26.1 Carbonyl Compounds

Question 1

What is a carbonyl compound?

Answer 1

any molecule containing the functional group C＝O

Question 2

What is a carbonyl group?

Answer 2

C＝O

Question 3

Name this molecule:

Answer 3

3-methylbutan-2-one

Question 4

Name this molecule:

Answer 4

propanal

Question 5

How are carbonyl compounds reduced?

Answer 5

+ NaBH₄, which acts as a reducing agent by donating H atom

Question 6

Write a general word equation for the reaction between an aldehyde + NaBH₄

Answer 6

aldehyde + [H] ⟶ primary alcohol

Question 7

Write a general word equation for the reaction between a ketone + NaBH₄:

Answer 7

ketone + 2[H] ⟶ secondary alcohol

Question 8

Why can ketones not be oxidised?

Answer 8

(oxidation is the loss of electrons, either by gaining oxygen or losing hydrogen)

ketones cannot lose an electron in the form of a hydrogen atom, or gain oxygen

Question 9

Under what conditions are aldehydes oxidised?

Answer 9

acidified potassium dichromate ions

Question 10

Why is the gain of hydrogen considered reduction?

Answer 10

reduction = reduction in oxidation number due to gain of electrons

H atom contains 1 electron

gaining a H atom therefore means the molecule has gained 1 electron.

Question 11

Carbonyl compound + HCN ⟶

Answer 11

hydroxynitrile

Question 12

Why is HCN, hydrogen cyanide, not used in the lab during the reaction between carbonyl compounds + HCN?

Answer 12

HCN = highly toxic liquid boiling just above room temperature

therefore sodium cyanide + sulfuric acid used instead.

Question 13

What is the name of the reaction mechanism when aldehydes are reduced when reacting with NaBH₄?

Answer 13

nucleophilic addition