WIM - Aldehydes and Ketones

Question 1

What is the differenc between an aldehyde and a ketone?

Answer 1

Aldehydes have their carbonyl group at the end of their carbon chain
Ketnes have their carbonyl group in the middle of their carbon chain

Question 2

Describe the setup required for a reflux reaction

Answer 2

A round bottomed flask containing the substance and some anti-bumping granules, above a heat source whilst connected to an open top, vertical Liebig condenser

Question 3

Name the mechanism by which a CN⁻ ion reacts with an aldehyde or ketone

Answer 3

Nucleophilic Addition

Question 4

What functional group do Aldehydes and ketones both contain?

Answer 4

Carbonyl (C=O)

Question 5

Give the reagents and conditions required to make an aldehyde and what is formed if they are oxidised further?

Answer 5

Primary alcohol heated with acidified potassium dichromate (VI) and distilled

A carboxylic acid will be produced if the aldehyde is oxidised further

Question 6

Give the reagents and conditions required to make a ketone and what is formed if they are oxidised further?

Answer 6

A secondary alcohol heated under reflux with acidified potassium dichromate (VI)

Ketones are very difficult to oxidise further

Question 7

Give an example of a strong oxidising agent which could oxidise a ketone and how would it be oxidised?

Answer 7

Potassium Manganate (VII) destructively oxidises ketones (breaks C-C bonds)

Question 8

State whether Hydrogen cyanide is a strong or weak acid and why

Answer 8

It’s a weak acid because it only partially dissociates in water to produce H⁺ and CN⁻ ions

Question 9

Give the formula for a cyanohydrin group and give another name for it

Answer 9

R₂C(OH)CN

AKA hydroxynitriles

Question 10

How are cyanohydrin groups formed?

Answer 10

The nucleophilic addition of a CN⁻ ion to a carbonyl group