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Supercritical fluids a clean route to polymer synthesis and polymer processing Steve Howdle of the School of Chemistry at the University of Nottingham UK describes his pioneering research work on the use of supercritical fluids in polymer science and his other contributions to the field of green chemistry that led to his receiving the 2001 Jerwood Salters’ Environment Award Introduction Dispersion polymerisation is an extremely important process both in the UK and worldwide for the synthesis of both commodity and speciality polymers based upon acrylate and methacrylate monomers. In 1995 J. M. DeSimone demonstrated that the conventional Steve Howdle dispersing solvent could be replaced by scCO2 and materials such as poly(methylmethacrylate) (PMMA) could be prepared effectively if the right stabiliser could be designed.In so doing DeSimone demonstrated that a stabiliser based upon a poly (dihydrofluorooctylacrylate) (PFOA) was highly effective. This breakthrough triggered a flurry of activity in both industry and academia targeted at developing new stabilisers and expanding the potential uses of scCO2 for polymerisation. Much of the excitement arose because in principle the use of scCO2 (or dense phase CO2) could at a stroke eliminate the need for the potentially toxic conventional solvents that are currently used in dispersion polymerisation. However conventional dispersion polymerisation studies over many years have shown that the structure and quantity of the stabiliser required is very system dependent and is critical not only to achieving a successful polymerisation but also to its potential commercial viability.Thus the key to success in this field is the design of stabilisers that function effectively in scCO2 lead to pure polymer product and are commercially viable. The performance requirements for an active stabiliser are that it anchors to the growing particle of polymer but at the same time has sufficient interaction with the scCO2 solvent for a stable dispersion to form. This prevents flocculation and precipitation and allows the polymerisation process to continue successfully to completion. Thus the stabilisers must contain both ‘CO2-phobic’ and ‘CO2-philic’ moieties.For example the PFOA pioneered by DeSimone contains a CO2-phobic hydrocarbon backbone that associates with the growing PMMA chains and a series of fluorinated tails to provide the required solubility in scCO2 (Fig. 1). Fig. 1 Poly(1,1-dihydroperfluorooctyl acrylate) stabiliser (DeSimone et al. Science 1994 265 356). Several other similar stabilisers have been developed by US and UK research teams (DeSimone Beckman Johnston Holmes) and the common theme is the presence of a CO2-philic fluorinated or siloxane based moiety and a hydrocarbon backbone. In all of these cases effective stabilisation is observed at typical stabiliser loadings of ca. 5 wt% with respect to monomer. However the stabilisers are not commercially available and they must be custom synthesised in most cases by demanding synthetic methodologies that may not commercially viable in their own right.Furthermore all of these stabilisers contain a hydrocarbon backbone from which hydrogen atoms may be abstracted during free radical polymerisation. The consequence of this is that a substantial portion of each stabiliser becomes covalently bonded into the PMMA product and the final polymer can seldom be regarded as ‘pure’. Also there is a substantial physical entrapment because the stabilisers are sufficiently large that entanglements within the product polymer trap them. Again from study on conventional dispersion polymerisation systems such contamination has been shown to drastically effect the resultant polymer performance by introducing problems such as blooming gloss reduction and interfacial delamination that should be avoided at all costs.Stabiliser incorporation is also a major drawback in the alternative approach of using siloxane macromonomers. This approach relies upon incorporation of a reactive stabiliser (macromonomer) (Fig. 2) into the backbone of the product PMMA at levels Fig. 2 PDMS macromonomer approach to stabilization of dispersion polymerization. Green Chemistry June 2002 DOI 10.1039/b204528c This journal is © The Royal Society of Chemistry 2002 NEWS & V I E W S G29 Fig. 3 Krytox 157 FSL – a commercially available carboxylic acid terminated n 2500 D n ~ 14). NEWS & V I E W S that can approach 3–5 wt% of the final polymer product.New strategies towards polymerisation in supercritical carbon dioxide My research has been targeted at developing stabilisers that have the correct amphiphilic balance to be good stabilisers but with none of the drawbacks described above. In order to do this we have developed a new stabiliser architecture based upon a single point anchoring mechanism. Here a single ‘polymer-philic’ end group provides the method for anchoring the stabiliser to the growing polymer particle and a short oligomeric chain provides solubility and ensures the minimum chance of physical entrapment in the polymer product. Additionally the link was designed not to be a ‘permanent’ covalent bond but rather a ‘reversible’ interaction.This is completely different to all of the previously published examples of stabilisers which rely upon large polymeric molecules with many anchor groups and substantial potential for entrapment in the final polymer product. We chose a carboxylic acid terminated perfluoropolyether (Fig. 3) where the perfluoropolyether (M interaction is through a hydrogen bond between the terminal acid functionality of the stabiliser and the ester grouping of MMA. Definitive proof of the hydrogen bonding interaction has been obtained through FTIR spectra of scCO2 solutions of MMA and the stabiliser. We believe that it is this same hydrogen bonding interaction that anchors the stabiliser to the growing polymer particles with the short perfluoropolyether (PFPE) tail (Fig.3) providing the ‘CO2-philicity’ that is required to stabilise the dispersion. This stabiliser is remarkably active. Only very low levels are required and we have demonstrated stabilisation with as little as 0.001 wt% with respect to MMA monomer yielding 99+% yield of PMMA of controlled molecular weight. However if control of the polymer morphology is also required then the stabiliser levels need to be raised to 0.1% (Fig. 4); still an order of magnitude lower than the previously reported materials. In addition the yield of polymer is almost Green Chemistry June 2002 Fig. 4 SEM image showing spherical particles of PMMA produced in scCO2 using Krytox 157 FSL as the stabilizer.quantitative and there are little or no residues of monomer in the final product. Additionally the structure of the stabiliser (Fig. 3) has been chosen because there are no C–H groups in the materials. Hence hydrogen abstraction and subsequent covalent bonding the final method by which the stabiliser could be retained by the polymer has been completely eliminated. From the resultant analysis of the polymer we have not yet been able to find any detectable residues of the stabilisers in the isolated polymer and we therefore conclude that • The hydrogen bonding mechanism is clearly reversible. • The comparatively small molecular size of the stabilisers and the positioning of the anchor group ensures that they are not physically entrapped in the polymer product • Covalent incorporation of the material has been removed by the elimination of C–H groups and hydrogen abstraction.One of the key requirements of higher performance speciality dispersion polymerisation products is that the morphology of the polymer is suitable for commercial application. We have demonstrated that the single-point anchoring stabilisers do indeed provide excellent steric stabilisation and good morphology control for polymerisation of PMMA (Fig. 4). Our work is now focussed upon copolymers. These are used in a very wide range of applications from adhesives coatings and structural materials; through to food wrapping cosmetic additives and medical implants.Some of the co-polymer compositions are extremely difficult to prepare in conventional solvent systems but in collaboration with Dr D. J. Irvine at Uniqema we are having some success in scCO2 using the single point anchoring stabilisers and producing materials in high yield with good polymer quality. In all cases the requirements for controlled G30 This journal is © The Royal Society of Chemistry 2002 residue free polymer products are paramount. Other green chemistry applications This work on polymerisation stimulated my interest to explore the reversible plasticisation of polymers using scCO2 and this has led to an entirely new supercritical mixing process for preparing novel biomaterials drug delivery devices and scaffolds for tissue engineering developed in collaboration with Prof.K. M. Shakesheff. The process relies upon the depression of glass transition temperature of polymers in the presence of scCO2 and then mixing of powdered bioactive material (e.g. drug growth hormone) into the plasticised polymer. It is particularly applicable to polymers such as poly(lactic acid) and poly(lactide-co-glycolide) that are widely used for such biomedical applications (Fig. 5). Briefly polymer Fig. 5 SEM image of fracture surface of novel porous bone material prepared from PLA and calcium hydroxyapatite. and the bioactive are placed inside a high-pressure autoclave and the polymer is plasticised by addition of scCO2. The precise conditions of temperature and pressure required to achieve this state are determined by the composition of the polymer but for the biodegradable polymers PLA and PLGA are at near ambient temperature (35 °C) and modest pressures (200 atm.) A highly efficient stirrer is then used to disperse the suspended bioactive particles throughout the swollen scCO2 / polymer mixture.The vessel is then depressurised to produce foamed bioactive composites with controlled porosity. The great attraction of this technique is that no conventional solvents are required and we have shown that for a very wide range of bioactives there is no loss of activity. Thus we have prepared scaffolds for hepatocyte (liver cell) growth and porous structures targeted at regenerating bone in vivo.Preliminary results have shown great promise and my first publication in the journal Bone has appeared very recently. Green chemistry in education In the last few years I have sought to work to raise the profile of chemistry and science in schools and colleges and in particular to encourage UCAS applications to scientific subjects. I present several lectures per year to schools and sixth-form colleges and organise two days of ‘A-level Chemistry’ for 500 Sixth Formers and their teachers in the School of Chemistry. Along with other colleagues at Nottingham ‘Training days’ for Sixth Formers in analytical/spectroscopic methods have also been developed and National Science Week (SET WeeK) exhibitions at Nottingham have been visited by three hundred 5–11 year old children over three days for each of the last three years.The event helps the children to learn through “hands–on” demonstrations about science and to discover what Universities do! I played a substantial role in designing and presenting ‘hands-on’ demonstrations of Green Chemistry at the ‘Tomorrow’s World Live’ Event at Earls Court (June 1999) the Nottinghamshire County Show (1998) the Royal Society ‘New Frontiers in Science’ Exhibition and at SET 99 – held in the Houses of Parliament. The events were attended by a broad spectrum of society including schoolchildren politicians Royalty and Nobel Prize winners! Along with my colleagues M. Poliakoff and M. W. George I will again be exhibiting Highlights Duncan Macquarrie reviews highlights from the recent literature Solvents Alternative solvents are one of the hot topics in green chemistry.Among the desired properties sought are a lack of volatility and ionic liquids have become very well researched. An alternative nonvolatile solvent class are polymers such as poly(ethylene glycol)s. Adina Haimov and Ronny Neumann of the Weizmann Institute in Rehovot Israel have now shown that PEGs are very well suited to the oxidation of alcohols to aldehydes with air using heteropolymetallates as oxidation catalysts (Chem. Commun 2002 876). Low molecular weight PEGs were found to give essentially complete oxidation to aldehyde. Oxidative dehydrogenation and sulfide oxidation were also shown to be possible albeit with lower conversions and selectivities respectively.Ionic liquids The use of enzymes in ionic liquids has recently been proven to be possible. One drawback to lipase-based acylation systems is that the enzyme decreases in activity with time due to the build up of acetaldehyde by-products (acetaldehyde is itself formed from the acyl donor). Toshiyuki Itoh and colleagues from Tottori University and Okayama University Japan have provided an elegant solution to this dilemma (Chem. Lett. 2002 154). They have used lipase in ionic liquids under reduced pressure to remove unwanted products from the system. This has meant that the vinyl acetate commonly used as acyl transfer agent could not be used as it was too volatile.Methyl esters proved to be the solution despite the adverse effects of methanol in conventional lipase systems. Green Chemistry June 2002 NEWS & V I E W S supercritical fluid research at the 2002 Royal Society Summer Exhibition in July. To broaden the appeal of chemistry I have led the team that has developed a new undergraduate course at Nottingham Green Chemistry and Process Engineering. This course is the first of its kind in the world and the first intake will arrive in October 2002. They will learn not only the application of the Twelve Principles of Green Chemistry but also a unique blend of Chemistry and Chemical Engineering that will equip them to put these principles into practice.(http://www.nottingham.ac.uk/chemistry/ student-opportunities/undergraduate/ greenchem.html) costly purification stages that currently are required; providing environmental economic and competitive advantages. Our research is certainly not finished and we anticipate new breakthroughs in the near future. If successful these further developments will substantially enhance the applicability and environmental impact of our work. Selected references Christian P.; Howdle S. M.; Irvine D. J. Macromolecules 2000 33 237–239. Christian P.; Irvine D. J.; Howdle S. M. et al; Macromolecules 2000 33 9222–9227. Cooper A. I. J. Mater. Chem. 2000 10 207–234. Macromol. Rapid Commun. 2000 21 Giles M. R.; Hay J.N.; Howdle S. M. 1019–1023. Giles M. R.; Winder R. J.; Hay J. N.; Howdle S. M. Polymer 2000 41 6723–6727. Giles M. R.; Griffiths R. M. T.; Silva M. M. C. G.; Howdle S. M. Macromolecules 2001 34 20–25. Howdle S. M.; Watson M.; Whitaker M.; Shakesheff K. M.; et al. Chem. Commun. 2001 109–110. Johnston K. P.; Harrison K. L.; Clarke M. J.; Howdle S. M.; et al.; Science 1996 271 624–626. Kendall J. L.; Canelas D. A.; Young J. L.; DeSimone J. M. Chem. Rev. 1999 99 Lepilleur C.; Beckman E. J. Macromolecules 543–563. 1997 30 745. Oreffo R. O. C; Howdle S. M; Shakesheff K.M. et al. Bone 2001 29 523–531. Yong T.-M.; Holmes A. B.; et al. Chem. Commun. 1997 18 1811. Conclusion The polymerisation processes described represent not only a replacement of conventional solvents with scCO2 but introduce a step-change in the approach to stabilising free radical dispersion polymerisation processes.Although we have not conducted a full life cycle analysis it is clear that the combination of zero residues elimination of conventional solvent and a facile route to high value structurally complex copolymers will be beneficial. Moreover the tantalising prospect of a single pot synthetic approach to such polymeric products will remove the need for the G31 This journal is © The Royal Society of Chemistry 2002 NEWS & V I E W S The use of a high boiling ester allowed the transfer of the acyl group with evaporation of methanol being selectively achieved in the involatile solvent.Yields were reasonably good and enantioselectivity was excellent. An interesting study on the role of solvent and co-solvent in lipase-catalysed reactions in ionic liquids has been published by Manikrao Salunkhe and co-workers at the Institute of Science in Mumbai India (Tetrahedron Lett. 2002 43 2979). Hydrophilicity/phobicity is an important parameter with hydrophobic systems giving higher rates of reaction. They conclude that a good choice of ionic liquid can provide a very effective and convenient recyclable system for lipase-catalysed acylations. Hydroamination is an addition reaction of an amine to a multiple bond. As such it is an inherently clean method for the formation of amines and imines.A team led by Thomas Müller at the Technical University of Munich Germany has Green Chemistry June 2002 developed a two-phase continuous system (Fig. 1) to carry out this reaction (Chem. Commun 2002 906). They used a heptane solution of reactants and an ionic liquid 1-ethyl-3-methylimidazolium trifluoromethane sulfonate containing zinc triflate as catalyst. In this system continuous conversion could be achieved using a continuous feed of heptane solution. Conversions were generally quantitative and a range of reactions (monomolecular and bimolecular) were demonstrated. University Japan has now shown that a polymer-supported Cu catalyst can oxidise phenols under relatively mild conditions (Bull. Chem. Soc. Jpn. 2002 75 311).Two types of oxidation are possible depending on the functionality at the C-4 position. If this is unsubstituted then formation of benzoquinones is favoured but if a methyl group is in the 4-position then benzylic oxidation takes place to give high yields of the aldehyde along with smaller amounts of some by-products. G32 Oxidation Oxidation using oxygen is an important route to functional molecules and a group led by Ken Takaki at Hiroshima Scandium triflate Hydroamination Heterogeneous asymmetric catalysts Highly efficient heterogeneous asymmetric catalysts are few and far between despite the growing number of effective homogeneous complexes which Fig. 1 This journal is © The Royal Society of Chemistry 2002 give excellent enantioselectivity.Keith Smith and Chia-Hui Liu of the University of Wales Swansea UK have published details of a Merrifield resin functionalised with an unsymmetrical salen ligand which functions as an efficient epoxidation catalyst (Chem. Commun. 2002 886). The catalyst which has Mn as the active metal centre has a loading of ca. 0.24 mmol g–1 and catalyses the epoxidation of 1,2-dihydronaphthalene with an ee of 94% identical to that obtained by model homogeneous equivalents. Reuse was also possible with a very slight reduction in ee. Scandium triflate belongs to an intriguing class of water-tolerant Lewis acids and as such is finding application in a range of reaction types as a potential replacement for the water-intolerant more conventional Lewis acids such as AlCl3.An example of its efficacy in the formation of tetrahydropyranyl ethers of alcohols has been published by Takeshi Oriyama and co-workers from Ibaraki University (Bull. Chem. Soc. Jpn. 2002 75 367). They have found that a wide range of such ethers can be prepared at room temperature in ethyl acetate in essentially quantitative yields. Washing the product-containing solution with water followed by evaporation of the water layer allowed complete recovery of the catalyst which could thus be reused. Scandium triflate has also been shown to effect the synthesis of indenochromans (Tetrahedron Lett. 2002 43 2999). Jhillu Yadav and colleagues from the Indian Institute of Chemical Technology in Hyderabad India have shown that the scandium triflate catalyses the addition of o-hydroxybenzaldehydes to indene under mild conditions.The intermediate hydroxy compound is then trapped by methylation with (MeO)3CH to give the tetracyclic product in high yields. Simple alkenes also react smoothly to give benzopyrans. Catalytic microreactors have the potential for intensive and flexible processing. A team led by Asterios Gavriilidis at University College London UK have published details of a microreactor coated with a thin film of TS-1 (Chem. Commun. 2002 878). The zeolitic catalyst formed a film a few microns thick on the channels of the microreactor. The catalyst was shown to be effective for the epoxidation of 1-pentene.Using hydrogen peroxide good yields were obtained which were dependent on residence time and reactor configuration. Interpenetrating polymer networks are an interesting class of polymers where two polymers are physically enmeshed in one another leading to a hybrid material with unique properties. One such system has been described by Vilas Athawale and Priti Pillay of the University of Mumbai India (Bull. Chem. Soc. Jpn. 2002 75 Catalytic microreactors Mesoporous silicas Hydration of alcohols Polymer systems Milder conditions and less corrosive catalyst systems are very desirable goals in the production of terephthalic acid. This journal is © The Royal Society of Chemistry 2002 Terephthalic acid production NEWS & V I E W S 369).What is particularly interesting about this polymer system is that it utilises as one of the two components a polyurethane which is made from renewable resources. The polyurethane is produced from hydrogenated castor oil as the diol and isophorone diisocyanate. Mechanical and chemical properties are discussed and the material shows some promising behaviour. Aluminium-containing mesoporous silicas have been known for about a decade and have medium acidity. A group led by Makoto Onaka of the University of Tokyo has now shown that these materials are excellent catalysts for the Diels–Alder reaction (Chem. Lett. 2002 166). Excellent yields were obtained for a range of substrate combinations and in general the catalysts outperformed a series of alternative solid catalysts.Reuse of the catalyst was possible although a slight decrease of activity was noted due to polymeric by-products on the catalyst surface but such byproducts should be relatively easily removed by calcination. The current Co/Mn/Br catalyst system is the subject of many efforts aimed at replacing Br in particular with a further important goal being the elimination of acetic acid solvent. A group led by Ki-Won Jun and Sang-Eon Park of the Korea Institute of Chemical Technology have developed a promising Br-free system based on the mesoporous silica SBA-15 functionalised with Co(iii) species (Chem. Lett. 2002 212). This catalyst is bound to the support via carboxylate ligands and the Co(iii) state is stabilised by additional pyridine ligands.Under conditions of relatively low pressure no solvent and at 130 oC this catalyst system was comparable to the existing commercial system which also runs in acetic acid solvent. Hydration of alcohols is carried out using aqueous sulfuric acid. A cleaner alternative would be to use a solid acid to carry out this very useful conversion. Duangamol Nuntasri Peng Wu and Takashi Tatsumi of Yokohama National University have now provided a highly active and selective catalyst which can hydrate cyclopentene effectively (Chem. Lett. 2002 2 224). Their catalyst MCM-22 was compared to various other potential catalysts and was found to have better selectivity than the others.HZSM-5 a well-established zeolite performed well but MCM-22 maintains Green Chemistry June 2002 G33 NEWS & V I E W S high selectivity at higher conversion than HZSM-5. Avoiding separation steps The development of consecutive reaction sequences without separations is one approach to minimising the waste generated during separation steps. The mild and selective oxidation of alcohols to acids using a combination of polymer-supported reagents has now been demonstrated by Kusoke Yasuda and Steven Ley of the University of Cambridge UK (J. Chem. Soc. Perkin 1 CRYSTAL Faraday Partnership on Green Chemical Technology The Faraday Partnership initiative in the UK is aimed at promoting improved interactions between industry and the science engineering and technology base.Malcolm Wilkinson describes the ‘CRYSTAL’ Faraday partnership for Green Chemical Technology. Mission and objectives The CRYSTAL Faraday Partnership was established in May 2001 and officially launched by Lord Sainsbury the Minister for Science and Technology in the UK Government on 23 October 2001. Chaired by Dr Robin Paul the Partnership’s mission is To be the lead organisation for the research development and implementation of green technologies and practices in the UK chemical and allied industries. CRYSTAL’s brief is to identify and match industry’s technology needs with opportunities presented by academia’s research output and thereby enhance business and environmental performance.In addition to promoting new and innovative research CRYSTAL will integrate and build on the activities of the existing consortia and network technology organisations (CANTO) significantly leveraging their impact. Green Chemistry June 2002 G34 CRYSTAL has six key objectives • Single point of contact for green chemical technology in the UK • Transfer new green technology and best practice into real application • Identify core research priorities matching industry’s needs with innovation in universities • Stimulate new research or practical applications where they are needed • Increase awareness of best practice for sustainable products and processes • Train those involved for the culture change required The Hub Partners are the Institution of Chemical Engineers the Royal Society of Chemistry and the UK Chemical Industries Association.They are joined by 10 CANTO 12 companies from all sectors of the industry and 18 university departments of chemistry and chemical engineering to form the network. These organisations direct CRYSTAL’s activities through a Board of Management supported by the Research Development and Technology Transfer (RD&TT) Steering Group and the Training Education and Networking (TEN) Steering Group. CRYSTAL operates from Rugby in the UK through a programme director and a network of technology translators whose job is to tackle the technical challenges on the ground. They have been active since January and have already held discussions with the majority of organisations in the network.These have resulted in an outline proposal to STI/MMI for development funding of a novel piece of equipment for VOC removal a confidential workshop on ionic liquids and identification of a supply chain consortium for research into biodegradable packaging material. CRYSTAL has also defined three priority areas of research focus for £1 million (ca. 1.5 million Euro) of earmarked EPSRC funding and has solicited 35 outline proposals which are currently being evaluated. In addition 7 Industrial CASE Awards have been allocated and one graduate student has commenced her research project. CRYSTAL and industry CRYSTAL like other Faraday Partnerships running in the UK has the objective of transferring technology from the SET base to industry.We are trying to generate a pipeline of technologies coming to application initially promoting the transfer of existing green chemical technologies (GCT) into industrial application; developing these where Structure and operation This journal is © The Royal Society of Chemistry 2002 2002 1024). The use of polymer-supported TEMPO polymer-supported chlorite (from amberlyst IRA900 by ion exchange with NaClO2) and an immobilised dihydrogenphosphate buffer effected the oxidation of a range of alcohols under very mild conditions. The method is tolerant to a wide range of groups including BOC acetals epoxides and nitro groups making it suitable for library generation.necessary using targeted funding sources; and supporting longer term research which will under-pin the next generation of GCT. All this of course requires an engaged and responsive industry but many see no benefit in applying GCT. As ICI’s David Bott Chair of the RD&TT points out in his recent article in CRYSTAL Window industry sees threats in the area rather than opportunities – upcoming legislation that changes the ground rules large capital expenditure and public humiliation if we talk about our advances and get it wrong. Because of this view industry tends to approach GCT at two levels. At one level the ‘pragmatic’ there are many simple changes to practices and processes that can yield small but important Announcing the fifth edition of the Interuniversity Consortium “Chemistry for the Environment” Admitted young scientists will receive full scholarships.Deadline for applications is June 15th 2002 Contacts Prof. Pietro Tundo (Director) tundop@unive.it Dr. Alvise Perosa alvise@unive.it ssgc@unive.it SUMMER SCHOOL ON GREEN CHEMISTRY September 08th – 14th 2002 Venezia Italy G35 Information and application http://www.unive.it/inca Green Chemistry June 2002 NEWS & V I E W S improvements in environmental impact whilst improving business profitability. The challenge is finding out what is available and how to get the expertise to implement it. The other end of the scale is the approach of making large capital investment in disruptive technologies which change the normal means of doing things.supply chain linked collaborations. Starting in May and continuing in the Autumn CRYSTAL will be holding Research Workshops open to a wider community to identify these potential collaborative areas of activity. In some ways CRYSTAL is a test for green chemistry; good science in itself is not sufficient to have value in societal terms it has to be transformed into applied technology which additionally requires positive economic and social returns; the triple bottom line. It is both a daunting and exciting challenge in which with the help of its network partners CRYSTAL is determined to play its part. For more details about CRYSTAL Faraday please contact Malcolm P Wilkinson on + 44 (0) 1788 434402 or by email mwilkinson@icheme.org.uk Challenge for CRYSTAL CRYSTAL is encouraging activity at both these levels through its technology translators visiting companies and universities to put the right people in touch with one another and at the second level trying to identify potential future areas of advance and investing in these.These are not just one-on-one relationships but will involve larger often This journal is © The Royal Society of Chemistry 2002 NEWS & V I E W S The CHEMRAWN Action Plan portion of the budget for the conference is reserved for the use of the Future Actions Committee. It is the job of the committee to work after the conference to facilitate the implementation of the ideas.Many of the recommendations from CHEMRAWN XIV (which took place at the University of Colorado Campus One of the key features of the IUPAC CHEMRAWN (Chemistry Research Applied to World Needs) meeting is the development of a set of implementation recommendations. These are distributed widely within government industry and academia to focus attention and funding on the specific issues raised. A significant The CHEMRAWN Action Plan is shown below Ongoing Activities CHEMRAWN XIV Recommended Actions National centers for green chemistry should be established or expanded and these centers should be linked to create an effective worldwide network. • National centers in US UK Australia Italy Japan • OECD recommendations and guidelines on establishing national programs (education and R&D elements) • EPA/GCI Industry R&D program Basic research funding in green chemistry needs to be significantly increased.• EPA ACS GCI GCN doing educational materials development • New Training Center at UO joins UMass- Boston 5/02 Educational initiative funding in green chemistry focused on curriculum materials development faculty training centers fellowships and recruitment and retention activities Increased incentives for the initial implementation of green chemistry technologies by industry to offset investment policy and regulatory barriers that may exist. • White House meeting between industry and Gov’t.to discuss (2002). • ACS support of tax break for dry-cleaning countered by DuPont opposition • OECD EU Japanese discussion on green chemistry especially with industry • GCI sponsored project w/ Zero Waste Alliance and US Dept. Commerce to educate Chinese business leaders • Some GCI support for international attendance at Gordon Conf. (Oxford) Green chemistry and next generation environmental technology market development project to build market position for commercial opportunities in international trade. International scientist exchange and research collaboration funding should be established Informational outreach to educate industry public and environmental groups of the benefits of green chemistry adoption. • OECD Sustainable Chemistry program • EU Sixth Framework • Numerous publications under development (texts articles case studies) • GCI funding evaluation of metrics of green chemistry performance • GCN JCII GCI planning major international (bi-annual) conferences on GC with initial focus on industry implementation OTHER Further information can be obtained from Denny Hjeresen (Email dlh@lanl.gov) Green Chemistry June 2002 G36 Boulder CO USA from 9-13 June 2001) deal with education R&D industrial implementation and other issues associated with green chemistry and are already being worked on by GCI (USA) OECD GCN(UK) JCII (Japan) Monash (Australia) and others.Potential CHEMRAWN XIV Targets • Support for international hub linking national centers into broader network. • Support for local programs to make links to international hub • Support for additional training centers ( ~ $400 K each) • Fund international distribution of ACS developed training and teaching labs • CRYSTAL Faraday type fellowship support • Project to develop test case for tax incentive either in OECD country or developing country • US DOC project funding available – match possible • Funding of SE Asia training workshop in Thailand (May 02) DONE • Additional regional Green Chemistry training programs (India South America Middle East) • Co-sponsorship of green chemistry summer school attendance (EU or Pan-American) Fund distribution of metrics study to international business and government organizations • Fund industry survey of impediments and incentives for green chemistry implementation • Fund distribution of OECD recommendations on establishing national programs to developing country governments • Fund specific attendees or sessions at international conferences • CHEMRAWN XIV funded position to work on developments full or half-time time (Clovis?) This journal is © The Royal Society of Chemistry 2002

ISSN:1463-9262    

DOI:10.1039/b204528c

出版商:RSC    

年代:2002

数据来源: RSC

摘要:

E D I T O R I A L It is especially pleasing to be able to start this editorial with the news that that the impact factor for this journal has reached the dizzy heights of 2.477 for the year 2001. This is our first “official” score although we did receive an unofficial rating of 2.2 for the year 2000. This is a tremendous achievement especially for a new journal and can be attributed to the very high quality of articles that we are attracting. I would like to take the opportunity to thank my colleagues at Cambridge and York for all of their hard work and my colleagues on the editorial board for their excellent support in making this the premier journal for green chemistry research and information. We have come a long way since those long planning meetings some four years ago when we were able to turn a dream into a reality.Green chemistry can indeed turn dreams into reality as was further witnessed this July when the world’s first supercritical fluids reaction plant was opened in Durham England. The plant which belongs to the Thomas Swan company is the latest in a long line of environmentally responsible technologies introduced by the company. The new facility will exploit proven new technology to replace conventional solvents by inert supercritical fluids for several key chemical technologies. Behind this excellent example of green chemical technology at work is a very successful academic–industrial collaboration with the University of Nottingham’s Chemistry Department (UK). Congratulations to the company and to the academic scientists involved in the associated pioneering research.Green Chemistry August 2002 G38 Impact Factors and Awards James Clark York UK July 2002 Congratulations are also due to this years winners of the US Presidential Green Chemistry Awards. These nicely illustrate DOI 10.1039/b206504p This journal is © The Royal Society of Chemistry 2002 the range of applications for green chemistry. Supercritical solvents are also featured here with a new cleaning application and a new family of CO2-soluble materials. The vital importance of green chemistry in the synthesis of pharmaceuticals is demonstrated in the new cleaner and simpler manufacture of Sertraline. Improvements include a reduction in the number of steps and in the number of solvents used – nicely illustrating the concept of green chemistry as being a series of reductions. I have written before about the (literally) growing importance of renewable feedstocks for sustainable chemicals manufacturing and the associated reduction in the use of fossil feedstocks. This will require continuous innovation in the way that we exploit biomass. The award for NatureWorksTM a new family of plastics manufactured entirely from renewable resources is a splendid example of this especially as production in the first world-scale 140,000 t/y plant began just a few months ago – another proven commercial-scale application of green chemistry. The US awards also honour another green chemistry reduction that of reduced toxicity for a new arsenic-free and chromium-free wood preservative. You can read more about these awards in this issue of Green Chemistry.

ISSN:1463-9262    

DOI:10.1039/b206504p

出版商:RSC    

年代:2002

数据来源: RSC

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Highlights Duncan Macquarrie reviews the recent literature on green chemistry Additions Cycloadditions can provide an excellent clean route to functional heterocycles. Zachary Demko and Barry Sharpless of the Scripps Institute La Jolla USA have recently reported examples of such chemistry which run without solvent and in almost quantitative yields (Angew. Chem. Int. Ed. 2002 41 2113). They have found that heating acyl cyanides with azides at 120 °C yields the tetrazole in yields of over 90%. No solvent is required for the reaction and the isolation step is relatively straightforward but could often be omitted in a multi-step synthesis. The products are versatile synthons for a range of further elaborations. Additions of aldehydes to alkyne derivatives is another potentially very clean route to highly versatile enone derivatives.Chul-Ho Jun and co-workers from Yonsei University in Seoul South Korea have now published details of the relatively unexplored addition of aldehydes to terminal alkynes (Angew. Chem. Int. Ed. 2002 41 2146). They found that the Rh catalysed addition of the two components proceeded smoothly under mild conditions in toluene to produce the branched enone as the major component (for aromatic aldehydes this product was formed exclusively). Yields varied from 63% to 98% with most examples being above 80%. CFCs The problem of what to do with CFCs is still a pressing one. Some work has been done which has provided routes whereby the CFCs can be converted to useful non-ozone-depleting raw materials such as tetrafluoroethene but this approach cannot be used for e.g.ClCF3. Now Noriyoki Sonoyama and Tadayoshi Sakata of the Tokyo Institute of Technology have described an electrochemical route which allows the production of trifluoroacetic acid from ClCF3 (Chem. Lett. 2002 444) They mixed the two gases under pressure in an autoclave and then electrolysed them in the absence of oxygen. The CF3 – anion formed is rapidly quenched by CO2 to give the carboxylic acid in yields of up to 85% with current efficiencies of around 70%. Carbonylations Dimethyl carbonate as seen as a safe alternative to phosgene for carbonylation reactions. Current synthetic routes to this material have room for improvement and mild and efficient conditions are still sought.The group led by Ichiro Yamanaka of the Tokyo Institute of Technology Japan have now published details of an electrolytic one-step route to dimethyl carbonate from methanol and CO under mild conditions (Chem. Lett. 2002 448). Since existing electrochemical routes are relatively inefficient the group redesigned both the cell and the electrode (Pd on a vapour grown carbon fibre) in order to enhance the concentration of the two reaction components at the electrode surface. They achieved 67% current efficiency and 82% selectivity based on CO under 1 atmosphere of CO and at room temperature. Aldol reactions The aldol addition is one of the most effective methods for building up complex organic molecules.In particular those which do not require pre-activation / protection sequences are particularly attractive from a green chemicals perspective and several groups have made advances in this area. One of the most challenging situation is that where two aldehydes must be coupled and so far little has been achieved in this area. Now Alan Northrup and David MacMillan of the California Institute of Technology USA have shown that not only is this possible but that it can be done with excellent selectivity using proline as catalyst (J. Am. Chem. Soc. 2002 124 6798). Slow addition of an aldehyde donor (typically propionaldehyde) to the aldehyde acceptor in a range of solvents at 4 oC gave yields of around 80% with anti:syn ratios of 3+1 to 24+1 and ee’s of > 95%.Ionic liquids Ionic liquids have been shown to be very versatile solvents for a wide range of reactions. The US group led by Jimmy Mays Christopher Brazel and Robin Rogers from the Universities of Alabama and Tennessee and the Oak Ridge National Laboratory have now shown that these liquids are useful in the free-radical polymerisation of methyl methacrylate and styrene (Chem. Commun. 2002 1368). They found that polymerisation in these liquids proceeded smoothly to give polymers with higher molecular weights than those formed in organic solvents. The polymer separated from the ionic liquid as the reaction proceeded and further purification with methanol or Green Chemistry August 2002 DOI 10.1039/b206505n This journal is © The Royal Society of Chemistry 2002 NEWS & V I E W S G39 NEWS & V I E W S aqueous ethanol could be used to remove traces of the ionic liquid.In a second paper they also show that the ionic liquids can behave as plasticisers in the polymers potentially giving a direct route to plasticised materials (Chem. Commun. 2002 1370). Additionally (Chem. Commun. 2002 1394) they demonstrate the alternating copolymerisation of styrene and CO. A further application of ionic liquids has been published. Kun Qiao and Youquan Deng of the Chinese Academy of Sciences in Lanzhou China have shown that carbonylation / esterification reactions can be eficiently carried out (New J.Chem. 2002 26 667). By using a transition metal / phosphine system in the presence of p-toluene sulfonic acid in ionic liquids they could react t-butanol with CO and ethanol to produce ethyl iso-valerate and ethyl t-valerate in total yields of up to ca.80%. Conventional solvents gave yields of < 38% with the main products in ethanol and toluene being isobutene and ethyl isobutyl ether. In general a 4+1 selectivity towards the iso-ester was found. Mesoporous materials Green Chemistry August 2002 clean method for the preparation of such materials is the formation of suitably substituted mesoporous silicas using neutral templates which can be washed out and recovered. Juan Melero and colleagues from Rey Juan Carlos University in Madrid Spain have now published details of a new silica-arene sulfonic acid material which has a higher acidity that the propane sulfonic acid-functionalised materials previously available (J.Mater. Chem. 2002 12 1664). They condensed 2(4-chlorosulfonylphenyl)- ethyltrimethoxysilane with tetraethoxysilane under aqueous conditions in the presence of a poly(alkylene oxide) surfactant to give the material which was capable of catalysing the Fries rearrangement of phenyl acetate with an activity similar to that of an amberlyst resin and about twice that of an alkane sulfonic acid-functionalised silica. An interesting extension of a known class of oxidation catalysts has been published by Didier Villemin and colleagues at the University of Caen (Synth.Commun. 2002 32 1501). They have coupled the known ability of supported metal phthalocyanines to catalyse the aerobic oxidation of e.g. hydroquinone to quinone to the ability of quinone to re-oxidise transition metals such as Pd and Ru (see below). In this way they have developed methods for the aerobic oxidation of alcohols to aldehydes alkenes to ketones and 1,3-hexadiene to 1,4-diacetoxycyclohexene. Yields in the first two reaction types were very high with excellent G40 CO2 as a raw material 2 to give the carbonate via Oxidations Fries rearrangement The development of strongly Bronsted acidic solids has been a lively theme in catalysis for some time.One potentially This journal is © The Royal Society of Chemistry 2002 selectivity while the third reaction type gave a yield of 50%. Catalysis J. Mol. Catal. A volumes 182-183 contain papers from the 10th International Symposium on Relations between Homogeneous and Heterogeneous Catalysis many of which are of interest in a green context. In particular the following two papers are of interest Michele Aresta and Angela Dibenedetto of the University of Bari Italy have published details on work relating to the use of CO2 as a raw material (J. Mol. Catal. A 2002 182-3 399). They have investigated both the reaction of CO2 with styrene oxide to give the carbonate and the direct reaction of styrene with oxygen and CO an intermediate epoxidations.Yields are good with the epoxide but considerably lower in the direct reaction. Nonetheless mechanistic work on the latter hints at possible improvements which might make the latter a very useful route to generating functional molecules in a clean and efficient fashion. Annie Commarieu and colleagues from Atofina in Lacq France have described the use of methanesulfonic acid as a biodegradable strong acid catalyst for the Fries rearrangement which is normally carried out industrially using HF or AlCl3 (J. Mol. Catal. A 2002 182-3 399). Looking at the first step of the paracetamol process they have optimised reaction conditions such that the desired para isomer can be produced selectively Presidential Green Chemistry Challenge Awards 2002 The following are the recipients of these prestigious US awards which recognize outstanding chemical technologies that incorporate the principles of green chemistry into chemical design manufacture and use and that have been or can be utilized by industry in achieving their pollution prevention goals Professor Eric J.Beckman University of Pittsburgh—for design of non-fluorous highly CO2-soluble materials Carbon dioxide an environmentally benign and nonflammable solvent has been investigated extensively in both academic and industrial settings. Solubility studies performed during the 1980s had suggested that CO2's solvent power was similar to that of n-alkanes leading to hopes that the chemical industry could use CO2 as a ‘drop-in’ replacement for a wide variety of organic solvents.It was learned that these solubility studies inflated the solvent power value by as much as 20% due to the strong quadrupole moment of CO2 and that carbon dioxide is actually a rather feeble solvent compared to alkanes. As the 1980s drew to a close a number of research groups began to explore the design of CO2-philic materials that is compounds that dissolve in CO2 at significantly lower pressures than do their alkyl analogs. These new CO2-philes primarily fluoropolymers opened up a host of new applications for CO2 including heterogeneous polymerization protein extraction and homogeneous catalysis. Although fluorinated amphiphiles allow new applications for CO2 their cost (approximately $1 per gram) reduces the economic viability of CO2 processes particularly given that the use of CO2 requires high-pressure equipment.Furthermore data have recently shown that fluoroalkyl materials persist in the environment leading to the withdrawal of certain consumer products from the market. The drawbacks inherent to the use of fluorinated precursors therefore have inhibited the commercialization of many new applications for CO2 and the full promise of CO2-based technologies has yet to be realized. To address this need Professor Eric Beckman and his group at the University of Pittsburgh have developed materials that work well exhibiting miscibility pressures in carbon dioxide that are comparable or lower than fluorinated analogs and yet contain no fluorine.Drawing from recent studies of the thermodynamics of CO2 mixtures Professor Beckman hypothesized that CO2-philic materials should contain three primary features • relatively low glass transition temperature • relatively low cohesive energy density • number of Lewis base groups Low glass transition temperature correlates to high free volume and high molecular flexibility which imparts a high entropy of mixing with CO2 (or any solvent). A low cohesive energy density is primarily a result of weak solute–solute interactions a necessary feature given that CO2 is a rather feeble solvent. Finally because CO2 is a Lewis acid the presence of Lewis base groups should create sites for specific favorable interactions with CO2.Professor Beckman’s simple heuristic model was demonstrated on three sets of materials functional silicones; poly(ether-carbonates); and acetate-functional polyethers. Poly(ether-carbonates) were found to exhibit lower miscibility pressures in CO2 than perfluoropolyethers yet are biodegradable and 100 times less expensive to prepare. Other families of non-fluorous CO2-philes will inevitably be discovered using this model further broadening the applicability of CO2 as a greener process solvent. Green Chemistry August 2002 Reviews NEWS & V I E W S (p/o up to 88.5 has been achieved at high conversions). Anhydrous conditions are necessary to avoid hydrolysis.Reaction conditions are relatively mild—temperatures around 100 oC and short reaction times (typically about 1 hour is sufficient). Lanthanide chemistry The latest issue of Chemical Reviews (2002 102 Part 6) is dedicated to lanthanide chemistry. Amongst several reviews covering many aspects of the chemistry of lanthanides are several on the catalytic and synthetic applications of lanthanide complexes (Gary Molander and Jan Antoinette Romero (page 2161); Masakatu Shibasaki and Naoki Yoshikawa (page 2187); Junji Inanaga and colleagues (page 2211); and lanthanide triflates (Shu Kobayashi and co-workers (page 2227). Asymmetric Michael additions A useful microreview on asymmetric Michael additions has been published by Dieter Enders and colleagues from the RWTH Aachen (Eur.J. Org. Chem. 2002 1877). G41 This journal is © The Royal Society of Chemistry 2002 NEWS & V I E W S SC Fluids Inc.—for SCORR (Supercritical CO2 Resist Remover) The semiconductor industry is the most successful growth industry in history with sales totaling over $170 billion in the year 2000. The fabrication of integrated circuits (ICs) relies heavily on photolithography to define the shape and pattern of individual components. Current manufacturing practices use hazardous chemicals and enormous amounts of purified water during this intermediate step which may be repeated up to 30 times for a single wafer. It is estimated that a typical chip-fabrication plant generates 4 million gallons of waste water and consumes thousands of gallons of corrosive chemicals and hazardous solvents each day.SC Fluids in partnership with Los Alamos National Laboratory developed a new process SCORR that removes photoresist and post-ash -etch and -CMP (particulate) residue from semiconductor wafers. The SCORR technology outperforms conventional photoresist removal techniques in the areas of waste minimization water use energy consumption worker safety feature size compatibility material compatibility and cost. The key to the effectiveness of SCORR is the use of supercritical CO2 in place of hazardous solvents and corrosive chemicals. Neat CO2 is also utilized for the rinse step thereby eliminating the need for a deionized water rinse and an isopropyl alcohol drying step.In the closed loop SCORR process CO2 returns to a gaseous phase upon depressurization leaving the silicon wafer dry and free of residue. SCORR is cost-effective for five principal reasons. It minimizes the use of hazardous solvents thereby minimizing costs required for disposal and discharge permits. It thoroughly strips photoresists from the wafer surface in less than half the time required for wet-stripping and far outperforms plasma resulting in increased throughput. It eliminates rinsing and drying steps during the fabrication process thereby simplifying and streamlining the manufacturing process. It eliminates the need for ultra-pure deionized water thus reducing time energy and cost.Supercritical CO2 costs less than traditional solvents and is recyclable. SCORR will meet future as well as current technology demands. To continue its astounding growth the semiconductor industry must develop ICs that are smaller faster and cheaper. Due to their high viscosity traditional wet chemistries Green Chemistry August 2002 cannot clean small feature sizes. Vapor cleaning technologies are available but viable methods for particle removal in the gas phase have not yet been developed. Using SCORR the smallest features present no barriers because supercritical fluids have zero surface tension and a ‘gaslike’ viscosity and therefore can clean features less than 100 nm.The low viscosity of supercritical fluids also allows particles less than 100 nm to be removed. The end result is a technically enabling ‘green’ process that has been accepted by leading semiconductor manufacturers and equipment and material suppliers. SCORR technology is being driven by industry in pursuit of its own accelerated technical and manufacturing goals. SCORR was initially developed through a technical request from Hewlett Packard (now Agilent). A joint Cooperative Research and Development Agreement between Los Alamos National Laboratory and SC Fluids has led to the development of commercial units (SC Fluids’ Arroyo™ System). Other industry leaders such as IBM ATMI and Shipley are participating in the development of this innovative technology.Pfizer Inc.—for green chemistry in the redesign of the Sertraline process Sertraline is the active ingredient in the important pharmaceutical Zoloft®. Zoloft® is the most prescribed agent of its kind and is used to treat an illness (depression) that each year strikes 20 million adults in the U.S. and that costs society $43.7 billion (1990 dollars). As of February 2000 more than 115 million Zoloft® prescriptions had been written in the US. Applying the principles of green chemistry Pfizer has dramatically improved the commercial manufacturing process of sertraline. After meticulously investigating of each of the chemical steps Pfizer implemented a substantive green chemistry technology for a complex commercial process requiring extremely pure product.As a result Pfizer significantly improved both worker and environmental safety. The new commercial process (referred to as the ‘combined’ process) offers substantial pollution prevention benefits including improved safety and material handling reduced energy and water use and doubled the overall product yield. Specifically a three-step sequence in the original manufacturing process was streamlined to a single step in the new G42 This journal is © The Royal Society of Chemistry 2002 sertraline process. The new process consists of imine formation of monomethylamine with a tetralone followed by reduction of the imine function and in-situ resolution of the diastereomeric salts of mandelic acid to provide chirally pure sertraline in much higher yield and with greater selectivity.A more selective palladium catalyst was implemented in the reduction step which reduced the formation of impurities and the need for reprocessing. Raw material use was cut by 60% 45% and 20% for monomethylamine tetralone and mandelic acid respectively. Pfizer also optimized its process using the more benign solvent ethanol for the combined process. This change eliminated the need to use distill and recover four solvents (methylene chloride THF toluene hexane) from the original synthesis. Pfizer’s innovative use of solubility differences to drive the equilibrium toward imine formation in the first reaction of the combined steps eliminated approximately 140 metric tons/year of the problematic reagent titanium tetrachloride.This process change eliminates 100 metric tons of 50% NaOH use 150 metric tons of 35% HCl waste and 440 metric tons of solid titanium dioxide wastes per year. By eliminating waste reducing solvents and maximizing the yield of key intermediates Pfizer have demonstrated significant green chemistry innovation in the manufacture of an important pharmaceutical agent. Cargill Dow LLC—for the NatureWorksTM PLA Process Nature WorksTM polylactic acid (PLA) is the first family of polymers derived entirely from annually renewable resources that can compete head-to-head with traditional fibers and plastic packaging materials on a cost and performance basis.For fiber consumers this will mean a new option for apparel and carpeting applications a material that bridges the gap in performance between conventional synthetic fibers and natural fibers such as silk wool and cotton. Clothing made with Nature WorksTM fibers features a unique combination of desirable attributes such as superior hand touch and drape wrinkle resistance excellent moisture management and resilience. In packaging applications consumers will have the opportunity to use a material that is natural compostable and recyclable without experiencing any tradeoffs in product performance. The Nature WorksTM PLA process offers significant environmental benefit in addition to the outstanding performance attributes of the polymer.Nature WorksTM PLA products are made in a revolutionary new process developed by Cargill Dow LLC that incorporates all 12 green chemistry principles. The process consists of three separate and distinct steps that lead to the production of lactic acid lactide and PLA high polymer. Each of the process steps is free of organic solvent – water is used in the fermentation while molten lactide and polymer serve as the reaction media in monomer and polymer production. Each step not only has exceptionally high yields ( > 95%) but also utilizes internal recycle streams to eliminate waste. Small (ppm) amounts of catalyst are used in both the lactide synthesis and polymerization to further enhance efficiency and reduce energy consumption.Additionally the lactic acid is derived from annually renewable resources PLA requires 20 to 50% less fossil resources than comparable petroleum-based plastics and PLA is fully biodegradable or readily hydrolyzed into lactic acid for recycling back into the process. While the technology to create PLA in the laboratory has been known for many years previous attempts at large scale production were targeted solely at niche biodegradable applications and were not commercially viable. Only now has Cargill Dow been able to perfect the Nature WorksTM process and enhance the physical properties of PLA resins to successfully compete with commodity petroleum-based plastics.Cargill Dow is currently producing approximately 4,000 metric tons of PLA per year to meet immediate market development needs. Production in the first world-scale 140,000 metric ton/yr plant began 1st November 2001. The Nature WorksTM process embodies the well-known principles of green CSI—for ACQ Preserve® the environmentally advanced wood preservative The pressure-treated wood industry is a $4 billion industry producing approximately 7 billion board feet of preserved wood per annum. More than 95 percent of the pressure-treated wood used in the United States is currently preserved with chromated copper arsenate (CCA). Approximately 150 million pounds of CCA wood preservatives were used in the production of pressure-treated wood in 2001 enough wood to build 435,000 homes.About 40 million pounds of arsenic and 64 million pounds of hexavalent chromium were used to manufacture these CCA wood preservatives. Over the past few years scientists environmentalists and regulators have raised concerns regarding the risks posed by the arsenic that is either dislodged or leached from CCA-treated wood. A principal concern is the risk to children from contact with CCA-treated wood in playground equipment picnic tables and decks. This concern has led to the increased demand for and use of alternatives to CCA. Chemical Specialties Inc. (CSI) developed its alkaline copper quaternary (ACQ) wood preservative as an environmentally advanced formula designed to replace the CCA industry standard.ACQ formulations combine a NEWS & V I E W S chemistry by preventing pollution at the source through the use of a natural fermentation process to produce lactic acid substituting annually renewable materials for petroleum-based feedstock eliminating the use of solvents and other hazardous materials completely recycling product and by-product streams and efficiently using catalysts to reduce energy consumption and improve yield. In addition Nature WorksTM PLA products can be either recycled or composted after use. bivalent copper complex and a quaternary ammonium compound in a 2:1 ratio. The copper complex may be dissolved in either ethanolamine or ammonia. Carbon dioxide (CO2) is added to the formulation to improve stability and to aid in solubilization of the copper.Replacing CCA with ACQ is one of the most dramatic pollution prevention advancements in recent history. Because more than 90 percent of the 44 million pounds of arsenic used in the U.S. each year is used to make CCA replacing CCA with ACQ will virtually eliminate the use of arsenic in the United States. In addition ACQ Preserve® will eliminate the use of 64 million pounds of hexavalent chromium. Further ACQ avoids the potential risks associated with the production transportation use and disposal of the arsenic and hexavalent chromium contained in CCA wood preservatives and CCA-treated wood. In fact ACQ does not generate any RCRA (Resource Conservation and Recovery Act) hazardous waste from production and treating facilities.The disposal issues associated with CCA-treated wood and ash residues associated with the burning of treated wood will also be avoided. In 1996 CSI commercialized ACQ Preserve® in the United States. More than 1 million active pounds of ACQ wood preservatives were sold in the U.S. in 2001 for use by thirteen wood treaters to produce over 100 million board feet of ACQ-preserved wood. In 2002 CSI plans to spend approximately $20 million to increase its production capacity for ACQ to 30 million active pounds. This will convert 60% of CSI’s production from CCA to ACQ with a plan to continue to increase ACQ sales while phasing out CCA production.Through investment in ACQ CSI has helped to trigger a significant market shift away from arsenic-based wood preservatives that will continue over the next several years. This shift will result in major benefits to public health and the environment. Green Chemistry August 2002 G43 This journal is © The Royal Society of Chemistry 2002 Green chemistry educational initiatives The following are two recent initiatives in green chemistry education in US universities Green chemistry earns a PhD A new green chemistry PhD programme is underway at the University of Massachusetts Boston. It is offered by the department of environmental sciences and administered by the department of chemistry. This programme which started last autumn is believed to be the first of its kind in the world.It is the brainchild of Professor John Warner. Student training will be essentially similar to other chemistry PhD students but will emphasise skills to design materials and processes that have minimal impact on human health and the environment. Major research areas include biodegradation bioremediation clean synthesis and environmental monitoring. The course requires students to take courses in environmental law and policy toxicology industrial chemistry environmental fate and transport. The course has been praised by a number of leaders in the world of green chemistry including Professor Terry Collins of Carnegie Mellon University Professor Janet Scott from the Centre for Green Chemistry at Monash University in Australia and Dr Mary Kirchoff of the US Green Chemistry Institute.The Vice President of pharmaceutical sciences at Pfizer Global R & D Berkeley Cue has noted that a green chemistry PhD would be a big plus for chemists interested in process development. The first student enrolled in UMB's green chemistry PhD programme is Amy Cannon. She is working on constructing solar energy devices in a more environmentally benign manner. The University of Oregon opens $1 million green chemistry laboratory The University of Oregon celebrated the official opening of its new $1 million Green Chemistry Laboratory and the adjacent Alice C Tyler Instrumentation Center in a noon time ribbon-cutting ceremony on 16th May 2002.UO President Dave Frohnmayer has said that the Green Chemistry Laboratory will make a significant contribution to sustainable and environmentally friendly advances in chemistry. The concept of green chemistry involves substituting more benign solvents and reagents for the hazardous chemicals traditionally used in organic chemistry laboratories. In the Green Chemistry Laboratory students learn the fundamentals of organic chemistry using less hazardous chemicals - an approach that is both more environmentally friendly and safer for students and teachers. Students also gain valuable experience identifying more environmentally benign (greener) chemical practices. All organic chemistry students at the UO—about 200 each term—are now using the new lab and practicing green chemistry.Adjacent to the Green Chemistry Laboratory is the new Alice C Tyler Instrumentation Center that will serve all undergraduates taking chemistry—about 1000 students a year. The new lab is spacious enough to have 48 students working comfortably and safely at one time. LEFT TO RIGHT – Allyn Brown Dave Frohnmayer Dennis Hjeresen Ken Doxsee and Jim Hutchison The instrumentation center funded with a grant of $300,000 from the Alice C Tyler Perpetual Trust gives students access to the full range of instruments essential in green chemistry. The Green Chemistry Institute of the American Chemical Society also supported the project with a $100,000 grant. Approximately $500,000 came from private donors and supplementary university funds. Together the lab and instrumentation center comprise approximately 4000 square feet on the first floor of Klamath Hall 1370 Franklin Blvd. Unlike many university laboratories known for their cramped feeling the new lab has high ceilings and many windows. Chemistry professors Jim Hutchison and Ken Doxsee are among the staff closely involved in the new initiative. Also participating in the ribbon-cutting ceremony were Allyn Brown representing the Alice C Tyler Perpetual Trust and Dennis Hjeresen director of the Green Chemistry Institute for the American Chemical Society. For further information contact Ross West (rwest@oregon.uoregon.edu) or Professor Jim Hutchison. (hutch@oregon.uoregon.edu) or see website http://www.uoregon.edu/ ~ hutchlab/greenchem/ DOI 10.1039/b206505n Green Chemistry August 2002 G44 NEWS & V I E W S This journal is © The Royal Society of Chemistry 2002

ISSN:1463-9262    

DOI:10.1039/b206505n

出版商:RSC    

年代:2002

数据来源: RSC