James ClarkDuncan Macquarrie

Handbook of Green Chemistry and Technology

Blackwell Publishing: 2002. 540pp. £149

Across the world, chemical manufacture is unsustainable. Its petroleum-based feedstocks are dwindling and the problems and cost of waste disposal are increasing rapidly. Environmental legislation is becoming ever more restrictive, and the industry has a poor public image. But modern society is almost totally reliant on the products of the chemical industry, and rising living standards in developing countries are increasing demand. We cannot just stop making chemicals. How then is chemical manufacturing to be transformed into a sustainable, non-polluting activity before the price of oil becomes prohibitive?

'Green chemistry' (see Nature 413, 257; 2001) is a relatively new approach to resolving this impasse by removing the hazards of chemical usage through the design of safer manufacturing processes and safer chemicals. It aims to achieve sustainability by increasing the use of biologically derived, renewable feedstocks and by minimizing waste. Such broad aims require a correspondingly wide range of skills; consequently, green chemistry involves toxicology and life-cycle assessment as well as chemistry and process engineering. Reaching these goals also demands unusually close collaboration between academia and industry.

The Handbook of Green Chemistry and Technology is a multi-authored book that aims to illustrate the state of the art across a wide range of green chemistry. It is not a revolutionary manifesto but rather a 'practical and rigorous' collection of reviews with references up to the end of 2000. The 23 chapters are the work of 28 authors from eight different countries but, disappointingly, only four of them are from industry. The coverage is broad, with chapters on most key aspects of green chemistry, including catalysis, solvents, reagents, life-cycle assessment and unconventional technologies such as ultrasound or microwaves for promoting reactions.

The chapter on 'Hydrogen Peroxide in Waste Minimization' quotes an industrial chemist who maintained that “almost all the chemistry really used was at least 50 years old”. This is a key problem of green chemistry. Often, what is new is the way that reactions are used, rather than the reactions themselves. The most enlightening chapters are those such as 'Waste Minimization in Pharmaceutical Process Development', in which particular examples explain the logic and science behind cleaner chemistry. Other chapters fail to highlight the 'green' aspects of their topic and are little more than convenient summaries of catalysis or technology. The chapter on 'Green Chemistry in Practice' is the only one to tackle the problems of non-petroleum feedstocks in any detail. Processing such feedstocks is an area in which biocatalysis is likely to have a major role, so it is disappointing to find biocatalysis discussed in only 21 pages, hardly more than are devoted in another chapter to the solid catalysts from a single company.

There is a useful introduction to electrochemistry, albeit with an unnecessary overlap with the chapter on fuel cells, and a succinct description of the use of high-pressure (supercritical) carbon dioxide as an environmentally less harmful replacement for conventional solvents. Ionic liquids — salts that melt below room temperature — are also being widely promoted as alternative solvents. Although these liquids are mentioned briefly in the context of phase-transfer catalysis, they warrant a chapter of their own. The book has an intriguing, abstract photograph on the cover, but readers have to wait until page 367 to discover that it is a “view of sheared thin films in a spinning disc reactor”. This reactor is briefly covered in a chapter on process intensification, which involves making chemicals in small, high-throughput equipment — another subject that deserved more space. The final chapter, on the extraction of green products, ends with the intriguing statement that the extraction of green (unroasted) coffee beans with superheated water “produced a brown liquid with the aroma of coffee”.

Overall, the book is a useful resource for those working in the area; it is not a guide for the novice green chemist. But it does show that there is more to green chemistry than merely using hydrogen peroxide to bleach your waste water so that people do not notice when you pour it into a river.