Transcript The 12 Principles of Green Chemistry

The Twelve Principles of
Green Chemistry
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12 Principles of Green Chemistry
1. Prevention. It is better to prevent waste than to treat or clean up waste after it is formed.
2. Atom Economy. Synthetic methods should be designed to maximize the incorporation of all materials used in the
process into the final product.
3. Less Hazardous Chemical Synthesis. Whenever practicable, synthetic methodologies should be designed to use and
generate substances that possess little or no toxicity to human health and the environment.
4. Designing Safer Chemicals. Chemical products should be designed to preserve efficacy of the function while reducing
toxicity.
5. Safer Solvents and Auxiliaries. The use of auxiliary substances (solvents, separation agents, etc.) should be made
unnecessary whenever possible and, when used, innocuous.
6. Design for Energy Efficiency. Energy requirements should be recognized for their environmental and economic impacts
and should be minimized. Synthetic methods should be conducted at ambient temperature and pressure.
7. Use of Renewable Feedstocks. A raw material or feedstock should be renewable rather than depleting whenever
technically and economically practical.
8. Reduce Derivatives. Unnecessary derivatization (blocking group, protection/deprotection, temporary modification of
physical/chemical processes) should be avoided whenever possible .
9. Catalysis. Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
10. Design for Degradation. Chemical products should be designed so that at the end of their function they do not persist
in the environment and instead break down into innocuous degradation products.
11. Real-time Analysis for Pollution Prevention. Analytical methodologies need to be further developed to allow for realtime in-process monitoring and control prior to the formation of hazardous substances.
12. Inherently Safer Chemistry for Accident Prevention. Substance and the form of a substance used in a chemical process
should be chosen so as to minimize the potential for chemical accidents, including releases, explosions, and fires.
Anastas, P. T.; Warner, J.C. Green Chemistry: Theory and Practice, Oxford University Press,1998.
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1. Prevention
It is better to prevent waste than to treat or
clean up waste after it is formed.
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Environmental Disasters
• Love Canal
– in Niagara Falls, NY a chemical and plastics company had used an old canal
bed as a chemical dump from 1930s to 1950s. The land was then used for a
new school and housing track. The chemicals leaked through a clay cap that
sealed the dump. It was contaminated with at least 82 chemicals (benzene,
chlorinated hydrocarbons, dioxin). Health effects of the people living there
included: high birth defect incidence and siezure-inducing nervous disease
among the children.
http://ublib.buffalo.edu/libraries/projects/lovecanal/
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Environmental Disasters
• Cuyahoga River – Cleveland, Ohio
– There were many things being dumped in the river such as: gasoline, oil, paint, and
metals. The river was called "a rainbow of many different colors".
– Fires erupted on the river several times before June 22, 1969, when a river fire captured
national attention when Time Magazine reported it.
Some river! Chocolate-brown, oily, bubbling with subsurface gases, it oozes rather
than
flows. "Anyone who falls into the Cuyahoga does not drown," Cleveland's citizens joke grimly.
"He decays."
Time Magazine, August 1969
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2. Atom Economy
Synthetic methods should be designed to
maximize the incorporation of all materials
used in the process into the final product.
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Organic Chemistry & Percent Yield
Epoxidation of an alkene using a peroxyacid
O
O
O
OH
+
Cl
100% yield
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Percent yield:
Percent yield:
% yield = (actual yield/theoretical yield) x 100
What is missing?
What co-products are made?
How much waste is generated?
Is the waste benign waste?
Are the co-products benign and/or useable?
How much energy is required?
Are purification steps needed?
What solvents are used? (are they benign and/or reusable?
Is the “catalyst” truly a catalyst? (stoichiometric vs. catalytic?)
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Balanced Reactions
Balanced chemical reaction of the epoxidation of styrene
O
O
O
O
OH
OH
+
+
Cl
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Cl
Atom Economy:
Atom Economy
% AE = (FW of atoms utilized/FW of all reactants) X 100
Balanced Equations
Focuses on the reagents
Stoichiometry?
How efficient is the reaction in practice?
Solvents?
Energy?
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Trost, Barry M., The Atom Economy-A Search
for Synthetic
Efficiency. Science 1991, 254, 1471-1477.
Rights
Reserved.
Atom Economy
Balanced chemical reaction of the epoxidation of styrene
O
O
O
O
OH
OH
+
+
Cl
Assume 100% yield.
100% of the desired epoxide product is recovered.
100% formation of the co-product: m-chlorobenzoic acid
A.E. of this reaction is 23%.
77% of the products are waste.
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Cl
3. Less Hazardous Chemical
Synthesis
Whenever practicable, synthetic
methodologies should be designed to
use and generate substances that
possess little or no toxicity to human
health and the environment.
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Less Hazardous Chemical Synthesis
Polycarbonate Synthesis: Phosgene Process
O
O
HO

OH
+
Cl
NaOH
Cl
*
O
Disadvantages
 phosgene is highly toxic, corrosive
 requires large amount of CH2Cl2
 polycarbonate contaminated with Cl impurities
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O
n
*
Less Hazardous Chemical Synthesis
Polycarbonate Synthesis: Solid-State Process
OH
HO
O
+
*
O
O
n
*
O
O
O

Advantages
 diphenylcarbonate synthesized without phosgene
 eliminates use of CH2Cl2
 higher-quality polycarbonates
Komiya et al., Asahi Chemical Industry Co.
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4. Designing Safer Chemicals
Chemical products should be designed
to preserve efficacy of the function while
reducing toxicity.
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Designing Safer Chemicals
Case Study: Antifoulants (Marine Pesticides)
http://academic.scranton.edu/faculty/CANNM1/environmentalmodule.html
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Designing Safer Chemicals:
Case Study: Antifoulants
Antifoulants are generally dispersed in the paint as it is
applied to the hull. Organotin compounds have
traditionally been used, particularly tributyltin oxide
(TBTO). TBTO works by gradually leaching from the
hull killing the fouling organisms in the surrounding
area
TBTO and other organotin antifoulants have long halflives in the environment (half-life of TBTO in seawater
is > 6 months). They also bioconcentrate in marine
organisms (the concentration of TBTO in marine
organisms to be 104 times greater than in the
surrounding water).
Organotin compounds are chronically toxic to marine
life and can enter food chain. They are
http://academic.scranton.edu/faculty/CANNM1/environmentalmodule.html
bioaccumulative.
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Designing Safer Chemicals:
Case Study: Antifoulants
Sea-Nine® 211
http://www.rohmhaas.com/seanine/index.html
Rohm and Haas
Presidential Green Chemistry Challenge Award, 1996
The active ingredient in Sea-Nine® 211, 4,5-dichloro-2-n-octyl-4isothiazolin-3-one (DCOI), is a member of the isothiazolone family
of antifoulants.
http://academic.scranton.edu/faculty/CANNM1/environmentalmodule.html
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Designing Safer Chemicals:
Case Study: Antifoulants
Sea-Nine® 211 works by maintaining a hostile growing environment for
marine organisms. When organisms attach to the hull (treated with
DCOI), proteins at the point of attachment with the hull react with the
DCOI. This reaction with the DCOI prevents the use of these
proteins for other metabolic processes. The organism thus detaches
itself and searches for a more hospitable surface on which to grow.
Only organisms attached to hull of ship are exposed to toxic levels of
DCOI.
Readily biodegrades once leached from ship (half-life is less than one
hour in sea water).
http://academic.scranton.edu/faculty/CANNM1/environmentalmodule.html
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5. Safer Solvents and
Auxiliaries
The use of auxiliary substances
(solvents, separation agents, etc.) should
be made unnecessary whenever
possible and, when used, innocuous.
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Safer Solvents
• Solvent Substitution
• Water as a solvent
• New solvents
– Ionic liquids
– Supercritical fluids
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Solvent Selection
Preferred
Useable
Undesirable
Water
Cyclohexane
Pentane
Acetone
Heptane
Hexane(s)
Ethanol
Toluene
Di-isopropyl ether
2-Propanol
Methylcyclohexane
Diethyl ether
1-Propanol
Methyl t-butyl ether
Dichloromethane
Ethyl acetate
Isooctane
Dichloroethane
Isopropyl acetate
Acetonitrile
Chloroform
Methanol
2-MethylTHF
Dimethyl formamide
Methyl ethyl ketone
Tetrahydrofuran
N-Methylpyrrolidinone
1-Butanol
Xylenes
Pyridine
t-Butanol
Dimethyl sulfoxide
Dimethyl acetate
Acetic acid
Dioxane
Ethylene glycol
Dimethoxyethane
Benzene
Carbon tetrachloride
“Green chemistry tools to influence a medicinal chemistry and research chemistry based organization”
Dunn and Perry, et. al., Green Chem., 2008, 10, 31-36
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Red Solvent
Reason
Flash point (°C)
Pentane
-49
Very low flash point, good alternative available.
Hexane(s)
-23
More toxic than the alternative heptane, classified as a HAP in the US.
Di-isopropyl ether
-12
Very powerful peroxide former, good alternative ethers available.
Diethyl ether
-40
Very low flash point, good alternative ethers available.
Dichloromethane
n/a
High volume use, regulated by EU solvent directive, classified as HAP in
US.
Dichloroethane
15
Carcinogen, classified as a HAP in the US.
Chloroform
n/a
Carcinogen, classified as a HAP in the US.
Dimethyl formamide
57
Toxicity, strongly regulated by EU Solvent Directive, classified as HAP in
the US.
N-Methylpyrrolidinone
86
Toxicity, strongly regulated by EU Solvent Directive.
Pyridine
20
Carcinogenic/mutagenic/reprotoxic (CMR) category 3 carcinogen, toxicity,
very low threshold limit value (TLV) for worker exposures.
Dimethyl acetate
70
Toxicity, strongly regulated by EU Solvent Directive.
Dioxane
12
CMR category 3 carcinogen, classified as HAP in US.
Dimethoxyethane
0
CMR category 2 carcinogen, toxicity.
Benzene
-11
Avoid use: CMR category 1 carcinogen, toxic to humans and environment,
very low TLV (0.5 ppm), strongly regulated in EU and the US (HAP).
Carbon tetrachloride
n/a
Avoid use: CMR category 3 carcinogen, toxic, ozone depletor, banned
under the Montreal protocol, not available for large-scale use, strongly
regulated in the EU and the US (HAP).
“Green chemistry tools to influence a medicinal chemistry and research chemistry based organization”
Dunn and Perry, et. al., Green Chem., 2008, 10, 31-36
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Solvent replacement table
Undesirable Solvent
Alternative
Pentane
Heptane
Hexane(s)
Heptane
Di-isopropyl ether or diethyl ether
2-MeTHF or tert-butyl methyl ether
Dioxane or dimethoxyethane
2-MeTHF or tert-butyl methyl ether
Chloroform, dichloroethane or carbon
tetrachloride
Dichloromethane
Dimethyl formamide, dimethyl acetamide
or N-methylpyrrolidinone
Acetonitrile
Pyridine
Et3N (if pyridine is used as a base)
Dichloromethane (extractions)
EtOAc, MTBE, toluene, 2-MeTHF
Dichloromethane (chromatography)
EtOAc/heptane
Benzene
Toluene
“Green chemistry tools to influence a medicinal chemistry and research chemistry based organization”
Dunn and Perry, et. al., Green Chem., 2008, 10, 31-36
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Pfizer’s results
Use of Solvent Replacement Guide resulted in:
• 50% reduction in chlorinated solvent use across the whole of their
research division (more than 1600 lab based synthetic organic
chemists, and four scale-up facilities) during 2004-2006.
• Reduction in the use of an undesirable ether by 97% over the same
two year period
• Heptane used over hexane (more toxic) and pentane (much more
flammable)
“Green chemistry tools to influence a medicinal chemistry and research chemistry based organization”
Dunn and Perry, et. al., Green Chem., 2008, 10, 31-36
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Safer solvents: Supercritical fluids
A SCF is defined as a substance above its critical temperature (TC) and critical pressure (PC). The
critical point represents the highest temperature and pressure at which the substance can exist
as a vapor and liquid in equilibrium.
http://www.chem.leeds.ac.uk/People/CMR/whatarescf.html
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http://www.uyseg.org/greener_industry/pages/superCO2/3superCO2_coffee.htm
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6. Design for Energy
Efficiency
Energy requirements should be
recognized for their environmental and
economic impacts and should be
minimized. Synthetic methods should be
conducted at ambient temperature and
pressure.
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Energy in a chemical process
•
•
•
•
•
•
Thermal (electric)
Cooling (water condensers, water circulators)
Distillation
Equipment (lab hood)
Photo
Microwave
Source of energy:
• Power plant – coal, oil, natural gas
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Energy usage
Chemicals and petroleum industries account for 50% of industrial
energy usage.
~1/4 of the energy used is consumed in distillation and drying
processes.
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Alternative energy sources:
Photochemical Reactions
Two commercial photochemical processes (Caprolactam process & vitamin D3)
1.
Caprolactam process
NOCl  NO˙ + Cl˙ (535nm)
+
Cl
+ HCl
NO
+ NO
NO
NOH.2HCl
+ 2 HCl
NOH.2HCl
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O
N
Alternative Energy Sources:
Microwave chemistry
• Wavelengths between 1 mm and 1 m
– Frequency fixed at 2.45 GHz
•
•
•
•
•
More directed source of energy
Heating rate of 10°C per second is achievable
Possibility of overheating (explosions)
Solvent-free conditions are possible
Interaction with matter characterized by penetration depth
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7. Use of Renewable
Feedstocks
A raw material or feedstock should be
renewable rather than depleting
whenever technically and economically
practical.
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Biomaterials [Carbohydrates, Proteins, Lipids]
Highly Functionalized Molecules
Petroleum Products [Hydrocarbons]
Singly Functionalized Compounds [Olefins, Alkylchlorides]
Highly Functionalized Molecules
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Polymers from Renewable Resources:
Polyhydroxyalkanoates (PHAs)
•
•
•
Fermentation of glucose in the presence of bacteria and propanoic acid
(product contains 5-20% polyhydroxyvalerate)
Similar to polypropene and polyethene
Biodegradable (credit card)
OH
O
R
OH
Alcaligenes eutrophus
OH
propanoic acid
HO
OH
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O
O
n
R = Me, polydroxybutyrate
R = Et, polyhydroxyvalerate
Polymers from Renewable Resources:
Poly(lactic acid)
http://www.natureworksllc.com/corporate/nw_pack_home.asp
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Raw Materials from Renewable Resources:
The BioFine Process
Paper mill
sludge
O
HO
Agricultural
residues,
Waste wood
O
Levulinic acid
Green Chemistry Challenge Award
1999 Small Business Award
Municipal solid waste
and waste paper
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Levulinic acid as a platform chemical
O
OH
O
HO
butanediol
OH
HO
HO
Acrylic acid
Succinic acid
O
O
O
O
HO
MTHF
(fuel additive)
THF
O
O
CH3
O
OH
HO
C
C
H2
C
H2
C
OH
O
O
H2N
O
Diphenolic acid
gamma
butyrolactone
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DALA (-amino levulinic acid)
(non-toxic, biodegradable herbicide)
8. Reduce Derivatives
Unnecessary derivatization (blocking
group, protection/deprotection,
temporary modification of
physical/chemical processes) should be
avoided whenever possible.
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Protecting Groups
2 synthetic steps are added each time one is used
Overall yield and atom economy will decrease
“Protecting groups are used because there is no direct way to solve the
problem without them.”
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NonCovalent Derivatization
Publications
Entropic Control in Materials Design
250
Transition Temperature
200
150
100
50
(c)
0
0
10
20
30
40
50
% Composition
60
70
80
90
100
“Noncovalent Derivatives of Hydroquinone: Complexes with Trigonal Planar Tris-(N,NDialkyl)trimesamides” Cannon, Amy S.; Foxman, Bruce M.; Guarrera, Donna J.; Warner, John C.
Crystal Growth and Design 2005, 5(2), 407-411.
"Synthesis of Tetrahedral Carboxamide Hydrogen Bond Acceptors" Cannon, Amy S.; Jian, Tian
Ying, Wang, Jun; Warner, John C. Organic Prep. And Proc. Int. 2004 36(4), 353-359.
“Synthesis of Phenylenebis(methylene)-3-carbamoylpyridinium Bromides” Zhou, Feng; Wang, ChiHua; Warner, John C. Organic Prep. And Proc. Int. 2004, 36(2), 173-177.
"Noncovalent Derivatization: Green Chemistry Applications of Crystal Engineering." Cannon, Amy
S.; Warner, John C. Crystal Growth and Design 2002, 2(4) 255-257.
“Non-Covalent Derivatives of Hydroquinone: Bis-(N,N-Dialkyl)Bicyclo[2.2.2]octane-1,4dicarboxamide Complexes.” Foxman, Bruce M.; Guarrera, Pai, Ramdas; Tassa, Carlos; Donna J.;
Warner, John C. Crystal Enginerering 1999 2(1), 55.
“Environmentally Benign Synthesis Using Crystal Engineering: Steric Accommodation in NonCovalent Derivatives of Hydroquinones.” Foxman, Bruce M.; Guarrera, Donna J.; Taylor, Lloyd D.;
Warner, John C. Crystal Engineering.1998, 1, 109.
“Pollution Prevention via Molecular Recognition and Self Assembly: Non-Covalent Derivatization.”
Warner, John C., in “Green Chemistry: Frontiers in Benign Chemical Synthesis and Processes.”
Anastas, P. and Williamson, T. Eds., Oxford University Press, London. pp 336 - 346. 1998.
“Non-Covalent Derivatization: Diffusion Control via Molecular Recognition and Self Assembly”.
Guarrera, D. J.; Kingsley, E.; Taylor, L. D.; Warner, John C. Proceedings of the IS&T's 50th Annual
Conference. The Physics and Chemistry of Imaging Systems, 537, 1997.
"Molecular Self-Assembly in the Solid State. The Combined Use of Solid State NMR and
Differential Scanning Calorimetry for the Determination of Phase Constitution." Guarrera, D.;
Taylor, L. D.; Warner, John. C. Chemistry of Materials 1994, 6, 1293.
"Process and Composition for Use in Photographic Materials Containing Hydroquinones.
Continuation in Part." Taylor, Lloyd D.; Warner, John. C., US Patent 5,338,644. August 16, 1994.
"Process and Composition for Use in Photographic Materials Containing Hydroquinones." Taylor,
Lloyd D.; Warner, John. C., US Patent 5,177,262. January 5, 1993.
"Structural Elucidation of Solid State Phenol-Amide Complexes." Guarrera, Donna. J., Taylor,
Lloyd D., Warner, John C., Proceedings of the 22nd NATAS Conference, 496 1993.
"Aromatic-Aromatic Interactions in Molecular Recognition: A Family of Artificial Receptors for
Thymine that Shows Both Face-To-Face and Edge-To-Face Orientations." Muehldorf, A. V.; Van
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Engen, D.; Warner, J. C.; Hamilton, A. D., J. Am. Chem. Soc., 1988, 110, 6561.
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9. Catalysis
Catalytic reagents (as selective as
possible) are superior to stoichiometric
reagents.
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Heterogeneous vs Homogenous
• Distinct solid phase
• Readily separated
• Readily regenerated &
recycled
• Rates not as fast
• Diffusion limited
• Sensitive to poisons
• Lower selectivity
• Long service life
• High energy process
• Poor mechanistic
understanding
• Same phase as rxn medium
• Difficult to separate
• Expensive and/or difficult to
separate
• Very high rates
• Not diffusion controlled
• Robust to poisons
• High selectivity
• Short service life
• Mild conditions
• Mechanisms well understood
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Heterogeneous vs Homogenous
• Distinct solid phase
• Readily separated
• Readily regenerated &
recycled
Green
catalyst
• Rates not as fast
• Diffusion limited
• Sensitive to poisons
• Lower selectivity
• Long service life
• High energy process
• Poor mechanistic
understanding
• Same phase as rxn medium
• Difficult to separate
• Expensive and/or difficult to
separate
• Very high rates
• Not diffusion controlled
• Robust to poisons
• High selectivity
• Short service life
• Mild conditions
• Mechanisms well understood
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Biocatalysis
• Enzymes or whole-cell
microorganisms
• Benefits
– Fast rxns due to correct
orientations
– Orientation of site gives high
stereospecificity
– Substrate specificity
– Water soluble
– Naturally occurring
– Moderate conditions
– Possibility for tandem rxns (onepot)
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10. Design for Degradation
Chemical products should be designed
so that at the end of their function they
do not persist in the environment and
instead break down into innocuous
degradation products.
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Persistence
• Early examples:
• Sulfonated detergents
–
–
–
–
Alkylbenzene sulfonates – 1950’s & 60’s
Foam in sewage plants, rivers and streams
Persistence was due to long alkyl chain
Introduction of alkene group into the chain increased degradation
• Chlorofluorocarbons (CFCs)
– Do not break down, persist in atmosphere and contribute to
destruction of ozone layer
• DDT
– Bioaccumulate and cause thinning of egg shells
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Degradation of Polymers:
Polylactic Acid



Manufactured from renewable resources
 Corn or wheat; agricultural waste in future
Uses 20-50% fewer fossil fuels than conventional
plastics
PLA products can be recycled or composted
Cargill Dow
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11. Real-time Analysis for
Pollution Prevention
Analytical methodologies need to be
further developed to allow for real-time
in-process monitoring and control prior to
the formation of hazardous substances.
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Real time analysis for a chemist is the
process of “checking the progress of
chemical reactions as it happens.”
Knowing when your product is
“done” can save a lot of waste,
time and energy!
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Analyzing a Reaction
What do you need to know, how
do you get this information and
how long does it take to get it?
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12. Inherently Safer Chemistry
for Accident Prevention
Substance and the form of a substance
used in a chemical process should be
chosen so as to minimize the potential
for chemical accidents, including
releases, explosions, and fires.
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Cyanide!
Phosgene!
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12. Inherently Safer Chemistry for Accident Prevention
Tragedy in Bhopal, India - 1984
In arguably the worst industrial accident in history, 40 tons of methyl
isocyanate (MIC) were accidentally released when a holding tank
overheated at a Union Carbide pesticide plant, located in the heart of the
city of Bhopal. 15,000 people died and hundreds of thousands more were
injured.
Chemists try to avoid things that explode, light on fire,
are air-sensitive, etc.
In the “real world” when these things happen, lives are lost.
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Bhopal, India
•
December 3, 1984 – poison gas leaked from a Union Carbide factory, killing
thousands instantly and injuring many more (many of who died later of
exposure). Up to 20,000 people have died as a result of exposure (3-8,000
instantly). More than 120,000 still suffer from ailments caused by exposure
What happened?
• Methyl isocyanate – used to make pesticides was being stored in large
quantities on-site at the plant
• Methyl isocyanate is highly reactive, exothermic molecule
• Most safety systems either failed or were inoperative
• Water was released into the tank holding the methyl isocyanate
• The reaction occurred and the methyl isocyanate rapidly boiled producing
large quantities of toxic gas.
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Chemical Industry Accidents
• U.S. Public Interest Research Group Reports (April 2004) find that
chemical industry has had more than 25,000 chemical accidents
since 1990
• More than 1,800 accidents a year or 5 a day
• Top 3: BP, Dow, DuPont (1/3 of the accidents)
http://uspirg.org/uspirgnewsroom.asp?id2=12864&id3=USPIRGnewsroom&
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