Green chemistry, what is this? A Google search for these two words gives >200, 000, 000 hits! Topping the list are the Royal Society of Chemistry with their Green Chemistry journal (sitting behind a paywall), followed closely by the American Chemical Society with their Green Chemistry Institute, which even asks for online donations to the cause (could this be called a donation wall?). Perhaps I should ask for donations to read the stuff I write here? The ACS even have Green Chemistry Awards and Grants. We have Green Chemistry Letters which, to their credit, is open access. Even the august pages of OPRD have turned green, and if your publication of your process chemistry is not green enough for them you risk the following: “The editors encourage all authors to consider these issues before submitting their papers to OPRD, and we warn that authors risk having papers rejected unless environmental impact and green chemistry principles are considered. ” (bold emphasis is not mine). So OPRD just how green are you as a journal? Where does the paper come from for the printed version, what about the wiring to transmit the electronic version and the computers required to read the latter, how green are those? Do they conform to your own standards, I doubt it very much.
So what is all this bull manure? “Green chemistry” now known as GrC (to distinguish it from gas chromatography, which is certainly not green) has been practised for years. So it seems this is another bandwagon for people and companies to jump on especially if they follow the 12 commandments reproduced below:
- It is better to prevent waste than to treat or clean up waste after it is formed.
- Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.
- Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
- Chemical products should be designed to preserve efficacy of function while reducing toxicity.
- The use of auxiliary substances (e.g. solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.
- Energy requirements should be recognized for their environmental and economic impacts and should be minimized. Synthetic methods should be conducted at ambient temperature and pressure.
- A raw material or feedstock should be renewable rather than depleting wherever technically and economically practicable.
- Reduce derivatives – Unnecessary derivatization (blocking group, protection/ deprotection, temporary modification) should be avoided whenever possible.
- Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
- Chemical products should be designed so that at the end of their function they do not persist in the environment and break down into innocuous degradation products.
- Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances.
- Substances and the form of a substance used in a chemical process should be chosen to minimize potential for chemical accidents, including releases, explosions, and fires.
Well I don’t know about the rest of you out there but I have been doing this for years, long before GrC was invented. It was and still is a requirement of any process that we came up with.
Just take another look at it, the manufacture of the feedstocks is most certainly not green as most of them, solvents and the like are obtained from petroleum products. Synthetic methods should be conducted at rt and normal pressure, great, this could well leave you with a hazardous process causing you to violate commandments 1, 3 & 12.
Natural products are well known for their very large range of biological activities, from antibiotics to anticancer agents and everything in-between. So how do we know this and in particular which compounds are responsible for the biological activity of interest? Well the people involved in this area go around collecting samples of material of interest, be it plant or animal, hundreds of kilos of the stuff, take it back to their labs, grind it all up and extract it with litres of solvent. Chromatographic separation, also using lots of solvents, yields a few mg or micrograms of material of interest. Imagine you are a sponge, sitting quietly on a rock minding your own business when you are scooped up along with thousands of your mates, placed in a grinder and washed with solvent. This does not sound very “green” to me. I wonder if the isolationists would manage to get their results published in OPRD? Probably not!
Have a look at that picture of a green periodic table at the top of the page, what a lot of rubbish that is. Hydrogen and oxygen benign? Try mixing them and adding some energy! What is benign about the halogens? I suppose chlorine is green, but that’s about it. Or those green transition metals? Chromium is a very toxic metal and its compounds are worse and the same can be said for nickel, copper, zinc, molybdenum, manganese, etc. Certainly their use does not adhere to the environmentally friendly commandment. I note that osmium is classified as expensive (yellow), should it not be light blue? Tin is also marked as green, didn’t they stop using tin compounds as anti-fouling agents on ships years ago because of the toxicity?. This sort of thing will get chemistry a bad name and needs to be re-thought.
Research chemistry, be it university or industrial are not too concerned with GrC. Their job is to make their targets ASAP and have them evaluated for the designed properties be it biological, mechanical or whatever. A quick scan through the pages of Organic Letters shows you just how green this research is. Organo-tins, organo-zincs, osmium tetroxide, halogens, metal catalysed coupling reactions to mention but a few and almost every week a new catalyst/ligand combination designed to be selective here or there, never saying how the ligand was synthesised except to provide some obscure reference. But it is a new catalyst and that must be good according to commandment number 9.
Don’t get me wrong, I am all for looking after our environment and developing safe and sustainable chemical processes but to give it a name and call chemistry green, which is something it will never really be , is stupid. It creates a false impression within the lay community. What we can do as chemists is to continue as we have done in the past by being aware of what we are using and its impact should something adverse happen. It’s called risk analysis and in the company I worked for it was taken very very seriously and I am sure it is the same throughout the chemical industry. Solvent re-use is something I always practised within the processes I developed. However, solvent recovery and re-use is very costly and ties up reactor capacity and manpower, two resources that could be better employed making even more money for the company. So as long as it is cheaper to dispose of waste material than it is to re-cycle it disposal will continue. Here governments need to step in and make the costs of disposal astronomically high so that chemical companies are forced to think about and apply re-cycling.
Anyway, enough ranting from me on this topic. May all your reactions be green and I hope they work. And the next time you submit a paper to OPRD write it in green ink.
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I fully appreciate your views on GrC, one can never be skeptical/cautious enough. My biggest issue with this subject is, that so many papers claim that their process is “green”, just because it qualifies for one or few of these principles, but they are hardly ever comparing their results with alternative approaches. Also, unfortunately I think this is the buzzword of this decade in academic research, so everything will be called green regardless of their real qualities for years…
Yes you are correct in what you say, it is the modern bandwagon for everyone to jump on, or be forced onto (if you want to publish in OPRD). But this one is here to stay,, unfortunately.
The table above misses Lutetium, and features Lanthanum twice.
Sorry, but I am not responsible for this version of the periodic table.