26.1 - Carbonyl Compounds Flashcards Preview

OCR A Chemistry A Level - Chapter 26 > 26.1 - Carbonyl Compounds > Flashcards

Flashcards in 26.1 - Carbonyl Compounds Deck (7)
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1

What is a carbonyl functional group and what are 2 carbonyl compounds?

- C=O

Aldehydes - carbonyl at end of chain

Ketones - carbonyl joined to 2 carbon atoms at the C of C=O

2

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)

3

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

4

How are aldehydes and ketones reduced?

CARBONYL COMPOUNDS + NaBH4

  • Sodium borohydride is a reducing agent 

ALDEHYDES REDUCTION

Aldehyde → 1o alcohol

CH3CH2CH2COH + 2[H] → CH3CH2CH2CH2OH

[H] - reducing agent 

KETONE REDUCTION

Ketone → 2o alcohol

CH3COCH3 + 2[H] → CH3CH(OH)CH3

5

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

6

Describe and explain the carbonyl reduction mechanism.

Nucleophilic addition

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

SEE TEXTBOOK

7

Draw and explain the NACN/H+ mechanism

SEE TEXTBOOK