The US chemical industry makes a wide variety of consumer products, or at least the chemicals that coat, color, and clean them. This includes things you use every day but never think about, like the coating on paper that makes it smooth, the dye in your clothes that makes them colorful, and the components in your toothpaste that enable it to clean your teeth. But in order to make these chemicals that are so ubiquitous in modern life, the chemical industry uses around 20% of the energy used by all industries in the US  while only employing around 7% of manufacturing workers . Further, it produces more than 2,000 metric tons of hazardous waste per day .
What is green chemistry?
Fortunately, the chemical industry is changing its wasteful ways. In the last twenty years, the EPA has encouraged companies to adopt the green chemistry philosophy, or the idea that we can decrease the hazardous chemicals given off as waste without giving up all of the perks of chemical products.
Under the principles of green chemistry, waste is avoided by intelligently designing a synthetic process that decreases pollution before it happens, limiting the environmental impact by going through fewer intermediates or by using chemically benign reagents rather than chemicals hazardous to humans and the environment. With the principles of green chemistry, different starting materials are used to make the same molecule in a simpler, more efficient process. The starting materials can be more complex, but should still be just as cheap and readily available. This reformulation can also lead to lower energy use and fewer greenhouse gas emissions by cutting out steps in synthetic processes, or by minimizing the use of high temperatures and pressures, which have a large energy cost.
Figure 1. In synthetic chemistry, individual parts of a molecule are often added separately. Sometimes, a protecting step is necessary to prevent one side of the molecule from reacting with a subsequent reactant, but it must then be removed or “deprotected”, adding a total of two steps to the reaction. This is shown in the second line of the “old reaction,” with the tan blocks protecting the corners so that the orange and yellow blocks can be added without disturbing the green block and the corners where the pink blocks need to go. This is unnecessary in the “Green” reaction where the pink and green blocks are added later in the process.
For example, SC Johnson recently reformulated Pledge, a multi-surface cleaning product, to contain fewer volatile organic compounds and be more biodegradable than the original . Volatile organic compounds, or VOC’s, are found in a variety of products because they clean efficiently and work well as solvents to keep all of the other components of the product together. However, they are hazardous pollutants because air carries them easily into the atmosphere, where they cause health issues and can lead to smog. By rethinking the mixture and adding cleaners that are not as harmful, SC Johnson was able to decrease the environmental footprint of the Pledge cleaning solution. As an added bonus, this new formula is 30% better at cleaning , making the product more attractive to consumers not only because it is safer, but also because it works better.
The Presidential Green Chemistry Challenge Awards
In 1995, President Clinton began recognizing advances in green chemistry by establishing the Presidential Green Chemistry Challenge Awards  to acknowledge the positive impacts that green chemistry can have on the environment. One of this year’s award winners is Geoffrey Coates of Cornell University, who has developed metal complexes that make plastics from more sustainable starting materials, including carbon monoxide (CO) and carbon dioxide (CO2) . Plastic is made up of individual molecules that are linked together to form a chain network, and Coates developed a way to make these individual molecules by reacting cheap starting materials with CO or CO2. This method not only sequesters CO2, keeping it out of our atmosphere so it cannot contribute to climate change, but also creates plastic without starting from fossil fuels. Further, these plastics do not contain bisphenol-A or other similar chemicals that may be hazardous to human health.
The principles of green chemistry are not limited to industrial applications, but can be applied to pharmaceuticals as well. One of the other Presidential Green Chemistry Challenge winners this year, Yi Tang, developed a new method to make the cholesterol drug simvastatin . This new method uses fewer hazardous solvents and cheaper starting materials than traditional methods. In particular, they improve the efficiency of the process by avoiding the need for “protecting groups.” A protecting group in chemistry involves protecting one side of your molecule, performing reactions on the other side of the molecule, and then finally “deprotecting” the first side to get back to where you started. This process prevents the first side from reacting with whatever you add to the other side, but it creates a lot of unnecessary waste. By rethinking the steps involved in making the pharmaceutical, Tang was able to cut out these wasteful steps.
Both of these examples illustrate the importance of research and development in green chemistry, as fundamentally new synthetic processes are necessary in some areas in order to achieve more environmentally benign waste, and less of it. In the long run, investment in green chemistry research saves money on waste management, since it is extremely expensive to dispose of hazardous waste.
Green Chemistry in Industry
The changes that are made to make chemistry “greener” can be economically beneficial for companies. Despite having smaller research and development divisions than large companies like SC Johnson Company, smaller companies are adopting green chemistry strategies as well. For example, a nameplate company in California moved from using toxic solvents, cleaning supplies, and inks to make their nameplates to using more benign chemicals, such as water-based solvents, to the same effect. By making this switch, the company saved money on waste cleanup and was able to make up for the research investment in less than two years . Furthermore, switching to nontoxic and environmentally benign chemicals made the company’s products more attractive to consumers and made the plant a safer place to work .
Green chemistry provides many benefits to human health and the environment by reducing waste without eliminating the end products of the manufacturing processes that we have come to rely on. Furthermore, in many cases there is a financial incentive for companies to produce less waste, which makes it likely that we’ll see more green chemistry initiatives in the future.
Katherine Phillips is a Ph.D. student in the chemistry department at Harvard.
 Worrell, E, Phylipsen, D, Einstein, D, and Martin, N. (2000) Energy Use and Energy Intensity of the U.S. Chemical Industry http://www.energystar.gov/ia/business/industry/industrial_LBNL-44314.pdf
 Bureau of Labor Statistics. “Industries at a Glance: Chemical Manufacturing” http://www.bls.gov/iag/tgs/iag325.htm
 AAAS Atlas of Population & Environment (2001) “Population Waste and Chemicals: Industrial Chemicals” http://atlas.aaas.org/index.php?part=2&sec=waste&sub=indchem
 California Green Chemistry Initiative (2008) “Frequently Asked Questions” http://www.dtsc.ca.gov/PollutionPrevention/GreenChemistryInitiative/upload/FAQs_greenchem.pdf
 SC Johnson (2009) “Greenlist Fact Sheet” http://www.scjohnson.com/en/press-room/fact-sheets/09-10-2009/Greenlist-Fact-Sheet.aspx
 American Chemical Society. “Green Chemistry at a Glance” http://portal.acs.org/portal/acs/corg/content?_nfpb=true&_pageLabel=PP_ARTICLEMAIN&node_id=830&content_id=CNBP_026133&use_sec=true&sec_url_var=region1&__uuid=bdf90049-ea0c-4db6-8561-4b9eaf066df1
 US Environmental Protection Agency “Green Chemistry” http://www.epa.gov/greenchemistry/index.html or http://www.epa.gov/greenchemistry/pubs/pgcc/past.html
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