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Cillit Bang degreasers (2 of 3)

One formulation of Cillit Bang degreaser includes the following active ingredients (the names are non-systematic):

  • A long-chain amine oxide
  • Ethanolamine
  • Glycol ethers

Perfume and, sometimes, dye is also added to make the product more attractive to the consumer.

We’ll look briefly at the chemistry and functions of these below.

Amine oxides

Amine oxides, Figure 13, are surfactants - they have the classic ‘tadpole-shaped’ molecule with a polar head and a non-polar tail (see Detergents and surfactants ). The tail can mix with non-polar grease molecules and the head with polar water molecules thus promoting mixing of grease and water. It also reduces the surface tension of water and allows water to ‘wet’ surfaces more effectively, that is to spread over them.

figure13

Figure 13: Structure of an amine oxide - the length of the hydrocarbon chain may vary (Click to expand)

Ethanolamine

Ethanolamine is a solvent. It has the formula shown in Figure 14.

figure14

Figure 14: Structure of ethanolamine

As well as acting as a solvent, ethanolamine raises the pH of the product, making it more alkaline.

Activity

Question 10

What is the systematic name of ethanolamine?

Answer 10

2-aminoethanol.

Question 11

  • What two functional groups does ethanolamine have?
  • Which of these groups is significantly basic?

Answer 11

  • Primary amine and primary alcohol.
  • Primary amine.

Question 12

  • Write an equation for the reaction of ethanolamine with water to show how ethanolamine makes the product more alkaline.
  • What feature of the ethanolamine molecule makes this reaction possible?

Answer 12

  • H2NCH2CH2OH + H2O arrow H3N+CH2CH2OH + OH-
  • A lone pair of electrons on the nitrogen atom.

Question 13

The oxygen atom of ethanolamine also has a lone pair of electrons. Explain why it is the lone pair of electrons on the nitrogen atom rather than that on the oxygen atom that is donated to a proton.

Answer 13

Nitrogen is less electronegative than oxygen (it has one less proton in its nucleus) so its lone pair is less strongly held and more easily donated to a proton.