Mechanochemistry might be an entirely new topic for many of you. But don’t worry, we’ve prepared a handy mechanochemical glossary to help you get to grips with some of the most used terms and concepts in this fascinating branch of chemistry.
Today’s article is the second in a series of four blogposts: our personal dictionary, with terms arranged in alphabetical order, of course. Our first instalment featured entries from A to D, with highlights like batch processes, Cocrystals or deracemisation. If you missed it, go and read it, we’ll be waiting here. And now, let’s get started!
Ecotoxicity
Ecotoxicity refers to the capability of a compound to harm both the environment and living organisms. Pharmaceuticals and their active metabolites —the substances that pharmaceuticals leave behind after metabolism has done its thing— have emerged as significant environmental toxicants. By design, pharmaceuticals produce pharmacological effects in living organisms, so they can adversely affect wildlife and ecosystem health. That’s why we need to manage them in an environmentally responsible manner. Aquatic ecosystems, including fish and other animal populations, are particularly vulnerable, as residues usually end up in rivers, lakes and groundwater aquifers. And how do the pharmaceuticals slip into the environment? Well, the main pathways include hospitals, pharmaceutical companies, and the direct disposal of unwanted or expired drugs.
Enantiomer
Enantiomers are molecules that share the same chemical formula but differ in their spatial structure. We can say they are mirror images of each other, very much like our hands: they have the same number of fingers and the same form, but cannot be overlapped. Typically, when we manufacture a chemical compound, it contains both enantiomers, forming what is known as a racemic mixture. However, because their spatial structure differs, they can behave quite differently. A famous example of this is thalidomide: one enantiomer causes severe foetal malformations, while the other is considered safe. If you want to know more about enantiomers, read our interview with the experts UCLouvain.
Environmental impact
An environmental impact is defined as any change to the environment. We usually use it with a negative meaning—something that’s harming the environment in any way—, but it can be positive too! In the context of mechanochemistry, we are specifically referring to the environmental impact of industrial chemistry, which include waste production and carbon emissions. Mechanochemistry offers a way to minimise this impact, reducing the emissions, the waste generated, and the energy consumed. So, overall, we could say that mechanochemistry has a positive environmental impact.
Excipient
Active pharmaceutical ingredients, aka APIs, are the components of medicines responsible for their therapeutic effects. However, they need a little help from their friends: the excipients. Excipients are additional ingredients included in pharmaceutical formulations to ensure proper functionality and effectiveness. They serve a variety of purposes, such as a shield that protects the active ingredient until it reaches the stomach or acting as a liquid vehicle to deliver this precious ingredient, or even as colourants to enhance the medicines’ aesthetic appearance.
Family of compounds
It can be defined as a group of compounds that share similar properties; molecules that have similar physical behaviour and often display predictable chemical reactivity. For instance, the well-known non-steroidal anti-inflammatory drugs (NSAIDs), including the widely used ibuprofen and naproxen, form a group of medicines commonly used to relieve pain and reduce inflammation. At IMPACTIVE, we are working in three API compound families. This means we are developing APIs that belong to three different groups with different effects, specifically, antidiabetics, anticancer and antihypertensives.
Green chemistry
Chemistry can also be carried out while taking the environment into account. We are talking about green chemistry here! This term refers to the design of chemical products and processes with the intention of making them less hazardous and more sustainable. This approach applies throughout the entire life cycle of a chemical product, including its design, manufacture, use, and ultimate disposal. But how do we know whether our chemistry is green? Fortunately, there are some rules to follow. The 12 principles of green chemistry, originally proposed by the chemists Paul Anastas and John Warner in 1998, serve as a guidance for developing greener chemicals and reactions. You can read more about these principles here.
Impossible reaction
Traditional chemical methods often encounter limitations due to high energy barriers and unfavourable reaction conditions. As a result, the are some reactions considered as “impossible” —like a tied-up dog, unable to sniff beyond the reach of its leash. Mechanochemistry offers a unique approach to overcoming these hurdles. The mechanical energy generated through grinding, crushing, milling and shearing breaks down strong bonds and induces reactions that were previously thought unattainable. We are cutting the dog’s leash, allowing it to explore freely.
Intermediate
In the context of pharmaceuticals, intermediates serve as building blocks in the synthesis of APIs and are formed during the reactions that convert raw materials into the final product. The synthesis of APIs typically involves multiple intermediates, each undergoing purification and chemical transformation as part of a complex, multi-step process. This process requires rigorous testing to ensure both purity and quality.
Kinetics
To carry out our work, we need to understand what occurs between molecules when they collide. That is, to understand their kinetics. Kinetics is the study of how reactants change into products over time. This includes both the chemical reaction rates and the factors influencing them, such as temperature, concentration, and pressure. Studying chemical kinetics involves examining reaction mechanisms, intermediate compounds, and methods to optimise reactions.
Lab scale
This refers to experiments and operations carried out on a small scale in a laboratory setting to test, develop, or optimise processes using minimal materials and under controlled conditions. It often involves specialised laboratory equipment, such as beakers, flasks, or small reactors, and focuses on research, feasibility studies, and refining techniques. At this scale, it is not possible to obtain large quantities of APIs, only a few grams. However, it’s a crucial step to design reactions that can work later on at an industrial stage. Some reactions need to walk so others can run.
Life cycle assessment (LCA)
Life cycle assessment (LCA) is a comprehensive analytical method for evaluating the environmental effects of a product, process, or service. It is not limited to the stages of manufacture or use but addresses the entire life span of the product. This includes all stages, from raw material extraction to distribution, use, and end-of-life disposal or recycling. However, this powerful tool goes beyond then simply asses environmental impacts; it also explores options for reducing them by identifying opportunities for improvement across the entire life cycle of the element under evaluation.
Liquid-assisted grinding (LAG)
Liquid-assisted grinding is a mechanochemical technique in which a minimal amount of solvent is added to solid reactants during grinding. Why? Doing things to enhance or control reactivity. This method can accelerate reactions and enable the formation of new solid forms, such as cocrystals and salts. It is particularly useful in drug development due to its efficiency, minimal material requirements, and environmentally friendly nature.
