Green Chemistry Education through TAs at the University of Toronto

By Julia Bayne, Member-at-Large for the GCI

Green chemistry education is one of our main initiatives within our chemistry department. As part of an ongoing collaboration, we, the Green Chemistry Initiative (GCI), work with the teaching faculty to help modify and improve the undergraduate curriculum through the incorporation of green chemistry. This partnership has resulted in a substantial increase in the amount of green chemistry taught in the classroom and the modification or replacement of a number of experiments in the laboratory component of these courses. For example, the University of Toronto offers a third year undergraduate chemistry course (CHM343H: Organic Synthesis Techniques) that has undergone a complete transformation and now largely emphasizes the main concepts of green chemistry. Not only is the theory discussed in lecture, but the students are also strongly encouraged (and graded on their ability) to integrate green chemistry practices into their experiments in the laboratory.[1]

Green Chemistry for TAs Handout - page 1

We created this handout to encourage TAs to teach their students the basics of green chemistry [PDF].

Although this initiative has emphasized educating the undergraduate students, we found that the teaching assistants (TAs) and laboratory demonstrators did not always have a strong training in green chemistry themselves, and therefore did not necessarily feel comfortable teaching green chemistry concepts to their students. With this in mind, our next goal was to create a handout for TAs that would contain a concise explanation of green chemistry, along with some tips that they could use to help encourage students to align their thinking with the 12 principles of green chemistry. This handout, entitled “Tips for Teaching Green Chemistry to Students (pdf)” contains a brief explanation of green chemistry and lists the 12 principles of green chemistry with a short summary to highlight each one. The handout also includes suggestions on how to encourage undergraduate students to properly implement these principles into their laboratory practice.

Subsequently, we chose to highlight four key teaching points (pdf) through fun graphics that help emphasize the importance of green chemistry in the lab. The key points are as follows: 1) Work on a small scale, 2) A higher LD50 (median lethal dose) value typically indicates a safer chemical, 3) Minimize solvent use when washing glassware, and 4) Separate waste in the correct container so it can be disposed of accordingly. By simplifying and highlighting these important points, we hope that TAs will feel more comfortable teaching a few basic green chemistry concepts to their students, and similarly, we hope that the students will gain a better understanding of how to apply the principles of green chemistry to real-world situations in the laboratory.

Green Chemistry for TAs Handout - page 2

Starting from the perspective of undergrad labs, we picked these 4 key green chemistry teaching points to emphasize to the TAs [PDF].

We anticipate that by reaching out to the graduate students who teach the lab component of the undergraduate courses, they will themselves be more comfortable and excited to teach students about green chemistry, including the straightforward substitutions and modifications it has to offer. Ultimately, we hope to see more enthusiasm among the undergraduate students as they grasp the importance and benefits of including green chemistry in the laboratory component of their courses and potentially research laboratories in the future.

References:

[1] Edgar, L. J. G.; Koroluk, K. J.; Golmakani, M. and Dicks, A. P. J. Chem. Ed. 2014, 91, 1040-1043.

Developing Green Chemistry Content for First-Year Undergraduate Laboratories

By Shawn Postle, Member-at-Large for the GCI

The Chemistry Teaching Fellows Program (CTFP) at the University of Toronto gives senior graduate students the opportunity to gain pedagogical experience by developing new educational content for undergraduate students within the chemistry department.

I recently had the opportunity to complete a CTFP project in collaboration with Dr. Barb Morra where we designed a new laboratory experiment for CHM 151Y, a first year organic chemistry course. The experiment that we aimed to replace involved the concurrent hydrogenation/dehydrogenation of cyclohexene using a palladium catalyst, to form cyclohexane and benzene. There were two main concerns with this experiment: the use and generation of carcinogenic and toxic chemicals, and the efficacy of a simple demonstration of alkene reactivity due to the lack of qualitative observations that could be made to differentiate the products from the starting material.

To address the shortcomings of the old experiment, we had three goals in mind while designing the replacement experiment: 1) to reinforce concepts of alkene chemistry learned in lecture, 2) to emphasize the importance of sustainable chemistry, and 3) to introduce thin-layer chromatography.

The L-proline catalyzed cyclization of L-linalool was an ideal reaction for satisfying these three criteria. In the lecture component of the course, students learn about electrophilic addition reactions of alkenes, such as halohydrin formation (Scheme 1a). For the experiment, we chose an intramolecular variation to show this same type of reactivity. The reaction carried out in the lab is the cycloetherification of L-linalool (Scheme 1b).

Green chemistry for alkene reactivity

Scheme 1: a) Halohydrin formation, b) Cycloetherification of L-Linalool

Students also perform thin-layer chromatography to verify that all of their starting material has been consumed. Thin-layer chromatography is an ideal technique for first year students, as it is a relatively simple method of analysis to understand and carry out.

In this new experiment, students are introduced to the 12 principles of green chemistry. We draw their attention to specific examples from the reaction to illustrate different principles. L-linalool, a terpene alcohol, is derived from renewable resources (principle #7). The reaction is catalyzed by innocuous L-proline, which reduces the reaction time from two days to a few minutes (principle #9). N-bromosuccinimide (NBS) is a safer alternative to elemental bromine as a source of electrophilic bromine (principle #4). Moreover, students are directed to the GlaxoSmithKline safer solvent guide to compare the properties and environmental impact of the solvent used to those employed in older cycloetherification reactions (principle #5). This gives students insight into how the 12 principles of green chemistry can be effectively applied with just a simple substitution.

Some of the 12 principles of green chemistry are fundamentally easy to understand, even for a first year student, but others require more chemistry background. It is through repeated exposure to these ideas that students can gain a fuller appreciation of their importance. Introducing students to the concept of sustainable chemistry throughout their chemistry education in a variety of courses helps students understand that green chemistry is not something separate from organic, inorganic, analytical or any other type of chemistry, but is rather a philosophy that can always be implemented.