Carboxylic Acids And Esters

Question 1

What is the functional group for carbocylic acids?

Answer 1

COOH

Question 2

What is the functional group for esters?

Answer 2

COOR

Question 3

What is the functional group for acyl chlorides?

Answer 3

CO-Cl

Question 4

What is the functional group for acid anhydrydes?

Answer 4

OC-O-CO

Question 5

What is the functional group for amides?

Answer 5

CO-NH2

Question 6

What is the general formula for carboxylic acids?

Answer 6

CnH2nOH

Question 7

Name 4 derivatives of carboxylic acids

Answer 7

Esters
Acyl chlorides
Amides
Acid anhydryde

Question 8

Describe the melting points, solubility and acidity of carboxylic acids

Answer 8

High melting and boiling points- due to hydrogen bonding between molecules
Low Mr carboxylic acids are soluble in water- form hydrogen bonding with water
Weak acids- only partially dissociate (donate H+ ions) in water

Question 9

Describe the test for carboxylic acids

Answer 9

Add sodium carbonate
If carboxylic acids are present, effervescence will be seen due to carbon dioxide

Question 10

What is the general formula of esters?

Answer 10

CnH2nO2

Question 11

What is a condensation reaction?

Answer 11

A reaction in whoch two molecules join together with the elimination of a small molecule

Question 12

What are the reagents and conditions of the preparation of esters using carboxylic acids and alcohols?

Answer 12

Reagents- concentrated H2SO4
Heat reflux

Question 13

What are the conditions for the preparation of esters using
Alcohol and acid anhydrides?

Answer 13

Heat

Question 14

What are the conditions for the preparation of esters using
Alcohol and acyl chlorides?

Answer 14

Room temperature

Question 15

State three ways in which esters can be prepared using alcohol

Answer 15

Carboxylic acid and alcohol
Acyl chloride and alcohol
Acid anhydryde and alcohol

Question 16

Compare the boiling points and solubility of esters and carboxylic acids

Answer 16

Esters have a lower bp and are less soluble than carboxylic acids as they do not form hydrogen bonds

Question 17

Name four uses of esters

Answer 17

Perfumes
Sweets
Solvents
Plasticisers

Question 18

What is aspirin?

Answer 18

An ester of 2-hydroxybenzoic acid

Question 19

How can aspirin be manufactured? What else does this reaction produce?

Answer 19

By reacting ethanoic anhydide with 2-hydroxybenzoic acid. This also produces ethanoic acid

Question 20

When manufactoring esters, why is ethanoic anhydride used instead of ethyl chloride?

Answer 20

It is less corrosive
Safer, as it produces ethanoic acid instead of HCL which is corrosive
Cheaper
Doesnt react with water as easily

Question 21

What is hydrolysis?

Answer 21

The breaking of bonds using water

Question 22

What are the reactants, products and conditions for the acid hydrolysis of esters?

Answer 22

Reactants- ester and water
Products- carboxylic acid and alcohol
Conditions- heat reflux with dilute H2SO4

Question 23

What are the resctants, products snd conditions for the alkaline hydrolysis of esters?

Answer 23

Reactants- esters and NaOH
Products- alcohol and Na salt of carboxylic acid
Conditions- heat reflux, dilute NaOH

Question 24

How can a carboxylic acid be obtained after the alkaline hydrolysis of esters?

Answer 24

By reacting the sodium salt with an acid

Question 25

What is a triglyceride?

Answer 25

A triester of glycerol and fatty acids

Question 26

What is the difference between fats and oils?

Answer 26

Fats are solid at room temp, as they contain saturated fatty acids Oils are liwuid at room temp, as they contain insaturated fatty acids

Question 27

Wha5 is the difference between saturated and unsaturated fatty acids?

Answer 27

Saturated fatty acids only contain single bonds between carbons, unsaturated contains double bonds

Question 28

What are the conditions, reactants and products of the alkaline hydrolysis of triglycerides?

Answer 28

Reactants- triglyceride, 3NaOH Products- glycerol, sodium salts of fatty acids Conditions- heat reflux

Question 29

What can the products of the hydrolysis of triglycerides be used for?

Answer 29

The sodium sakts of fatty acids can be used as soaps

Question 30

What is biodiesel?

Answer 30

A mixture of methyl esters of long chain carboxylic acids

Question 31

How can buodiesel be manufactured? And what are its conditions?

Answer 31

By reacting methanol with vegetable oil (triglyceride) in the presence of a catalyst- KOH.

Question 32

What is the name for the manufacturing of biodiesel?

Answer 32

Trans Esterification

Question 33

Out of alcojols. Aldehydes and carboxylic acids, which has the highest boiling point? Why?

Answer 33

Catboxylic acids as they form stronger hydrogen bonds between molecules that require more energy to be overcome

Question 34

What is acylation?

Answer 34

Where an acyl group is introduced to another molecule

Question 35

What is an acyl group?

Answer 35

A group with the formula R-C=O -X

Question 36

What are acid derivatives, give two examples

Answer 36

Acid derivatives are molecules with acyl groups Acyl chloride and acid anhydrides

Question 37

What is a nucleophile?

Answer 37

An electron pair donor

Question 38

Are carboxylic acids or acid derivatives more reactive?

Answer 38

Acid derivatives are more reactive, due to the polarity of their carbonyl group. They react with nucleophiles

Question 39

What type opf reaction is the hydrolysis of acyl chloride? What are its products?

Answer 39

Nucleophilic addition elimination Produces HCl and carbocylivc acids. This produces a solution with a low pH

Question 40

What are the reagents and observations with the hydrolysis of acyl chlorides?

Answer 40

Reagents- water Observations- HCl gives off steamy fumes

Question 41

What are the products of reacting ammonia with acyl chlorides, and what is the mechanism?

Answer 41

Produces amides and HCl Nucleophilic additiopn elimination

Question 42

What are the products of reacting alcohols with acyl chlorides, and what is the mechanism?

Answer 42

Produces esters and HCl Nucleophilic addition elimination

Question 43

What are the products of reacting primary amines with acyl chlorides, and what is the mechanism?

Answer 43

Produces amides and HCl Nucleophilic addition elimination

Question 44

What are the products of reacting water with acid anhydrides, what is the type of reaction and what is the mechanism?

Answer 44

Produces two carboxylic acids Hydrolysis reaction with nucleophilic addition elimination

Question 45

What are the products of reacting ammonia with acid anhydrides, and what is the mechanism?

Answer 45

Produces a carboxylic acid and amide Nucleophilic addition elimination reaction

Question 46

What are the products of reacting primary amines with acid anhydrides, and what is the mechanism?

Answer 46

Produces an amide and carboxylic acid Nucleophilic addition elimination

Question 47

What are the products of reacting alcohol with acid anhydrides, and what is the mechanism?

Answer 47

Produces an ester and carbocyliuc acid Nucleophilic addition elimination reaction

Question 48

Why are nucleophilic addition eliminatiopn reactions with acid anhydrides better than with acyl chlorides?

Answer 48

Acyl chlorides produce HCl wi]hich is very corrosive, whereas acid anhydrides produce carboxyli acids, whioch are much less corrosive