Green chemistry and its role for sustainability

Green Chemistry and its Role for
Sustainability
As
A branched topic of the UNESCO
conference on ESD
Bonn, Germany, 2009

Presenter: Dr. Zeinab Shaaban Abu-Elnaga
Faculty of Science
Mansoura University
Egypt
2009



Learning 0bjectives
To conceptualize the sustainability and ESD
To understand how to apply this concept in our
research fields of interest aiming to safe our plant
To think prospectively about how to change our
education subjects to be sustainable learning tools
by Investigating examples of green chemistry
applications relevant to students
To understand the important role of the green
chemistry and how to deal with it in our practical life
The topic is very vast but I have tried to cover it in one
lecture and I will give the links for more details of
each sub-topic

2009

Performance Objectives:
To understand the importance of Green chemistry for
sustainability
To design and interpret greener route to the traditional
chemical reactions
To learn how to teach green chemistry as a lab course

2009



Sustainability
•

Meeting the needs of the present generation without
compromising the needs of future generations
Is the goal

•

Green chemistry: technologies of the invention, design
and application of chemical products and processes to
reduce or to eliminate the use and generation of
hazardous substances ,and where possible utilize
renewable raw materials
is the means

Primary pollution prevention not remediation

Use of chemistry for improved environmental performance



As human beings --- we are part of the environment
The way in which we interact with our environment influences
the quality of our lives
Sustainable
development
the goal

Industrial
ecology

Green
Chemistry
A tool

Green chemistry, lies at the heart of the industrial ecology

2009



Green chemistry, is called also Benign chemistry or clean
chemistry for sustainability
•

Refers to the field of chemistry dealing with

1- Synthesis (the path to making chemicals)
2- Processing (the actual making of chemicals)
3- Use of chemicals that reduce risks to humans and
impact on the environment
Green chemistry education: A key to sustain the
development of new educational materials


Green Chemistry Is About...
Waste
Materials
Hazard
Risk

Energy
Cost
2009



Principles of Green Chemistry
Prevent waste.
Design safer chemicals and products.
Design less hazardous chemical syntheses.
Use renewable feed stocks.
Use catalysts, not stoichiometric reagents: 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.
Avoid chemical derivatives: Avoid using blocking or protecting groups or any
temporary modifications if possible. generate waste.

Maximize atom economy.
Use safer solvents and reaction conditions
Increase energy efficiency.
Design chemicals and products to degrade after use.
Analyze in real time to prevent pollution.
Minimize the potential for accidents.
Originally published by Paul Anastas and John Warner in Green Chemistry:
Theory and Practice (Oxford University Press: New York, 1998).

2009



Now, how can we deal with green chemistry
at our practical life
Just we need to change our mind
set and applying the concept in
Classrooms
laboratory
manufacture
And

finally

environment

the

surrounding

• If the chemical reaction of the type
• A+B

P+W

• Find alternate A or B to avoid W
• Example 1:
• Disinfection

of

water

by

chlorination.

Chlorine oxidizes the pathogens there by
killing them, but at the same time forms
harmful chlorinated compounds.
• A remedy is to use another oxidant, such as
O3 or supercritical water oxidation
2009



Example 2 of green chemistry
•

Production of allyl alcohol CH 2=CHCH2OH

•

Traditional route: Alkaline hydrolysis of allyl chloride, which
generates the product and hydrochloric acid as a by-product
CH2=CHCH2Cl + H2O
problem

•

CH2=CHCH2OH + HCl
product

Greener route, to avoid chlorine: Two-step using propylene
(CH2=CHCH3), acetic acid (CH3COOH) and oxygen (O2)

CH2=CHCH3 + CH3COOH + 1/2 O2

CH2=CHCH2OCOCH3 + H2O

•

CH2=CHCH2OCOCH3 + H2O

CH2=CHCH2OH + CH3COOH

Added benefit: The acetic acid produced in the 2 nd reaction
can be recovered and used again for the 1 st reaction, leaving
no unwanted by-product.

2009



Example 3 of green chemistry
•

Production of styrene (=benzene ring with CH=CH 2 tail)

•

Traditional route: Two-step method starting with benzene,
which is carcinogenic) and ethylene to form ethylbenzene,
followed by dehydrogenation to obtain styrene
CH2CH3

+ H2C=CH2

catayst

ethylbenzene
CH2-CH3

CH=CH2

catayst
styrene
ethylbenzene

•

Greener route: To avoid benzene, start with xylene (cheapest
source

of

aromatics

and

environmentally

safer

than

benzene).
•

Another option, still under development, is to start with
toluene (benzene ring with CH 3 tail).

2009



Green chemistry education
Chemistry students need to be encouraged
to consider the principles of green chemistry

when designing processes and choosing
reagents
Interactive Teaching Units (ITU) have been
developed

specifically

to

introduce

undergraduate students to green chemistry
There are numerous scholarships and
grants available for researchers and young
2009
scholars who are furthering the goals
of green



conclusion
Green Chemistry:
Preventing Pollution
Sustaining the Earth
Green chemistry has come a long way since its birth in 1991,
growing from a small grassroots idea into a new approach to
scientifically-based environmental protection
All over the world, governments and industries are working
with “green” chemists to transform the economy into a
sustainable enterprise

Who knows? Green chemistry may be the next social
movement that will set aside all the world’s differences and
allow for the creation of an environmentally commendable
civilization

2009



References
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2009