Chemical Exposure &
Environmental Contamination
Chapter 3
• How are chemicals released into the
environment?
• What are the impacts on the
environment?
– The list of potentially hazardous
compounds is large BUT many organic
compounds are not harmful
• Volatility (inhalation)
• Solubility (particularly water)
Chemical Exposure &
Environmental Contamination
• Volatile Organic Compounds (VOCs)
– Solvents, plasticizers, cleaners, air
deodorants, paints, smoking, driving
• Emissions
– Air, water, and soil pollution
• So, what can we do?
Go Green!??
What does Going Green Mean?
Becoming an Eagles Fan?
Being a Frog?
Going Green
Introduction to Green Chemistry
Chapter 5
• How do we deal with Chemical
Exposure?
– Traditional Approaches
• Minimize risk by limiting exposure & reducing
quantities used
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–
“scrubbers”
Treatment of waste water
Incineration
Chemical treatment
Waste minimization
Introduction to Green Chemistry
– Green Chemistry Strategies
• Minimize risk by striving to eliminate or reduce
use & generation of hazardous substances
Risk = f(exposure, hazard)
• The 12 principles of green chemistry serve as a
guide
– Paul Anastas and John Warner
12 Principles of Green Chemistry
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Waste Prevention
Atom Economy (Chapter 8)
Less Hazardous Chemical Synthesis (Chapter 8)
Designing Safer Products
Safer Solvents and Auxiliaries (Chapter 6)
Design for Energy Efficiency
Use of Renewable Feedstocks (Chapter 9)
Reduce Derivatives (Chapter 8)
Catalysis (Chapter 7)
Design for Degradation (Chapter 9)
Real-time Analysis for Pollution Prevention
Accident Prevention
Green Chemistry Metrics
How do we measure the “greenness” of a reaction?
• Percent (Chemical) Yield
Chemical Yield
mols (g) pdt obtained
=
x100%
mols (g) pdt possible
• Atom Economy


Atom Economy =
MWdesired pdt
MW
x100%
starting materials
– How much of the reactants remain in the final product
– Does not account for solvents, reagents, reaction yield, and
reactant molar excess
• Atom Efficiency
Atom Efficiency
= (% Yield)(Atom Economy)
Green Chemistry Metrics (cont)
• Effective Mass Yield
Product (Kg)
EMY =
x100%
Hazardous reagents (Kg)
– What is benign? Who decides?
– Ignores stoichiometry

• E-Factor
E - Factor =

Total Waste (Kg)
Product (Kg)
– Typically split into 2 sub-categories: organic & aqueous
waste
– Smaller is better