Green Chemistry The Green Chemistry Assistant: Expanding the horizons of green chemistry in chemical education Robert M. Hanson, Paul R. Campbell, Elizabeth R. Johnson, Gary O. Spessard, and Marc A. Klingshirn St. Olaf College Northfield, MN st ACS National Meeting, Atlanta, Georgia March 27, 2006

Green Chemistry My Goals Today Briefly discuss the important distinction between equations and reactions, and between reactions and processes. Introduce a new web-based tool – the Green Chemistry Assistant.

Green Chemistry My Goals Today Share what we have learned about our students from using the GCA. Share what we have learned about green chemistry from our students.

Green Chemistry Three Levels of Green Chemistry Equations HCl (aq) + NaOH (aq)  NaCl (aq) + H 2 O (l)

Green Chemistry Three Levels of Green Chemistry Reactions

Green Chemistry Three Levels of Green Chemistry Processes

Green Chemistry Three Levels of Green Chemistry Equation Atom Economy = 40%

Green Chemistry Three Levels of Green Chemistry Reaction Atom Economy = 40%

Green Chemistry Three Levels of Green Chemistry Reaction

Green Chemistry Three Levels of Green Chemistry Reaction

Green Chemistry Three Levels of Green Chemistry Reaction

Green Chemistry Three Levels of Green Chemistry Reaction Atom Economy = 40%

Green Chemistry Three Levels of Green Chemistry Reaction Atom Economy = 40% before… …after

Green Chemistry Three Levels of Green Chemistry Reaction – Excess, Limiting Reactant Experimental Atom Economy = 26% before… …after

Green Chemistry Three Levels of Green Chemistry …provides context Process... Process Mass Efficiency = 1% unrecovered CH 2 Cl 2 unrecyclable silica gel

Green Chemistry Three Levels of Green Chemistry Process Mass Efficiency = 10% …can involve more than one step Process…

Green Chemistry Three Levels of Green Chemistry Process Mass Efficiency = 10% …allows for comparison Process… Process Mass Efficiency = 1%

Green Chemistry Three Levels of Green Chemistry Equation, Reaction, and Process Wouldn’t it be nice to have access to a tool that would allow us to quickly make comparisons like this?

Green Chemistry Green Chemistry Assistant Based on the EPA “Green Chemistry Expert System” User-friendly interface designed to assist students in analyzing the atom economy, and safety of chemical processes

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant

Green Chemistry My Goals Today Share what we have learned about our students from using the GCA.

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant Lessons learned: Students need help just writing the balanced chemical equations. Process is important, as most real experiments involve more than one process step.

Green Chemistry Green Chemistry Assistant Lessons learned: We need lab manuals that are more explicit in guiding students to an understanding of the overall set of process steps they will be carrying out.

Green Chemistry My Goals Today Share what we have learned about our students from using the GCA. Share what we have learned about green chemistry from our students.

Green Chemistry Green Chemistry Assistant

Green Chemistry Green Chemistry Assistant Lessons learned: Introducing green chemistry provides a rich context for discussing safety, including nomenclature, CAS registry numbers, MSDS sheets, and health and environmental hazards.

Green Chemistry Green Chemistry Assistant Lessons learned: All is not as simple as one might think from what is in the literature in terms of the definitions of green measures.

Green Chemistry Green Chemistry Assistant Question: What is the balanced chemical equation for this reaction?

Green Chemistry Green Chemistry Assistant Is it this?... (atom economy = 88%)

Green Chemistry Green Chemistry Assistant …or this? (atom economy = 66%)

Green Chemistry Green Chemistry Assistant On assumptions regarding atom economy: “The process of calculating atom economy may be simplified by only considering key reactants. For example, ‘catalysts’ used in stoichiometric quantities, or the acid or base used in hydrolysis, are considered to be reactants. These examples are in contrast to common inorganic reagents, even when used in stoichiometric quantities (e.g. potassium carbonate…), which have been ignored. Inorganic reagents and/or other material are not included in the calculations as long as at least two other reacting substances are identified.” Constable, Curzons, and Cunningham, Green Chemistry, 2002,

Green Chemistry Green Chemistry Assistant Question: What is the balanced chemical equation for this reaction?

Green Chemistry Green Chemistry Assistant Question: Is this one reaction or two?

Green Chemistry Green Chemistry Assistant Question: What is the atom economy?

Green Chemistry Green Chemistry Assistant Overall Atom Economy = 60%

Green Chemistry Green Chemistry Assistant Overall Atom Economy = 72%

Green Chemistry Green Chemistry Assistant In practice, Step 3 is important!

Green Chemistry Green Chemistry Assistant Lessons learned: Getting students thinking about the overall process is good. Expecting them to do it on their own because it’s “simple” is asking too much. The Green Chemistry Assistant enables us to explore the nature of green chemistry processes and green chemistry measures.

Green Chemistry  Faculty  Gary Spessard, Marc Klingshirn, Paul Jackson  Students  Paul Campbell, Allison Christensen, Elizabeth R. Johnson, Tim Barker, Tyler Drake, David Harris  Technology Support  Dan Beach  Financial support  WM Keck Foundation  Howard Hughes Medical Institute Green Chemistry Assistant

Green Chemistry  Upcoming double-header symposia of possible interest in 2006:  “Web-Based Applications for Chemical Education” ACS CCCE online CONFCHEM, May 5 – June  “Web-Based Applications for Chemical Education” 19 th BCCE, July 31 – Aug 2 Green Chemistry Assistant