Learn how to identify tertiary alcohols
In a primary alcohol, the carbon which carries the -OH group is only attached to one alkyl group.
In a secondary alcohol, the carbon with the -OH group attached is joined directly to two alkyl groups, which may be the same or different.
In a tertiary alcohol, the carbon atom holding the -OH group is attached directly to three alkyl groups, which may be any combination of same or different.
Learn reactions and observations with potassium ca
Carboxylic acids can be identified by using potassium carbonate
- Solid dissolves
Chemical tests on carbonyl compounds
Detecting a carbonyl group
- use 2,4-DNPH (Bradys reagent)
- If added to an aldehyde or ketone a yellow or orange precipitate will be formed.
- confirms the presence of a C=O bond.
Aldehyde or Ketone?
- Tollens reagent added
- Oxidise aldehydes to carboxylic acids
- Aldehyde = silver precipitate / silver mirror
- Ketone = no reaction
Oxidisation of alcohols
Alcohol to aldehyde
CH3CH2OH + [O] --> CH3CHO + H2O
Aldehyde to carboxylic acid
CH3CH2OH + 2[O] --> CH3COOH + H2O
Alcohol to ketone
CH3CHOHCH3 + [O] --> CH3COCH3 + H2O
ORANGE TO GREEN
What is important when carrying out oxidation reactions to ensure correct observations?
Excess of reagent to ensure you observe the full colour change or reaction that is taking place.
Hydrolysis of esters
Acid hydrolysis of esters:
- Heated under reflux with dilute sulfuric acid or dilute hydrochloric acid.
CH3COOCH2CH2CH3 + H2O --> CH3COOH + HOCH2CH2CH3
Ester + Water --> Carboxylic acid + Alcohol
Alkaline hydrolysis of esters:
- Sodium hydroxide is refluxed with the ester.
CH3CH2COOCH2CH3 + NaOH --> CH3CH2COO-Na+ + HOCH2CH3
Ester + Sodium hydroxide --> sodium salt + alcohol