Chapter 26 - Carbonyls and carboxylic acids

Question 1

What is a carbonyl group?

Answer 1

C=O

Question 2

What is an aldehyde?

Answer 2

The carbonyl functional group is found at the end of the chain

Question 3

What is a ketone?

Answer 3

The carbonyl group is found in the middle of the chain

Question 4

Suffix for aldehyde

Answer 4

-al

Question 5

Suffix for ketone

Answer 5

-one

Question 6

What is produced when aldehydes are refluxed with acidified dichromate ions?

Answer 6

Carboxylic acids

Question 7

How do you produce carboxylic acids from aldehydes?

Answer 7

Reflux the aldehyde with acidified dichromate ions

Question 8

What is produced when ketones are refluxed with acidified dichromate ions?

Answer 8

No reaction

Question 9

What two bonds are found in the C=O bond?

Answer 9

Sigma and pi bonds

Question 10

Why do carbonyls not react in the same way as alkenes?

Answer 10

The C=O bond is polar

Question 11

Why do nucleophiles react with carbonyls?

Answer 11

There is a positively charged carbon atom

Question 12

Which compound is used as a reducing agent?

Answer 12

NaBH4 - must be heated

Question 13

What is produced when aldehydes are reduced?

Answer 13

Primary alcohols

Question 14

How are primary alcohols produced?

Answer 14

Reduction of aldehydes

Question 15

What is produced when ketones are reduced?

Answer 15

Secondary alcohols

Question 16

Why is the reaction of carbonyls and HCN useful?

Answer 16

It is a way of extending the carbon chain

Question 17

What conditions are needed for carbonyls to react with HCN?

Answer 17

Sodium cyanide and sulphuric acid

Question 18

Describe the mechanism of the nucleophilic addition of carbonyls with NaBH4

Answer 18

The lone electrons from the H- ion is donated to the carbocation
This forms a dative covalent bond
The pi bond breaks by heterolytic fission, forming an intermediary
The oxygen atom of this molecule donates an electron pair to a hydrogen atom in a water molecule
This forms an alcohol

Question 19

Describe the mechanism of the reaction of carbonyls with NaCN

Answer 19

The lone pair of electrons on the CN- is donated to the carbocation of the carbonyl, forming the dative covalent bond
The pi bond in the C=O bond breaks by heterolytic fission
The intermediate donated an electron pair to a hydrogen ion

Question 20

Which compound is used to identify the a carbonyl group?

Answer 20

2,4-DNP

Question 21

What is the positive test for a carbonyl group?

Answer 21

An orange precipitate forms

Question 22

Which test distinguishes between aldehydes and ketones?

Answer 22

Using Tollens’ reagent

Question 23

What will happen when Tollens’ reagent is mixed with an aldehyde?

Answer 23

A silver mirror effect is produced

Question 24

What will happen when Tollens’ reagent is mixed with a ketone?

Answer 24

No reaction

Question 25

Why are carboxylic acids soluble?

Answer 25

The C=O bond and O-H bonds are polar so form hydrogen bonds with water molecules

Question 26

Up to what number of carbon atoms are carboxylic acids soluble?

Answer 26

4

Question 27

Why does the solubility of carboxylic acids decrease with increasing chain length?

Answer 27

The non-polar carbon chain has a greater effect on solubility than the polar bonds

Question 28

What strength are carboxylic acids?

Answer 28

Weak

Question 29

What is produced when carboxylic acids react with metals?

Answer 29

Hydrogen gas and the carboxylate salt

Question 30

What is produced when carboxylic acids react with metal oxides?

Answer 30

A salt and water

Question 31

What is produced when carboxylic acids react with alkalis?

Answer 31

A salt and water

Question 32

What is produced when carboxylic acids react with carbonates?

Answer 32

Carbon dioxide, water and a salt

Question 33

How can you test for a carboxylic acid?

Answer 33

Add carbonate | Carboxylic acids are the only organic compounds acidic enough to react with them

Question 34

What are the four carboxylic acid derivatives?

Answer 34

Ester Acyl chloride Acid anhydride Amide

Question 35

How to name an ester

Answer 35

The carboxylic acid becomes the -oate | The alkyl chain attached then becomes the first word

Question 36

How to name an acyl chloride

Answer 36

Remove the -oic acid suffix from the carboxylic acid an replace with -oyl chloride

Question 37

What is an acid anhydride?

Answer 37

Water is removed from two carboxylic acid molecules

Question 38

Describe the process of esterification

Answer 38

An alcohol is warmed with a carboxylic acid | H2SO4 catalyst

Question 39

Ester functional group

Answer 39

COO

Question 40

Acyl chloride functional group

Answer 40

COCl

Question 41

Amide functional group

Answer 41

CONH2

Question 42

Describe the acid hydrolysis of esters

Answer 42

Ester is heated under reflux with dilute acid catalyst | Ester is hydrolysed into a carboxylic acid and an alcohol

Question 43

Is acid hydrolysis or alkaline hydrolysis reversible?

Answer 43

Acid

Question 44

Describe the alkaline hydrolysis of esters

Answer 44

Ester heated under reflux with hydroxide ions (e.g. NaOH) | Alcohol and sodium salt formed

Question 45

What compound is used to make acyl chlorides?

Answer 45

SOCl2

Question 46

What two gases are created when an acyl chloride is made?

Answer 46

SO2 and HCl

Question 47

How do esters react with nucleophiles?

Answer 47

They retain the C=O bond but lose the chloride ion

Question 48

What is produced when acyl chlorides react with alcohols?

Answer 48

Esters

Question 49

What is produced when acyl chlorides react with phenols?

Answer 49

Phenyl esters

Question 50

Which compound is made when an acyl chloride forms either an ester or carboxylic acid?

Answer 50

HCl

Question 51

What is produced when carboxylic acids react with water?

Answer 51

Carboxylic acids

Question 52

What is produced when an acyl chloride reacts with ammonia?

Answer 52

Primary amide and NH4Cl

Question 53

What is produced when an acyl chloride reacts with an amine?

Answer 53

Secondary amide and the chloride salt