carboxylic acids and esters

Question 1

what is the functional group of a carboxylic acid

Answer 1

• COOH

(C=O and C-OH)

Question 2

how do you name carboxylic acids?

Answer 2

-oic acid

Question 3

explain whether carboxylic acids are soluble in water and what influences their solubility

Answer 3

• dissolve in polar substances like water
• because hydrogen bonds can form between the oxygen in the carboxyl group and hydrogen in water
• or hydrogen in the carboxyl group (C=O) can form hydrogen bonds with oxygen in the water
• the hydrocarbon chain is non-polar so it doesn’t dissolve, the longer the chain the less soluble the carboxylic acid is

Question 4

what are the intermolecular forces in carboxylic acids

Answer 4

hydrogen bonds in solid state - very strong

Question 5

what are esters (what are they formed from), functional group and their general formula?

Answer 5

• formed from carboxylic acids and alcohols
• RCOOR’
• (C=O) and (C-O-C)

Question 6

write an equation for the reaction of ethanoic acids with propan-1-ol

Answer 6

CH3COOH + CH3CH2CH2OH -> CH3COOCH2CH2CH3 + H2O

(propyl ethanoate)

Question 7

how do you name esters

Answer 7

• start with alcohol group that has replaced the hydrogen
• then acid part

Question 8

what characteristic properties do esters have

Answer 8

• volatile (easily evaporated at normal temperatures)
• pleasant fruity smells

Question 9

what are some uses of esters

Answer 9

• flavourings
• perfumes
• solvents (short chain only)
• plasticisers

Question 10

how could you distinguish carboxylic acids from other -OH containing compounds

Answer 10

• add NaHCO3
• acids will produce sodium salt, water and carbon dioxide

Question 11

write an equation for the reaction of ethanoic acid with NaOH

(carboxylic acid plus NaOH makes what?)

Answer 11

CH3COOH + NaOH -> H2O + CH3COO-Na+

a carboxylate salt

Question 12

write an equation or the reaction of ethanoic acid with Na2CO3

Answer 12

2CH3COOH + Na2CO3 -> 2CH3COO-Na+ + H2O + CO2

Question 13

write an equation for the reaction of ethanoic acid with calcium oxide

Answer 13

2CH3COOH + CaO -> (CH3COO)2Ca + H2O

Question 14

describe the acidity of carboxylic acids

Answer 14

• carboxylic acids are weak acids
• dissociate partially to form H+ and a carboxylate ion

Question 15

describe the reactions of carboxylic acids as weak acids

Answer 15

• they react with carbonates to form salt, water and carbon dioxide
• react with bases to form a salt and water
• react with metals to produce salt and hydrogen

Question 16

what catalyst is needed for the formation of esters from alcohols and carboxylic acids

Answer 16

conc strong acid
e.g. H2SO4

Question 17

what catalyst is needed for the hydrolysis of esters

Answer 17

dilute strong acid
e.g. H2SO4

Question 18

what is an alternative method of hydrolysis

Answer 18

base hydrolysis

Question 19

what are the advantages of base hydrolysis

Answer 19

• reaction goes to completion due to neutralisation by base
• more product in the mixture than acid catalysed hydrolysis

Question 20

what are carboxylic acid derivatives

Answer 20

molecules that have the acyl group (-COCL) on their first carbon as a part of their structure, formed from carboxylic acids

Question 21

name 2 acid derivatives and give their functional groups

Answer 21

• acyl chlorides: RCOCL
• acid anhydrides: RCOOCR / (RCO)2O

Question 22

how do you form an acyl chloride

Answer 22

react a carboxylic acid with SOCL2

Question 23

how do you name an acyl chloride

Answer 23

• oyl chloride

Question 24

if the nucleophile is ammonia for the acylation of acyl chlorides/acid anhydrides what are the products of the reaction

Answer 24

an amide

Question 25

write an equation for the reaction of ethanoyl chloride and ammonia

Answer 25

CH3COCL + 2NH3 -> CH3CONH2 + NH4Cl

Question 26

if the nucleophile is a primary amine, what are the products of the acylation of acyl chlorides or acid anhydrides

Answer 26

n-substituted amine

Question 27

write an equation for the reaction of ethanoyl chloride and methaylamine

Answer 27

CH3COCl + CH3NH2 -> CH3CONHCH3 + CH3NH3Cl

Question 28

write the equation for the reaction of ethanoyl chloride and methalyamine

Answer 28

CH3COCl + CH3NH2 -> CH3CONH2CH3 + HCl

Question 29

if the nucleophile is an alcohol, what are the products of the acylation of acyl chlorides or acid anhydries

Answer 29

an ester

Question 30

write an equation for the reaction of ehtanoyl chloride and ethanol

Answer 30

CH3COCl + CH3CH2OH -> CH3COOCH2CH3 + HCl

Question 31

if the nucleophile is water what are the products of the acylation of acyl chlorides or acid anhydries

Answer 31

carboxylic acid
hydrolysis produces an ester linkage

Question 32

what is the name of this reaction (the acylation of acyl chlorides/acid anhydries) with water as a nucleophile

Answer 32

hydrolysis

Question 33

write an equation for the reaction of ehtanoyl chloride and water

Answer 33

CH3COCl + H2O -> CH3COOH + HCl

Question 34

what is the functional group of a carboxylic acid?

Answer 34

• COOH

(C=O and C-OH)

Question 35

what is produced when acyl chlorides react with water

Answer 35

carboxylic acids and HCl gas

Question 36

what is produced when acyl chlorides react with ammonia

Answer 36

• amides and HCl gas

Question 37

what is produced when acyl chlorides react with alcohol

Answer 37

esters and HCl gas

Question 38

what is produced when acyl chlorides react with primary amines

Answer 38

produce n substituted amides and HCl gas

Question 39

what is produced when an acid anhydride reacts with alcohol

Answer 39

• esters

Question 40

compare the reaction of an acid anhydride with alcohol to the reaction of an acyl chloride with alcohol

Answer 40

less vigorous than acyl chlorides