Sep 10, 2023

From Green Chemistry to Sustainable Chemistry to Regenerative Chemistry?

Updated: Sep 11, 2023

From Green Chemistry to Sustainable Chemistry to Regenerative Chemistry?

Chemistry in general has got a very bad reputation, partly deserved, partly not. When people are asked what they associate with the terms chemistry and physics two very different images manifest themselves.

Whereas physics is associated with high-tech computers, shiny spaceships, and Albert Einstein's friendly face [1], chemistry is generally associated with disasters (Seveso [2], Bhopal [3], etc.) and environmental contamination and the suffering of humans and animals alike resulting from these.

That physics is also responsible for nuclear disasters (Chernobyl [4], Fukushima [5], etc.) not to mention nuclear weapons is another matter.

Life, as we know it, is chemistry. A rather complex kind of chemistry perhaps but chemistry nonetheless.

Put the other way 'round: Our way of 'doing' chemistry is rather crude compared to what nature has evolved over many hundreds of millions of years. This brings about numerous hazards and the disasters mentioned above testify to that. However, just as life is chemistry, so our 'human' chemistry is (and will remain!) part of everyday life, from pharmaceuticals over clothes to plastic bags to... It is therefore imperative that we make our use of chemistry as safe and benign as possible and this has been realised in the chemical world (both industrial and academic) for quite a while now.

DNA, molecules and human body — Life is chemistry

The idea that chemistry has to become more benign and safe formed in the 80s. In particular, the visible effects of chemical pollution and the experience of resource depletion made chemists think about safer and more efficient ways of doing things. In 1998, two American scientists, Paul Anastas and John Warner, summarised these ideas under the heading of "The twelve principles of Green Chemistry".[6] In somewhat abridged form these are:

I - Prevention of waste is better than cleaning up waste.

II - Waste reduction. Synthetic methods should aim at every atom in a molecule of starting material ending up in the desired product. (Atom economy)

III - Synthetic methods should avoid using or generating toxic substances.

IV - Safer chemicals. A substance having the same effect while being less toxic than another is preferable.

V - Safer solvents and auxiliaries. Auxiliary substances should be avoided wherever possible, and as non-hazardous as possible when they must be used.

VI - Efficiency. Energy requirements should be minimized, and processes should be conducted at ambient temperature and pressure whenever possible.

VII - Use of renewable feedstocks

VIII - Reduce derivatives. Unnecessary generation of derivatives - such as the use of protecting groups - should be minimized or avoided if possible.

IX - Use catalytic reagents instead stoichiometric ones.

X - Design for degradation. Chemicals should be designed in such a way that they degrade at their end of life.

XI - Real-time analysis for pollution prevention

XII - Inherently safer chemistry for accident prevention

A more detailed version illustrated with examples may be found on the pages of the American Chemical Society (ACS). [7] Some of these points may not mean a lot or may sound repetitive to the layman but they are important.

Green Chemistry has quickly become a well-established field. The Royal Society of Chemistry, [8] the British equivalent to the ACS, has duly launched an entire journal devoted to the field, aptly named Green Chemistry.[9]

So, that was some 25 years ago. And today?

If you take a closer look at the 12 principles you will find many important aspects, however, one of the most important aspects of what we now call sustainable development seems to be missing, namely circularity. Nowadays, principle number ten seems almost problematic because it stipulates that chemicals should degrade, thus releasing the material that has gone into these chemicals back into nature, albeit in a non-toxic and even benign form. That is linear, not circular.

Indeed, the term Sustainable Chemistry makes the rounds as a distinct concept which is different from and more encompassing than Green Chemistry. Green Chemistry is primarily concerned with reducing the inherent dangers. Sustainable Chemistry, on the hand, is concerned with reducing the overall effect of the chemistry we perform on the environment, including the use of the finite resources we take from our planet.

Nowadays, the chemical world embraces not only changes in chemistry itself, but also changes in the way the chemical industry works.

An example would be chemical leasing, a business model in which chemicals are not sold but leased, just as in leasing a car. For example, a company might lease solvents to degrease sheets of metal.

Another novel business model is to change the basis on which chemicals are sold. Conventionally, chemicals are sold by weight or by volume. However, they might also be sold according to their use. Consider a paint manufacturer producing paints for, say, the hulls of ships. Selling the paint for the ship according to the area that has to be painted, would put the onus on the paint manufacturer to develop paints which can cover a bigger area per unit weight of paint.

So, where is Chemistry heading?

The word is that chemists have to become molecular managers. Just as managers in a company have to deploy resources according to the project at hand and differently once the next project comes around, chemists will need to use molecules this way in one context and that way in another, just as a manager doesn't hire a completely different set of people for every different project. The methodologies for this approach will have to be developed.