6b

Question 1

what does the reactivity of carboxylic acids and their derivatives depend on

Answer 1

the degree of delocalisation the substituent has

aka the e- donating power of the substituent

Question 2

rate carboxylic acid derivatives from least delocalising to most delocalising

Answer 2

• acyl chloride (weak - e- negative)
• anhydride (e- negative and 2 diff resonance structures)
• ester (some delocalisation of lone pair)
• amide (strong delocalisation - N isnt as electronegative)
• carboxylate ion (complete delocalisation)

Question 3

acyl chloride to carboxylic acid

Answer 3

h20
20*C
fast reaction

Question 4

acid anhydride to carboxylic acid

Answer 4

h20
20*C
slow

Question 5

ester to carboxylic acid

Answer 5

h20
heat
acid / base catalyst

Question 6

amide to carboxylic acid

Answer 6

prolonged heating
strong acid/ base catalyst

Question 7

electrohilicilty and degree of delocalisation

Answer 7

more delocalisation = less + charge = less likely to be attacked by nucleophiles = less electrophilic.

Question 8

carboxylic acid to acyl chloride

Answer 8

carb acid

Cl – s = o – Cl

Question 9

what is a fischer reaction

Answer 9

carboxylic acid to ester reaction

Question 10

what is needed in a fischer reaction

Answer 10

carboxylic acid
H2SO4 / HCl catalyst
PRIM / SEC ALCOHOL R-OH

Question 11

describe the fischer reaction

Answer 11

carb acid to ester
=o is protonated

1-2-addition of alcohol to C+

deprotonation of alcohol

protonation of OH to form water

OH lone pair kicks off water

OH is deprotonated by water

ester is formed

Question 12

acyl chlorides to esters

Answer 12

acyl chloride
base
alcohol

gives an ester

Question 13

why can tertiary alcohols not react with carboxylic acids to form esters

Answer 13

too bulky

Question 14

when is a fischer reaction used

Answer 14

when u need to make simple esters

methyl // ethyl esters

Question 15

rds of fischer reaction

Answer 15

addition of alcohol

Question 16

acyl chlorides to esters mechanism

Answer 16

alcohol attacks electrophilic C

alcohol is deprotonated by a base

O- kicks of Cl

ester is formed.
Cl- is formed

Question 17

when are esters made from acyl chlorides

Answer 17

when u need specific // complex esters

Question 18

why is a base used for acyl chloride mechanisms

Answer 18

u want to quench the HCl - u dont want it to form

Question 19

what base can be used for acyl chloride to ester synthesis

Answer 19

pyridine

Question 20

what esle can be used instead of cab acids and acyl chlorides to give esters

Answer 20

acid anhydrides can also be used

Question 21

what is the rds of acyl chloride to ester synthesis

Answer 21

alcohol attacking electrophilic carbon..

alcohol nucleophilic attack.

Question 22

what is a transesterification reaction

Answer 22

switching from one ester to a different ester

Question 23

what is needed in an acid catalysed transesterification reaction

Answer 23

ester
alcohol osolvent
H+ catalyst
heat and reflux

Question 24

acid catalysed transesterification reaction mechanism

Answer 24

O is protonated
alcohol attacks C
old ester group is kicked off by OH lone pair

O is deprotonated

new ester is formed.
we protonate the group we want to remove

Question 25

ester to carb acid

Answer 25

acid catalysed hydrolysis of esters

Question 26

what is needed in the acid catalysed hydrolysis of an ester to a carboxylic acid

Answer 26

ester H3O+ H2O

Question 27

acid catalysed hydrolysis of ester to carb acid mechanism

Answer 27

o is protonated by H3O+ water attacks C water is deprotonated water is protonated ester is kicked off carboxylic acid is formed

Question 28

how else can a ester be hydrolised to give a carboxylic acid

Answer 28

base catalysed hydrolyis

Question 29

what is needed in the base catalysed hydrolysis of an ester to give a carb acid

Answer 29

ester NaOH H20

Question 30

why is base catalysed hydrolysis of an ester to give a carboxylic acid preferred

Answer 30

bc its irreversible the final product is a carboxylic acid

Question 31

base catalysed hydrolysis of ester to give a carboxylic acid can also be called

Answer 31

SAPONIFICATION

Question 32

describe a saponification reaction

Answer 32

base catalysed hydrolysis from ester to carboxylic acid. OH attacks carbon ester is protonated O- kicks off ester carboxylic acid is formed

Question 33

acyl chloride to amide needs

Answer 33

acyl chloride excess amine gives an amide

Question 34

acyl chlorides to amides mechanism

Answer 34

amine // ammonia attacks the C ammonia is deprotonated O- kicks off cl

Question 35

why cant carboxylic acids react with ammonia//amines

Answer 35

carboxylic acids are acids amines + amides are basic they form ammonium salts 20*C.

Question 36

acid catalysed hydrolysis of amides

Answer 36

amide + H3O+ + h20 gives a carboxylic acid O is protonated,, water attacks C,, water is deprotonated,, amine is protonated lone pair on O kicks off amine water neutralsises Oxygen carboxylic acid is made

Question 37

in nature,, what turns esters into carboxylic acids

Answer 37

esterase enzymes

Question 38

in nature,, what turns amides into carboxylic acids

Answer 38

amidases