Chemistry 2.0
Our economy and culture are impacted by Chemistry in almost every way. It offers us contemporary conveniences but also modern issues like pollution and hazardous waste. A new area known as “green chemistry” emerged in the early 1990s as a result of a reconsideration of the kinds of chemical processes and technologies that were feasible.
In the US, Pollution Prevention Act of 1990 established a strategy for eradicating pollutants without resorting to treatment and disposal, preferring instead to use superior design. The intention was to bring the concept of “source reduction” to the attention of the public and industry. Therefore, preventing pollution was preferable and more effective than attempting to contain or clean it up.
“Green chemistry,” often called “sustainable chemistry,” focuses on designing and improving goods and processes to reduce or eliminate the usage and production of hazardous materials.
The aim of green chemistry is to reduce chemical-related impact on human health and virtually eliminate contamination of the environment through dedicated, sustainable prevention programs. In addition to looking for more eco-friendly reaction medium, green chemistry aims to lower reaction temperatures and speed up reactions. In short, it focuses on processes and products that reduce or eliminate the use of polluting substances
The idea of “greening chemistry” emerged in the regulatory and economic worlds as a logical development of efforts to prevent pollution. Our attempts to enhance commercial goods, medications, and crop protection also unintentionally harmed the environment and people.
It is the use of a set of guidelines that minimises or completely does away with the generation of hazardous materials in the design, manufacturing, and consumption of chemical products.
What sets green chemistry apart from pollution cleanup?
By lowering or completely eliminating the risks associated with chemical feedstocks, reagents, solvents, and products, green chemistry minimises pollution at its source.
In contrast, remediation, also known as cleaning up pollution, entails treating waste streams (also known as end-of-the-pipe treatment) or clearing up spills and other releases into the environment. Hazardous chemical separation from other materials, followed by treatment to render them non-hazardous or concentration for safe disposal, are some examples of remediation. Green chemistry is not used in the majority of cleanup operations. While remediation eliminates harmful materials from the environment, green chemistry prevents the creation of hazardous materials in the first place.
A technology might also be considered green chemistry if it lessens or does away with the dangerous chemicals needed to remove environmental pollutants.
Simvastatin, a drug first marketed under the name Zocor®, is a popular prescription for the treatment of high cholesterol. This drug was made using a multistep, conventional procedure that generated a lot of toxic waste and required a lot of hazardous reagents. A cheap feedstock and a modified enzyme were used to generate a synthesis by Yi Tang, a professor at the University of California. The enzyme and the chemical procedure were both optimised by the biocatalysis company Codexis. As a result, there is a significant decrease in risk and waste, and the product is affordable and fits consumer expectations.
In addition to attempting to measure a chemical process’s “greenness,” additional criteria like chemical yield, the cost of reaction components, hardware requirements, chemical handling safety, energy profile, and simplicity of product workup and purification are also being taken into consideration.
Another method that is thought to be promising for accomplishing green chemistry objectives is bioengineering. Several significant process chemicals can be synthesised in artificial organisms, including shikimate, a precursor to Tamiflu that Roche ferments in bacteria.
Green chemistry’s 12 principles
These principles demonstrate the breadth of the concept of green chemistry* :
Over the past 25 years, green chemistry has grown from a restricted field of study to one that is now home to hundreds of specialised journals, conferences, research centres, and awards. Green chemists have also achieved technological advancements outside of academia. In the industry today, innovations resulting from adherence to the 12 principles are standard practice. These developments led to whole new production techniques, improved safety in the chemical industry, and offered others more environmentally friendly options.
Some clear examples of its impact are the Nobel prizes awarded for green chemistry. In 2005 the discovery of the catalytic chemical process metathesis took home the chemistry award. Metathesis is the breaking and reformation of carbon double bonds so that chemical groups change places. The reactions are made possible using catalysts in accordance with principle nine. This method led to more efficient and cleaner synthesis for a variety of products and is now routine in the pharmaceutical and plastics industries.
The hierarchy appears as follows for people who are developing and applying green chemistry:
- Chemical Hazard Prevention and Source Reduction
* Converting feedstocks, reagents, and solvents into chemical products that are less hazardous to the environment and public health *;
* designing chemicals to be less harmful to these things
* Designing processes and syntheses that produce little to no chemical waste;
* designing processes and syntheses that consume less energy or water;
* designing feedstocks derived from abundant waste or annually renewable resources;
* designing chemical products for reuse or recycling; designing processes for the reuse or recycling of chemicals. - Chemicals that are treated to make them less dangerous before being disposed of.
- Safely discarding untreated substances, and only doing so in the event that no other possibilities remain.
*Chemicals that are less hazardous to human health and the environment are:
- Less toxic to organisms
- Less damaging to ecosystems
- Not persistent or bioaccumulative in organisms or the environment
- Inherently safer to handle and use because they are not flammable or explosive.
There are a lot of safer substitutes for these hazardous solvents thanks to the development of green chemistry. It is well known that the green solvents that are emerging as substitutes are biodegradable and sourced from renewable resources. Therefore, by creating safer substitutes, green chemistry holds considerable promise for reducing the toxicity of some industrial situations.
Green solvent
Paints and coatings account for 46% of the use of solvents in human activities. Applications with lower volume usage include chemical synthesis, adhesives, degreasing, and cleaning. Conventional solvents are frequently chlorinated or hazardous. Conversely, green solvents are ideally more sustainable and typically less detrimental to human health and the environment. Solvents should ideally come from renewable resources and biodegrade into a harmless byproduct, which is often a naturally occurring substance. Thus, while choosing a solvent for a product or process, the environmental impact of solvent manufacture must be taken into account. Therefore, a solvent may by definition be considered green for a particular use (since it does less environmental damage than any other solvent that may be used for that purpose) but not necessarily green for another. Easy recycling, easy biodegradation, and minimal toxicity are a few expected qualities of green solvents.
Alternative solvents:
| Class | Toxic solvents | Green Solvents |
| Alcohols | Methanol, Acetonitrile | Isopropyl Alcohol, Ethanol |
| Ethers | Diethyl Ether, Toluene, Tetrahydrofuran, 1.4-dioxane, Dichloromethane | Diethylene glycol dibutyl ether, Dimethoxy Methane, Cyclopentyl methyl ether, 2-methyl Tetrahydrofuran. |
| Esters | Benzene, Chloroform, Dichloromethane | Dibasic esters (mixture of dimethyladipate, dimethylglutarate, dimethylsuccinate), Ethyl lactate, Methyl acetate |
| Organic Carbonates | Dimethylformamide, Dimethylsulfoxide, N-Methyl-2-pyrrolidon | Ethylene carbonate, Propylene carbonate, 1,2-Butylene carbonate, Dimethyl carbonate |
| Volatile methyl siloxanes | Xylene, Toluene | Octamethyl-trisiloxane, Decamethyl-tetrasiloxane |
| Methyl ketones | Acetone | 4-Hydroxy-4-methyl-2-pentanone |
In conclusion, the ultimate goal of “green chemistry” is to completely stop
adding chemicals to the environment. Although this goal currently appears unachievable, advancements in the study of green chemicals and their application through subsequent strategies will undoubtedly result in safer specialty chemicals and far more satisfying processes for the chemical industry. The chemical industry’s cleanliness and safety have significantly improved as a result of green chemistry developments, which are gradually replacing antiquated methods of production. But further understanding of the relationships between the 12 principles is needed for the next step, according to green chemists like Anastas. Green chemistry will cease to be a distinct field and become the sole way that chemistry is done when a more comprehensive approach to the chemical sciences is taken.
– Dr. Subramanian s Iyer
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