Presidential Green
Chemistry Challenge
2003 Award Recipients
Recycled/Recyclable — Printing with Vegetable Oil Based Inks
on 100% Postconsumer, Process Chlorine Free Recycled Paper
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wEPA
United States EPA744-K-03-001
Environmental Protection June 2003
Agency www.epa.gov/greenchemistry
Office of Pollution Prevention and Toxics (7406M)
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Contents
2003 Winners
Academic Award: Professor Richard A. Gross,
Polytechnic University 7
Small Business Award: AQraQuesl Inc. 3
Alternative Synthetic Pathways Award: Sud-Chemie Inc. 5
Alternative Solvents/Reaction Conditions Award: DuPont.... 7
Designing Safer Chemicals Award:
Shaw industries, Inc. 9
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Academic Category
Professor Richard A. Gross
Polytechnic University
New Options for Mild and Selective Polymerizations Using Upases
Isolated Upases, harvested from living organisms, have been used as catalysts
for polymer synthesis in vitro. Professor Richard Gross's developments on
lipase-catalyzed polymer synthesis have relied on the ability of enzymes to
reduce the activation energy of polymerizations and, thus, to decrease process
energy consumption. Further, the regioselectivity of lipases has been used to
polymerize polyols directly. Alternative synthetic pathways for such polymeriza-
tions require protection-deprotection chemical steps. The mild reaction condi-
tions allow polymerization of chemically and thermally sensitive molecules.
Current alternative chemical routes require coupling agents (e.g., carbodiimides)
that would be consumed in stoichiometric quantities relative to the reactants.
Fundamental studies of these polymerizations have uncovered remarkable
capabilities of lipases for polymerization chemistry. Selected examples include:
(i) lipases catalyze transesterification reactions between high-molecular-weight
chains in melt conditions; (ii) lipases will use non-natural nucleophiles such as
carbohydrates and monohydroxyl polybutadiene (Mn 19,000) in place of water;
(Hi) the catalysis of ring-opening polymerization occurs in a controlled manner
without termination reactions and with predictable molecular weights; and (iv)
the selectivity of lipase-catalyzed step-condensation polymerizations leads to
nonstatisticai molecular weight distributions (well below 2.0). These accom-
plishments are elaborated below.
A series of polyol-containing polyesters was synthesized via a one-pot lipase-
catalyzed condensation polymerization. By using various mixtures of polyols
(e.g., glycerol, sorbitol) with other diacid and diol building blocks, the polyols are
partially or completely solubilized, resulting in highly reactive condensation
polymerizations. By this method, organic solvents and activated acids (e.g.,
divinyl esters) are not needed. The polymerization reactions give high-molecu-
lar-weight products (A4w up to 200,000) with narrow polydispersities (as low as
1.3). Further, the condensation reactions with glycerol and sorbitol building
blocks proceed with high regioselectivity. Although the polyols used have three
or more hydroxyl groups, only two of these hydroxyl groups are highly reactive in
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the polymerization. Thus, instead of obtaining highly crosslinked products, the
regioselectivity provided by the lipase leads to lightly branched polymers where
the degree of branching varies with the reaction time and monomer stoichiom-
etry. By using lipase as the catalyst, highly versatile polymerizations result that
can simultaneously polymerize lactones, hydroxyacids, cyclic carbonates, cyclic
anhydrides, amino alcohols, and hydroxylthiols. The method developed offers
simplicity, mild reaction conditions, and the ability to incorporate carbohydrates,
such as sugars, into polyesters without protection-deprotection steps.
Professor Gross's laboratory discovered that certain lipases catalyze trans-
esterification reactions between high-molecular-weight chains that contain
intrachafn esters or have functional end groups. Thus, lipases, such as Lipase B
from Candida antarctica, catalyze intrachain exchange reactions between
polymer chains as well as transesterification reactions between a monomer and
a polymer. For polymers that have melting points below 100 °C, the reactions
can be conducted in bulk. Transacylation reactions occur because the lipase
has the ability to accommodate large-molecular-weight substrates and to
catalyze the breaking of ester bonds within chains. Immobilized Candida
antarctfca Lipase B (Novozyme-435) catalyzed transesterification reactions
between aliphatic polyesters that had Mn values in excess of 40,000 g/mol. In
addition to catalyzing metal-free transesterifications at remarkably low tempera-
tures, lipases endow transesterification reactions with remarkable selectivity.
This feature allows the preparation of block copolymers that have selected block
lengths.
2 2003 Academic Auj
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Small Business Category
AgraQuest, Inc.
Serenade®: An Effective, Environmentally Friendly Biofungicide
Serenade® Biofungicide is based on a naturally occurring strain of Bacillus
subtilis QST-713, discovered in a California orchard by AgraQuest scientists.
Serenade® has been registered for sale as a microbial pesticide in the United
States since July 2000. It is also registered for use in Chile, Mexico, Costa Rica,
and New Zealand. Registration is pending in the Phillippines, Europe, Japan,
and several other countries. The product is formulated as a wettable powder,
wettable granule, and liquid aqueous suspension. Serenade® has been tested
on 30 crops in 20 countries and is registered for use in the United States on
blueberries, cherries, cucurbits, grape vines, greenhouse vegetables, green
beans, hops, leafy vegetables, mint, peanuts, peppers, pome fruit, potatoes,
tomatoes, and walnuts. It is also registered for home and garden use.
AgraQuest has been issued four U.S. patents and several international patents
are pending on the QST-713 strain, associated antifungal lipopeptides, formula-
tions, and combinations with other pesticides.
Serenade® works through a complex mode of action that Is manifested both by
the physiology of the bacteria and through the action of secondary metabolites
produced by the bacteria. Serenade® prevents plant diseases first by covering
the leaf surface and physically preventing attachment and penetration of the
pathogens. In addition, Serenade® produces three groups of lipopeptides
{iturins, agrastatins/plipastatins, and surfactins) that act in concert to destroy
germ tubes and mycelium. The iturins and plipastatins have been reported to
have antifungal properties. Strain QST-713 is the first strain reported to produce
iturins, plipastatins, and surfactins and two new compounds with a novel cyclic
peptide moiety, the agrastatins. The surfactins have no activity on their own,
but low levels (25 ppm or less) in combination with the iturins or the agrastatin/
plipastatin group cause significant inhibition of spores and germ tubes. In
addition, the agrastatins and iturins have synergistic activities towards inhibition
of plant pathogen spores.
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The Serenade® formulation is available as a wettable powder, wettable granule,
and aqueous suspension that is applied just like any other foliar fungicide. It
can be applied alone or tank mixed; it can also be alternated with traditional
chemical pesticides. Serenade® is not toxic to beneficial and nontarget organ-
isms, such as trout, quail, lady beetles, lacewings, parasitic wasps, earthworms,
and honey bees. Serenade*' is exempt from tolerance because there are no
synthetic chemical residues and it is safe to workers and ground water.
Serenade®'s wettable granule formulation is listed with the Organic Materials
Review Institute (OMRI) for use in organic agriculture and will continue to be
listed under the National Organic Standards, which were enacted in the United
States in October 2002.
Serenade-'s novel, complex mode of action, environmental friendliness, and
broad spectrum control make it well-suited for use in integrated pest manage-
ment (IPM) programs that utilize many tools, such as cultural practices, classical
biological control, and other fungicides. Serenade® can be applied right up until
harvest, providing needed pre- and post-harvest protection when there is
weather conducive to disease development around harvest time.
4 2003 Small Business Award
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Alternative Synthetic Pathways Category
Sud-Chemie Inc.
A Wastewater-Free Process for Synthesis of Solid Oxide Catalysts
borne major achievements in pollution reduction have been made recently
through advancement of catalytic technologies. One such effort is in the area
of hydrogen and clean fuel production. However, the synthesis of catalysts for
such reactions is often accompanied by the discharge of large amounts of
wastewater and other pollutants, such as NOx, SOx, and halogens.
As a result of their commitment to continuously develop and invest in new and
improved catalyst synthesis technologies, Sud-Chemie successfully developed
and demonstrated a new synthetic pathway that is able to achieve virtually zero
wastewater discharge, zero nitrate discharge, and no or little NOx emission.
Meantime, it substantially reduces the consumption of water and energy. For
example, it is estimated that about 378,900 tons of wastewater discharges,
about 14,300 tons of nitrate discharges, and about 3,800 tons of NOx emissions
can be eliminated for every 5,000 tons of oxide catalyst produced.
The new synthetic pathway is based on very simple chemistry. Instead of acid-
base precipitation typically using metal nitrate as raw material, the new process
starts with a clean metal that is readily and economically available in commercial
quantities. The synthesis proceeds by reaction of the metal with a mild organic
acid in the presence of an oxidation agent. The function of the acid is to
activate the metal and extract electrons to form the oxide precursor. With
assistance of the oxidation agent (typically air), a porous solid oxide is synthe-
sized in one step at ambient temperature without any wastewater discharge.
The other active ingredients of the catalyst can be incorporated using the
concept of wet-agglomeration. In contrast, the precipitation process requires
intensive washing and filtration to remove nitrate and the other salts. Further,
the new process substantially reduces the consumption of water and energy for
production of solid oxide catalysts over conventional methods. The emission in
the entire process is only pure water vapor and a small amount of CO2 that is
generated during spray drying and after-burning of hydrogen.
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This wastewater-free process for making solid oxide catalysts has been demon-
strated and more than 300 kg of the metal oxide catalysts has been produced.
Patent protection is being sought for the development. The catalysts made by
the green process give superior performance in the synthesis of clean fuels and
chemicals. The market for such solid oxide catalysts is estimated to be approxi-
mately $100 million. Sud-Chemie Is the first in the industry to use the green
process for making a catalyst for the synthesis of "green" fuels and chemicals.
6 2003 Alternative Synthetic Pathways Award
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Alternative Solvents/
Reaction Conditions Category
DuPont
Microbial Production of 1,3-Propanediol
DuPont is integrating biology in the manufacture of its newest polymer
platform, DuPont Sorona® polymer. Combining metabolic engineering with
polymer science, researchers are Introducing a microbial process in a business
that, historically, has relied solely on traditional chemistry and petrochemical
feedstock. This achievement, comprising biocatalytic production of
1,3-propanediol from renewable resources, offers economic as well as environ-
mental advantages. The key to the novel biological process is an engineered
microorganism that incorporates several enzyme reactions, obtained from
naturally occurring bacteria and yeast, into an industrial host cell line. For the
first time, a highly engineered microorganism will be used to convert a renew-
able resource into a chemical at high volume.
The catalytic efficiency of the engineered microorganism allows replacement of
a petroleum feedstock, reducing the amount of energy needed in manufactur-
ing steps and improving process safety. The microbial process is environmen-
tally green, less expensive, and more productive than the chemical operations it
replaces. 1,3-Propanediol, a key ingredient in the Sorona® polymers, provides
advantageous attributes for apparel, upholstery, resins, and nonwoven applica-
tions.
Scientists and engineers from DuPont and Genencor International, Inc. rede-
signed a living microbe to produce 1,3-propanediol. Inserting biosynthetfc
pathways from several microorganisms into an industrial host cell line allows the
direct conversion of glucose to 1,3-propanediol, a route not previously available
in a single microorganism. Genes from a yeast strain with the ability to convert
glucose, derived from cornstarch, to glycerol were inserted into the host. Genes
from a bacterium with the ability to transform glycerol to 1,3-propanediol were
also incorporated. Additionally, the reactions present naturally in the host were
altered to optimize product formation. The modifications maximize the ability of
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the organism to convert glucose to 1,3-propanediol while minimizing its ability
to produce biomass and unwanted byproducts. Coalescing enzyme reactions
from multiple organisms expands the range of materials that can be economi-
cally produced by biological means.
For more than 50 years, scientists have recognized the performance benefits of
polyesters produced with 1,3-propanediol; however, the high cost of manufac-
turing the ingredient using petroleum feedstock and traditional chemistry kept it
from the marketplace. The biological process using glucose as starting material
will enable cost-effective manufacture of Sorona® polymer, which will offer
consumers fabrics with softness, stretch and recovery, easy care, stain resis-
tance, and colorfastness. A unique kink in the structure of the polymer contain-
ing 1,3-propanediol allows recovery at a high rate when it is stretched. As a
result, Sorona® improves fit and comfort because a fabric quickly recovers its
original shape when stretched, for example, in knees or elbows. The resilience
of Sorona® also adds beneficial features to automotive upholstery and home
textiles. In resin applications, Sorona® barrier characteristics protect moisture,
taste, and odor.
Biology offers chemical manufacturers attractive options for the production of
chemicals while adhering to the principles of Green Chemistry. This microbial
production of a key polymer ingredient from renewable sources is one example.
By integrating biology with chemistry, physics, and engineering, DuPont
develops new solutions that enhance the environment and improve upon
existing materials.
8 2003 Alternative Solvents/Reaction Conditions Award
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Designing Safer Chemicals Category
Shaw Industries, Inc.
EcoWorx™ Carpet Tile: A Cradle-to-Crad!e Product
Historically, carpet tile backings have been manufactured using bitumen,
polyvinyl chloride (PVC), or polyurethane (PU). While these backing systems
have performed satisfactorily, there are several inherently negative attributes
due to their feedstocks or their ability to be recycled. Although PVC has, to-date,
held the largest market share of carpet tile backing systems, it was our intent to
design around PVC due to the health and environmental concerns around vinyl
chloride monomer, chlorine-based products, plasticized PVC-containing phtha-
late esters, and toxic byproducts of combustion of PVC, such as dioxin and
hydrochloric acid. While some claims are accepted by the Agency for Toxic
Substances and Disease Registry and the U.S. Environmental Protection Agency,
those resulting from publicly debated consumer perceptions provide ample
justification for finding a PVC alternative.
Due to the thermoset cross-linking of polyurethanes, they are extremely difficult
to recycle and are typically downcycled or landfilled at the end of their useful
life. Bitumen provides some advantages in recycling, but the modified bitumen
backings offered in Europe have failed to gain market acceptance in the United
States and are unlikely to do so.
Shaw selected a combination of polyolefin resins from Dow Chemical as the
base polymer of choice for EcoWorx™ due to the low toxicity of its feedstocks,
superior adhesion properties, dimensional stability, and its ability to be recycled.
The EcoWorx™ compound also had to be designed to be compatible with
nylon carpet fiber. Although EcoWorx™ may be recovered from any fiber type,
nylon-6 provides a significant advantage. Polyolefins are compatible with
known nylon-6 depolymerization methods. PVC interferes with those processes.
Nylon-6 chemistry is well known and not addressed in first generation
production.
From its inception, EcoWorx™ met all of the design criteria necessary to satisfy
the needs of the marketplace from a performance, health, and environmental
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standpoint. Research indicated that separation of the fiber and backing through
elutriation, grinding, and air separation proved to be the best way to recover the
face and backing components, but an infrastructure for returning postconsumer
EcoWorx™ to the elutriation process was necessary. Research also indicated
that the postconsumer carpet tile had a positive economic value at the end of
its useful life. The cost of collection, transportation, elutriation, and return to the
respective nylon and EcoWorx™ manufacturing processes is less than the cost
of using virgin raw materials.
With introduction in 1999 and an anticipated lifetime often to fifteen years on
the floor, significant quantities of EcoWorx™ will not flow back to Shaw until
2006 to 2007. An expandable elutriation unit is now operating at Shaw, typically
dealing with industrial EcoWorx™ waste. Recovered EcoWorx™ is flowing back
to the backing extrusion unit. Caprolactam recovered from the elutriated nylon-6
is flowing back into nylon compounding. EcoWorx™ will soon displace all PVC
at Shaw.
10 2003 Designing Safer Chemicals Award
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