esters and acid anhydrides

structure: substitute an organic group for the H in acids

Nomenclature (naming): first part from alcohol, second part from acid e.g methyl ethanoate = CH3COOCH3

e.g propanoic acid + methanol —> methyl propanoate + water

making esters from carboxylic acid = add alcohol and conc H2SO4 (makes water as well)

Hydrolysis of esters

  • esters are unreactive compared with acids and acyl chlorides

there are 2 types of hydrolysis reactions that can take place, acid hydrolysis and alkali hydrolysis

acid hydrolysis example (breaking of ester chain)=

CH3COOCH3 + H2O ⇌ CH3COOH + CH3OH

products: carboxylic acid and alcohol

Alkali hydrolysis example (breaking ester change)=

CH3COOCH3 + NaOH —> CH3COO- Na+ + CH3OH

  • very soluble in water

  • products= soluble sodium salt and alcohol (salt can then be used to make salts via saponification)

Uses of esters:

  • solvents

  • adhesives

  • perfumes

  • fruity flavours

  • soaps

Acid anhydrides

group display:

formed by dehydrating a carboxylic acid

reaction paths of of acid anhydrides: