction, i.e. for which the equilibrium would lie furtherest to the left with Keq <<<1.
Acetone, a ketone, reacts with appropriate bases to form a type of carbanion known as an enolate Base-H Base- H3CT CH2 enolate acetone (a) Circle the base(s) shown below that would permit this equilibrium to lie far to the right with Keq 100. H3C H CH H2SO4 Li-N XCH3 H3C H (b) Draw a box around the one compound above that would be the least favorable for this reaction, i.e. for which the equilibrium would like furthest to the left with Keq I.Explanation / Answer
The keto group is an electronwithdrawing group making the alpha carbons acidic.
Though these carbons are cidic, they are weak acids, so needs a very strong base to remove such proton to form the enolate ionin high concentration (to make Keq >100)
a)Thus very strong bases like LDA (lithium diisopropyldiimide), NaNh2 are used togenerate the enolate anion.
b) The compound that is least favorable to form enolate anion is H2 SO4 which is a atrong acid by itself.
Aan acid can not remove an acidic proton from acetone to give the enolate ion. Thus Keq << 1 .