Green Chemistry: Definition, Principles, Examples, Importance

Green Chemistry: Whenever we think about the ‘Green’ color, the first thing that comes into our mind is our beautiful environment which is full of natural beauty! But nowadays as science and technology have progressed, the level of pollution is on the rise. Scientists have thus discovered a new field in Chemistry known as Green Chemistry.

Green Chemistry is also called “Sustainable Chemistry”. This branch of Chemistry is used for designing chemical products and methods that reduce hazardous chemical substances from being generated. This would help us to design an efficient planet in which all living creatures can co-depend on each other to benefit themselves.

Introduction To Green Chemistry

Anastas is known as the father of Green Chemistry. The idea of Green Chemistry was developed to minimise pollution in the \(1990{\text{s}}\). Then in \(1998\), Paul Anastas and John C. Warner co-authored the pioneering book, Green Chemistry: Theory and Practice. They developed the Twelve Principles of Green Chemistry that can be grouped into “Reducing Risk” and “Minimizing the Environmental Footprint.”

Green chemistry can be defined as designing chemical products and processes that minimize or eliminate the use or development of hazardous substances. This is new revolutionary progress in the field of chemistry. Let’s ‘Go Green’ and learn about green chemistry which is full of innovations, new ideas, and of course, eco-friendly!

What is Green Chemistry?

Green chemistry is a newly emerging field to design, synthesize and implement chemical products by scientists and engineers that would protect and benefit the economy, people, and our planet by finding creative and innovative methods to reduce waste, conserve energy, and discover replacements for hazardous substances.

It is a sustainable method that would protect our ecosystem from hazardous and toxic chemicals.

Principles of Green Chemistry

There are twelve basic principles of Green Chemistry that can be grouped into “Reducing Risk” and “Minimizing the Environmental Footprint.”

1. Prevent Waste – Instead of treating or cleaning up waste after they are created, it is always recommendable to prevent waste. Nowadays, chemists are involved in design techniques that reduce pollution and problems caused by hazardous waste by preventing waste production.

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2. Atom Economy – The second principle deals with the designing of synthetic methods to maximize the incorporation of all materials or atoms used in the process into the final product. Atom economy means “what atoms of the reactants are integrated into the desired products and what atoms are wasted?”

3. Less Hazardous Chemical Syntheses – Synthetic methods should be designed to use and generate chemical substances that are non-toxic to human health and the environment wherever possible.

4. Designing Safer Chemicals – Chemicals and drugs should be designed with such strategies, that they would work efficiently in our body without being toxic.

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5. Safer Solvents and Auxiliaries – This principle affirms that the use of solvents and other auxiliaries (separating agents) should “be made unnecessary wherever possible and harmless when used”. In many chemical reactions, there would be no reaction possible without suitable solvents and separation agents. Nowadays, chemists are promoting chemical reactions using water as solvents in many syntheses.

6. Design for Energy Efficiency – Chemists should avoid carrying a particular reaction in high temperature and pressure or using other energy sources as it is a wastage of energy in the form of electricity or some other. Synthetic chemical methods should be carried preferably at ambient temperature and pressure.

7. Use of Renewable Feedstocks – A raw material or feedstock should always be renewable rather than depleting whenever economically and technically realistic. For example, instead of taking carbon from coal, which is a fossil fuel, we should extract it from the air itself where carbon dioxide is present.

8. Reduce Derivatives – Unnecessary use of derivatives (use of blocking groups, protecting or deprotecting group, temporary modification of physical/chemical processes) should be minimized or avoided in chemical synthesis as much as possible because such steps in a chemical reaction can require additional reagents and can generate waste.

9. Use Catalysis – Catalytic reagents are superior to stoichiometric reagents (which are consumed in a reaction). Catalytic reagent reduces the reaction time and is also recyclable.

10. Design for Degradation – Chemical products should be designed in such a manner so that at the end of their function or use they break down into harmless degradation products and do not persist in the environment

11. Real-time Analysis for Pollution Prevention – Analytical methodologies should be developed to allow real-time, in-process monitoring and control of any harmful effects before the formation of hazardous substances.

12. Inherently Safer Chemistry for Accident Prevention – Substances and their forms that are used in a chemical process should be chosen in such a manner so that they minimise the potential for chemical accidents, including explosions, releases, and fires.

Thus by following these principles we can develop safer conditions for chemists or workers, a safer environment for the public, and a safer planet for all of us!

Importance of Green Chemistry

Green Chemistry takes a life cycle approach: in the early stages of design and production of chemicals, it considers waste production, safety, energy use, and toxicity to reduce the impact of final production, its use, and disposal.

Promoting Green Chemistry is a fundamental approach in shaping a sustainable economic growth model. As we know, hazardous chemicals are responsible for various environmental issues that include ozone depletion, global warming, smog formation, pollution, etc., and are also toxic to humans, plants, and animals.

There is an utmost need of green chemistry and promoting methods that would be eco-friendly for chemical synthesis. Green Chemistry is very important for our future world.

Green Chemistry Examples

Green Chemistry is applied to several fields like pharmaceuticals, industries, and households too for minimizing the use of harmful or hazardous chemicals. Some of the examples of green chemistry are as follows:

1. Green Solvents: As an alternative to petrochemical solvents, eco-friendly green solvents or bio solvents such as water, alcohol, etc. are used in chemical synthesis.
2. Polystyrene (a petroleum product) is a good heat insulator used in food packaging. In the past years, this packaging was expanded with tCFCs, but nowadays they are replaced by carbon dioxide or cardboard containers.
3. Adipic Acid is widely used in the synthesis of Nylon. But this adipic acid is made from carcinogenic benzene. Hence, scientists have developed genetically altered bacteria as a catalyst to synthesize adipic acid from glucose.
4. For dry-cleaning of clothes, initially, kerosene or gasoline was used but now chlorinated solvents are used for this purpose which is another very useful invention of green chemistry.
5. Biodiesel is produced from renewable resources and is less dangerous than petrol and diesel because it is less combustible.
6. New biocatalysts are developed using an enzymatic process for the treatment of type-\(2\) diabetes with equivalent potential as other drugs which reduce waste, improve yield, and safe. This eliminates the necessity for a metal catalyst.
7. One of the most reliable discoveries in this field was the development of the metathesis of olefin.  This reaction was developed by Robert Grubbs, Richard Schrock, and Yves Chauvin, who won the Nobel Prize for Chemistry in \(2005\).
8. Production of Hydrazine: Earlier hydrazine was produced by the Olin Raschig process, which involved the use of ammonia and sodium hypochlorite. But this was replaced by the peroxide process where ammonia was allowed to react with hydrogen peroxide. In this alternate method, water is the only side product. Also, it does not require any auxiliary extracting solvents.

Current Research in Green and Sustainable Chemistry

Biodegradable Plastics: The use of plastic is increasing the amount of pollution in the environment. Plastic particles and other plastic-based pollutants have been discovered in our environment and food chain, posing a health risk. Biodegradable plastics material focuses on producing a more sustainable and greener world with a less environmental footprint from this standpoint.

This assessment should take into account the objectives and priorities for generating a wide range of biodegradable polymers across their full life cycle. Biodegradable plastics can have features similar to standard plastics while also providing additional benefits due to their reduced carbon dioxide impact on the environment, as long as proper waste management, such as composting, is implemented.

Optimisation of Lactic Acid Production: Lactic acid is the starting material for poly-lactic acid. The goal of this study was to make lactic acid from agro-industrial wastes as a low-cost, renewable substrate while also lowering pollution levels in the environment. Agro-industrial wastes produced sixteen bacterial isolates. Hydrochloric acid, sulfuric acid, and sodium hydroxide were used to chemically hydrolyse agricultural and industrial wastes.

Using 16S rRNA, the highest yield of lactic acid was discovered. The best conditions for producing lactic acid were discovered. Sulfuric acid was used to precipitate calcium sulphate from calcium lactate generated during culture fermentation. To make pure lactic acid, the filtrate containing organic acid was evaporated.

Green Chemistry Impact Factor

The impact factor is the measure of the constancy with which an average article of any journal is cited in a year. This helps to measure the importance or rank of a particular topic of the journal worldwide. Green chemistry is the most peer-reviewed topic in scientific journals with an impact factor of \(9.480\). This means it is a very useful branch of chemistry.

Green Chemistry Project

Bio-diesel (a mixture of methyl esters and fatty acids) is an alternative diesel fuel extracted from renewable resources like edible and non-edible vegetable oils and animal fats. The basic similarity between diesel derived from petroleum and these natural oils and fats is that they are made up of triglycerides. Due to this reason, the idea of ‘Bio-diesel’ came forward. In India, it is extracted from the transesterification of oil obtained from the Jatropha curcas plant.

The chemical reaction involved to convert this Tree Borne Oilseed is transesterification which is a very simple and non-toxic method. Indian Oil Corporation has set up a laboratory-scale plant of capacity of \(100\,{\text{kg/day}}\) for transesterification designing large set up plants in the future. These large plants will be useful in the centralized production of bio-diesel in the future.

Summary

The conclusive aim of green chemistry is to stop the streaming of chemicals flowing into the environment entirely. Of course, it is not a complete solution to all the environmental problems but it may be very helpful in reducing pollution to a certain extent.

Thus, green chemistry is a very innovative way to produce non-toxic and non-hazardous chemicals and protect the environment. As per the current green chemistry, scientists are involved all over the world to develop sustainable techniques. Government and industries are also interested in this field that would help us to grow our economy sustainably.

Frequently Asked Questions on Green Chemistry

Q.1: Who invented Green Chemistry?
Ans. The idea of green chemistry was developed initially as a reaction to the Pollution Prevention Act of \(1990\), in the U.S. to eliminate pollution by the improved the design of chemicals used in various fields. At that time Paul Anastas and John C. Warner invented the idea of green chemistry.

Q.2: What are the 12 principles of Green Chemistry?
Ans: The twelve principles of green chemistry are: Prevention, Atom economy, Less hazardous chemical syntheses, Designing safer chemicals, Safer solvents, and auxiliaries, Design for energy efficiency, Use of renewable feedstock, Reduce derivatives, Catalysis, Design for degradation, Real-time analysis for pollution prevention, Inherently safer chemistry for accident prevention.

Q.3: Where is Green Chemistry used?
Ans. Green chemistry is used in the chemical industry it is used in processes such as distillation, product drying, electrolysis, and waste treatment. Presently, the energy used in chemical industries are still relying mainly on fossil fuels, but still, the use of these non-renewable sources of energy can be reduced in several ways.

Q.4: What is Green Chemistry?
Ans. Green Chemistry, also known as sustainable chemistry is the design of chemical products and processes that eliminate or minimize the use or generation of hazardous chemical substances. It prevents pollution at the initial molecular level.

Q.5: Does Chemistry improve your life?
Ans. Chemistry has drastically improved our life. Research is constantly going on and increasing our understanding of chemistry and resulting in discoveries. Chemistry helps us solve many future problems, including sustainable energy and food production, protecting our environment by proper management, providing safe drinking water, and promoting better human and environmental health. Everything around us, all commodities that we use green chemistry in day to day life are the inventions of chemistry. We cannot exist without chemistry as what we breathe is itself a result of chemical reactions.

Q.6: Who is the Father of Green Chemistry?
Ans. Anastasis known as the father of green chemistry. In 1998, Paul Anastas and John C. Warner co-authored the pioneering book, Green Chemistry: Theory and Practice.

Q.7: What is the aim of Green Chemistry?
Ans: Green Chemistry aims to design safer chemical products and processes that reduce or eliminate the use and generation of hazardous substances.

Q.8: Why is Carbon Monoxide considered to be more dangerous than Carbon Di Oxide?
Ans: Carbon monoxide combines with Haemoglobin to form a very stable compound known as Carboxyhaemoglobin when its concentration in blood reaches 3-4%, the oxygen carrying capacity of the blood is greatly reduced. This results into headache, nervousness and sometimes death of the person. On the other hand CO₂ does not combine with Haemoglobin and hence is less harmful than CO.

Q.9: Which gases are responsible for Greenhouse Effect?
Ans: The gases that are responsible for the Greenhouse Effect include Carbon Di Oxide, Methane, Nitrous oxide, water vapours, CFCs and Ozone.

Q.10: What compound is formed when Carbon Monoxide combines with blood?
Ans: The compound formed when CO combines with blood is called Carboxyhaemoglobin.

Q.11: What is Chlorosis?
Ans: The slowdown of chlorophyll formation process in plants with the presence of SO₂ is called Chlorosis.

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