Green chemistry is the design of chemical products and processes to reduce or eliminate hazardous substances. It encourages the use of economical and eco-friendly techniques to improve yields and reduce waste. The principles of green chemistry include preventing waste, designing safer chemicals and reactions, using renewable starting materials, and developing catalytic processes to minimize byproducts. Adopting these principles can help avoid pollution disasters and make chemical processes safer and more sustainable.

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Green Chemistry and it’s Applications
by
Dr.Y.Aparna
Assistant Professor in Chemistry
Department of Sciences and Humanities
Matrusri Engineering College,Saidabad

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Purpose of green Chemistry

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San jacinto river flow disaster in USA -1994

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Air pollution disaster

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Land pollution

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Greenery getting diminished

10. Green Chemistry and it’s Applications
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MATRUSRI
ENGINEERING COLLEGE
Green chemistry is the design of chemical products and processes that
reduce or eliminate the use and generation of hazardous substances.

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•Green chemistry discusses the engineering concept of pollution prevention
and zero waste both at laboratory and industrial scales.
•It encourages the use of economical and eco compatible techniques that not
only improve the yield but also bring down the cost of disposal of wastes at
the end of a chemical process.

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Twelve Principles of Green Chemistry
1. Prevention of waste.
2. Atom economy.
3. Less hazardous chemical synthesis.
4. Designing safer chemicals.
5. Safer solvents and auxiliaries.
6. Design for energy efficiency.
7. Use of renewable feed stocks.
8. Reduce derivatives.
9. Catalysis.
10. Design for degradation.
11. Real-Time analysis for pollution prevention.
12. Inherently Safer Chemistry for Accident Prevention.

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MATRUSRI
ENGINEERING COLLEGE
1.Prevention of Waste/ By products:
Preventing waste is better than treating or cleaning up waste after
it is created.
->In a manufacturing process, in addition to by products the unreacted
starting materials also form a part of waste.
->If the waste is disposed in the atmosphere, sea or land it adds to the
pollution.
->Synthetic pathway must be designed in such a way that the formation
of by products are minimised.

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15. 2.Atom Economy: Synthetic methods should try to maximize
the incorporation of all materials used in the process into the final
product. This means that less waste will be generated as a result.
The maximum incorporation of the atoms of the reactants
and reagents into the final products is called atom
economy.

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Ex:Rearrangement reactions
% atom economy=137.14/137.14 x 100
=100%

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Ex:Elimination reactions
% atom economy = 27%

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3.Less hazardous chemical synthesis:
Synthetic methods should avoid using or generating
substances toxic to humans and/or the environment.
->Whenever applicable synthetic methodologies
should be designed to use and generate substances
that posess little or no toxicity to human health and
environment.

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1984 –Union carbide India Limited –pesticide factory

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4.Designing safer chemicals: Chemical products should
be designed to achieve their desired function while being
as nontoxic as possible
->chemical products should be designed to preserve
efficacy and at the same time reduce toxicity.
->chemicals like drugs, paints, cosmetics etc., should be
safe to use.
thalidomide

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MATRUSRI
ENGINEERING COLLEGE
The drug “thalidomide” prescribed for nausea and vomiting during
pregnancy had adverse effects, led to birth defects like deformed limbs.
Therefore, chemical products should be designed to affect their desired
function while reducing toxicity.

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MATRUSRI
ENGINEERING COLLEGE
5.Safer solvents and auxiliaries:
The solvents used in a reaction should not cause environment pollution.
Auxiliary substances should be avoided wherever possible, and as
nonhazardous as possible when they must be used.
We can avoid separating techniques by using volatile organic solvents
like ether, alcohols,acetone, DMSO.
Aqueous or solid phase reactions can be carried out.If water cannot be
used then ionic liquids can be used.
For example: Benzene and CCl4 are highly carcinogenic. Alternative
solvents like H2O,C2H5OH,ionic liquids,NH3 are green solvents.

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Ionic liquids

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6.Design for energy efficiency: Conventional
heating methods are not energy efficient and the
rate of reaction may be slow. The alternative energy
sources like microwave, ultrasound or sunlight/UV
may be used.

27. Ultra sound assisted Cannizaro reaction:
Williamson synthesis (microwave/ultrasound simulated):

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Oxidation of toluene
Esterification

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MATRUSRI
ENGINEERING COLLEGE
7.Use of renewable feed stocks: Raw material feed stock should be
renewable. Whenever it is practical to do so, renewable feed stocks or raw
materials are preferable to non-renewable ones

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8.Reduce derivatives: Unnecessary derivatization like
blocking groups, protection or de-protection, temporary
modification of physical or chemical methods should be
minimized as such steps require additional reagents and
generate unwanted byproducts.
Ex: deprotection of acetal

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9.Catalysis: Catalytic reagents are superior to stoichiometric
reagents.Catalytic reagents can be used in small quantities to
repeat a reaction compared to stoichiometric reagents.
Ex:Phase transfer catalysts in organic synthesis and biocatalysts
(yeast, enzymes etc.) may be used.
Pencillin acylase

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toluene to p-xylene

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10.Design of degradation: Chemical products should be designed so
that at the end of their function they do not persist in the environment and
breakdown into small products.

35. 11.Real-time analysis: Analytical methodologies need to
be developed to control the formation of hazardous
substance.
->In the process of chemical reaction,optimising the
reaction conditions are very important.
->Over do and under do leads to wastage.
Advanced and sophisticated tool may help reduce
pollution
12.Accident Prevention: The substance and the form of
chemical used in a process should be chosen so as to
minimize chemical accidents, explosion and fires.
Ex:Bhopal gas tragedy took over 50,000 lives due to
release of 40tons of MIC