17b - Carbonyl Compounds Flashcards
1
Q
Bonding in carbonyls
A
- Can form London forces and Permanent dipole-dipole interactions
- Cannot form hydrogen bonds with each other
2
Q
Solubility of carbonyls
A
- lower carbonyls can form hydrogen bonds with water so they are soluble to some extent
- Solubility decreases as chain length increases as the hydrocarbon part becomes more significant
3
Q
Aldehyde + Fehling’s solution
A
- Deep blue solution -> red precipitate
4
Q
Aldehyde + acidified potassium dichromate
A
- orange to green as Cr becomes reduced
5
Q
Aldehyde + Tollens’ reagent
A
- Colourless –> silver mirror
6
Q
Aldehyde + LiAlH4 (dry ether)
A
- Primary alcohol is formed
7
Q
Ketone + LiAlH4 (dry ether)
A
- Secondary Alcohol is formed
8
Q
In equations what are oxidising agents and reducing agents represented as?
A
- Oxidising : [O]
- Reducing : [H]
9
Q
What does the Iodine in presence of reaction with carbonyl compounds show?
A
- Presence of a (CH3CO) group
- can give false results as some alcohols contain CH3COH which can react
10
Q
What is the qualitative test for a carbonyl compound? and how can we identify the compund?
A
- 2,4-DNPH
- Dry the derivative and measure its melting temperature
- Compare with data book values
11
Q
Why when you add KCN in the presence of HCN it would produce a racemic mixture? (Nucleophilic addition)
A
- Forms a racemic mixture as the C=O is planar and can be attacked from both sides
