Organic - 3.8 Aldehydes & Ketones

Question 1

What do aldehydes oxidise to?

Answer 1

Carboxylic Acids

Question 2

What do aldehydes reduce to?

Answer 2

Primary alcohols

Question 3

Can ketones be oxidised?

Answer 3

No

Question 4

What is the result of Benedict’s/fehlings and aldehyde

Answer 4

Blue to brick Red

Question 5

What is the result of benedicts/fehlings and ketone?

Answer 5

Stays blue

Question 6

What is the result of tollens and aldehyde?

Answer 6

Silver mirror

Question 7

What is the result of tollens and ketone?

Answer 7

Stays clear

Question 8

What type of reaction reduces aldehydes and ketones to alcohols?

Answer 8

Nucleophilic addition

Question 9

What is a key reagent in the reduction of carbonyls?

Answer 9

Sodium borohydride

Question 10

In what form is the cyanide likely to be in a nucleophilic addition reaction?

Answer 10

KCN

Question 11

Why will a racemic mixture form from the addition of cyanide to a carbonyl?

Answer 11

It is the same likelihood that each enantiomer will form

Question 12

Which hydride is used in the nucleophilic addition reaction?

Answer 12

Sodium Borohydride NaBH4

Question 13

What reactant is required to form a hydroxynitrile from an aldehyde?

Answer 13

KCN

Question 14

What are ketones reduced to?

Answer 14

Secondary alcohol

Question 15

What forces are there between molecules of aldehydes and molecules of ketones?

Answer 15

Van der waals forces of attraction between molecules.

Permanent dipole dipole attractions between polar carbonyl groups on different molecules.

Question 16

Why do aldehydes and ketones mix well with water?

Answer 16

The polar carbonyl groups are able to form hydrogen bonds with water molecules.