Tag Archives: solvents

Etzkorn solo photo

Green Chemistry at Virginia Tech Part III

For my third and final interview in the Virginia Tech series, I had the privilege of interviewing Dr. Felicia Etzkorn (pictured left), pioneer of the green chemistry course at Virginia Tech. The green chemistry course was her idea back in 2003. She and her colleague, Dr. Tim Long, decided to team-teach it just for fun. A couple of years later Dr. Etzkorn decided she was going to approach it more seriously. As a result, she had to write a course proposal for Virginia Tech’s course catalogue. The course was approved by three different curriculum committee levels. Afterwards, she developed course material and lectures, and taught the class for three years, from 2007 – 2009. She is excited to be teaching it again this Spring 2012.

 

Dr. Etzkorn also applies her passion for green chemistry to the local Blacksburg community. She designed a green science experiment for middle school students. Under the program, she brings the students into one of the labs at Virginia Tech to let them make their own polymer of lactic acid. The procedure allows them to make polylactic acid derived from soybeans, similar to a process used for biodegradable plastic containers for salads.

 

 

The students got a chance to come to Tech and get to do the experiment using solvent free polymerization and a non-toxic catalyst. First they had to stir and heat the mixture to get the polymer following lab procedures. Then the students made small toys by pouring polymer into clay molds they made in art class (pictured right – the brown items: shells, lips et.c are the PLA polymer, the grey figures are clay molds.). Since it does biodegrade the students were even encouraged to compost it. They were really enthusiastic about green chemistry.

 

 

Dr. Etzkorn also studies neural tube defects in mice with Dr. Hrubec, her collaborator. In the experiments, the control mice start getting neural tube disorder at a shocking rate of 20%, leading to many control experiments to see what was causing it. One suspect turned out to be from our every day tap water: epilepsy and bipolar disorder medication Cardamazepine. Dr. Etzkorn explains: “We cannot get any water that doesn’t have it to some extent and the mice are very sensitive to these agents.” The second suspect is a quaternary ammonium compound used to sanitize the lab. More experiments have yet to be conducted to determine the culprit.

 

AGC congratulates the diverse work that Dr. Etzkorn does with green chemistry and environmental health sciences and wishes her success in the future.

 

Shake it up: A greener method for upset tummy medicine.

André, V, A Hardeman, I Halasz, RS Stein, GJ Jackson, DG Reid, MJ Duer, C Curfs, MT Duarte and T Friščić. 2011. Mechanosynthesis of the metallodrug bismuth subsalicylate from Bi2O3 and structure of bismuth salicylate without auxiliary organic ligands. Angewandte Chemie International Edition http://dx.doi.org/10.1002/anie.201103171.

Synopsis by: Audrey Moores and Wendy Hessler, Dec 15, 2011

This sounds like a kitchen recipe: mix A with B, add a few drops of water, a pinch of salt and then shake. Except, researchers followed these simple directions in a laboratory to make the main ingredient in the popular stomach and intestinal remedy sold under the brand name Pepto-Bismol.

To make the drug this new way, they mixed the two main dry ingredients then added the rest and vigorously shook the paste in a special shaker. The breakthrough – an important step forward in the emerging field of mechanochemistry – uses less energy and solvent than the current way the drug is produced. And it creates no harmful by-products.

This discovery is showing that using simpler chemistry methods can improve processes as complex as drug synthesis and also aids understanding of how drugs work.

 

Context

The image of chemistry is intimately linked with the idea of mixing together liquids. But a new field of chemistry – namely mechanochemistry – proposes to make molecules by mixing solids without adding copious amounts of liquid solvents.

In mechanochemistry, the reagents are loaded into a small cylinder with two metal or ceramic balls. This cylinder is shaken very fast to allow proper mixing. The advantages of this technique are multiple. The products are collected pure, the reactions proceed faster than in solution, and less energy is required to perform the mixing compared to what is needed to heat large amount of solvents.

Variations of this method include addition of a few drops of solvent or a very small amount of salts. This permits the use of slower shaking, thus reducing energy use even more.

Pepto-Bismol is a popular stomach and intestinal relief medication. It is composed of a metal called bismuth and aspirine. To be active, bismuth and aspirine have to form chemical bonds together.

Currently, the drug is made by mixing water solutions of these two ingredients. After reacting, the excess water is removed, which costs energy, time and money. Previous efforts to find simpler, less wasteful, mechanical ways to manufacture the compounds have failed.

This bismuth-aspirin drug has been used for more than a century, yet chemists do not know exactly what its chemical structure looks like when the active ingredients combine. This has limited understanding of how the drug functions in the stomach.

 

What did they do?

A group of researchers from Cambridge, United Kingdom, wanted to improve the existing synthesis of a pharmaceutical group of compounds called bismuth salicylates. The most well-known variety is bismuth subsalicylate, the active ingredient in Pepto-Bismol, an over-the-counter medicine used to treat nausea, heartburn, diarrhea and other stomach and intestinal symptoms.

They were looking for a way to make the desired bismuth subsalicylate using a method that was more energy efficient, faster, yielded fewer harmful byproducts and used less solvent than the current way to make the drug.

Instead of first dissolving the two key ingredients – bismuth oxide and aspirine – in liquid solvents and then mixing the two fluids together, the researchers chose a simpler method. They mixed the dry powders in a mechanochemical mill.

It was not the first attempt to produce this drug in such a simple fashion, but past trials were met with little success. This time, the research group added a few drops of water and a pinch of salt. During ingredient shaking, the presence of the water and the salt enabled the formation of the drug in very high yields.

They tested different ratios of bismuth oxide and aspirine, different volumes of water and a variety of salts. After each attempt, they identified the products produced during the reaction.

 

What did they find?

The researchers first added a few drops of water to the bismuth oxide and aspirine powders. This helped the reaction and products did form, but none were the active ingredient bismuth subsalicylate they were looking for.

They redid the experiment adding a little bit of salt with the water to the powders. A series of different salts were tested. They discovered that potassium nitrate and ammonium nitrate were very efficient in promoting the reaction and afforded the desired drug in high yields.

The reason why the addition of water and salt is required is not completely understood, but the researchers believe that it helps the molecules organize and “find their place” in the final molecular architecture.

 

What does it mean?

By testing a new method of mixing ingredients, this group of chemists was able to produce a commercially important drug using less energy and solvent. They also are the first to identify the chemical structure of a compound similar to bismuth subsalicylate.

The discovery of this new synthetic method is important because it opens the way toward more energy efficient and less polluting drug fabrication. The chemists only had to mix two essential ingredients with tiny amounts of water and nitrate salts – less than 5 percent. Interestingly, these salts do not seem to mix with the final product, which allows for easy separation in the end. Also, this new process generates only water as a by-product. It is thus compatible with drug synthesis.

The secondary discovery of the compound’s chemical structure may seem surprising. Although it has been known for more than a century that the ingredient in Pepto-Bismol is active, the actual way it works is still unclear. In fact, no chemist had isolated and identified the three-dimension chemical structure of any bismuth salicylates. It is a little bit as if engineers were trying to understand the way an engine works without having the knowledge of the shape of its mechanical pieces.

In this study, the researchers were able to decipher the structure of a compound very close to the ingredient bismuth subsalicylate found in over-the-counter medicine. This is a vital step towards understanding the biological activity of this much-used drug. This discovery was possible because the method afforded an unusually pure product, another common advantage of mechanochemistry.

The use of mechanochemistry at a production scale has been demonstrated, for example, on the synthesis of an anti-inflammatory drug/carrier composite. This new discovery may thus lead to a more optimal production of Pepto-Bismol and other medicines. Read more science at Environmental Health News.

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Green Chemistry at Virginia Tech Part I

Being a recent graduate of the University of Virginia, it is a little hard for me to write this article on all the innovation and leadership that is happening at Virginia Tech in the field of Green Chemistry (note: the two schools are notorious rivals). However, this is one topic on which I must concede: Tech just does it better.

To begin my series of Green Chemistry interviews with faculty and staff at Virginia Polytechnic Institute and State University (also known as Virginia Tech, VTech, and Tech), I interviewed Dr. Timothy Long. Dr. Long’s dedication to greener chemistry can be seen in both his teaching and in his research. I had the privileged opportunity to discuss his background, career at Tech, and plans for the future.

After receiving his PhD in chemistry, Dr. Long spent nine years in the chemical industry, where his passion for greener processes developed. He described: “they (industry) were very aware of green chemistry, motivated by economics and affordability.” Once exposed to this mentality, Dr. Long got passionate and wanted to see how to apply this mentality to his research and teaching. When he came to VTech twelve years ago he wanted a more sustainable way of doing things. He described: “I want to weave the principles of green chemistry into my teachings and research.”

A major contribution from Dr. Long’s lab is the more sustainable production of PSA (pressure sensitive adhesive used in many forms of tape and sticky notes). Previously, these compounds used petroleum-derived precursors that had terminal ester bonds. Dr. Long’s polyesters have that same ester bond but in the middle of the polymer. This structural change allows the compound to be made without solvent, while also allowing biodegradability. Killing two green chemistry birds with one stone.

Virginia Tech offers a course in green chemistry taught alternatively by Dr. Long and Dr. Etzkorn. It is a 4000 level class for undergraduates which caters to mainly to chemistry, biology, and business majors. Each semester the course has 45 students. The course takes an interdisciplinary approach to green chemistry as it integrates the science and concepts with society. It seeks to understand how chemistry is perceived in the wider community. While there is no green chemistry minor at Tech, the engineering school has a green engineering minor. Dr. Long also wants to make the green chemistry course mandatory for chemistry graduates. Currently he is submitting a proposal for a nanoscience degree at the University that would incorporate fundamentals of toxicology, essential for our upcoming chemists.

Dr. Long described the passion of Tech’s students to be more sustainable, commenting on their successful Earth Week each year and the increasing amounts of activity on campus. Tech is also hosting the World Polymer Conference next year – which is geared to making a more sustainable, healthy, and safer world.

AGC wishes Dr. Long success in all these ventures and applauds his success thus far.

Interview by: Mana Sassanpour, AGC

Pie Chart

Analysis of Green Chemistry publications over the past four years.

This figure is taken from Green chemistry: state of the art through an analysis of the literature by V. Dichiarante, D. Ravelli and A. Albini. Green Chemistry Letter and Reviews Vol. 3, No. 2, June 2010, 105-113.

 

As the label indicates, the pie chart shows a distribution of green chemistry topics as analyzed by articles produced in the year 2008. The majority of the pie chart (about 50%) is attributed to catalysis – or starting a reaction, under more favorable conditions that require less resources, whether those resources are heat, energy, reagents etc. Specifically, metal catalysts were the most cited catalysts used in many different reactions, specifically in those involving enzymes. Acids are also seen in this category, and according to the article, are used mainly in condensation reactions. The next largest section of the pie (about 40%) is attributed to media, or where/in what the reaction takes place. Many reactions require some liquid for a reaction to take place. Many of these liquids, especially in organic chemistry, are volatile or toxic compounds. As a result, most of the research done with green chemistry and the media of reactions use either no solvent, which allows for most reduction of waste. Water has also gained a prominent role in green chemistry literature as it is our universal solvent and usually can be recycled in a reaction. Ionic liquids are the third major media hit; they are liquids that have charged compounds in the solution to help guide a reaction. Ionic liquids are usually not volatile and are stored more easily compared to their organic counterparts. Finally, the last 10% of the pie chart goes to ‘new methods,’ or novel ways to do old reactions. Using microwaves to start and maintain a reaction is the most prominent method, followed by some research advances in photochemistry and ultrasounds, using light or sound respectively in reactions.

chemistry classroom

AGC Goes to School

 

Advancing Green Chemistry has recently been invited to speak at several universities in the Charlottesville area. Most recently, AGC staff member, Mana Sassanpour, gave a presentation on the 12 principles of green chemistry to undergraduates at the University of Virginia.  In the presentation she showed examples that the students are familiar with from their own classes and lives.

For example, principle number 5: ‘Using safer solvents and reaction conditions’. UVA undergrads use DMSO and ether as solvents in many organic chemistry labs – often without ever knowing how harmful and toxic these substances are. By showing them that pharmaceuticals that used to use similar solvents are now using water as a replacement, Mana showed how to positively alter reaction conditions. In addition, her presentation opened students to an emerging field of chemistry: mechanochemistry. Mechanochemistry does not use solvents at all, but rather relies on a grinding mechanism to start and push a reaction. This field of chemistry has been applied to the production of pepto-bismol, a compound that everyone is familiar with, making the synthesis solvent-less. The students’ favorite part was the picture of the pepto-bismol ice-cream. Yumm.

Mana’s second lecture at UVA was directed towards the Chemistry Department. This lecture was followed up with a great question and answer session, really engaging the whole audience. For the most part, each participant asked a question, creating a really involved dialogue.

Up next, Mana hopes to lecture at Eastern Mennonite University!

 

Shortcut converts common cellulose into useable parts.

Synopsis by Wim Thielemans, Sep 23, 2011

Long, J, B Guo, X Li, Y Jiang, F Wang, SC Tsang, L Wang and KMK Yu. 2011. One step catalytic conversion of cellulose to sustainable chemicals utilizing cooperative ionic liquid pairs. Green Chemistry http://dx.doi.org/10.1039/c1gc15597k.

A new one-step process blends a pair of specially selected solvents with cellulose, overcoming a big hurdle in the race to use the plant-based material as a reliable source of chemicals and fuels.

Pairing up a unique blend of specialized chemical solvents with plant cellulose has solved a looming problem for chemists grappling to find an efficient method to break apart naturally abundant cellulose.

The one-step process uses two ionic liquids to break cellulose down into its smaller chemical pieces and convert these pieces into useful chemicals. This is an important feat since cellulose is targeted as an alternative source for the chemicals and fuels currently derived from fossil fuels.

The results show for the first time that combinations of ionic liquids can be very useful in guiding more efficient chemical reactions that create less waste and more product. The findings are interesting because they show it is possible to combine several processing steps just by choosing the correct mixture of solvents.

Cellulose is a major part of plant cells and is the most abundant renewable material on Earth. Every year, plants, algae and some bacteria produce in excess of an estimated 100 billion metric tons. Cellulose is not a food and is a waste product of agriculture.

An enormous research effort is underway to understand how to use cellulose as a starting material for biofuel and chemical production in order to replace crude oil. In this process, cellulose – a long chain of identical chemical units – needs to be separated into the individual units.

The key challenge to convert cellulose into chemicals is its poor solubility – that is, it does not break up easily in liquids. Chemical reactions, though, require close contact between all the parts to work well. In 2002, researchers reported that some ionic liquids were very good at dissolving cellulose.

Ionic liquids are salts – a designation for chemicals made up of both a positively and a negatively charged component– that are liquid at low temperatures, unlike common salts such as table salt. Bulky positive and negative groups that make up the ionic salts hinder their packing into a solid crystal. Thus, they stay liquid to much lower temperatures – even room temperature.

In this work, Chinese researchers used a mixture of two ionic liquids. The first was chosen to dissolve cellulose. The second was chosen because it increases cellulose breakdown into its individual units, and further, into useful chemicals.

Under the right conditions, all the cellulose was broken down. The reaction products were also removed from the ionic liquid mixture by simply adding an insoluble solvent such as methanol or hexane. While there were a variety of different reaction products, up to 48.5 percent of the cellulose could be converted to a single product: 2-(diethoxymethyl)furan. This chemical, in turn, can be easily converted into a variety of other products useful for the chemical and pharmaceutical industries.

The choice of the solvent to extract the reaction products from the ionic liquid also allows researchers to select the reaction products that are recovered.

The ionic liquid mixtures were also reused. No real difference in performance and composition was noticed over 10 repeated reactions.

The researchers chose to dissolve cellulose first followed by a reaction to convert cellulose into smaller, more useful products. However, the results suggest the system is versatile and – depending on which ionic liquids are selected – could be extended to several reactions in a row. Ionic liquids will certainly hold some surprises in the future.

Read more science at Environmental Health News.

 

Bacteria rejoice: study identifies safe solvents.

Bacteria rejoice: study identifies safe solvents.

Synopsis by Wim Thielemans and Wendy Hessler, August 2, 2011

Wood, N, JL Ferguson, HQ Nimal Gunaratne, KR Seddon, R Goodacre and GM Stephens. 2011. Screening ionic liquids for use in biotransformations with whole microbial cells. Green Chemistry http://dx.doi.org/10.1039/c0gc00579g.

Chemists took a first step towards designing a more environmentally-friendly solvent known as ionic liquids by identifying those that won’t kill the bacteria used to transform raw materials into useable products.

For the first time, a large number of the new type of solvents were tested on the E. coli bacteria strains that are widely used in industry. Many of them did not harm the bacteria and may be hopeful candidates for industry.

Ionic liquids’ popularity is growing as researchers eye them to replace toxic, smelly and polluting organic solvents currently used to produce all manner of chemicals and consumer products.

 

Context

To make chemicals, solvents are commonly required.Solvents dissolve gases, solids or liquids into a solution. They can help to bring the reacting chemicals in contact, separate the products from reactants and sometimes even speed up the chemical reaction. Unfortunately, many solvents are toxic, volatile – they evaporate quickly and/or flammable. It is therefore important to perform reactions without solvents, if possible, or use more benign solvents.

Ionic liquids are a relatively new class of solvents. They are salts – a designation for chemicals made up of both a positively and a negatively charged component– that are liquid at low temperatures, unlike common salts such as kitchen salt. Bulky positive and negative groups that make up the ionic salts hinder their packing into a solid crystal. Thus, they stay liquid to much lower temperatures – even room temperature.

People are interested in using ionic liquids because they have extremely low volatility resulting in virtually no vapor emissions. The properties of these ionic liquids (solvating power, melting point, water solubility) can also be easily varied by changing the positive and negative groups.

Researchers wish to use ionic liquids for industrial biotransformation – a process in which bacteria produce chemical products. The most commonly known biotransformation is sugar fermenting into ethanol – the way beer and wine are produced. However, fuel from renewable resources – i.e. biofuel – and even valuable chemicals can also be made this way.

Biotransformation has the potential to have a much lower impact on the environment than pure chemical reactions.

What did they do?

In this work by researchers from the United Kingdom, the toxicity of 90 different ionic liquids was tested in the laboratory using the bacterium Escheria coli (E. coli).

E. coli regularly receives negative press attention because it can cause food poisoning in people. However, it is also used frequently in industrial biotransformation

The major problem in biotransformations is that the produced chemicals are sometimes toxic to the bacteria. So as the bacteria become more efficient at producing the wanted product, they become less efficient because they die. And this is where ionic liquids can play an important role. By using an ionic liquid in which the reaction product, which is toxic to the bacteria, is soluble, the product could be extracted from the aqueous broth of bacteria before it accumulates too much, becomes too toxic and kills the bacteria.

This plan requires ionic liquids that are not toxic to the bacteria. The work described here begins to identify the nontoxic varieties by looking at the effect of the different ionic liquids on cell viability and growth rates. The researchers examined in high throughput tests ionic fluids that can dissolve (miscible) or remain undissolved (immiscible) in water.

What did they find?

Various ionic liquids were found to be non-toxic towards E. coli. There were both water miscible and immiscible ionic liquids that did not show toxicity. Importantly, the ionic liquids displayed similar toxic behavior based on their specific negative and positive chemical groups.

With this information, it is possible to start to predict the toxicity of ionic liquids towards E. coli if they contain the same charged groups as those used in this study. Surprisingly, it was also possible to prepare a type of ionic liquid called quaternary ammonium salt ionic liquids that were non-toxic to E. coli by changing the negative ion attached to it. This is a remarkable result since quaternary ammonium salts are being widely investigated for use as antibacterial agents on hard surfaces.

What does it mean?

Many types of ionic liquids were compatible with the bacteria E. coli and could be candidates for industrial uses that transform starting materials into products.

The results are very important because the toxicity trends prove that it is possible to start to rationally design ionic liquids.

The study shows it is possible to make a certain ionic liquid that has the toxicity effect that is required by choosing the positive and negative ions that it is made from. It is already possible to adjust physical parameters, such as melting point, freezing point and solvating power, i.e. the amount of a specific chemical that can be dissolved. This work thus adds another parameter that can be manipulated, adding another benefit to the use of ionic liquids.

This work is the first in a range of studies that will need to be performed to isolate which ionic liquids will perform the best. While 90 ionic liquids is a large number, more ionic liquids will need to be studied to help form a much better idea of their toxicity towards E. coli and other bacteria useful to industry.

See more science at Environmental Health News.

 

 

Novel, sugar-based surfactants more stable and sustainable.

Synopsis by Evan Beach and Wendy Hessler. Jan 12, 201

Foley, PM, A Phimphachanh, ES Beach, JB Zimmerman, and PT Anastas.  2011.  Linear and cyclic C-glycosides as surfactants. Green Chemistry http://dx.doi.org/10.1039/C0GC00407C.


2011-0106ecoproducts
xrrr/flickr

Context

Surfactants – the active ingredients in many household products, including cleaners and personal care products – are produced on the scale of millions of tons per year. In nearly every application, after a few minutes of use, they are rinsed with water either down the drain or directly into the environment.

Unsurprisingly, there have been harmful effects from such large-scale releases. When surfactants are slow to break down in the environment, problems range from unsightly foaming to toxic effects on aquatic organisms. Some of these chemicals – for example, the widely used nonylphenol ethoxylates – have been implicated in endocrine disruption. The term is used to describe substances that can alter hormone activity in the body.

There has been a push in recent years toward sugar-based surfactants because of improved biodegradability and lower toxicity. They are also derived from natural and renewable sources, adding another “green chemistry” benefit.

Sugar-based surfactants have been commercially available for more than a decade. Formulations of the alkyl polyglycosides (APGs) are used in a variety of consumer products for laundry, hair and skin care. On an ingredient label they are usually identified as a variety of “glucosides,” for example decyl glucoside or lauryl glucoside. The use of APGs is growing at a faster rate than petroleum-based surfactants.

However, chemists are trying to improve APGs. Many of the sugar-derived chemicals can fall apart when exposed to acids in water because the link between the water-loving and oil-loving ends of the APG molecules is vulnerable. Also, depending on the variety of the APG produced, the manufacturing process relies on high temperature and pressure and energy-consuming purification steps.

What did they do?

Researchers investigated a new process to make a stronger chemical bond in one particularly weak spot of sugar-based surfactant molecules. The researchers transformed a precursor chemical by treating it with a chemical mix that included alkyl aldehydes.

Several sugar derivatives with straight or cyclic tails were produced, depending on the conditions that were used to convert the intermediary chemical. The new chemicals were tested for surface tension and foaming and the results were compared to current APG surfactant performance.

The researchers showed that the new surfactants could be prepared in a two-step reaction under mild conditions, using only a minimum of solvent. It was not necessary to purify the products by column chromatography, a procedure that would consume large volumes of potentially hazardous solvents. This improves the prospects for producing the chemicals on a large scale.

The scientists show that the technical performance of the new surfactants is as good as existing APG technology. This was determined by measuring surface activity – how efficient the chemicals are at reducing the surface tension of water. It is important for surface tension to drop quickly with just a small amount of added chemical, for surfactant applications. The best chemical tested in the study worked at just 40 milligrams (the weight of a few grains of rice) per liter.

The researchers also explored the foaming properties of the new chemicals. Foaming is desirable for some personal care products like shampoos, but would be a disadvantage in laundry applications and some industrial cleaners. The Yale chemicals were low foamers compared to a conventional surfactant, sodium dodecyl sulfate (SDS). But when mixed with SDS, the resulting foam lasted longer. Thus they could be useful in either low- or high-foam formulations.

The biodegradability of the new chemicals was not measured, but U.S. Environmental Protection Agency software suggests that the changes made to improve acid stability will not affect how microbes disassemble the chemicals. The glucose end of the molecule contains many carbon-oxygen bonds that are common places for microbial attack. If the surfactants are made from long, straight-chain aldehydes, that should also provide bacteria with a familiar food source.

What does it mean?

The new sugar-based surfactants may offer more stable and sustainable varieties to use in consumer products. The novel chemicals are more stable under harsh conditions and work just as well in laboratory tests as the sugar-based surfactants currently used. In addition, their chemical production is a significant improvement over current methods in that it uses less resources and produces a wider array of chemicals with surfactant properties.

2010-0106surfactantsmolecules
Evan Beach

This new family of sugar-based surfactants complements APGs that are already on the market. A wider variety of molecular structures means that manufacturers of green consumer products are more likely to come up with formulations that meet all the goals of function, performance, economy and low environmental footprint.

Replacing the weak spot in APGs with a sturdier alternative allows the sugar-based chemicals to be used in more applications. The two parts of the new molecule are linked with a bond between two carbon atoms instead of a bond between an oxygen and a carbon atom. The stronger carbon-carbon bond is unaffected by strong acid. That robustness could help in industrial applications and heavy-duty household formulations, for example acidic tile cleaners.

The new surfactants are made from glucose, which is widely found in nature. It is one of the components of table sugar and is the repeating chain unit in cellulose, which gives plants their supporting structure. Glucose acts as the water-loving part of the surfactant. The oil-loving part of the surfactant is made from aldehydes. Aldehydes are a diverse set of chemicals; some occur in nature and others are produced from petrochemicals. In this study, the aldehydes could be obtained by treating plant oils.

The researchers say their next step will be to explore algae as a possible source for all of the surfactants’ starting materials. The carbohydrate portion of algal biomass could provide the sugar, and algal oils could give the right kinds of aldehydes. Algae oils are particularly rich in carbon-carbon double bonds that can react with ozone to produce aldehydes. If that approach is successful, surfactant production could supplement algae-to-fuel technology.

Drug makers: reuse solvents, reduce emissions.

Raymond, MJ, CS Slater and MJ Savelski.  2010.  LCA approach to the analysis of solvent waste issues in the pharmaceutical industry. Green Chemistry 12:1826-1834.

Synopsis by Evan Beach, Jan 04, 2011

It might seem like a common-sense approach for pharmaceutical makers to re-use solvents instead of incinerating them, but many companies don’t. A new study suggests they should.

Researchers for the first time have quantified the benefits of reusing the solvents. They find that recycling produces fewer emissions and uses less energy than making those chemicals from scratch. These results show the most important way that manufacturers can reduce waste – particularly carbon dioxide emissions.

However, the benefits were seen only when the entire life cycle of the solvent was evaluated. If the solvent is only considered within the boundaries of the pharmaceutical factory, the total emissions are underestimated. The study clearly shows the importance of considering the entire life cycle of solvent production, use and disposal.

By far, solvents are the biggest contributors to pharmaceutical-related emissions, the authors report in the December issue of Green Chemistry. Their research shows that the amount of energy needed to produce fresh solvent and burn waste is much higher than the energy needed to run reduction and recycling programs.

Solvents far outweigh other chemicals in pharmaceutical manufacturing; pound for pound they account for more than 80 percent of the materials used in the average process. They serve a useful role, helping to bring reactants closer together and washing away impurities between steps.

But, this comes at a price: solvents also account for more than 80 percent of the nearly 200 million pounds of waste emitted by the industry. Beyond the factory gates, there are also hidden costs in terms of carbon dioxide emissions. Carbon dioxide is produced from the fuel used to heat chemical reactions and transport products between plants. Considering the entire life cycle of a solvent, as much as 98 percent of the environmental emissions can be due to carbon dioxide.

The scientists considered three case studies: one was an oncology drug being developed by Bristol-Myers Squibb, the second was Pfizer’s Celebrex product, and the last was a manufacturing intermediate used by Novartis to produce a hypertension drug. In each case, the researchers tallied up all the energy and materials used as well as all of the environmental emissions. Their analysis included manufacturing of solvents that occurred outside the pharmaceutical factory itself. They compared scenarios with or without the use of solvent reduction and recycling techniques.

In every case, cutting back on fresh solvent or burning less solvent waste reduced emissions by more than 90 percent. It was also seen that some solvents have a much greater impact than others. For example, one of the most widely used solvents is tetrahydrofuran, which causes 10 times as much water use in the manufacturing plant and accounts for more energy use – cradle-to-grave – than any other solvent tested.

This research shows there are definite environmental benefits to solvent reduction and recycling and provides examples of how this can be put into practice.