Carbonyl Compounds

Question 1

Give the notation of aldehydes

Answer 1

RCHO

Question 2

Give the notation of ketones

Answer 2

RCOR

Question 3

How do you name aldhydes

Answer 3

Add al onto alkyl

Question 4

How do you name ketones

Answer 4

Add one onto alkyl

Question 5

How do you differentiate between aldehydes and ketones via a test

Answer 5

Add acidfied Potassium dichromate

Only aldehydes will oxidise causing colour change from orange to green

Question 6

By what mechanism do carbonyl react, why

Answer 6

Nucleophillic addition

Negetive oxygen

Double bond= addition

Question 7

Why do carbonyl react differently to alkenes

Answer 7

The oxygen is more electronegetive

Carbon is partially positive so is attacked by nucleophile

Unlike c=c

Question 8

How are carbonyls reduced

Answer 8

H- acts as nucleophile form NaBH4

Reduces to original alcohol

Question 9

What are the dangers of HCN

Answer 9

It’s a poisonous gas

Very volatile

Question 10

Why might HCN be used?

Answer 10

To increase carbon chain length

Question 11

Describe the reaction between a nucleophile and a carbonyl

Answer 11

Nucleophile attacks partially positive carbon by donating a pair of electrons forming dative bond

Pi bond in c=o breaks by heterolytic fission so oxygen has a lone pair and is negetive

Lone pair on O2 os donate to a H+ in acid or H2O

Question 12

Describe the qualitative test for a carbonyl bond

Answer 12

2,4-DNP / 2,4-DNPH/ Brady reagent

Yellow to orange

Preciptitae formed.

Question 13

How do you determine the carbonyl used once you’ve added 2,4-DNP

Answer 13

Recrystalise and purify precipitate

Test melting point and compare to data base

Question 14

Why does care need to be taken when using 2,4-DNP

Answer 14

It’s hazardous

Friction or a blow will cause explosion

Question 15

How do you differentiate between a ketone and aldehyde without reflux

Answer 15

Use tollens reagent

Oxidses aldehydes to carboxylic acid

Silver mirror produced

Question 16

How is tollens reagent made and why

Answer 16

Short self life

Silver nitrate, aqueous ammonia and sodium hydroxide

Question 17

What are the results for addition of Fehlings solution

Answer 17

Aldehyde= blue to red

Ketone = not change

Question 18

How do you name carboxylic acids

Answer 18

Place oic acid at end of alkyl name

Question 19

Are carboxylic acids soluble, why

Answer 19

Yes

Hydrogen bonds with water molecules via OH or c=o

Question 20

What occurs to the solubility of carboxylic acids as carbon chain increases, why

Answer 20

Solubility decreases and non-polar chain has greater effect

Question 21

What do carboxylic acids undergo redox with, what is produced

Answer 21

Metals

Carboxylate salt from Carboxylate ion

Question 22

What substances react with carboxylic acids in neutralisation

Answer 22

Metal oxides and carbonates and alkalis

Question 23

What is produced when metals oxides reacts with a carboxylic acid

Answer 23

Salt water

Question 24

What is produced when alkalis reacts with a carboxylic acid

Answer 24

Salt water

Question 25

Why might you not observe anything when a carboxylic acid and alkali react

Answer 25

They are both in solution

Question 26

What is produced when carbonates reacts with a carboxylic acid

Answer 26

Salt water carbon dioxide

Question 27

How do you distinguish between carboxylic acids and phenols

Answer 27

Only carboxylic acids are acidic enough to react with carbonates and produce co2

Question 28

What are carboxylic acid derivatives

Answer 28

A compound that can be hydrolysed to produce the parent carboxylic acid

Question 29

What are the carboxylic acid derivatives

Answer 29

Esters Acyl chlorides Acid anhydrides Amides

Question 30

What do all carboxylic acid derivatives contain

Answer 30

Acyl group Electronegetive atom

Question 31

How do you name esters

Answer 31

Alkyl of alcohol chain Parent carboxylic acids Oic to oate

Question 32

How do you name acyl chlorides

Answer 32

Oic to oyl chloride Use parent carboxylic acid

Question 33

How are acid anhydrides produced

Answer 33

Condensation reaction between two carboxylic acids

Question 34

State the reactants, products and reagents for esterification

Answer 34

Alcohol and carboxylic acid Ester and water Concentrated sulphuric acid Reflux

Question 35

Describe how you would do esterification

Answer 35

Add acid carboxylic acid and alcohol to test tube Shake and warm Cool and add sodium carbonate to remove excess carboxylic acid

Question 36

What are the different methods of hydrolysis of esters

Answer 36

Via acids, alkaline

Question 37

Describe the different methods of esterification

Answer 37

Alcohol and carboxylic acid Acid anhydrides or acyl chloride and alcohol or phenol

Question 38

Describe acid hydrolysis or esters

Answer 38

Reverse of esterification Reflux with Dilute sulphuric acid Produce alcohol and carboxylic acid

Question 39

Describe alkaline hydrolysis of esters

Answer 39

Saponification Irreversible Reflux with OH- Carboxylate salt and alcohol formed

Question 40

How do you prepare and acyl chloride

Answer 40

React carboxylic acid and thionyl chloride Produce SO2 and Hcl gas which are toxic

Question 41

What do acyl chloride react with

Answer 41

Nucleophile Alcohols and phenol and water

Question 42

What does the hydrolysis or acyl chlorides require and produce

Answer 42

Requires water Carboxylic acid and Hcl Very violent

Question 43

Which is more reactive: Acyl chlorides Acid anhydrides

Answer 43

Acyl chlorides

Question 44

When might acid anhydrides be used

Answer 44

Instead of acyl chlorides in esterification and production of carboxylic acids via hydrolysis Less reactive and No Hcl

Question 45

What does the reaction between acyl chloride and ammonia produce

Answer 45

Primary amide and ammonium chloride