C23: 3. Which of the following will form enolates in small equilibrium amounts (

Question

C23:

3. Which of the following will form enolates in small equilibrium amounts (the equilibrium favors the starting materials) when treated with NaOCH 2 CH 3 ? Choose all that apply. (23 .3)

4. Which of the following will form enolates in stoichiometric or near stoichiometric amounts (the equilibrium heavily favors enolate formation) when treated with NaOCH 2 CH 3 ? Choose all that apply. (23.3)

5. Which of the following will form enol ates in stoichiometric or near stoichiometric amounts (the equilibrium heavily favors enolate formation) when treated with LDA? Choose all that apply. (23.3)

. Which of the following will form enolates in small equilibrium amounts (the equilibrium favors the starting materials) when treated with NaOCH2CH3? Choose all that apply. (23.3) 4. Which of the following will form enolates in stoichiometric or near stoichiometric amounts (the equilibrium heavily favors enolate formation) when treated with NaOCH2CH3? Choose all that apply. (23.3) 5. Which of the following will form enolates in stoichiometric or near stoichiometric amounts (the equilibrium heavily favors enolate formation) when treated with LDA? Choose all that apply. (23.3)

Explanation / Answer

By understanding the pKa values of the relevant acidic protons we can choose suitable bases for forming the corresponding enolates.

conversion of enol to enolate depends on the base used. the stronger the base with higer Pka than the reactant the equilibrium will shift to enolate.

Note:-The pKa values associated with bases is normally meant to refer to the true pKa's of their conjugate acids;

3)

Answer : A, B & E

as alkoxide has Pka of ~16

compound A has Pka of ~25 (ester) so it will form the least amount of enolate

compound B has Pka of ~20 (ketone) so it will form the least amount of enolate

compound C has Pka of ~17  (aldehyde) so it will form more enolate than ketone

for generating the enolate in small quantities, an alkoxide base is ideal

4)

Answer: C & D

in option C & D have two carbonyl groups attached to same carbon making it more acidic Pka ~11 & ~9 respectively for C & D

alkoxide has Pka of 16 so the equilibrium will favor the enolate

5)

Answer:- A, B, C, D, E

all the compounds shown will form the enolate in stoichiometric amount with LDA as it is very strong base Pka ~38

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.