Aldehydes and ketones Flashcards
1
Q
How do you make Tollens’ reagent?
A
- Add silver nitrate solution (colourless) to a test tube
- Add NaOH to same test tube - pale brown precipitate forms
- Add a few drops of ammonia until precipitate dissolves
2
Q
How do you use the Tollens’ reagent?
A
Add aldehyde / ketone to Tollens’ and place in hot water bath (don’t use Bunsen burner as aldehydes / ketones are flammable)
3
Q
What does the reduction of aldehydes and ketones form?
A
Primary and secondary alcohols
4
Q
What can be used to reduce aldehydes and ketones?
A
NaBH₄ dissolved in methanol and water
5
Q
What nucleophile is produced from the reducing agent?
A
H⁻
6
Q
What mechanism occurs when an aldehyde or ketone is reduced?
A
Nucleophilic addition
7
Q
How do you form hydroxynitriles?
A
Potassium cyanide reacting with carbonyl compounds
8
Q
What is the nucleophile used in the production of a hydroxynitrile?
A
:CN⁻ (from HCN or KCN)
9
Q
What are the risks of using KCN?
A
- It is an irritant
- When it reacts with moisture, forms a toxic gas (HCN)
10
Q
How can you reduce the risks of KCN?
A
- Wear gloves
- Wear safety goggles
- Wear a lab coat to prevent contamination
- Use a fume cupboard
