Hydroxynitriles

Question 1

What is a hydroxynitrile?

Answer 1

Hydroxynitriles are compounds with both a hydroxy (-OH) and cyanide (-CN) functional group

Question 2

How can you produce a hydroxynitrile?

Answer 2

They can be prepared from the nucleophilic addition of aldehydes and ketones.

Aldehyde/ketone + NaCN (aq) + H2SO4

Question 3

Where is the negative charge on a cyanide ion?

Answer 3

The negative charge on the cyanide ion is on the carbon atom and not on the nitrogen atom.

Question 4

What is the problem with producing hydroxynitriles?

Answer 4

NaCN is deadly when ingested.
HCN is deadly when inhaled.

Question 5

Why don’t we react aldehydes and ketones directly with HCN?

Answer 5

HCN is incredibly dangerous. It is colourless, volatile (its boiling point is only just above room temperature) and extremely poisonous.

As a result, HCN is very difficult to use safely in a laboratory, and we use NaCN and H2SO4 instead

Question 6

Why is NaCN and H2SO4 used in the production of hydroxynitriles instead of HCN?

Answer 6

When you mix a solution of NaCN with a solution of H2SO4, some of the H+ ions and CN- ions react to form HCN, which can then go on to react with the aldehyde/ketone.

H+ (aq) + CN- (aq) → HCN (aq)

So essentially, in both cases, the reactant is HCN.

The only reason we use NaCN and H2SO4 instead of pure HCN is because this experimental set-up produces HCN in a more controlled and less dangerous manner.