Ch. 21: Alpha Carbon (Enols & Enolates)

Question 1

Alpha Halogenation of Ketones

Answer 1

[H3O+], Br2; adds Br to alpha carbon

Question 2

Alpha Halogenation of Carboxylic Acids

Answer 2

1. Br2, PBr3 2. H2O; adds Br to alpha carbon

Question 3

Haloform Reaction (Ketone to Carboxylic Acid)

Answer 3

1. NaOH, Br2 2. H3O+

Question 4

Aldol addition

Answer 4

NaOH, H2O

Question 5

Aldol condensation

Answer 5

heat, -H2O

Question 6

Crossed/Intramolecular Aldol Condensation

Answer 6

NaOH, heat

Question 7

Claisen Condensation (regular, crossed & intramolecular)

Answer 7

1. NaOEt 2. H3O+ (workup); adds COOH

Question 8

Alkylation via Enolate Ions (2 reagents)

Answer 8

1. LDA, -78 C 2. RX (places R on other alpha carbon)
   or 1. NaH, 25 C 2. RX (places R on same alpha carbon)

Question 9

Masonic Ester Synthesis

Answer 9

1. NaOEt 2. RBr 3. H3O+, heat (ester to carboxylic acid)

Question 10

Acetoacetic Ester Synthesis

Answer 10

1. NaOEt 2. RBr 3. H3O+, heat (reduces to singular ketone w/ R)

Question 11

Stabilized Carbon Nucleophiles (2; Micheal Addition)

Answer 11

For aldehyde: 1. R2CuLi 2. H3O+
For ketone: 1. KOH 2. R-COH 3. H3O+
(adds R or R-COH)

Question 12

Stork Examine Synthesis

Answer 12

1. R2NH, [H+], -H2O 2. R-Ketone 3. H3O+ (adds R-Ketone)

Question 13

Robinson Annulation