Carbonyl Compounds

Question 1

Primary OH oxidation

Answer 1

Oxidised to aldehyde, then to carboxylic acid

Mix with H2SO4 (H+ source) and K2Cr2O7^2- (Cr2O7^2- source)

Question 2

Secondary OH oxidation

Answer 2

Ketone

Heat with H+/Cr2O7^2-

Question 3

Reduce carbonyls

Answer 3

Via reducing agent with hydride H- ion

E.g NaBH4 and LiAIH4 (they only reduce C=O, not C=C

Question 4

Nucleophilic addition

Answer 4

e- deficient C attracts nucleophiles, allowing an addition reaction to occur across C=O

Aldehydes an ketones OH via NaBH4 or LiAIH4 are nucleophilic addition

Question 5

Nucleophilic addition of HCN

Answer 5

Occurs in presence of NaCN- and sulfuric acid

Added across -als and -ones →hydroxynitrile

Cyanide ions presence essential

Question 6

HCN uses

Answer 6

Results in a nitrile. Can increase C-C chain
Can be:
Hydrolysed by water in dilute acid to make carboxylic acid
Reduced by Na in ethanol to make amine

Question 7

Test for carbonyl

Answer 7

In Brady’s reagent.

Produce orange-yellow crystals via a condensation reaction which ID C=O

Question 8

Aldehyde test

Answer 8

• al+Tollen’ reagent →silver mirror
• al+Fehling’s or Benedict’s solution →brick-red precipitate of Cu2O
• al+ H+/Cr2O7^2-. Orange Cr2O7^2- →green Cr^3+

Question 9

Test for methyl in carbonyl

Answer 9

Mix with I2 in OH-(aq) →pale yellow crystals of ChI3