The Green Chemistry Assistant: Expanding the horizons of green chemistry in chemical education

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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 55057
• hansonr_at_stolaf.edu
• 231st ACS National Meeting, Atlanta, Georgia
• March 27, 2006

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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.

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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.

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Three Levels of Green Chemistry

• Equations

HCl (aq) NaOH (aq) ? NaCl (aq) H2O (l)
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Three Levels of Green Chemistry

• Reactions

http//www.uncw.edu/smec/gk_fellows/askscience.htm
l
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Three Levels of Green Chemistry

• Processes

www.shelldeerpark.com/chemical.htm
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Three Levels of Green Chemistry

• Equation

Atom Economy 40
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Three Levels of Green Chemistry

• Reaction

Atom Economy 40
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Three Levels of Green Chemistry

• Reaction

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Three Levels of Green Chemistry

• Reaction

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Three Levels of Green Chemistry

• Reaction

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Three Levels of Green Chemistry

• Reaction

Atom Economy 40
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Three Levels of Green Chemistry

• Reaction

Atom Economy 40
before after
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Three Levels of Green Chemistry

• Reaction Excess, Limiting Reactant

Experimental Atom Economy 26
before after
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Three Levels of Green Chemistry

• Process...

unrecyclable silica gel
unrecovered CH2Cl2
Process Mass Efficiency 1
provides context
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Three Levels of Green Chemistry

• Process

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

• Process

Process Mass Efficiency 10
Process Mass Efficiency 1
allows for comparison
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Three Levels of Green Chemistry
Equation, Reaction, and Process Wouldnt it
be nice to have access to a tool that would allow
us to quickly make comparisons like this?
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• 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

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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My Goals Today

• Share what we have learned about our students
  from using the GCA.

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

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

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• 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.

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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.

38
Green Chemistry Assistant http//fusion.stolaf.ed
u/gca
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

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

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• 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.

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• Question
• What is the balanced chemical equation for
  this reaction?

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• Is it this?... (atom economy 88)

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• or this? (atom economy 66)

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

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,
521-527
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• Question
• What is the balanced chemical equation for
  this reaction?

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• Question
• Is this one reaction or two?

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• Question
• What is the atom economy?

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

Overall Atom Economy 60
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

Overall Atom Economy 72
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

In practice, Step 3 is important!
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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

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

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• 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

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Green Chemistry Assistant http//fusion.stolaf.ed
u/gca

• Upcoming double-header symposia of possible
  interest in 2006
• Web-Based Applications for Chemical Education
• ACS CCCE online CONFCHEM, May 5 June 30
  www.stolaf.edu/depts/chemistry/bh/confchem
• Web-Based Applications for Chemical Education
• 19th BCCE, July 31 Aug 2