The Greening of Chemistry

Professor James Clark, Director Green Chemistry Network
University of York

Chemistry can be made greener, cleaner and more efficient by ensuring that it is economically sound, environmentally compatible and socially acceptable. We need to provide a growing world population with the necessary food and healthcare and an acceptable standard of living in a way that does not harm the planet.

Green Chemistry is now accepted worldwide as the term to describe the development of more environmentally friendly, sustainable chemical products and processes. It can be considered as a set of reductions.

It requires fundamental changes in the way we practice chemistry, how we teach chemistry and our attitude towards the use of raw materials and chemical products. The drive towards clean technology in the chemical industry, with an increasing emphasis on the reduction of waste at source, provides unprecedented opportunities for innovation and new technology. Mature chemical processes that are often based on technology developed in the first half of the 20^th Century, may no longer be acceptable in these environmentally conscious days. "Enviro-economics" and the "triple bottom line" of economic, environmental and social benefit will be the driving forces for new products and processes. The "costs of waste" are rapidly escalating thanks to new and tougher legislation and an increasingly hostile general public.

Making Green Chemistry Happen

The rapidly growing interest in Green Chemistry is witnessed by a growing number of national and transnational initiatives including networks, awards, schemes, conferences and educational programmes. The two principle initiatives in the UK are the Royal Society of Chemistry's Green Chemistry journal and the Green Chemistry Network.

Contacts: Professor James Clark jhc1@york.ac.uk

Mr Mike Lancaster ml13@york.ac.uk

Dr Helen Coombs hvc1@york.ac.uk

The GCN promotes awareness and facilitates education, training and the practice of green chemistry in industry academe and schools. The effective incorporation of the ideas of Green Chemistry throughout the educational system including continuing education are vital not only to the better practice of chemical manufacturing in the future but also to help to reverse the decline in applications to read chemistry at University. Real progress is now being made in this with a new GCSE resource book, a new Faraday partnership "Crystal" which will facilitate technology transfer, and new University courses.

Green Chemical Manufacturing

How can we improve the efficiency of a chemical process and reduce its environmental impact? This requires the availability of an ever-growing toolkit of clean technologies that can be applied individually or more frequently in combination (e.g. through collaboration between chemists and chemical engineers) to green a chemical process.

Measuring Greeness

Yield and selectivity are commonly employed to define the efficiency of a chemical reaction but these are not especially useful in measuring the amount of waste generated in a chemical manufacturing process. From an environmental (and increasingly economic) point of view it is more important to know how many atoms of the starting materials are converted to the desired product. Atom economy is one way of measuring the greeness of a chemical process. It can be done theoretically, before any chemistry is done, chemists can evaluate alternative routes. Yield and selectivity are important but if a particular route is only giving a maximum of 20% atom utilisation it will still produce an unacceptable level of waste. Many traditional and still widely used chemical reactions including halogenations and oxidations, as well as reactions employing solvents and reagents, have low atom utilisations and this is reflected in the relatively large amounts of waste generated by the higher value end of the manufacturing industries. Waste to product ratios of much greater than 10 are not uncommon!

A Greener Future

What will a chemical manufacturing company look like in the future? The dirty and threatening skyscraper-sized industry of the past will no longer be acceptable. Excessive storage and transport of hazardous material will also be increasingly avoided. The future manufacturing company should be:

• Small and flexible, designed to manufacture exactly what is required when it is required
• Giving zero emissions, recycling "unused atoms" and producing only biodegradable waste
• Making full use of local resources including energy sources (solar, water, wind etc), crops as raw materials, clays as catalysts, etc
• Producing safe, long lifetime products that at the end of their lifetime are either returned to the supplier or are biodegradable

These are challenging but also exciting days for chemistry. The industry has to change to meet the new more complex demands of society. To achieve this we must influence all aspects of the subject - education, research and application. There are almost unlimited opportunities to exploit new technologies and to improve the world's living standards while not threatening its future. As Mahatma Gandi said "There is enough for everybody's need in this world but not enough for everybody's greed".