4.2 The Principles of Green Chemistry

The 12 principles of Green Chemistry provide a basis with which to assess the sustainability of a chemical manufacturing process or procedure. These are illustrated in Figure 5

Figure 4 The 12 principles of Green Chemistry

Show description|Hide description

The figure illustrates the 12 principles of green chemistry. A table is titled ‘Green Chemistry’, next to an image of a round bottom flask containing a green liquid and a green leaf. The table has three columns and four rows depicting the following twelve principles:

1. Prevent waste.
2. Maximise atom economy.
3. Less hazardous chemical synthesis.
4. Safer chemicals and products.
5. Safer solvents and reaction conditions.
6. Increase energy efficiency.
7. Use renewable feedstocks.
8. Avoid chemical derivatives (protect groups).
9. Use catalysts.
10. Design chemicals and products to degrade after use.
11. Analyse in real time to prevent pollution.
12. Minimise potential for accidents.

Figure 4 The 12 principles of Green Chemistry

You can find out a little more about each of the principles below.

Let’s return to the 2-chloropropane synthesis and put its “green credentials” to the test.

First a reminder of the reaction.

Figure 5Synthesis of 2‑phenylpropane

Less obvious, but to this you could add:

Principle 6 is violated, since a large amount of energy is required especially during removal of the excess benzene.

Principle 12 is not obeyed as benzene is highly flammable.

This is by no means a complete list, but it does give you a flavour of the types of consideration involved.

In fact there is a greener way of producing 2‑phenylpropane which you’ll look at next.