26.1 Compounds containing the carbonyl group

Question 1

What is a carbonyl group

Where is it found

Answer 1

It is a C=O bond

This is present in aldehydes and ketones

Question 2

What is the difference between aldehydes and ketones

How are they names

Answer 2

Aldehydes have the carbonyl group at the end whilst ketones have it in the middle

Aldehydes have suffix al whilst ketones have suffix one

Eg propanal vs propanone

Question 3

Describe boiling points of aldehydes and ketones

Answer 3

The C=O bond is very polar so permanent dipole-dipole forces are present throughout the molecules

So the boiling points are higher than with alkanes/alkenes of the same mr

However they’re still lower than with alcohols which have hydrogen bonding occurring between the molecules

Question 4

Are aldehydes and ketones soluble in water

Answer 4

. Shorter chain ones are so mix completely with water because hydrogen bonds form between the oxygen of the carbonyl compound and water

However as length of carbon chain increases, they get less soluble

Question 5

Are carbonyl compounds reactive?

Answer 5

Almost all reactions involve the C=O bond
You may think that because the C=O bond is strong it makes it unreactive but thats not true

This is because the big difference in electronegativity between the C f+ and O f- makes the bond very polar

So nucleophillic agents attack the C f+

Also since there is a double bond, addition reactions can occur as it is unsaturated