While today's chemical industry produces a lot of residues, and residues from pharmaceuticals, fertilizers and detergents eventually end up in the environment, green chemistry as a way of thinking considers the entire life cycle of a product from the start. In a recent article, an Estonian chemist uses drug development as an example of how green chemistry can be used in large-scale industry to reduce pollution.
Senior researcher at the Tallinn University of Technology (TalTech) Mihkel Koel is an analytical chemist specializing in determining the chemical composition of substances. He said that "analytical chemistry, where all kinds of additives and solvents are used to prepare the sample, must also be environmentally friendly."
"I would even argue that conventional chemistry and green chemistry should not differ in any way," he added.
In a recently published work, Koel proposes a broader application of "green principles," such as "minimizing the generation of waste" and "reducing the use of materials."
"What I was trying to convey is that 'quality development' through the methods of green chemistry is not just applicable in the pharmaceutical industry [where it is most widely used] but can also be implemented in any other area of general chemistry."
Each field of chemistry can be made more environmentally conscious by incorporating green principles into its analytical phase, i.e. the examination of chemical composition and substances.
Until recently, the chemical industry created new substances essentially on a problem-by-problem basis: if you need an effective cleaning agent, you synthesize one. According to Mihkel Koel, both the pharmaceutical and everyday household chemical industries use a wide range of complex compounds to create new substances.
"Historically, it was common for chemists to think, 'Let's combine a few molecules to create a fantastic new substance,' and if solvents and residues are produced during the process, they can be thrown away."
The researcher said that "we shouldn't do that anymore." In contrast to the relatively simple problem-solving procedure, chemists will have to work harder in the future to come up with way to prevent residue. "The molecule does not have to be simple; creating it might take a bit more effort from the scientist."
The application of green chemistry in the pharmaceutical sector leads to the production of new medication under the safest conditions possible and with the aid of carefully selected solvents, derivatives and components. The efficacy of the resulting medicine would not be compromised.
Koel emphasizes that quality design (design-by-quality, abbreviated as DbQ) is all about setting the boundaries while producing a chemical compound. For instance, in the case of medicines, these limits include toxicity and efficacy.
These new concepts are particularly valuable when inventing a medicine or other product from scratch. "In the pharmaceutical industry, it is much more difficult when something is already in production. This is reflected in the price of medicines," he explained.
However, he said that large pharmaceutical corporations are attempting to simplify and make their operations environmentally friendly. "The most striking example of manufacturing modification in the big pharmaceutical industry is Viagra. Initially, a single gram required liters of solvents and hundreds of stages for synthesis," Koel said. "Nowadays, a gram of Viagra can be made with three to four reaction steps and mere milliliters of solvent."
A less complicated and safer manufacturing process should result in a lower price for the consumer. "However, because new products require more thought and testing, the initial pricing may be slightly higher," the researcher said.
Koel and the ERA (European Research Area) Chair of Green Chemistry at Tallinn University of Technology (TalTech), which he founded, have been the leading proponents of green chemistry in Estonia for the past decade. Koel said that this way of thinking is spreading gradually in Estonia: "Although there is no dedicated subject on green chemistry," he explains, "all of our chemistry faculty have incorporated it into their lectures." Postgraduate students presenting their dissertations must also demonstrate use of green chemistry principles.
Koel said that the situation at the industrial level in Estonia is different. "Sadly, the Estonian chemical industry is relatively small and has not undergone any significant improvements," Koel said. The green chemistry principles should be, however, integrated into the operations of new and startup companies.
What makes chemistry green?
"Prevention is the first and most important principle: leftovers should be kept to a minimum," Koel said, as "preventing residues is less expensive than treating them and cleaning up the environment." Second, in green chemistry, each atom introduced into a chemical reaction must be included in the final product, so that green chemistry is also energy-efficient. "This means that at best we should do the reaction at room temperatures, without much heating or cooling involved," Koel explained.
Some of the principles address safety measures: the working conditions, the material to be designed, the additives to be used and the finished product must all be as safe as possible. "When we synthesize, we should ensure that we do not use temperatures that are too high, too much pressure, too dangerous or, for example, harmful solvents," the researcher said.
These principles reduce the number of process steps that require extensive use of derivatives or modified chemicals and maximizes the use of reaction catalysts.
Renewable raw materials should be favored whenever possible, and the same green chemistry principles apply.
One of the major concepts in green chemistry, Koel said, is extensive planning across the board. "The most obvious example is the infamous pesticide DDT," the researcher explained. Originally intended as an insecticide, it had disastrous consequences for all other forms of life and is now prohibited. DDT is still used in some places, Koel said, and the toxin has survived in the wild.
It is also critical to think about ways to avoid accidents during the synthesis process. "Yes, we can devise safeguards for chemists; however, the higher the quality of our chemistry, the less protective gear we need."
Editor: Kristina Kersa