3-Methylbutan-2-one, (CH3)2CH-CO-CH3, can give two enolates. Which statements are correct?

The thermodynamic enolate has a tetrasubstituted C=C

NaOEt in EtOH under equilibrating conditions gives mainly CH3-C(O^-)=C(CH3)2

LDA in THF at -78 degC gives mainly CH2=C(O^-)-CH(CH3)2

The kinetic enolate is the more stable enolate

The thermodynamic enolate has a tetrasubstituted C=C

NaOEt in EtOH under equilibrating conditions gives mainly CH3-C(O^-)=C(CH3)2

LDA in THF at -78 degC gives mainly CH2=C(O^-)-CH(CH3)2

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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3g3217

3-Methylbutan-2-one, $(CH X_{3}) X_{2} CH - CO - CH X_{3}$ , can give two enolates. Which statements are correct?

AThe kinetic enolate is the more stable enolate
BThe thermodynamic enolate has a tetrasubstituted $C = C$
CNaOEt in EtOH under equilibrating conditions gives mainly $CH X_{3} - C (O X^{-}) = C (CH X_{3}) X_{2}$
DLDA in THF at $- 78^{\circ} C$ gives mainly $CH X_{2} = C (O X^{-}) - CH (CH X_{3}) X_{2}$

Answer: B, C, D

LDA removes the more accessible methyl H irreversibly, giving the kinetic enolate with a 1,1-disubstituted

C = C

. Equilibration gives

CH X_{3} - C (O X^{-}) = C (CH X_{3}) X_{2}

, whose

C = C

carries three alkyl groups plus the oxygen substituent (four non-hydrogen substituents), so it is tetrasubstituted and more stable. The kinetic enolate is thus less stable.

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3-Methylbutan-2-one, (CHX3​)X2​CH−CO−CHX3​, can give two enolates. Which statements are correct?

Answer: B, C, D

More questions on Reaction energy profiles, kinetic vs thermodynamic control

3-Methylbutan-2-one, $(CH X_{3}) X_{2} CH - CO - CH X_{3}$ , can give two enolates. Which statements are correct?