Carboxylic Acids ORGANIC

Question 1

What are carboxylic acids?

Answer 1

Compounds that contain carboxyl function group -COOH

Question 2

What is the general formula of a carboxylic acid and the shorthand version?

Answer 2

CₙH₂ₙ₊₁COOH
RCOOH

Question 3

Why aren’t numbers used in nonmenclature of carboxylic acids?

Answer 3

Carboxyl group is always on first carbon atom

Question 4

What is the molecular formula for methanoic acid?

Answer 4

HCOOH

Question 5

Which carboxylic acids are water-soluble?

Answer 5

Those with fewer than six carbon atoms per molecule

Question 6

Why are carboxylic acids weak?

Answer 6

Only partially ionise in aqueous solution to give low concentration of hydronium and alkanoate ions

Question 7

What is useful for testing for presence of carboxylic acids?

Answer 7

Concentration of hydrogen ions is sufficient to react with aqueous solution of sodium carbonate/hydrocarbonate to produce carbon dioxide

Question 8

How are esters formed from carboxylic acids?

Answer 8

Condensation reaction between alcohol and carboxylic acid in presence of concentrated strong acid catalyst

Question 9

What is the condensation reaction that forms esters known as?

Answer 9

Esterification

Question 10

What is eliminated in esterification?

Answer 10

Water molcule eliminated from acid and alcohol reacting

Question 11

What are esters?

Answer 11

Carboxylic acid derivatives containing ester group -COO-

Question 12

What pattern does nomenclature of esters follow?

Answer 12

-oic acid suffix replaced with -oate
Alkyl chain attached to oxygen of COO- is added as first word

Question 13

What are esters used for?

Answer 13

Flavourings/fragrances
Plasticisers
Solvents

Question 14

How can esters be used to test for presence of alcohol or carboxylic acid?

Answer 14

Unknown substance can be warmed with carboxylic acid in presence of catalyst
Excess acid removed by adding alkaline solution
If remaining mixture has sweet smell of ester, presence of alcohol confirmed

Question 15

What are plasticisers?

Answer 15

Additivies mixed into polymers to increase flexibility

Question 16

How do ester plasticisers work?

Answer 16

By penetrating between polymer chains increasing distance between

Question 17

Why are esters ideal for use as solvents?

Answer 17

Low toxicity
Low volatility
Relatively cheap

Question 18

What molecules are naturally occurring esters?

Answer 18

Triglycerides

Question 19

What is biodiesel?

Answer 19

Fuel made from renewable vegetable oils rather than non sustainable petrochemicals

Question 20

How is biodiesel produced?

Answer 20

Transesterification
Triglyceride converted or tranesterified into less viscous fatty acid ester using alcohol
Acids and alkalis can both be used to catalyse reaction

Question 21

What is the reverse of esterification reaction?

Answer 21

Hydrolysis

Question 22

What is ester hydrolysis used for?

Answer 22

Creating biodegradable plastics

Question 23

What are esters hydrolysed to?

Answer 23

Carboxylic acid and alcohol or salts of carboxylic acids

Question 24

What happens when ester heated under reflux with acid?

Answer 24

Equilibrium mixture established
Hydrolysis reaction not complete

Question 25

What happens when ester heated under reflux with dilute alkali?

Answer 25

Irreversible reaction Ester fully hydrolysed and reaction complete

Question 26

What does carboxylic acid produced in ester hydrolysis react with? What is formed?

Answer 26

Reacts with excess alkali to form carboxylate salt and alcohol

Question 27

What is saponification?

Answer 27

Process where vegetable oils and animal fats can be hydrolysed in alkaline conditions with aqueous sodium hydroxide to form soaps

Question 28

What are soaps?

Answer 28

Carboxylate salts of long-chain carboxylic acids

Question 29

What is produced when triglycerides are hydrolysed in hot alkaline conditions?

Answer 29

Mixture containing glycerol and salts of fatty acids

Question 30

What is nomenclature name for glycerol?

Answer 30

propane-1,2,3-triol

Question 31

What is acylation?

Answer 31

The method of including acyl groups into compounds

Question 32

What is needed for acylation?

Answer 32

Acylating agents (acyl chlorides or acid anhydrides)

Question 33

What are acyl chlorides?

Answer 33

Derivatives of carboxylic acids by substitution of -OH group by chlorine atom

Question 34

What suffix is used for an acyl chloride?

Answer 34

-oyl chloride

Question 35

What are acid anhydrides?

Answer 35

Derivatives of carboxylic acids formed by substitution of -OH group by alkanoate

Question 36

What suffix is used for an acid anhydride?

Answer 36

-oic anhydride

Question 37

What nucleophilic addition-elimination reactions do acyl chlorides undergo?

Answer 37

Hydrolysis Reaction with alchols to form esters Reaction with ammonia and primary amines to form amides

Question 38

What is formed in hydrolysis of acyl chlorides?

Answer 38

Carboxylic acid and HCl molecule

Question 39

How is hydrolysis of acyl chlorides a nucleophilic addition-elimination reaction?

Answer 39

Water molecule added across C=O bond HCl molecule eliminated

Question 40

How is formation of esters from acyl chlorides a nucleophilic addition-elimination reaction?

Answer 40

Alcohol adds across C=O bond HCl molecule eliminated

Question 41

How is formation of amides from acyl chlorides a nucleophilic addition-elimination reaction?

Answer 41

Amine or ammonia molecule adds across C=O bond HCl molecule eliminated

Question 42

How are amides formed from acyl chlorides?

Answer 42

Nitrogen atom in ammonia and primary amine has lone pair of electrons to attack carbonyl carbon atom in acyl chloride

Question 43

What two steps are seen in nucleophilic addition-elimination reactions?

Answer 43

Addition of nucleophile across C=O bond Elimination of small molecule

Question 44

What uses do acylation reactions have?

Answer 44

Pharmaceutical Textile

Question 45

How is aspirin manufactured?

Answer 45

By reacting salicylic acid with ethanoic anhydride in acylation reaction

Question 46

What is the word equation for the industrial manufacture of aspirin?

Answer 46

salicylic acid + ethanoic anhydride -> aspirin + ethanoic acid

Question 47

Why aren't acyl chlorides used as acylating agent for aspirin production?

Answer 47

Rapid production of highly corrosive hydrogen chloride gas

Question 48

Why are acid anhydrides preferred as acylating agent for aspirin production?

Answer 48

Cheaper to produce Less reactive Reactions easier to control