What is a carbonyl functional group and what are 2 carbonyl compounds?
Aldehydes - carbonyl at end of chain
Ketones - carbonyl joined to 2 carbon atoms at the C of C=O
How doe aldehydes oxidise?
They oxidise to cabroxylic acids under reflux w/ K2Cr2O7/H2SO4
(Ketones do not oxidise - good way to distinguish between aldehydes and ketones)
What occurs during carbonyl nucleophilic addition?
- C=C non-polar, C=O is polar
- C=O polarity attracts nucleophiles to atack
- Nucleophilic addition as opposed to electropgilic addition of C=C
How are aldehydes and ketones reduced?
CARBONYL COMPOUNDS + NaBH4
- Sodium borohydride is a reducing agent
Aldehyde → 1o alcohol
CH3CH2CH2COH + 2[H] → CH3CH2CH2CH2OH
[H] - reducing agent
Ketone → 2o alcohol
CH3COCH3 + 2[H] → CH3CH(OH)CH3
What happens when you add HCN to a carbonyl compound?
- HCN adds across C=O of aldehydes & ketones
HCN: colourless, poisonous liquid
- To make HCN
2NaCN + H2SO4 → 2HCN + Na2SO4
- Useful reaction to increase carbon chain length
- 2NaCN + H2SO4 → 2HCN + Na2SO4
Describe and explain the carbonyl reduction mechanism.
1. Hydrogen lone pair on hydride ion attracted to C (partially positive).
2. π-bond breaks b heterolytic fission
3. Dative covalent bond forms
4. Intermediate (-ve charge) is protonated
Draw and explain the NACN/H+ mechanism