- Green chemistry
Green chemistry, also called sustainable chemistry, is a chemical philosophy encouraging the design of products and processes that reduce or eliminate the use and generation of hazardous substances. Whereas
environmental chemistryis the chemistry of the natural environment, and of pollutant chemicals in nature, green chemistry seeks to reduce and prevent pollutionat its source. In 1990the Pollution Prevention Actwas passed in the United States. This act helped create a "modus operandi" for dealing with pollution in an original and innovative way. It aims to avoid problems before they happen.
As a chemical philosophy, green chemistry derives from
organic chemistry, inorganic chemistry, biochemistry, analytical chemistry, and even physical chemistry. However, the philosophy of green chemistry tends to focus on industrial applications. Click chemistryis often cited as a style of chemical synthesis that is consistent with the goals of green chemistry. The focus is on minimizing the hazard and maximizing the efficiency of any chemical choice. It is distinct from environmental chemistrywhich focuses on chemical phenomena in the environment.
2005 Ryoji Noyoriidentified three key developments in green chemistry: use of supercritical carbon dioxideas green solvent, aqueous hydrogen peroxidefor clean oxidations and the use of hydrogen in asymmetric synthesis. ["Pursuing practical elegance in chemical synthesis" Ryoji Noyori Chemical Communications, 2005, (14), 1807 - 1811 [http://www.rsc.org/publishing/journals/CC/article.asp?doi=b502713f Abstract] ] Examples of applied green chemistry are supercritical water oxidation, on water reactions and dry media reactions. Bioengineeringis also seen as a promising technique for achieving green chemistry goals. A number of important process chemicals can be synthesized in engineered organisms, such as shikimate, a Tamifluprecursor which is fermented by Roche in bacteria.
Paul Anastas, then of the
United States Environmental Protection Agency, and John C. Warner developed 12 principles of green chemistry, [cite web | title=The 12 Principles of Green Chemistry | work= United States Environmental Protection Agency| url=http://www.epa.gov/greenchemistry/pubs/principles.html | accessdate=2006-07-31] which help to explain what the definition means in practice. The principles cover such concepts as:
* the design of processes to maximize the amount of raw material that ends up in the product;
* the use of safe, environment-benign substances, including solvents, whenever possible;
* the design of energy efficient processes;
* the best form of waste disposal: do not create it in the first place.
The 12 principles are:
# "Prevent waste:" Design chemical syntheses to prevent
waste, leaving no waste to treat or clean up.
# "Design safer
chemicals and products:" Design chemical products to be fully effective, yet have little or no toxicity.
# "Design less hazardous chemical syntheses:" Design syntheses to use and generate substances with little or no toxicity to humans and the environment.
renewablefeedstock:" Use raw materialsand feedstock that are renewable rather than depleting. Renewable feedstock are often made from agricultural products or are the wastes of other processes; depleting feedstock are made from fossil fuels( petroleum, natural gas, or coal) or are mined.
catalysts, not stoichiometric reagents:" Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.
# "Avoid chemical derivatives:" Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.
atom economy:" Design syntheses so that the final product contains the maximum proportion of the starting materials. There should be few, if any, wasted atoms.
# "Use safer
solvents and reactionconditions:" Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals. If a solvent is necessary, water is a good medium as well as certain eco-friendly solvents that do not contribute to smog formation or destroy the ozone.
energy efficiency:" Run chemical reactions at ambient temperatureand pressure whenever possible.
# "Design chemicals and products to degrade after use:" Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment.
# "Analyze in real time to prevent
pollution:" Include in-process real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts.
# "Minimize the potential for accidents:" Design chemicals and their forms (
solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.
Presidential Green Chemistry Challenge Awards
The Presidential Green Chemistry Challenge Awards [cite web | title=The Presidential Green Chemistry Awards | work=
United States Environmental Protection Agency| url=http://www.epa.gov/greenchemistry/pubs/pgcc/presgcc.html | accessdate=2006-07-31] began in 1995 as an effort to recognize individuals and businesses for innovations in green chemistry. Typically five awards are given each year, one in each of five categories: Academic, Small Business, Greener Synthetic Pathways, Greener Reaction Conditions, and Designing Greener Chemicals. Nominations are accepted the prior year, and evaluated by an independent panel of chemists convened by the American Chemical Society. Through 2006, a total of 57 technologies have been recognized for the award, and over 1000 nominations have been submitted.
*In 2006, Professor Galen J. Suppes, from the
University of Missouri–Columbia, was awarded the Academic Award for his system of converting waste glycerinfrom biodieselproduction to propylene glycol. Through the use of a copper-chromite catalyst, Professor Suppes was able to lower the required temperature of conversion while raising the efficiency of the distillation reaction. Propylene glycol produced in this way will be cheap enough to replace the more toxic ethylene glycolthat is the primary ingredient in automobile antifreeze.
Archer Daniels Midland(ADM) and [http://www.novozymes.com/en Novozymes N.A.] won the Greener Synthetic Pathways Award for their enzymeinteresterification process. In response to the FDAmandated labeling of "trans"-fats on nutritional information by January 1, 2006, Novozymes and ADM worked together to develop a clean, enzymatic process for the interesterificationof oils and fats by interchanging saturated and unsaturated fatty acids. The result is commercially viable products without "trans"-fats. In addition to the human health benefits of eliminating "trans"-fats, the process has reduced the use of toxic chemicals and water, prevents vast amounts of byproducts, and reduces the amount of fats and oils wasted.
*In 2002, Cargill Dow (now [http://www.natureworksllc.com/corporate/nw_pack_home.asp NatureWorks] ) won the Greener Reaction Conditions Award for their improved
polylactic acid polymerizationprocess. Lactic acidis produced by fermenting corn and converted to lactide, the cyclic dimer ester of lactic acid using an efficient, tin-catalyzed cyclization. The L,L-lactide enantiomer is isolated by distillation and polymerized in the melt to make a crystallizable polymer, which has use in many applications including textilesand apparel, cutlery, and food packaging. Wal-Marthas announced that it is using/will use PLA for its produce packaging. The NatureWorks PLA process substitutes renewable materials for petroleum feedstocks, doesn't require the use of hazardous organic solvents typical in other PLA processes, and results in a high-quality polymer that is recyclableand compostable.
Dow Chemicalwon the 1996 Greener Reaction Conditions award for their 100% carbon dioxideblowing agent for polystyrenefoam production. Polystyrene foam is a common material used in packing and food transportation. Seven hundred million pounds are produced each year in the United States alone. Traditionally, CFCand other ozone-depleting chemicals were used in the production process of the foam sheets, presenting a serious environmental hazard. Flammable, explosive, and, in some cases toxic hydrocarbons have also been used as CFC replacements, but they present their own problems. Dow Chemical discovered that supercritical carbon dioxideworks equally as well as a blowing agent, without the need for hazardous substances, allowing the polystyrene to be more easily recycled. The CO2 used in the process is reused from other industries, so the net carbon released from the process is zero.
Shaw Industrieswas recognized with the Designing Greener Chemicals Award for developing EcoWorx Carpet Tile. 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. Shaw selected a combination of polyolefin resins 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 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. EcoWorx is recognized by MBDC as a certified Cradle to Cradledesign.
Royal Australian Chemical Institute(RACI) presents Australia’s Green Chemistry Challenge Awards. This awards program is similar to that at the EPA, although the Institute has included a category for Green Chemistry education as well as Small Business and Academic or Government. The Canadian Green Chemistry Medal is an annual award given to an individual or group for promotion and development of green chemistry in Canadaand internationally. The winner is presented with a citation recognizing the achievements together with a sculpture. [cite web | title=Announcing the 2005 Canadian Green Chemistry Medal | work=RSC Publishing | url=http://www.rsc.org/Publishing/Journals/gc/News/Green.asp | accessdate=2006-08-04]
Green Chemistry activities in
Italycenter around an inter-university consortium known as INCA. Beginning in 1999, the INCA has given three awards annually to industry for applications of green chemistry. The winners receive a plaque at the annual INCA meeting. [cite web | title=Chemistry for the Environment | work=Interuniversity Consortium | url=http://www.incaweb.org/ | accessdate=2007-02-15]
Japan, The Green & Sustainable Chemistry Network(GSCN), formed in 1999, is an organization consisting of representatives from chemical manufacturers and researchers. In 2001, the organization began an awards program. GSC Awards are to be granted to individuals, groups or companies who greatly contributed to green chemistry through their research, development and their industrialization. The achievements are awarded by Ministers of related government agencies. [cite web | title=Green & Sustainable Chemistry Network, Japan | work=Green & Sustainable Chemistry Network | url=http://www.gscn.net/aboutE/index.html | accessdate=2006-08-04]
United Kingdom, the Crystal Faraday Partnership, a non-profit group founded in 2001, awards businesses annually for incorporation of green chemistry. The Green Chemical Technology Awards have been given by Crystal Faraday since 2004; the awards were presented by the Royal Society of Chemistry prior to that time. The award is given only to a single researcher or business, while other notable entries are given recognition as well. [cite web | title=2005 Crystal Faraday Green Chemical Technology Awards | work=Green Chemistry Network | url=http://www.chemsoc.org/networks/gcn/awards.htm | accessdate=2006-08-04] The Nobel PrizeCommittee recognized the importance of green chemistry in 2005 by awarding Yves Chauvin, Robert H. Grubbs, and Richard R. Schrockthe Nobel Prize for Chemistryfor "the development of the metathesis method in organic synthesis." The Nobel Prize Committee states, "this represents a great step forward for 'green chemistry', reducing potentially hazardous waste through smarter production. Metathesis is an example of how important basic science has been applied for the benefit of man, society and the environment." [cite web | title=The Nobel Prize in Chemistry 2005 | work=The Nobel Foundation | url=http://nobelprize.org/nobel_prizes/chemistry/laureates/2005/press.html | accessdate=2006-08-04]
Attempts are being made not only to quantify the "greenness" of a chemical process but also to factor in other variables such as
chemical yield, the price of reaction components, safety in handling chemicals, hardware demands, energy profile and ease of product workup and purification. In one quantitative study, ["EcoScale, a semi-quantitative tool to select an organic preparation based on economical and ecological parameters". Van Aken K, Strekowski L, Patiny L Beilstein Journal of Organic Chemistry, 2006 2:3 ( 3 March 2006 ) [http://bjoc.beilstein-journals.org/content/pdf/1860-5397-2-3.pdf Article] ] the reduction of nitrobenzeneto anilinereceives 64 points out of 100 marking it as an acceptable synthesis overall whereas a synthesis of an amideusing HMDS is only described as adequate with a combined 32 points.
Green chemistry is increasingly seen as a powerful tool that researchers must use to evaluate the environmental impact of nanotechnology. [ [http://www.nanotechproject.org/file_download/files/GreenNano_PEN8.pdf Green nanotechnology] ] As
nanomaterialsare developed, the environmental and human health impacts of both the products themselves and the processes to make them must be considered to ensure their long-term economic viability.
Research is currently ongoing in the area of
supramolecular chemistryto develop reactions which can proceed in the solid state without the use of solvents. The cycloadditionof "trans"-1,2-bis(4-pyridyl)ethylene is directed by resorcinolin the solid state. This solid-state reaction proceeds in the presence of UV light in 100% yield. [cite journal | author = L. R. MacGillivray, J. L. Reid and J. A. Ripmeester | title = Supramolecular Control of Reactivity in the Solid State Using Linear Molecular Templates | year = 2000 | journal = J. Am. Chem. Soc.| volume = 122 | issue = 32 | pages = 7817–7818 | doi=10.1021/ja001239i]
Reducing market barriers
In March 2006, the University of California published a landmark report by Dr. Michael P. Wilson and colleagues, Daniel A. Chia and Bryan C. Ehlers, on green chemistry and chemicals policy for the California Legislature entitled, Green Chemistry in California: A Framework for Leadership in Chemicals Policy and Innovation (http://coeh.berkeley.edu/news/06_wilson_policy.htm). The report finds that long-standing weaknesses in the U.S. chemical management program, notably the
Toxic Substances Control Act(TSCA) of 1976, have produced a chemicals market in the U.S. that discounts the hazardous properties of chemicals relative to their function, price, and performance. The report concludes that these market conditions represent a key barrier to the scientific, technical, and commercial success of green chemistry in the U.S., and that fundamental policy changes are needed to correct these weaknesses.
The report describes three primary U.S. policy weaknesses: (1) The Data G
U.S. Environmental Protection Agency. Even if test results are submitted, they may be claimed as confidential and cannot be disclosed. As a consequence, industrial buyers, workers, and consumers may not have the information they need to make informed decision about the chemicals they use. This data gap allows potentially hazardous chemicals to remain competitive in the market, and may undermine the commercial success of less hazardous products; (2) The Safety G
The UC report calls for a modern, comprehensive chemicals policy to motivate new investment in green chemistry by improving transparency and accountability in the chemicals market. The report argues that these changes are needed soon, given the growing body of scientific information on the health and environmental effects of many chemicals, and the expected doubling of global chemical production over the next 25 years. Recommendations include (1) regulations to improve the generation and flow of information on the health and environmental effects of chemicals; (2) enhancing the capacity of public agencies to assess chemical risks and control those of greatest concern; and (3) increasing public investments in green chemistry research, education, and technology diffusion. The report argues that by taking these steps, California can position itself to become a global leader in green chemistry innovation, and that doing so will address a growing set of health and environmental problems related to chemicals and will open new possibilities for investment, employment, and productive capacity in California in green chemistry.
In January 2008, the University of California at Berkeley and Los Angeles produced a second report, Green Chemistry: Cornerstone to a Sustainable California (http://coeh.berkeley.edu/greenchemistry/briefing/). Commissioned by California EPA and endorsed by 127 UC faculty members from seven UC campuses and the UC national labs, the Cornerstone Report builds on the findings of the 2006 UC report to the California Legislature (noted above) and presents new cost estimates of the health and environmental consequences of existing chemical and product management approaches. The Cornerstone Report proposes policy strategies to stimulate investment in green chemistry by steadily closing the data, safety and technology gaps. California EPA Secretary Linda Adams released a statement noting that "the University of California's green chemistry report supports and reinforces the significance of the state's new environmental protection initiative on green chemistry. The University of California is an important partner in our efforts to establish a first-of-its-kind comprehensive policy for managing toxic chemicals in products." (http://www.calepa.ca.gov/PressRoom/Releases/2008/PR1-011708.pdf)
Bioremediation- a technique that generally falls outside the scope of green chemistry
Green computing- a similar initiative in the area of computing
Green Chemistry (journal)- a journal published by the Royal Society of Chemistry
* [http://www.epa.gov/greenchemistry/ EPA Green Chemistry Program Website]
* [http://www.acs.org/greenchemistry American Chemical Society Green Chemistry Institute]
* [http://www.dtsc.ca.gov/PollutionPrevention/GreenChemistryResources/index.cfm California Department of Toxic Substances Control, Green Chemistry Initiative]
* [http://www.rsc.org/chemsoc/gcn/index.htm Green Chemistry Network (GCN)]
* [http://coeh.berkeley.edu/greenchemistry/ University of California, Berkeley, Program in Green Chemistry and Chemicals Policy]
* [http://www.greenchemistry.yale.edu/ Center for Green Chemistry and Green Engineering at Yale University]
* [http://www.greenchemistry.net/ Green Chemistry Centre of Excellence at the University of York, UK]
* [http://www.csg.dtu.dk/ Center for Sustainable and Green Chemistry at the Technical University of Denmark]
* [http://www.megrec.org/ Mediterranean Countries Green Chemistry Network]
* [http://www.rand.org/pubs/monograph_reports/MR1682/index.html Next Generation Environmental Technologies Published by RAND]
* [http://tauac.typepad.com/ac/2007/02/green_your_beak.html Green Chemistry at Tel Aviv University]
* [http://www.chinacleanenergyinc.com/chemicals.htm China Clean Energy (Green chemicals as coproduct of biodiesel production)]
* [http://www.beyondbenign.org/index.html Beyond Benign Foundation for Green Chemistry Education]
* [http://www.rsc.org/Publishing/Journals/gc/Index.asp Green Chemistry] , Journal of the
Royal Society of Chemistry
Wikimedia Foundation. 2010.