Dr Barker

Question 1

EWG ___ hydration

Answer 1

Promote

Question 2

EDG ___ hydration

Answer 2

Inhibt

Question 3

Relative reactivities at C=O

Answer 3

Acid chloride, anhydride, aldehyde, ketone, ester, amine

Question 4

EWG ___ acidity

Answer 4

Increase = lower pKa gives more stable anion

Question 5

EDG ___ acidity

Answer 5

Decreases = higher pKa so less stable anion

Question 6

How are enolates stabilised

Answer 6

Resonance stabilised by delocalisation of negative charge onto oxygen

Question 7

Why is LDA a good base

Answer 7

Very sterically hindered so is a poor nucleophile

Question 8

When are crossed aldol reactions successful

Answer 8

Only one carbonyl has enolisable alpha-H and the non-enolisable carbonyl compound is more electrophilic

Question 9

Use of reformatsky reaction

Answer 9

React with aldehydes and ketones but not ester so no danger of self reaction

Question 10

Claisen produces

Answer 10

1,3-dicarbonyls with ester group

Question 11

What does final step of Claisen require

Answer 11

irreversible deprotonation

Question 12

What’s Robinson annulation

Answer 12

Michael addition followed by intramolecular aldol condensation

Question 13

Robinson annulation produces

Answer 13

6 membered rings

Question 14

What base is needed to deprotonate phophonium salts

Answer 14

nBuLi

Question 15

How are ylides formed

Answer 15

PPh3 and alkyl halide

Question 16

Stabilised ylides

Answer 16

Have another group to stabilise eg C=O or CN

Question 17

What to stabilised ylides produce

Answer 17

E/trans alkenes

Question 18

What base s needed to deprotonate stabilised ylides

Answer 18

NaOEt

Question 19

What do unstabilised ylides give

Answer 19

Z/cis alkenes

Question 20

Can unstabilised ylides be stored

Answer 20

No

Question 21

compare reactivity of stabilised and unstabilised ylides

Answer 21

Stabilised only react with aldehydes and unstabilised react with aldehydes and ketones

Question 22

What does aldol condensation produce at a) low temps and b) high temps

Answer 22

A) β-hydroxycarbonyl
B) E1cB removal of water gives enal

Question 23

Prep of organocopper reagents

Answer 23

1. Alkyl halide and lithium gives alkyl lithium
2. 2 x alkyl lithium and CuI in ether gives organocopper and lithium salt

Question 24

Product of tandem conjugate addition of cuprate

Answer 24

Alkyl groups installed trans due to sterics and needs reactive alkylation agents eg non-sterically hindered alkyl bromides

Question 25

What’s needed to reduce aldehydes and ketones

Answer 25

NaBH4

Question 26

What’s needed to reduce esters and amines

Answer 26

LiAlH4

Question 27

Carboxylic acid and alcohol gives

Answer 27

Ester and water, reversible reaction

Question 28

Alcohol and acid chloride/ anhydride

Answer 28

Gives carboxylic acid

Question 29

Reformatsky and carbonyl gives

Answer 29

β-hydroxyester at low temps or enone at high temps