UofT Demonstrates its Commitment to Sustainable Chemistry

“We’re very pleased and proud to announce that the Chemistry Department has recently joined the Green Chemistry Commitment (GCC)!” – Dr. Andy Dicks, University of Toronto, Associate Professor

gci-group-photo-sept27-2016

GCI Members Fall 2016

The University of Toronto has recently signed the GCC making us the first school outside of the United States to sign onto this impactful commitment, which now contains 33 colleges and universities. The GCC is overseen by Beyond Benign, a United States not-for-profit organization created by Dr. Amy Cannon and Dr. John Warner, a founder of the principles of green chemistry. Within the GCC, academic institutions collaborate to share resources and know-how in order to positively impact how the next generation of scientists are educated about sustainability issues. Participating departments commit to green chemistry instruction as a core teaching mandate. The aim is to provide undergraduates and graduates with the required understanding to make green chemistry become standard practice in laboratories around the world. This, in turn, ensures that when graduates of the university enter the workforce, they are armed with the knowledge of how to make molecules and processes more sustainable and less toxic by adhering to the Twelve Principles of Green Chemistry.

The GCC unites the green chemistry community around shared goals and a common vision to grow departmental resources to allow a facile integration of green chemistry into the undergraduate laboratories as well as to improve connections with industry which creates job opportunities for sustainability-minded graduates. Their website offers many resources for those interested in reading actual case studies and laboratory exercises, so please click here to visit their website and be informed!

Our chemistry department has already improved the green chemistry content in our undergraduate laboratories by updating the first year courses and upper year synthetic chemistry courses to include various graded questions about the Twelve Principles as well as ensuring the undergraduates are thinking about how they could make their current lab protocols more sustainable. Additionally, students can choose to study the fate of chemicals in our environmental chemistry courses offered. Of course there’s always room to improve, so the Green Chemistry Initiative (GCI), in collaboration with Dr. Andy Dicks, is working on evaluating the undergraduate chemistry curriculum’s current focus on sustainable chemistry and toxicology, in hopes to further improve our undergraduate’s learning experience. The GCI also provides many educational opportunities to department members such as our Seminar Series as well as many outreach opportunities, making our group a driving force in the integration of green chemistry principles to the department. Lastly, the University of Toronto chemistry courses reach thousands of students a year, and by being the first Canadian university to sign this commitment, we are working towards a greener future in Canada!

Thank you for celebrating this very momentous achievement with us!
Karl Demmans, Ian Mallov, Shira Joudan, and Laura Reyes

Green Chemistry Principle #5: Safer Solvents and Auxiliaries

By Laura Reyes, Co-Chair for the GCI

5. Safer Solvents and Auxiliaries: The use of auxiliary substances (e.g. solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.

The 5th principle of green chemistry promotes the use of Safer Solvents and Auxiliaries. This includes any substances that do not directly contribute to the structure of the reaction product but are still necessary for the chemical reaction or process to occur. In the video for Principle #5, we talk about the impact of solvent waste and illustrate it by substituting dichloromethane, a commonly-used solvent, with a safer alternative.

Solvents are the most common example of auxiliary substances. Usually, solvents themselves do not react with the reagents but are still necessary in reactions in order to dissolve reagents, mix all reaction components, and control the temperature of the reaction. After the reaction, more solvents are then often used to separate and purify the product from other reaction components and any side-products.

This reliance on solvents means that a massive amount of solvent waste is generated during a typical chemical reaction. Reducing solvent use is therefore usually a high priority for chemists working on making their reactions greener, especially when working on an industrial scale.

For example, Pfizer was able to reduce the amount of solvent waste generated in its synthesis of Viagra from 1300 kilograms to just 22 kilograms for every kilogram of Viagra made.[1] This huge reduction, and others like it throughout the chemical industry, ends up making a big difference in the resulting environmental impact and demand on resources.

Although reducing solvent amounts altogether is certainly important, it’s also good to remember that every solvent has its own properties. A toxic and environmentally persistent solvent like dichloromethane should be avoided whenever possible. Many guides have been created to help chemists replace solvents of concern, such as these guides by Pfizer, GlaxoSmithKline, and Sanofi. A recent paper also compiled these guides into a more comprehensive overview.

In our video, we used column chromatography to show an example of solvent substitution in action. Column chromatography is a separation method commonly used by chemists. It works very well for separations but, like many other solvent-based separation methods, the downside is that a large amount of solvent is required.

Columns

We separated compounds found in spinach extract using column chromatography, to show how solvents can be substituted for safer choices.

We used a convenient guide for substituting dichloromethane in our column chromatography demo.[2] Using this guide, we replaced the dichloromethane/ethyl acetate (95:5) mixture in Column 1 with its alternative of heptane/isopropanol (85:15) mixture in Column 2. We then compared the separation of compounds in spinach extract between the two columns.

Column chromatography is a complicated process with a lot of factors to consider, so we had to simplify it for the purpose of the video. This YouTube video explains the basics very well for those who want to learn more. Essentially, the compounds that flow through the column are passed between the solid phase (the silica gel in the column) and the liquid phase (the solvent) at different rates, which causes them to separate as they travel downwards. The solvent choice greatly influences how well compounds separate. Although no two solvents work exactly the same way, substitution guides like the one we used in our video have already done the tedious work to help chemists choose the greenest option that will work for their reactions.

Considering the integral use of solvents throughout chemistry, the implementation of Principle #5 in even seemingly small ways can end up drastically reducing the amount of solvents used altogether and move towards safer options whenever solvents are required.

References:

[1] Pfizer’s reduction of waste in Viagra production: P. J. Dunn, et al., Green Chem. 2004, 6, 43-48.

[2] Dichloromethane use, concerns, and substitution in column chromatography: J. P. Taygerly, et al., Green Chem. 2012, 14, 3020-3025.

Solvent selection guides:

Pfizer: K. Alfonsi, et al., Green Chem. 2008, 10, 31-36.

GlaxoSmithKline: R. K. Henderson, et al., Green Chem. 2011, 13, 854-862.

Sanofi: D. Prat, et al., Org. Process Res. Dev. 2013, 17 (12), 1517-1525.

Compilation of guides: D. Prat, et al.Green Chem. 201416, 4546-4551.

Green Chemistry Principle #4: Designing Safer Chemicals

By Laura Reyes, Co-Chair for the GCI

4. Designing Safer Chemicals: Chemical products should be designed to carry out their desired function, while minimizing their toxicity.

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Since chemicals are everything, if products were truly “chemical-free” they would actually be “substance-free”!

The 4th principle of green chemistry, Designing Safer Chemicals, might sound like a paradox to many people. The very concept of safe chemicals is not exactly common. Usually, all chemicals are depicted as toxic substances.

However, the word chemicals is used misleadingly in our everyday lives. Chemicals are literally everything around us – every substance that is made of matter is a chemical. This makes consumer labels claiming to be “Chemical-Free” meaningless! If used properly, chemical-free products would be completely empty.

With this in mind, Principle #4 is a reminder to chemists that it is our responsibility to design all chemicals to not only be efficient at their given purpose, but to also reduce their toxicity by design.

Reducing toxicity is a constant priority in chemistry. The challenge comes in knowing what makes a molecule toxic. When it comes to molecules that have never been made before, toxicity becomes an even bigger concern. The field of toxicology allows us to either predict or test for a molecule’s toxicity, making partnerships between chemists and toxicologists incredibly important. Many green chemistry educators are also pushing towards including a working knowledge of basic toxicology into undergraduate chemistry degrees, to train all future chemists to consider toxicity from the very beginnings of molecular design.

In our video, we feature a great example of how a chemical’s toxicity can be reduced by rethinking its design. This example was the 2014 winner of the Presidential Green Chemistry Challenge Award in the category of Designing Safer Chemicals. The award was given to The Solberg Company for making a new type of firefighting foam that does not use fluorosurfactants, which are environmentally persistent, bioaccumulative, and toxic. The new firefighting foam mix works just as well as previous foams, yet does not have these negative impacts! We talk about the chemistry behind this in the video, and Chemical & Engineering News has a post with more details on Solberg’s foam mix for those interested.

For consumers, it can be overwhelming knowing that the term “chemical-free” tells us absolutely nothing about the product. Here’s a couple of reliable guides for consumer products that will help you make an informed decision about what can be considered safe or not. Please let us know of other guides we may have missed in the comments below, and remember to share this post with anyone who might find it useful!

GoodGuide – This is an excellent database of consumer product information, across many categories such as food, personal care, and household items. We like GoodGuide because their team includes chemists and others with a scientific background, who work together to analyze products, rather than basing their guide on hearsay.

Design for the Environment – This program is a partnership with the US EPA, to help consumers choose products that have been deemed safer for human health and the environment. Look for the Design for the Environment label on products while shopping.

Chemical Waste FAQs

By Peter Mirtchev, Member-at-Large for the GCI and Laura Reyes, Co-Chair for the GCI

All chemists create chemical waste, it’s simply part of our job. Recently, we started a Waste Awareness Campaign to track the amount of waste being generated by our chemistry department. Aside from this, the chemical waste disposal process was a bit of a mystery. Learning how to properly sort, label, and dispose of chemical waste should be part of every chemists’ early training, but typically gets overlooked. In academic research labs, waste disposal habits tend to get passed down from one person to the next, and often stem from tradition rather than regulation. With this post, we hope to clarify some of the confusion surrounding proper disposal of different types of chemical waste.

We recently co-hosted a seminar about waste disposal with the Chemistry Students’ Union. Our speakers were Ken Greaves (Chemistry Department Supplies & Services Supervisor) and Rob Provost (Environmental Protection Manager at the UofT EH&S Office). We found that many members of the department had important questions regarding proper disposal practices and what happens to chemical waste after it is picked up. We have summarized the crucial points of the talk in Q&A format below. There’s also very useful information at this EH&S website on chemical waste. If you have other unanswered questions regarding chemical waste, leave them in the comments and we’ll get them answered for you!

Disclaimer: the information below is specific to the Department of Chemistry at the University of Toronto, and may change according to institution. Check with your own institution regarding the rules of chemical waste disposal.

Q: What are the most common types of chemical waste produced in a research laboratory?

A: Solvents. At the University of Toronto, the three most common chemicals are 1) acetone, 2) hexanes, and 3) dichloromethane. The Department of Chemistry purchases over 10,000L of acetone per year alone.

Q: What is considered ‘flammable’ waste?

A: A flammable liquid is one that has a flashpoint of 23.8°C or lower.

Q: Is a mixture of water and organic solvents considered aqueous or flammable waste?

A: If the mixture is more than 50% water, it is considered aqueous waste. If it is less than 50% water, it is considered flammable waste. If the amounts are uncertain, treat as aqueous (see below for more about the treatment of waste types).

Q: What mixtures are treated as chlorinated waste? Continue reading

Green Chemistry Principle #3: Less Hazardous Synthesis

By Kenny Chen, Member-at-Large for the GCI and Laura Reyes, Co-Chair for the GCI

3. Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.

The idea of practicing safe chemistry sounds intuitive, but contemporary technology, policy, and knowledge of long-term health and environmental impacts are often limiting factors in determining how safe a process is. In other words, scientists are always working with what they have in terms of technology and knowledge of hazards, and that story may change as we learn more.

In our video, we briefly described the recent history of technologies used to generate chlorine gas, focusing on the transition from mercury cell processes to membrane cell processes.

Chlorine has been produced industrially since the 19th century, when it was widely used in textiles and paper industries. Nowadays, it is essential in many plastics and chemical industries, for example to make the plastic polyvinyl chloride or PVC.

In the past, the mercury cell process was widely used to make chlorine. We now know that resulting contamination from mercury waste has tragic health and environmental effects, but that was not always the case due to previous limitations in technology, knowledge of heavy metal accumulation, and resulting policies. For example, as we talk about in the video, the mercury cell-based chloralkali process caused the infamous case of Minamata disease that struck Ontario in 1970, severely affecting two native communities.

Now, the membrane cell is the preferred choice for the chloralkali process. The increased use of this cellulose-based technology has resulted in decreased use of the mercury cell, which in turn has reduced mercury emissions into the environment.

Despite large improvements, even in 2013 more than 5 tonnes of mercury were released into the environment due to the chloralkali process, which leaves significant room for improvement as we move forward, whether by improved technology or stricter regulation.

Sometimes, we can’t help but learn new information over time about the long-term safety of technologies and chemical processes. Even so, we must use the knowledge that is available at all times so that we can create and modify processes that are less hazardous by design. In this way, we will have inherently safer chemistry by keeping green chemistry principle #3 in mind.

References

Handbook of Chlor-Alkali Technology – History of the Chlor-Alkali Industry (http://link.springer.com/book/10.1007%2Fb113786)

Best Available Techniques (BAT) Reference Document for the Production of Chlor-alkali (http://www.eurochlor.org/chlorine-industry-issues/chlor-alkali-bref.aspx)

Chlorine Industry Review 2013-2014 (http://www.chlorinethings.eu/files/downloads/annual-report-2014-full-final.pdf)

Green Chemistry Principle #2: Atom Economy

By Melanie Mastronardi, Chair for the GCI and Laura Reyes, Secretary for the GCI

2. Atom Economy: Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.

Atom Economy, the 2nd principle of green chemistry, comes down to preventing waste on a molecular level. It is an example of a green chemistry metric, which helps us understand the efficiency of a reaction. The equation for atom economy, shown below, essentially tells us the percentage of atoms that end up in the desired reaction product compared to how many atoms are put into the reaction. The higher the atom economy the better, since any atoms that are not incorporated into the final product are considered wasted.

In the GCI’s second video, Brian and Melanie outlined the concept of atom economy by comparing two different synthetic methods for making the over-the-counter drug ibuprofen.

As a supplement to the video, here we show how we did the atom economy calculations:

Brian's Reaction Scheme                  Melanie's Reaction Scheme

The % atom economy is calculated using the molar mass values indicated for each molecule in the reactions schemes above, excluding catalysts since they can be reused and therefore do not count towards a reaction’s atom economy. The atom economy for Brian’s reaction is determined as follows:

Brian's Reaction AE Calculation

For Melanie’s reaction, the atom economy calculation looks like this:

Melanie's Reaction AE Calculation

It’s clear through these two calculations that the new method for making ibuprofen, shown by Melanie, is much more atom economical at 77%, compared to 40% for the old method shown by Brian. Another way to think of this is that previously, 60% of the reagents used in the making of ibuprofen were wasted, but this was improved to only 23% being wasted. On an industrial scale, that’s a huge difference!

In the video, Melanie also explains that in the industrial process for her reaction, the excess acetic acid by-product that is formed ends up getting sold for other purposes, meaning that it doesn’t go to waste, so her % atom economy essentially ends up being 100%.

Be sure to also check out all of the videos in our campaign on our YouTube channel and keep an eye out for those to come!