Green Chemistry

The U.S. Environmental Protection Agency defines green chemistry as consisting of:

...chemicals and chemical processes designed to reduce or eliminate negative environmental impacts. The use and production of these chemicals may involve reduced waste products, non-toxic components, and improved efficiency.

The EPA goes further, citing the 12 principles of green chemistry as defined by Paul Anastas and John Warner in Green Chemistry: Theory and Practice (Oxford University Press: New York, 1998):

1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up.

2. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no toxicity.

3. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to humans and the environment.

4. Use renewable feedstocks: Use raw materials and feedstocks that are renewable rather than depleting. Renewable feedstocks are often made from agricultural products or are the wastes of other processes; depleting feedstocks are made from fossil fuels (petroleum, natural gas, or coal) or are mined.

5. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.

6. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.

7. Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. There should be few, if any, wasted atoms.

8. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals.

9. Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible.

10. Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment.

11. Analyze in real time to prevent pollution: Include in-process real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts.

12. Minimize the potential for accidents: Design chemicals and their forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.

Green chemistry is gaining momentum among researchers, manufacturers and regulators due to the numerous benefits. A recent PubMed search of titles and abstracts for containing the phrase produced over 600 peer-reviewed articles covering a broad range of disciplines including chemical catalysis, biofuel production and purification, pharmaceutical synthesis and drug delivery, nanotechnology and MEMS, toxicology and environmental science, and economics. This broad-based interest in making manufacturing processes safer, more environmentally benign and less raw material intensive has the potential to provide tangible and intangible benefits across a similarly wide range of commercial activities worldwide.

by reducing raw material consumption and shipping costs, lower risk of accidents, lower production costs, and reduced regulatory risk. For example, major pharmaceutical companies produce up to 5000 metric tons of hazardous waste per year, the vast bulk of which is used solvent. Many firms are implementing solvent recycling, and have successfully cut solvent waste from 6-17%.

The costs associated with a properly implemented benign manufacturing plan can be recovered in costs reductions, while also preparing your company for a changing regulatory environment and increased global competitiveness.

The principles of green chemistry can be applied for small molecule and protein purification as well. While bench scale conventional chromatography is typically not very resource intensive, if the process is scaled to an industrial level, the costs for chromatography resin and the large volumes of solvents or buffers can quickly escalate. For example, one estimate of the cost for preparation of chromatography buffers is $5 per liter, and the cost for affinity resins for antibody purification such as protein A can exceed $10,000 per liter. If your process requires 20 – 30 column volumes for the entire cycle, and 5 liter bed volume, the cumulative cost for this process can easily exceed $50,000. By developing production processes that anticipate future scale up, or converting current processes to greener methods, you can reap the reward of substantial cost savings, and reduced environmental impacts on the production scale.

On average, solvent consumption is reduced 10- to 50-fold upon conversion from conventional chromatography to SMB Chromatography. Another important benefit is the reduced solid phase volume required for processing a given racemic mixture, cell lysate, or tissue culture fluid feedstock. Since the Octave process is continuous, 50-70% of the solid phase is engaged in separation, at all times.

The Octave platform is an invaluable process development tool for the conversion of conventional chromatography production processes to more environmentally benign methods. Key parameters in the purification process can be quickly optimized, allowing the rapid development of pilot-scale alternative using the software and tools provided with the Octave System. An excellent case study of the benefits of fully scaled SMB Chromatography is the purification of Paclitaxel production, where solvent consumption was reduced by 68%, while labor costs were reduced by 78%. The superior performance of SMB Chromatography makes a compelling case for the acquisition of bench scale SMB process development unit to rapidly convert current and future processes to the most efficient method possible. The Semba Octave System is the fastest, easiest pathway to "greening" your production process.

A good primer on the benefits of SMB Chromatography for industrial scale small molecule processing as well as for biopharma can be found here, and is worthwhile reading.