Carboxylic acids
 

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Carboxylic acids RCOOH.

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Carboxylic acid → ester
Reagents: alcohol and a little concentrated sulphuric acid catalyst
Conditions: heat under reflux

This is an equilibrium reaction.

CH3COOH + CH3CH2OH   CH3COOCH2CH3 + H2O


Alkanes & alkenes
Arenes
Halogenoalkanes
Alcohols
Aldehydes and ketones

Carboxylic acids
Acyl chlorides
Amines
Nitro compounds
Nitriles
Amides

Ester hydrolysis (equilibrium)
Reagents: dilute sulphuric acid
Conditions: heat under reflux

This gives an equilibrium mixture:

CH3COOCH2CH3 + H2O     CH3COOH + CH3CH2OH


Ester hydrolysis (non-equilibrium)
Reagents: dilute aqueous sodium hydroxide
Conditions: heat under reflux

This gives complete hydrolysis to the sodium salt of the acid. The free acid is formed by acidification with dilute hydrochloric acid, which is a stronger acid than the carboxylic acid:

CH3COOCH2CH3 + NaOH → CH3COO- Na+ + CH3CH2OH

CH3COO- Na+ + HCl → CH3COOH + NaCl


 

Carboxylic acid (as its ester) → alcohol
Reagents: lithium aluminium hydride, followed by water.
Conditions: Direct reduction of the acids is difficult, and they are usually converted into an ester first. This is then heated under reflux with lithium aluminium hydride in dry ether, the mixture cooled, and followed by the cautious addition of water in the fume cupboard since hydrogen is evolved.

The reducing agent can be indicated by [H] in this case.

CH3CH2COOCH2CH3 + 4[H]  " CH3CH2CH2OH + HOCH2CH3


 

Carboxylic acid → acid (acyl) chloride
Reagents: phosphorus pentachloride
Conditions: r.t.

CH3COOH + PCl5 → CH3COCl + HCl + POCl3


 

JRG Beavon 2002