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Question 1

if you start with a chiral molecule, and have it undergo acidic or basic conditions, what happens to the chiral carbon upon enolization

Answer 1

it will form an enol, which is sp2 hydridized and it loses its chiralty

Question 2

what happens to the chiral molecule after it becomes enolized and then is transformed back into the keto form?

Answer 2

it becomes sp3 again and is racemized to form a 50/50 mix of enantiomers

Question 3

what types of ketones can be racemized

Answer 3

originally chiral sp3 alpha carbons on the ketone will be racemized and lose their stereochemistry

Question 4

will you see racemization with non-chiral alpha carbons?

Answer 4

no, it only occurs when the molecule is chiral

Question 5

what are the conditions for a haloform

Answer 5

a methyl ketone treated with a X2 halogen and excess base

Question 6

what does X2 and excess base form with a methyl ketone

Answer 6

it forms a carboxylate salt and a haloform

Question 7

what is an indicator that a haloform reaction has occured

Answer 7

yellow ppt forms in the reaction

Question 8

what does the OH do after we add three additions of halide to an alpha carbon on a keto?

Answer 8

the three halides form a good LG so the hydroxide can perform nucleophilic acyl substitution

Question 9

When reacting a carboxylic acid with 1.) X2 and phosphorous and 2.) H20

Answer 9

you form a alpha halo carboxylic acid

Question 10

when reacting a alpha halocarboxylic acid with NH2, what is the product

Answer 10

an alpha amino acid

Question 11

when reacting an alpha halocarboxylic acid with 1.) OH and 2.) H30, what is the product

Answer 11

an alpha-hydroxy carboxylic acid

Question 12

which way does equilibrium lie when trying to enolize a keto with NaOEt

Answer 12

it favors the formation of the weaker acid so it will favor the reactants

Question 13

why is ethoxide not a good base for enolization?

Answer 13

the pka of a keto acid is 19-20 while the pka of ethanol is 16 pka, since ethanol is the stronger acid the equilibrium is not favorable and does not favor the formation of ethanol and the enolate

Question 14

why is LDA better to use for enolization than EtO

Answer 14

because of pkas, when using LDA, the weaker acid is formed on the product side which makes the equilibrium favorable in the forward direction

Question 15

what is the pka for a protonated LDA? what about EtO? which is the weaker conjugate acid?

Answer 15

the pka for a protonated LDA is 38, for EtOH it is 16. The weaker acid is LDA and favored by equillibrium

Question 16

how do you use LDA

Answer 16

it needs to be prepared in-situ and acts as a strong base for enolization

Question 17

how do you prepare LDA in situ

Answer 17

you use n-butyl lithium and diisopropyl amine to create butane which bubbles off in solution and LDA

Question 18

what is the thermodynamic and kinetic product of an enolate

Answer 18

the thermodynamic product is the predominate product at equillibrium and it is the more substituted enolate

the kinetic product is the faster forming product from the least hindered alpha proton

Question 19

when is the thermodynamic product favored

Answer 19

when using a non sterically hindered base like OH

Question 20

when is the kinetic product favored

Answer 20

when using a sterically hindered base like NDA

Question 21

what type of reaction is alkylation with an enolate

Answer 21

SN2 reaction

Question 22

why can an enolate perform nucleophillic substitution?

Answer 22

it is nucleophillic

Question 23

what type of substrates cannot undergo alkylation with an enolate

Answer 23

3° alkyl halides

Question 24

what type of substrates undergo alkylation the fastest with an enolate

Answer 24

methyl> 1° > 2° alkyl halides

Question 25

why are beta dicarbonyls more acidic than regular ketos

Answer 25

they have more opportunities for resonance so they form a more stable conjugate base