Carbonyls 2

Question 1

What are aldehydes oxidised to?

Answer 1

COOH

Question 2

What oxidising agents are used?

Answer 2

CrO3
KMnO3
HNO3

Question 3

What is ethinylestradiol used in?

Answer 3

Formulation of combined pill

Question 4

What is required in ethinylestradiol?

Answer 4

NaNH2

Liquid NH3

Question 5

Why do all COOH derivatives react by same mechanism?

Answer 5

Polarity of carbonyl group

Question 6

What happens in nucleophilic acyl substitution?

Answer 6

Nu- adds carbonyl carbon
= forms tetrahedral anionic intermediate
Leaving group expelled
Tetrahedral intermediate eliminated weakest base

Question 7

When is Nu- expelled and why?

Answer 7

Nu- weaker than leaving group

= Nu- more stable than L-

Question 8

When is L- expelled and why?

Answer 8

L- weaker than Nu-

= leaving group more stable than Nu-

Question 9

Which intermediate will decompose the fastest?

Answer 9

One with best leaving group

Question 10

What happens to reactivity as leaving group becomes more basic?

Answer 10

Decreases

Question 11

Why is a WB more electronegative?

Answer 11

Able to accommodate negative charge better

Question 12

Why is a WB better at inductive e- withdrawal from carbonyl C?

Answer 12

Increases electrophilicity of carbonyl carbon
More electrophilic carbonyl groups = more reactive to addition
Carbonyl carbon more susceptible to nucleophilic attack

Question 13

Are acid halides more reactive than amides?

Answer 13

YES

Question 14

Why is chloride good leaving group?

Answer 14

Undergoes acyl substitution easy

Question 15

Is chloride useful in pharmaceutics?

Answer 15

Too reactive

Question 16

What do you need to synthesise acid chlorides?

Answer 16

COOH + SOCl2 (thionyl chloride)

Question 17

What reactions can acid chlorides undergo?

Answer 17

Nucleophilic acyl substitution
Hydrolysis
—-> ester/amides

Question 18

What happens in nucleophilic substitution of acid chloride?

Answer 18

Follows general mechanism

Halogen replaced by OH, OR, OC(=O)R or NH2

Question 19

What is formed acid chloride + NH3?

Answer 19

Amide

Question 20

What is formed acid chloride + R’OH?

Answer 20

Ester

Question 21

What is formed acid chloride + R’CO2-?

Answer 21

Acid anhydride

Question 22

What is formed acid chloride + H2O?

Answer 22

Carboxylic acid

Question 23

What is does acid chloride hydrolysis form?

Answer 23

COOH

Question 24

What happens in acid chloride hydrolysis?

Answer 24

Add H2O

Tetrahedral intermediate undergoes elimination of Cl- + loss of H+ to give COOH

Question 25

What is formed acid chloride + alcohol?

Answer 25

Ester

Question 26

What is formed acid chloride + NH3?

Answer 26

Primary amide

Question 27

What is formed acid chloride + RNH2?

Answer 27

Secondary amide

Question 28

What is formed acid chloride + R2NH?

Answer 28

Tertiary amide

Question 29

What must be present to form ester from acid chloride?

Answer 29

Presences of tertiary amine base OR NaOH

Question 30

What reactions can acid anhydrides undergo?

Answer 30

----> esters

Question 31

What does acetic anhydride form?

Answer 31

Acetate ester

Question 32

Are anhydrides less reactive than acid chlorides?

Answer 32

YES

Question 33

What reactions can esters undergo?

Answer 33

Transesterification Aminolysis Reduction

Question 34

What happens in transesterification?

Answer 34

Alkoxy group replaced by another with acid or base catalyst

Question 35

What is required in transesterification?

Answer 35

Large excess of alcohol

Question 36

What happens in aminolysis?

Answer 36

NH3, primary amine or secondary amine react to form amide

Question 37

What is the equation for aminolysis?

Answer 37

RCOOEt + NH3 ----> RCONH2 + EtOH

Question 38

What happens in reduction of esters?

Answer 38

Yields 2x = aldehyde the primary alcohol

Question 39

What is required in reduction of esters?

Answer 39

LiAlH4

Question 40

What is Xenical (active orlistat)?

Answer 40

Anti-obesity drug

Question 41

Where does Xenical work?

Answer 41

Locally in stomach + small intestine

Question 42

What does Xenical prevent?

Answer 42

Action of gastric + pancreatic lipases

Question 43

How does Xenical work?

Answer 43

Irreversible acylation of active site serine in phospholipase Inactive enzyme cannot hydrolyse triglyceride = block fat uptake

Question 44

What is acetylcholinesterase responsible for?

Answer 44

Nerve-impulse transmission

Question 45

What is the second site of reactivity for aldehydes, ketones, esters + N,N-disubstituted amides?

Answer 45

Alpha H | = acidic enough to be removed by strong base

Question 46

In reaction elonate ions + enols what does the reaction at C or O depend on?

Answer 46

Electrophile + reaction conditions

Question 47

Where does protonation normally occur in reaction of elonate ions + enols?

Answer 47

O site

Question 48

What is the consequences of enolization?

Answer 48

Stability | Racemization = any chiral centre next to carbonyl prone to racemization

Question 49

What happens when alpha carbon is halogenated?

Answer 49

Electrophilic