This presentation is prepared for First Year Engineering Students at Savitribai Phule Pune University. It is introduction of green chemistry to understand the problems caused by using hazardous chemicals and its solution.

1. Green Chemistry

2. Paul Anastas: Father of Green Chemistry 2

3. Green Chemistry is about reducing
• Waste
• Materials
• Hazards
• Risks
• Energy
• Cost
3

4. Goals of Green Chemistry
1. To reduce adverse environmental impact, try appropriate and
innovative choice of material & their chemical
transformation.
2. To develop processes based on renewable rather than non-
renewable raw materials.
3. To develop processes that are less prone to obnoxious
chemical release, fires & explosion.
4. To minimize by-products in chemical transformation by
redesign of reactions & reaction sequences.
4

5. Goals of Green Chemistry
6. To develop products that degrade more rapidly in the
environment than the current products.
7. To reduce the requirements for hazardous persistent solvents
& extractants in chemical processes.
8. To improve energy efficiency by developing low temperature
& low pressure processes using new catalysts.
9. To develop efficient & reliable methods to monitor the
processes for better & improved controls.
5

6. Principles of
Green Chemistry

7. The 12 Principles of Green Chemistry
1. Prevention of Waste or by-products
7

8. The 12 Principles of Green Chemistry
1. Prevention of Waste or by-products
“It is better to prevent waste
than to treat or clean up waste
after it is formed”
8

9. The 12 Principles of Green Chemistry
•
9

10. The 12 Principles of Green Chemistry
3. Minimization of hazardous products
Wherever practicable, synthetic methods should be
designed to use and generate substances that possess
little or no toxicity to people or the environment.
10

11. The 12 Principles of Green Chemistry
3. Minimization of hazardous products
11

12. The 12 Principles of Green Chemistry
4. Designing Safer Chemicals
Chemical products should be designed to effect their
desired function while minimising their toxicity.
12

13. The 12 Principles of Green Chemistry
5. Safer Solvents & Auxiliaries
“The use of auxiliary substances (e.g. solvents,
separation agents, etc.) should be made unnecessary
wherever possible, and innocuous when used”
13

14. The 12 Principles of Green Chemistry 14
5. Safer Solvents & Auxiliaries

15. The 12 Principles of Green Chemistry
6. Design for Energy Efficiency
Energy requirements of chemical processes should be
recognised for their environmental and economic
impacts and should be minimised. If possible, synthetic
methods should be conducted at ambient temperature
and pressure.
15

16. The 12 Principles of Green Chemistry
6. Design for Energy Efficiency
Developing the alternatives for energy generation
(photovoltaic, hydrogen, fuel cells, bio based fuels,
etc.) as well as
Continue the path toward energy efficiency with
catalysis and product design at the forefront.
16

17. The 12 Principles of Green Chemistry
7. Use of Renewable Feedstock
“A raw material or feedstock should be renewable rather
than depleting whenever technically and economically
practicable.”
17

18. The 12 Principles of Green Chemistry 18
7. Use of Renewable Feedstock

19. The 12 Principles of Green Chemistry
8. Reduce Derivatives
Unnecessary derivatization (use of blocking groups,
protection/de-protection, and temporary modification
of physical/chemical processes) should be minimised or
avoided if possible, because such steps require
additional reagents and can generate waste.
19

20. The 12 Principles of Green Chemistry
8. Reduce Derivatives
More derivatives involve
 Additional Reagents
 Generate more waste products
 More Time
 Higher Cost of Products
20

21. The 12 Principles of Green Chemistry
9. Catalysis
Catalytic reagents (as selective as possible) are
superior to stoichiometric reagents.
e.g. Toluene can be exclusively converted into p-xylene
(avoiding o-xylene & m-xylene) by shape selective
zeolite catalyst.
21

22. The 12 Principles of Green Chemistry
10. Designing of degradable products
Chemical products should be designed so that at the
end of their function they break down into innocuous
degradation products and do not persist in the
environment.
22

23. The 12 Principles of Green Chemistry 23

24. The 12 Principles of Green Chemistry
11. New Analytical Methods
“Analytical methodologies need to be further
developed to allow for real-time, in-process monitoring
and control prior to the formation of hazardous
substances.”
24

25. The 12 Principles of Green Chemistry
12. Safer Chemicals For Accident Prevention
“Analytical Substances and the form of a substance used in
a chemical process should be chosen to minimise the
potential for chemical accidents, including releases,
explosions, and fires.”
25

26. Efficiency Parameters

27. 1. Reaction Yield
The reaction should have high percentage of yield.
•
27

28. 2. Atom Economy
•
28

29. 2. Atom Economy
e.g.
1. Rearrangement Reactions:
These reactions involves rearrangement of atoms that
forms molecule. Hence, the atom economy of these
reactions are 100%.
2. Addition Reactions:
These reactions involves addition of two or more
molecules without elimination that forms molecule.
Hence, the atom economy of these reactions are 100%
29

30. 2. Atom Economy
e.g. Consider the following reaction to find out atom
economy.
30
CH3 CH2 C OC2H5
O
+ CH3 NH2
Ethyl propionate
Mol wt 102.13
Methyl amine
Mol wt 31.05
CH3 CH2 C NHCH3
O
N-Methyl propionate
Mol wt 87.106
+ H5C2 OH
Ethyl Alcohol
Mol wt 46.06

31. 3. Conversion Factor
•
31

32. 4. Reaction Selectivity
•
32

33. 5. Environmental Load Factor 33
• It is represented by E and it should be minimum for reaction.

34. 6. Mass Intensity 34
E = MI - 1

35. Pathways to Synthesis
Traditional & Green

36. Traditional Pathway of
Synthesis of Adipic Acid
36
benzene
N i - A l 2 O 3
3 0 0 - 8 0 0 p s i
cyclohexane
C O , O 2
1 2 0 - 1 4 0 p s i
O
cyclohexanone
+
OH
cyclohexanol
C u , N H 4 V O 3
H N O 3
COOH
HOOC
Adipic acid

37. Drawbacks of Traditional Pathway
• Use of non-renewable, carcinogenic feedstock
• The reaction is energy consuming which works on
higher temperature & pressure
• More steps are required for synthesis
37

38. Green Pathway of
Synthesis of Adipic Acid
38
By Scientist Frost
at Michigan University, America
O
OH
OH
OH
OH
OH
D-glucose
E - c o li
COOH
O
OH
OH
3-dehydroxyshikimate
E - c o li
HOOC
COOH
cis, cis-muconic acid
E - c o li
HOOC
COOH
Adipic acid

39. Advantages of Green Pathway
• The reaction is cheap by using renewable
feedstock
• It requires safer pressure and temperature
• Fewer steps are required for synthesis
39

40. Traditional Pathway of
Synthesis of Polycarbonates
40
OH C
CH3
CH3
OH
Bisphenol-A
O C O
O
C
CH3
CH3
n
Polycarbonate
+ COCl 2
+ (n-1) NaCl
H 2 O / C H 2 C l2
I n t e r f a c ia l
p o ly m e r iz a t io n

41. Drawbacks of Traditional Pathway
• Uses of non-renewable (CH2Cl2), poisonous
solvent which is difficult to separate from
product
• Uses poisonous starting material phosgene
41

42. Green Pathway of
Synthesis of Polycarbonates
42
Komia and his team,
Asahi Chemicals, Japan
OH C
CH3
CH3
OH
Bisphenol-A
S o lid s t a t e
p o ly m e r iz a t io n
O C O
O
Ph Ph
O C O
O
C
CH3
CH3
n
Polycarbonate

43. Advantages of Green Pathway
• The reaction does not require solvent, it carries
in molten state
• It avoids use of poisonous starting materials.
43

44. NH2
Cl-CH2COOH
NH
COOH
NaNH2
N
H
C
OH
Oxidation
N
H
C
O
N
H
C
O
TryptophanAniline
Indigo Dye
Traditional Pathway of
Synthesis of Indigo dye

45. Drawbacks of Traditional Pathway
• Uses of toxic aniline and harmful chloro-acetic
acid as a starting material
45

46. N
H
C
OH
Oxidation by air
N
H
C
O
N
H
C
O
L-Tryptophan
Indigo Dye
Tryptophanse
Enzyme N
H
CH
Naphthalene
Deoxygenase Enzyme
N
H
CH
OH
OH
Indole
Green Pathway of
Synthesis of Indigo dye

47. Advantages of Green Pathway
• Renewable plant origin starting material
• Eco-friendly process
• Less steps in synthesis without waste matter
47

48. • Energy
• Global Change
• Resource Depletion
• Food Supply
• Toxics in the Environment
Major uses of Green Chemistry

49. Green chemistry Not a solution to all
environmental problems But the most
fundamental approach to prevent
pollution.
Conclusion

50. References
1. Green Chemistry: Environmentally Benign Reaction
By V. K. Ahluwalia, Ane Books India
1. Engineering Chemistry
By Jain & Jain
1. Engineering Chemistry
By O. G. Palanna