P13 Important petrochemical products : ethanoic acid (acetic acid)

Aim: To describe the main uses of ethanoic acid (acetic acid), an important feedstock.

Ethanoic acid (acetic acid) fulfils a role in the organic chemical industry analogous to that fulfilled by sulphuric acid in the inorganic chemical industry.

5 million tons of ethanoic acid (acetic acid) are produced annually.

Production
Bacterial oxidation of ethanol to ethanoic acid (acetic acid) is industrially not feasible for the large scale production of anhydrous ethanoic acid (glacial acetic acid).

Currently three synthesis processes are used :

  • carbon monoxide insertion into methanol :
    ð in the presence of a nickel diiodide catalyst at 200 °C and a pressure of 140-700 bar; or
    ð in the presence of a rhodium-phosphine complex at 150-200 °C and a maximum pressure of 70 bar.
  • aerial oxidation of ethanal (acetaldehyde) in the presence of manganese-, cobalt- or copper ethanoate (acetate) catalysts
  • liquid phase hydrocarbon oxidation of naphtha (mainly butane) in the presence of cobalt-, chromium-, vanadium- or manganese ethanoate (acetate) followed by a complex separation process.
   Uses of ethanoic acid (acetic acid)

In the synthesis of:
ð
 ethenyl ethanoate (vinyl acetate) by the reaction of ethene, ethanoic acid (acetic acid) and oxygen in the presence of a palladium-lithium acetate catalyst.
Poly(ethenyl ethanoate) [poly(vinyl acetate)] is used for :
- the production of polyvinyl acetals
- the production of poly(ethenol) [poly(vinyl
   alcohol)] (PVA) which itself is used in :
  • adhesives for wood, paper and metal
  • toothpaste
  • cosmetic preparations

- chewing gum
- plastics-based paints
- adhesives
ð
 propenoic acid (acrylic acid) by the vapour phase reaction of methanal (formaldehyde) and ethanoic acid (acetic acid) in the presence of a catalyst
  • as a non-aqueous solvent e.g. in the oxidation of 1,4-dimethylbenzene (p-xylene) to benzene-1,4- dicarboxylic acid (terephthalic acid)
  • as an estering reagent e.g. in the synthesis of :
    ð cellulose ethanoate (cellulose acetate)
    ð methyl ethanoate (methyl acetate), used :
       - for the removal of paint,
       - as a solvent for varnishes
    ð ethyl ethanoate (ethyl acetate), used as a
       solvent or coatings, plastics etc.
    ð 2-propyl ethanoate (isopropyl acetate), used as
       a solvent for inks and paints.
    ð butyl ethanoate (butyl acetate), used as a
       solvent for varnishes
  • in the fermentation industry in the synthesis of various amino acids e.g. lysine, glutamic acid etc.