——Introduction of the results of the 2005 U.S. President's Green Chemistry Challenge Award
On June 20, 2005, the 2005 award ceremony was held in Washington, D.C., where six projects were awarded for the above five awards. This article describes 6 award-winning projects.
1. Renewal of the Synthetic Route Award
The 2005 Updated Synthetic Route Award rewarded two projects: Archer Daniels Midland and Novozymes, a special lipase, that uses a special lipase, Lipozyme, to prepare products with low levels of trans fats and fats from vegetable oils through enzyme-catalyzed trans-exchange reactions, as well as a new synthetic route designed by Merck GmbH.
Enzymatic transesterification technology from Archer Daniels Midland and Novozymes
Providing the public with a particular focus on health products and developing environmentally responsible production technologies are two of the major challenges facing the food and food ingredient industries. The enzymatic ester exchange technology being industrialized by Archer Daniels Midland (ADM) and Novozymes has a significant positive impact on public health not only by reducing the content of trans fatty acids in food, but also by eliminating waste from chemical transesterification reactions, which is also of great benefit to the environment.
Triglycerides are composed of one glycerol molecule and three fatty acid molecules. The fatty acids in triglycerides are mainly unsaturated fatty acids, making triglycerides liquid at room temperature. Producers partially hydrogenate the fats in triglycerides to make them solid, producing trans fatty acids during the hydrogenation process. In addition, in many processed foods, high concentrations of trans fatty acids have also been found. Consumption of trans fatty acids is a high risk factor for heart disease. In order to minimize the content of trans fats in foods, the U.S. Food and Drug Administration (FDA) requires that the content of trans fatty acids must be indicated on the nutrition ingredient labels of all foods after January 1, 2006. To this end, the U.S. food and food ingredient industries are looking for ways to reduce the amount of trans fatty acids in foods.
Of all the measures to reduce trans fatty acids in food, the transesterification reaction is the most effective because it preserves the benefits of some of the hydrogenated vegetable oils. During the ester exchange process, triglycerides containing saturated fatty acids are exchanged with triglycerides containing unsaturated fatty acids to exchange one or two saturated fatty acids to form triglycerides that do not contain any trans fatty acids. There are two types of transesterification reactions: chemical exchange reactions and enzymatic transesterification. Enzymatic transesterification has many advantages over chemical exchange reactions, such as milder reaction conditions and no harmful chemical by-products. And the reaction can be stopped within a specified period of time, can be accurately known to the extent of transesterification and mastery and the like. However, the cost of the enzyme during processing and the stability of the use of process enzymes limit its application in the large-scale fat production industry.
Novozymes and DM have industrialized enzymatic transesterification technology through extensive and in-depth collaborative research with Novozymes, which won the President's Green Chemistry Challenge Award in 2001 for its outstanding contributions to the enzyme processing of fabrics. Novozymes is responsible for providing an efficient and low-grade immobilized enzyme, and ADM has developed a process that stabilizes the immobilized enzyme so that the enzyme is successfully converted into commodities. Enzyme-catalyzed transesterification reactions can provide food companies with oils and foods that contain no or only small amounts of trans fatty acids. Since its first products went on the market in 2002, ADM has produced more than 6810 tons of transesterification oil. Now ADM is expanding its enzymatic processing capabilities on 2 production lines in the U.S.
Enzyme-catalyzed transesterification reaction technology has a positive effect on protecting the environment and human health, it avoids the use of a variety of corrosive chemicals and the generation of by-products and waste, but also improves the use of food oil resources. For example, candidate butter and shortening consume about 4.54 million tons of hydrogenated soybean oil per year. Compared to partial hydrogenation methods, the ADM/Novozymes method is capable of saving 180,000 tons of soybean oil per year. The enzymatic acid exchange process also saved 9,080 tons of sodium methanol, 53,000 tons of soap, 22,700 tons of bleaching powder, and 227,100 m3 of water. The enzymatic process provides the public with trans fatty acids and a large number of polyunsaturated fatty acids in the exchange of ester exchange oils, which are used to replace partially hydrogenated oils and contribute to improving public health.
Merck synthesizes Aprepitant's new route
Emend is a new drug used to prevent nausea and vomiting produced by the course of cancer chemotherapy. Clinical results have shown that taking Emend during or shortly after chemotherapy relieves nausea and vomiting, with the active ingredient Aprepitant (a P-substance neurokinin-1 receptor antagonist). Aprepitant contains 2 hybrid rings and 3 chiral centers and is a target substance that is difficult to synthesize. Merck's first-generation commercial synthesis route is based on existing synthesis reactions and takes 6 steps to complete. Raw material and environmental costs along with this route, as well as safety issues during production operations, led Merck to develop a complete synthetic route.
Merck's new synthetic route embodies several important principles of green chemistry. It synthesizes Aprepitant in three steps that fully embody the principles of atomic economy using four types of fragments that match each other in size and structure. The original route requires the use of a stoichiomerimetric expensive, complex chiral acid to establish the absolute three-dimensional structure of Aprepitant, and the new synthetic route requires a chiral alcohol as a raw material, and the alcohol itself is obtained by catalyzing asymmetric reactions. Merck's new route establishes the remaining 2 chiral centers in the Aprepitant molecule using the stereochemical structure of this chiral alcohol feedstock in the subsequent 2 consecutive steps, using a practical crystal-induced asymmetric conversion technique.
Innovations in synthetic routes have increased Aprepitant yields by almost 2x. In addition, some of the techniques developed for new synthetic routes are novel and have great application prospects. In particular, the idea of selecting molecules containing a chiral center in the target molecule and establishing a highly selective remaining chiral center is available for the large-scale synthesis of many chiral molecules, especially chiral drugs. The adoption of the new synthetic route completely improves the negative environmental impact of the Aprepitant production process and eliminates all operational hazards in the first generation of synthetic routes, including the absence of sodium cyanide, titanium diethylene, ammonia, etc. The shortening of the route and the mild reaction conditions also significantly reduce energy consumption. More importantly, the amount of raw materials and water required for the new synthetic route is only 20% of the original route. With the new synthetic route, Merck can reduce wastewater emissions by approximately 340m3 per 1 tAprepitant produced.
Merck's new route synthetic Aprepitant uses green chemistry principles to significantly reduce production costs while reducing environmental impact. Merck adopted the new synthetic route in the first year of production of Emend, so Merck will reap the benefits of this new route throughout the life of Emend's products. The introduction of a new synthetic route at the beginning of production has led to a significant reduction in the production cost of Aprepitant, which fully proves that green chemistry schemes can be cost-effective.
2. Award for Changing Solvent/Reaction Conditions
BASF corporation has received the Change Solvent/Reaction Condition Award for developing a UV-curable, one-component, low volatile organic compound (VOCs) automotive refinish primer.
In North America, the market share of automotive refinish coatings exceeds $2 billion/a, with more than 50,000 automotive refurbishment sites using these coatings. Over the past decade, both automotive refurbers and paint manufacturers have had to respond to increased government emission standards for VOCs. Initially, the manufacturer utilized a two-component reactive polymer mass polyurethane rubber and used certain solvents as carriers to maximize its performance and meet the requirements of VOCs emission standards. However, with the strict emission standards of VOCs, manufacturers have to change their production formulas, and the products produced by the new formulas have the problem of slow film formation. Of course, there is no problem with VOCs in the use of water-soluble coating, but its use is limited by the time of water evaporation. Therefore, there is an urgent need for a new type of coating with fast film formation and good performance while meeting the VOCs emission standards.
Through in-depth research and exploration, BASF invented a new polyurethane acrylate oligomer primer. While the double bond of acrylate is destroyed by the free radical reaction, the polyurethane acrylate oligomer monomer is crosslinked and enters the membrane, thereby improving the adhesion and water resistance, solvent resistance, hardness and flexibility of the membrane, while also accelerating the curing speed. Under the sun or near ultraviolet lamp (UV-A), the primer solidifies in a matter of minutes. BASF's UV-curable primer technology significantly reduces energy consumption by eliminating the need for baking curing as is done in the traditional way. The application of this new polyurethane acrylate oligomer primer accelerates the curing time by more than 10 times, requires fewer preparation steps, has a lower cost of use, and the paint film is durable, more corrosive, and can be stored indefinitely.
BasF's primer VOCs have a mass concentration of 204g/L, which is 50% lower than conventional products. This product meets the urgent needs of the South Coast California market. The low VOCs content and excellent performance of this product also ensure that it can be accepted and recognized by the entire US market. This one-component product reduces hazardous waste emissions and also avoids the use of solvents. The use of maintenance equipment in the past year shows that its use is only 1/3 of the regular amount, and the amount of waste is reduced from 20% to zero. The eco-efficient product, which requires fewer synthetics than traditional isocyanate-based coatings and does not require too much expensive personal protective equipment, is the first product in BASF's automotive refurbishment coating line, including Glassurit, a water-soluble primer with a global market. In the near future, one-component, UV-A curable transparent coatings will also be introduced. BASF is committed to providing local small painting shops with a range of products of reliable quality, affordability, energy saving, convenience and speed, while at the same time ensuring the health and safety of workers during the production and use of these products. To achieve these goals, BASF has embarked on an independent assessment of the eco-efficiency of its products.
3. Design Safety Chemicals Award
The Design Safety Chemicals Award was awarded to Archer Daniels Midland for developing a non-volatile, reactive polymerizer that significantly reduces the volatile organic compound content in latex coatings.
Since the 1980s, waterborne latex coatings have been widely used in areas such as construction and industry. Traditional latex coatings are mostly emulsions of tiny particles of synthetic resins (such as acrylate-based or styrene-based polymers, etc.). They all require a sufficient amount of polymerizer to form a coating film. The polymerization agent softens the latex particles so that they flow together to form a continuous film with excellent performance. After the membrane is formed, the traditional coccluent slowly diffuses from the membrane into the atmosphere. With the evaporation of the polymerization agent, the vitrification transition temperature of the latex polymer increases and the membrane hardens. Alcohol esters and ether alcohols such as ethylene glycol monobutyl ester (EGBE) and 2,2,4-trimethyl-1,3-pentylene glycol monoisobutyrate (Texanol) are commonly used as polycondenses, they are volatile organic compounds. The construction industry is the largest market for the use of latex coatings, with the United States alone using 2.34 million m3 in 2001. According to the coagulant contains a volume ratio of 2% to 3% of the coating, which is equivalent to about 54,000 tons of coalescing agents that have been used in the United States every year and about 16.3 tons of global coagulation agents. Now, almost all of these solvents are floating in the air.
Both from an environmental and economic point of view, people have been trying to reduce the amount of VOCs paint formulations. The invention of a new type of latex polymer without a polymerizer can solve this problem, but the film formed by these polymers is generally relatively soft, thus increasing the cost in the synthesis, testing, and commercialization process. Moreover, without a coagulant, cracks will occur when air-dried at room temperature and cannot adhere firmly to the surface of the substrate. Archer RCTM offers a coagulant that has the same efficacy as conventional products, but avoids harmful VOCs emissions. Unlike traditional polymerizers, which are volatile in the air, the unsaturated fatty acids in Archer RCTM products are crosslinked into the coating through oxidation reactions.
Archer RCTM product preparation is achieved by transesterification between vegetable oil fatty acid esters and propylene glycol to form propylene glycol esters. Corn oil and sunflowers are the raw materials of choice for the production of Archer RCTM because they contain more unsaturated fatty acids and avoid the yellowing caused by linolenic acid caused by the use of soybean oil and flaxseed oil. Once the film is formed, Archer RCTM remains in the coating film, increasing the overall durability of the latex paint and being more price-competitive than volatile polymerizers.
Archer Daniels Midland developed and experimented with a large number of paint formulations and in March 2004 replaced Archer RCTM with traditional cocamerators that were comparable to commercialized coagulants such as Texanol. In addition, the Archer RCTM offers advantages such as low odor, enhanced abrasion resistance, and good coverage.
4. Academic Awards
Professor Rogers of Alabama University received the Academic Award. He established a "platform strategy" for the preparation of novel materials from ionic liquids to dissolve and treat cellulose.
Most chemical companies are now working on bio-refining using renewable resources. In a typical bio-refining process, complex natural polymers such as cellulose are first dissociated into building blocks such as ethanol and lactic acid, and then reassembled into complex target polymers. However, if new polymers can be synthesized directly using the biological complexity of natural polymers, many dissociation and recombination steps will be eliminated. Professor Rogers and his research team have created a "platform strategy" that successfully harnesses the biological complexity of a natural renewable polymer, cellulose, to directly synthesize novel materials. This strategy potentially reduces the dependence on petroleum-based feedstocks when synthesizing polymers.
Since the 1940s, the potential value of cellulose has not been developed in part due to the shift in attention to petroleum polymers, the difficulty of modifying the properties of cellulose polymers, and the very limited solvent for dissolving cellulose. Professor Rogers' technique follows the two basic principles of green chemistry, namely the development of environmentally friendly solvents and the synthesis of new materials using bio-renewable data as raw materials. Professor Rogers found that cellulose from various sources (such as fibrous materials, unorganized materials, cotton, pulp, bacteria, filter paper, etc.) can be rapidly dissolved in an ionic liquid with a low dissolving point called 1-butyl-3-methylimidazole ([C4mim]Cl) through gentle heating (especially microwave heating). Using traditional extrusion spinning or molding techniques, this cellulose dissolved in an ionic liquid can easily form the desired shape in water, such as optical fibers, membranes, microbeads, flocs and the like.
By adding functional additives to the ionic liquids of the above cellulose, Professor Rogers has been able to prepare several mixed or composite materials. Before or after the cellulose is dissolved by the ionic liquid, these additives such as dyes, coordination agents, other polymers, etc. can be dissolved in the ionic liquid, and others such as nanomaterials, clays, enzymes, etc. can be dispersed in the ionic liquid. Using this simple method that does not involve chemical bond variation, Professor Rogers prepares capsule-like cellulose synthesizers with adjustable spatial structure, function, and rheological capacity. Ionic liquids can save energy through methods such as a novel salt or common cation exchange. Professor Rogers is now working on the one hand to develop improved and more efficient methods for synthesizing [C4mim] Cl, and on the other hand to conduct research in toxicology, engineering development, commercialization and so on.
Professor Rogers and the research team are currently conducting market research on selected materials, developing business plans to bring their target materials to market by joining forces with other chemical companies or starting their own small businesses. Chemical principles will guide its development work and product selection, such as the selection of polypropylene thermoplastic materials used in the automotive industry, so that the new materials developed have low cost, good elasticity, light weight, low toxicity, wear resistance, improved biodegradability and other characteristics, but also will greatly reduce the amount of plastic produced from petroleum as raw materials.
Professor Rogers took advantage of the fact that ionic liquids can act as solvents and combined a novel technique to dissolve and recombine cellulose or similar polymers to create a platform for synthesizing novel materials using natural polymers as raw materials. He stressed that as long as chemical principles are applied to guide process development and commercialization, the use of this synthesis platform will produce a range of new materials with market prospects and will eliminate or reduce the use of products synthesized from petroleum products.
Small Business Award
Metabolix won the 2005 Small Business Award for successfully using biotechnology to synthesize natural plastics.
Metabolix is a company that develops polyesters, polyhydroxy fatty acid esters (PHAs). Polyhydroxy fatty acid esters are a class of widely used, environmentally friendly, high-performance bioplastics, which are synthesized using biocatalytic technology from renewable substances such as corn starch, sucrose, cellulose hydrolysates and vegetable oils. In many applications, PHAs can be used as a long-term alternative to petrochemical plastics.
Metabolix uses biotechnology to introduce the entire enzyme catalytic reaction into certain bacteria, using bacteria as miniature reactors, from which the bacteria synthesize PHAs, thus realizing the living enzyme catalytic reaction. On commercial devices, it has been fully demonstrated that these bacteria are able to synthesize a series of PHAs polymers very efficiently, with high yield, good reproducibility, and stability. In addition, the commercialization process for recycling PHAs has also been developed and put into use. For enzymes that perform non-innate metabolic pathways, figuring out the procedural expression of their exogenous chromosome intact gene decoding is a key technique in biotechnology applications. With its achievements in this area, Metabolix joined forces with Archer Daniels Midland Company to promote the commercial production of polyhydroxy fatty acid esters (PHAs) for bioplastics, and in November 2004 announced the construction of a 50,000-tonne-per-year PHAs production plant in the Midwest of the United States.
These new natural PHAs plastics are very versatile, and have a series of physical properties that can be used to replace the current petrochemical synthetic plastics, so they have a wide range of application prospects. From rigid to highly elastic PHAs have excellent barrier properties and are also resistant to hot water and grease erosion. Metabolix has designed a PHAs production solution that can run on existing equipment and prepares products for different occasions by means of jet molding, thermoplastic molding, blow molding, and extrusion molding, depending on the application.
Metabolix's PHAs natural plastics will bring a number of benefits to protect the environment, such as reduced dependence on oil and reduced greenhouse gas emissions. At present, the production of PHAs is based on renewable sugar, vegetable oil, etc., and it is possible to use plants as direct raw materials in the future. In addition, the use of PHAs will greatly reduce the amount of "white waste", reduce the burden of municipal waste disposal, and protect water and wetland ecosystems. Because PHAs can be degraded into harmless substances in a variety of aerobic and anaerobic environments, including soil, rivers, seawater, septic systems, anaerobic organisms, and compost.
Metabolix's PHAs production technology is the first plastic production technology based on the commercialization of renewable resources, which utilizes "live" biocatalysts to eventually convert renewable resources into copolymer products during bacterial fermentation. PHAs are also the first family of plastics to combine a wide range of uses with biodegradable properties in a variety of environments. The use of PHAs instead of traditional petrochemical synthetic plastics also has clear economic benefits. Producing 25 million tPHAs of natural plastics could replace nearly half of the petrochemical synthetic plastics currently used in the United States, which would reduce imports of oil by 200 million to 230 million barrels per year, and if the price of oil per barrel is assumed to be $30 to $40, $6 billion to $9 billion could be saved.