2.13a: demonstrate an understanding that the processes in the chemical industry are being reinvented to make them more sustainable (‘greener’) by: (i) changing to renewable resources (ii) finding alternatives to very hazardous chemicals (iii) discovering catalysts for reactions with higher atom economies, eg the development of methods used to produce ethanoic acid based on catalysts of cobalt, rhodium and iridium (iv) making more efficient use of energy, eg the use of microwave energy to heat reactions in the pharmaceutical industry (v) reducing waste and preventing pollution of the environment

Changing to renewable resources:

• some raw materials can be used as an alternative to crude oil
• eg. ethanol can be made from sugar cane by fermentation, and dehydration of the ethanol can make ethene, from which poly(ethene) can be polymerised
• eg. water bottles are made from poly(lactic acid) which is made in the breaking down of carbohydrates by bacteria. The lactic acid then undergoes condensation polymerisation to form PLA, which is widely recycled and is biodegradable
• renewable energy sources can be used instead of fossil fuels to generate the energy needed for chemical reactions in industry
• eg. wind power, solar power, geothermal power, etc.

Finding alternatives to very hazardous chemicals:

• using alternative reagents that are less toxic and designing synthetic routes that do not require toxic intermediates and solvents
• eg. Zoloft was initially synthesised in a four-step process using several harmful VOCs (volatile organic compounds). A new route was designed with only two steps and less toxic ethanol as a solvent
• eg. CFCs were once widely used in refrigerators and aerosols, but were found to damage the ozone layer, leading to an increase in rates of skin cancer. Now, less harmful HFCs are used, but they are still greenhouse gases

Discovering catalysts for reactions with higher atom economies:

• new catalysts may allow existing reactions to occur at lower temperatures and yields, to raise atom economies and yields
• catalysts tend to provide cleaner energy profiles and so higher yields with less waste
• catalysts are not used up, so can be recycled and used over and over again

Making more efficient use of energy:

• use reactions that occur at low temperatures and pressures
• utilise any energy released by the reaction
• catalysts are key in saving energy as they allow reactions to occur at lower temperatures
• small-scale chemical reactions can now be heated using microwave energy, giving faster reaction times and cleaner reaction profiles

Reducing waste and preventing pollution of the environment:

• reactions with high atom economies, high yields and cleaner reaction profiles
• waste products should be recycled if possible