Aldehydes and Ketones II: Enolates

Question 1

carbon adjacent to carbonyl carbon

Answer 1

α-carbon

Question 2

hydrogen attached to α-carbon; relatively acidic and can be removed by a strong base

Answer 2

α-hydrogen

Question 3

effect of oxygen of carbonyl that weakens the C-H bonds on α-carbons

Answer 3

electron-withdrawing

Question 4

deprotonation of an α-carbon, forming a carbanion:

Answer 4

Question 5

less reactive toward nucleophiles because of α-carbon destabilization and steric hindrance

Answer 5

ketones

Question 6

presence crowds transition step and increases its energy; also donates electron density to carbanion, making it less stable

Answer 6

additional alkyl group

Question 7

traditional form aldehydes and ketones exist in (C=O)

Answer 7

keto form

Question 8

less common form aldehydes and ketones exist in;

ene + ol = double bond + hydroxyl group

Answer 8

enol form

Question 9

isomers that can be interconnected by moving a hydrogen and a double bond; keto and enol forms are ____ of one another

Answer 9

tautomers

Question 10

deprotonated form of enol; they are good nucleophiles

Answer 10

enolate

Question 11

enolization (tautomerization):

Answer 11

Question 12

reaction where an enolate attacks an α, β-unsaturated carbonyl, creating a bond

Answer 12

Michael addition

Question 13

step of Michael addition- base deprotonates α-carbon (making it a good nucleophile):

Answer 13

Question 14

step of Michael addition- carbanion attacks the double bond (resulting in Michael addition):

Answer 14

Question 15

enolate favored by fast, irreversible reactions at lower temperatures with strong, sterically hindered bases

Answer 15

kinetic enolate

Question 16

enolate favored by slower, reversible reactions at higher temperatures with weaker, smaller bases

Answer 16

thermodynamic enolate

Question 17

kinetic and thermodynamic enolate:

Answer 17

Question 18

tautomers of imines; imines are thermodynamically favored, so are the more common tautomer

Answer 18

enamines

Question 19

enamination (tautomerization):

Answer 19

Question 20

reaction where the aldehyde or ketone acts as both nucleophile and electrophile, resulting in formation of a C-C bond in a new ____ molecule

Answer 20

aldol condensation

Question 21

aldol condensation:

contains both aldehyde and alcohol functional groups

Answer 21

aldol

Question 22

aldol condensation:

the enolate formed from deprotonation of the α-carbon acts as the ____

Answer 22

nucleophile

Question 23

aldol condensation:

the aldehyde or ketone in form of the keto tautomer acts as the ____

Answer 23

electrophile

Question 24

aldol condensation:

first step; two molecules come together forming the aldol

Answer 24

condensation reaction

Question 25

aldol condensation:

second step after aldol is formed; results in α, β-unsaturated carbonyl

Answer 25

dehydration reaction

Question 26

aldol condensation step 1- forming the aldol:

Answer 26

Question 27

aldol condensation step 2- dehydration of aldol:

Answer 27

Question 28

reverse of aldol condensation; catalyzed by heat and base; bond between α- and β-carbon is cleaved

Answer 28

retro-aldol reaction

Question 29

retro-aldol reaction:

Answer 29