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Green Chemistry ist eine Begriff der die eine Chemie ohne grosse Umweltbelastungen beschreibt.[1] Dabei wird vor allem auf die Verwendung von natürlichen Lösungsmitteln, umweltverträglichen Reagenzien, geringen Nebenprodukten und geringem Abfall Wert gelegt.

Es ist eine Art chemische Philosophie und betrifft die Organische Chemie, Anorganische Chemie, Biochemie, Analytische Chemie und die Physikalische Chemie. Der Fokus ist auf der Minderung der Gefahr und der Maximierung der Leistungsfähigkeit eines chemischen Prozesses.

Im Jahr 2005 definierte Ryoji Noyori drei Grundsätze für green chemistry: den Gebrauch von überkritischem Kohlendioxid als grünes Lösungsmittel, wässriges Wasserstoffperoxid für sauberes Oxidationen und der Gebrauch des Wasserstoffs in der asymetrische Synthese. [2] Beispiele für eine angewandte green chemistry sind die Oxidationen in überkritischen Wasser, Reaktionen in Wasser als Lösungsmittel oder lösungsmittelfreie Reaktionen.

Biotechnologie ist eine versprechende Technik um auf umweltfreundlich Weg Chemikalien zu synthetisieren. Derzeit werden wichtige Prozesschemikalien wie die Zitronensäure oder die Shikimisäure, ein wichtiger Vorläufer zur Synthese von Tamiflu auf einem biotechnologischem Weg bei Roche hergestellt.

Konzepte[Bearbeiten | Quelltext bearbeiten]

Paul Anastas und John C. Warner von der Environmental Protection Agency und John C. Warner entwickelten zwölf Grundprinzipien von Green Chemistry[3] :

  1. Verschmutzung vermeiden: Chemische Synthesen bzw. Prozesse und Reaktoren so gestalten, dass Verschmutzungen und Verseuchungen vermieden werden.
  2. Sicherere chemische Produkte designen: Betonung von effektiven Produkten, die bei gleichem Nutzen weniger giftig sind als vergleichbare Materialien
  3. Die Herstellung von weniger gefährlichen Stoffen: die Erstellung und Nutzung von Substanzen, von denen keine Gefahr für Mensch und Umwelt ausgeht.
  4. Die intensive Nutzung erneuerbarer Rohstoffe.
  5. Nutzung von Katalysatoren anstelle von stöchiometrischen Reagenzien.
  6. Die Vermeidung unnötiger Zwischenstufen in chemischen Prozessen
  7. Die Maximierung der Atomeffizienz: Synthesen und Reaktionen so gestalten und nutzen, dass sie die maximale Ausbeute ermöglichen. Es sollten keine/wenige Atome der Ausgangsreagenzien übrig bleiben.
  8. Anwendung von sicheren Lösungsmitteln und Reaktionsbedingungen; wenn möglich Einsatz von Hilfsstoffen vermeiden.
  9. Die Erhöhung der Energieeffizienz: wenn möglich Durchführung von Reaktionen bei Raumtemperatur
  10. Die Herstellung von Chemikalien und Produkten, die nach der Nutzung natürlich abgebaut werden können, ohne der Umwelt zu schaden.
  11. Echtzeitüberwachung, Kontrolle und Steuerung aller Vorgänge, um Verschmutzung und Verunreinigungen und damit Verschwendung vorzubeugen.
  12. Das Risiko für Unfälle minimieren.

Presidential Green Chemistry Challenge Awards[Bearbeiten | Quelltext bearbeiten]

The Presidential Green Chemistry Challenge Awards[4] 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 1996, Dow Chemical won the 1996 Greener Reaction Conditions award for their 100% carbon dioxide blowing agent for polystyrene foam 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, CFC and 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 dioxide works 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.
Lactide
  • In 2002, Cargill Dow (now NatureWorks) won the Greener Reaction Conditions Award for their improved polylactic acid polymerization process. Lactic acid is 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 textiles and apparel, cutlery, and food packaging. Wal-Mart has 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 recyclable and compostable.
  • In 2003 Shaw Industries was 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 Cradle design.
Trans and cis fatty acids
  • In 2005, Archer Daniels Midland (ADM) and Novozymes N.A. won the Greener Synthetic Pathways Award for their enzyme interesterification process. In response to the U.S. Food and Drug Administration (FDA) mandated labeling of trans-fats on nutritional information by January 1, 2006, Novozymes and ADM worked together to develop a clean, enzymatic process for the interesterification of 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.
Glycerine to propylene glycol
  • In 2006, Professor Galen J. Suppes, from the University of Missouri in Columbia, Missouri, was awarded the Academic Award for his system of converting waste glycerin from biodiesel production 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 glycol that is the primary ingredient in automobile antifreeze.

Other awards[Bearbeiten | Quelltext bearbeiten]

The Royal Australian Chemical Institute (RACI) presents Australia’s Green Chemistry Challenge Awards. This awards program is similar to that of the United States Environmental Protection Agency‎ (EPA), although the RACI has included a category for green chemistry education as well as small business and academic or government. Vorlage:Clarify

The Canadian Green Chemistry Medal is an annual award given to an individual or group for promotion and development of green chemistry in Canada and internationally. The winner is presented with a citation recognizing the achievements together with a sculpture.[5]

Green Chemistry activities in Italy center 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.[6]

In 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.[7]

In the 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.[8]

The Nobel Prize Committee recognized the importance of green chemistry in 2005 by awarding Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock the Nobel Prize for Chemistry for "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."[9]

Trends[Bearbeiten | Quelltext bearbeiten]

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,[10] the reduction of nitrobenzene to aniline receives 64 points out of 100 marking it as an acceptable synthesis overall whereas a synthesis of an amide using 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.[11] As nanomaterials are 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.

Laws[Bearbeiten | Quelltext bearbeiten]

In 2007, Europe put into place the Registration, Evaluation, Authorisation, and Restriction of Chemicals (REACH) program, which requires companies to provide data showing that their products are safe. The US Toxic Substances Control Act, passed in 1976, has no similar provisions.

On September 29, 2008 California approved two laws which encourage green chemistry, launching the California Green Chemistry Initiative. The law requires California's Department of Toxic Substances Control to prioritize "chemicals of concern", and puts the burden of testing on the agency rather than industry. The laws were criticized by Paul Anastas, who stated that the laws did not go far enough in encouraging research, education, and industry incentives.[12]

Examples[Bearbeiten | Quelltext bearbeiten]

Supramolecular chemistry[Bearbeiten | Quelltext bearbeiten]

Research is currently ongoing in the area of supramolecular chemistry to develop reactions which can proceed in the solid state without the use of solvents. The cycloaddition of trans-1,2-bis(4-pyridyl)ethylene is directed by resorcinol in the solid state. This solid-state reaction proceeds in the presence of UV light in 100% yield.[13]

Cycloaddition of trans-1,2-bis(4-pyridyl)ethylene

Reducing market barriers[Bearbeiten | Quelltext bearbeiten]

In March 2006, the University of California published a report by Dr. Michael P. Wilson and colleagues, Daniel A. Chia and Bryan C. Ehlers, on potential 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. Drs. Wilson and Schwarzman of UC Berkeley published their analysis in the August issue of Environmental Health Perspectives (EHP) in an article entitled, Toward a New U.S. Chemicals Policy: Rebuilding the Foundation to Advance New Science, Green Chemistry, and Environmental Health[14].

Education[Bearbeiten | Quelltext bearbeiten]

The University of Massachusetts, Boston became the first university in the World to offer a Ph.D. in Green Chemistry.[15] In 2005, the University of Oregon's chemistry department unveiled the Greener Education Materials, a database of green chemistry topics.[16] In 2009, Oxford University Press/ACS Symposium Series published Green Chemistry Education: Changing the Course of Chemistry.[17] The book contains essays from a broad array of educators who share their best practices for the incorporation of green chemistry into the chemistry and chemical engineering curricula.

Laboratory chemicals[Bearbeiten | Quelltext bearbeiten]

Several laboratory chemicals are controversial, and alternatives have been explored. The Massachusetts Institute of Technology has created the Green Alternatives Wizard to help identify alternatives. Ethidium bromide, xylene, mercury, and formalin have been identified as "worst offenders" which have alternatives.[18]

Organometallic chemicals[Bearbeiten | Quelltext bearbeiten]

Following green chemistry principles, ionic liquids and microreactors were recently used to synthesize and purify extremely reactive organometallic compounds for ALD and CVD applications, with improved safety in operations and efficient production of ultra-high purity organometallics.[19][20]

Scientific uncertainty[Bearbeiten | Quelltext bearbeiten]

Following historical analyses of the green chemistry development, there have been advocates of green chemistry whom look upon green chemistry as an innovative way of thinking. On the other hand, there have been chemists whom argued that green chemistry is no more than a public relations label. In fact, a lot of chemists use the term green chemistry indepedently from the green chemistry paradigm, as proposed by Anastas and Warner. This explains the uncertainty of the scientific status of green chemistry.[21]

See also[Bearbeiten | Quelltext bearbeiten]

Vorlage:Portal box

Einzelnachweise[Bearbeiten | Quelltext bearbeiten]

  1. http://www.epa.gov/greenchemistry/
  2. Pursuing practical elegance in chemical synthesis Ryoji Noyori Chemical Communications, 2005, (14), 1807 - 1811 Abstract
  3. The 12 Principles of Green Chemistry. In: United States Environmental Protection Agency. Abgerufen am 31. Juli 2006.
  4. The Presidential Green Chemistry Awards. In: United States Environmental Protection Agency. Abgerufen am 31. Juli 2006.
  5. Announcing the 2005 Canadian Green Chemistry Medal. In: RSC Publishing. Abgerufen am 4. August 2006.
  6. Chemistry for the Environment. In: Interuniversity Consortium. Abgerufen am 15. Februar 2007.
  7. Green & Sustainable Chemistry Network, Japan. In: Green & Sustainable Chemistry Network. Abgerufen am 4. August 2006.
  8. 2005 Crystal Faraday Green Chemical Technology Awards. In: Green Chemistry Network. Abgerufen am 4. August 2006.
  9. The Nobel Prize in Chemistry 2005. In: The Nobel Foundation. Abgerufen am 4. August 2006.
  10. 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 ) Article
  11. Green nanotechnology
  12. Renner R. (November 19, 2008). California launches nation’s first green chemistry program. Environmental Science & Technology.
  13. L. R. MacGillivray, J. L. Reid and J. A. Ripmeester: Supramolecular Control of Reactivity in the Solid State Using Linear Molecular Templates. In: J. Am. Chem. Soc. 122. Jahrgang, Nr. 32, 2000, S. 7817–7818, doi:10.1021/ja001239i.
  14. Wilson M, Schwarzman M. 2009. Toward a New U.S. Chemicals Policy: Rebuilding the Foundation to Advance New Science, Green Chemistry, and Environmental Health 117(8) 1202-1209 and A358. Available: http://www.ehponline.org/docs/2009/0800404/abstract.html and EHP Science Selections, http://www.ehponline.org/docs/2009/117-8/ss.html#chem
  15. http://www.chem.umb.edu/graduate/phd.html
  16. EurekAlert. (2009). Thinking of turning your chemistry green? Consult GEMs. AAAS.
  17. Green Chemistry Education: Changing the Course of Chemistry (= ACS Symposium Series. Band 1011). American Chemical Society, 2009, ISBN 978-0-8412-7447-1, doi:10.1021/bk-2009-1011.
  18. Coombs A. (2009). Green at the Bench. The Scientist.
  19. Method of Preparing Organometallic Compounds Using Microchannel Devices, 2009, Francis Joseph Lipiecki, Stephen G. Maroldo, Deodatta Vinayak Shenai-Khatkhate, and Robert A. Ware, US 20090023940
  20. Purification Process Using Microchannel Devices, 2009, Francis Joseph Lipiecki, Stephen G. Maroldo, Deodatta Vinayak Shenai-Khatkhate, and Robert A. Ware, US 20090020010
  21. J.A. Linthorst: An Overview: Origins and Development of Green Chemistry. In: Foundations of Chemistry. 12. Jahrgang, Nr. 1, 2010, S. 55–68, doi:10.1007/s10698-009-9079-4.

External links[Bearbeiten | Quelltext bearbeiten]

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