BASIC GREEN CHEMISTRY

1. GREEN CHEMISTRY
1
Dr.Gurumeet C
Wadhawa ,Assistant Professor,
Department of Chemistry.
Rayat Shikshan sansthas Veer
Wajekar ASC
College,Phunde,Uran

2. 2
GREEN CHEMISTRY
GREEN CHEMISTRY
PREVENTING POLLUTION
SUSTAINING THE EARTH

3. WHAT IS GREEN CHEMISTRY?
It is better to prevent waste than to clear it up
afterwards.
% Atom economy is the new % yield
The strive towards the perfect synthesis
Benign by design
Environmentally friendly and economically sound.
3

4. 4
Natural processes Chemical processes
(Lab)
Sun light (energy Source) Thermal / Electrical heating
Enzyme Catalyzed Catalysts are used
Highly specific Not specific
pH-7 pH- variable
Room Temperature Temperature Variable
Water is Used As Solvent Organic solvents are used
Exclusive and pure products are
formed
Mixture are obtained
Environmentally Friendly producing
no pollution
Wastes formed Pollute the
environment

5. Scarcityof naturalresourcesoccurdueto theirhugeconsumption
5

6. WHY CHEMICAL MANUFACTURING IS ESSENTIAL ?
6
Requirements of essential commodities on a very large
scale such as:-
Synthetic Fibers
Plastic
Pharmaceuticals
Dyes
Fertilizers
Pesticides

7. THE NEED OF GREEN CHEMISTRY IS DUE TO ADVERSE
EFFECT OF GLOBAL WARMING
7
Deplication of Earth

8. FORTHCOMING SITUATION
8

9. What is Green Chemistry?
9
It is better to prevent waste than to clear it
up afterwards.
% Atom economy is the new % yield
The strive towards the perfect synthesis
Benign by design
Environmentally friendly and economically
sound.

10. BENEFITS OF GREEN CHEMISTRY
10
Non-Toxic
Safe
Economical
Atom
Efficient
Sustainable
Simple
Environment
Friendly
Avoid
Waste
Green
Chemistry

11. 11
PREVENTING WASTES
Design experiments to Reduce or
eliminate waste.
Incorporate materials used in a process
into the final product.

12. 12

13. THE 12 PRINCIPLES OF GREEN CHEMISTRY
 Prevention of waste
 Atom Economy
 Less Hazardous Chemical Syntheses
 Design Safer Chemicals
 Safer Solvents and Auxiliaries
 Design for Energy Efficiency
 Use Renewable Feedstocks
 Reduce Derivatives
 Catalysis
 Design for Degradation
 Real-time Analysis for Pollution Prevention
 Inherently Safer Chemistry for Accident
Prevention
13

14. WHAT IS ATOM ECONOMY?
14
A + B P
Reactant Product
+ U
Unwanted Material
Mass of Product
% Atom economy = 100  ----------------------
Mass of Reactants

15. 15
Example
+ 4.5 O2 O
O
O
+ 2 CO2 + 2H2O
78 144
98
98
% Atom economy = 100  -------------- = 44.1%
78 +144

16. ATOM UNECONOMIC REACTIONS
Example:-
16
• Substitution
• Elimination
• Wittig
• Grignard

17. SUBSTITUTION REACTION (ATOM UN-ECONOMIC)
17
H3C
(CH2)4
C
H2
OH
+ SOCl2 H3C
(CH2)4
C
H2
Cl
+ SO2 + HCl
102 119 120.5
64 36.5
120.5
% Atom economy = 100  --------- = 54.5%
102+119
SO2 and HCl are unwanted by products reducing the overall
atom economy.

18. SUBSTITUTION REACTION
(ATOM UN-ECONOMIC)
18
120.5
% Atom economy = 100  ----------- = 54.5%
102+119
SO2 and HCl are unwanted by products reducing the overall atom
economy.
H3C
(CH2)4
C
H2
OH
+ SOCl2
H3C
(CH2)4
C
H2
Cl + SO2 + HCl
102 119 120.5 64 36.5

19. ELIMINATION REACTIONS
19
56
% Atom economy = 100  ----------- = 45.9%
122
H3C
H
C
Br
H2
C CH3 t-BuOK
-HBr
H3C C
H
C
H
CH3 KBr t-BuOK
136
122
56

20. ATOM ECONOMIC REACTIONS
Example:-
20
• Rearrangement
• Addition
• Diels-Alder
• Other Concerted reactions.
( Pericyclic)

21. REARRANGEMENTS
21
Ex. Claisen Rearrangement
O
200O
C
O
H
OH
Product
134
Phenyl allyl ether
( Reactant ) 134
134
% Atom economy = 100  ------ = 100 %
134

22. ADDITION REACTIONS
22
R
R
H
H
+ HBr
R
R
CH3
Br
% Atom Economy = 100%

23. DIELS ALDER REACTIONS
23
+ 
h
Atom Economy = 100%

24. Solvents and Green
Chemistry…
24

25. WHY ARE REACTIONS PERFORMED USING SOLVENTS?
 To dissolve reactants.
 To slow or increase the rate of reactions.
 To act as a heat sink or heat transfer agent.
 To prevent hot spots and run-away reactions.
25

26. ISSUES WITH ORGANIC SOLVENTS
 Organic solvents are of concern to the chemical
industry because of the sheer volume used in
synthesis, processing, and separation.
 Organic solvents are expensive
 Organic solvents are highly regulated.
 Many organic solvents are volatile, flammable,
toxic, and carcinogenic.
26

27. SOLVENT ALTERNATIVES
Use of solvent less reactions
Use of “non-organic” solvents
Processing technology
27

28. ADVANTAGES TO SOLVENT LESS
ORGANIC REACTIONS
 There is no reaction medium to collect,
purify, and recycle.
 Reaction times can be dramatically
shortened.
 Lowered energy usage.
 Considerable reduction in batch size
volume.
 Less expensive.
28

29. WAYS TO BE SOLVENT-FREE
 Neat – reagents react together in the liquid
phase in the absence of a solvent.
 Solid-state synthesis – two macroscopic
solids interact directly and form a third,
solid product without the intervention of a
liquid or vapor phase.
29

30. “THE USE OF AUXILIARY SUBSTANCES (E.G. SOLVENTS,
SEPARATION AGENTS, ETC.) SHOULD BE MADE UNNECESSARY
WHEREVER POSSIBLE, AND INNOCUOUS WHEN USED”
Solvent less reaction:
30
NH2
R
CHO
R'
R''
R'''
N C
H
R' R''
R'''
Solid A Solid B
Solid C (quantitative yield)
H2O
Grind

31. 31
R
O
H
R'-NH2
KH2PO4, rt
R N
H
R'
P
O
P(OEt)3
O
O
Solvent free,
Potassium dihydrogen phosphate: an inexpensive reagent for the
solvent-free, one-pot synthesis of α-aminophosphonates
Ratnadeep S. Joshi, and Charansingh H. Gill*
Green Chemistry letters & Reviews ( Accepted-2010)

32. LIMITATIONS
 Not all reactions will work in the absence of
solvent.
 Function of catalysts.
 Exothermic reactions are potentially dangerous.
 Specialized equipment needed for some
procedures.
 If aqueous quench and organic extraction are
performed, this reduces green benefits.
32

33. USE OF NON-ORGANIC SOLVENTS
Ionic liquids
Water
33

34. 34

35. PROPERTIES OF IONIC LIQUIDS
 Good solvents for a wide range of both organic and
inorganic materials.
 Have potential to be highly polar yet
noncoordinating.
 By varying cations and anions, ionic liquids can be
tailored for specific applications.
 Possibility for reaction rate enhancement, higher
selectivity and higher yields.
35

36. PROPERTIES OF IONIC LIQUIDS
 High thermal stability
 Often immiscible with organic solvents and/or water
 No measurable vapor pressure
 Non-flammable
 Can be recycled
 Are they safer than solvents?
36

37. IONIC LIQUIDS HAVE BEEN USED AS
SOLVENTS IN A VARIETY OF REACTIONS
 Heck Reaction
 Friedel-Crafts reactions
 Diels-Alder reactions
 Hydrogenation reactons
37

38. OTHER APPLICATIONS OF IONIC LIQUIDS
 As biphasic systems in combination with organic
solvent or water in extraction and separation
technologies.
 For catalyst immobilization and recycling.
 As electrolytes in electrochemistry.
38

39. LIMITATIONS OF IONIC LIQUIDS
 Very expensive compared to organic solvents (100
to 1000 x).
 Have to be made, often using solvent.
 Products have to be extracted from ionic liquid
using solvent.
 May have to wash with water prior to reuse.
39

40. ORGANIC REACTIONS IN AQUEOUS MEDIA
 Water–Isn’t that bad
for my organic
reaction?
40

41. ORGANIC REACTIONS IN AQUEOUS MEDIA
 Most of the world’s chemistry occur in aqueous
media.
41

42. WHY WATER?
 Cost - water is the world’s cheapest solvent.
 Safety – doesn’t get any safer than water.
 Some reactions work better in water.
42

43. GREEN CONCERNS OF WATER
 The product may need to be extracted into an
organic solvent to purify it.
 This generates aqueous effluent containing solvent,
which must be properly disposed.
43

44. 44
Eco-friendly and facile synthesis of 2-substituded -1H-imadazol [4, 5-b] pyridine in
aqueous media by air oxidation
Rajesh P. Kale and C.H.Gill
Tetrahedron letters 50, (2009), 1780-1782
N
NH2
NH2
H
O
R
Water
1000
C, 10-12h
N N
H
N R

45. LIMITATIONS OF WATER AS A SOLVENT
 Some reactions will never work in water.
 Poor solubility of most organic compounds.
 Solubility may be increased by use of organic co-
solvents, PH control, surfactants, and hydrophilic
auxiliaries.
45

46. USE SAFER SOLVENTS FOR CHEMICAL PROCESSES
Return safe substances to the environment
Design for biodegradability
Eliminate the use of toxic solvents to dissolve
reacting materials
46

47. THE CHEMICAL INDUSTRY IN THE 21ST CENTURY
MEETING SOCIAL, ENVIRONMENTAL AND ECONOMIC
RESPONSIBILITIES
 Maintaining a supply of innovative and viable
chemical technology
 Environmentally and socially responsible chemical
manufacturing
 Teaching environmental awareness throughout the
education process 47

48. STRATEGIES FOR REDUCING WASTE….
48
 Reduce
 Reuse
 Recycle
 Rebuy
 Rethink

49. 49
MICROWAVE

50. MICROWAVES.
 Microwaves have wavelengths between 1cm to 1 meter, located
between IR and Radio/Radar frequencies.
 The mechanism of how energy is impacted to a substance under
microwave irradiation is complex.
 Microwaves may be considered a more efficient source of
heating than conventional source of heating, the energy is
directly imparted to the reaction medium rather than through
the walls of a reaction vessel.
50

51.  The combination of solvent free procedures and MW
irradiation can be used to carryout a wide range of reaction
within short reaction times and with high conversions
selectively.
 This approach is efficient, easy to perform, economic and
less polluting as solvents are avoided.
51

52. BENEFITS OF MICROWAVE
 Very rapid reactions ( few minutes)
 Higher degree of purity achieved due to short residence
time at high temperature
 No local Overheating
 Yields often better.
 Pure Products
52

53. OXIDATION OF ALCOHOLS
53
R R
OH
R R
O
PCC/MW
2-10 min
R OH
MnO2-Bentonite
MW/1-min
R-CHO

54. REARRANGEMENTS
54
Ph
Ph
O
O
Celite/KOH
MW/45-145 sec
Ph
Ph
COOH
OH
56-98%
Benzil Benzilic acid
Ph
Ph
OH
OH
pinacol
Clay/MW
5 min
Ph CHO
H
Ph
Pinacolone

55. FRIES & BECKMANN CAN ALSO BE CARRIED
OUT UNDER MW
HETEROCYCLIC SYNTHESIS
55
Ph N R
H
BnO COCl
Et3N/DCM
MW /2 Min N
H
R
H
BnO
O
Ph
-Lactams(Antibiotics)
75%

56. LIMITATIONS OF MICROWAVE
 The boiling points of solvents are reached rapidly,
leading to fire and explosions.
 Absence of measurement and control of temperature.
56

57. LIMITATIONS CAN BE OVERCOME BY
57
Using Solvent free Techniques.
Operating MW ovens with a monomode reactor
Alkylations
Oxidation
 Rearrangements, ets.
Examples:-

58. Microwave assisted one pot synthesis of substituted [1,2,4]-
Triazolo [1’,2’:1,2]pyrimido[6,5-b]-quinoline and its antibacterial
activity.
R. S. Joshi and C.H.Gill
Arkivoc (Communicated)
N Cl
O
R1
R2
R3
HN
N
N
H2N
MW, 10-15Min N N
N
N
N
R1
R2
R3
SiO2/K2CO3

59. WHAT IS SONOCHEMISTRY?
59
Study of chemical changes that occur
in presence of sound or ultra-sound.

60. SOME PROPERTIES OF
SONOCHEMICAL / ULTRASOUND
RADIATIONS
 Frequency ranges from 20 KHz to 10 MHz
(Human hearing upper limit is 18 KHz)
 Region 20-100 KHz is best for chemical transformation
 Frequency range 1-10 MHz are suitable for ultrasound
imaging of body organs
60

61. CLASSIFICATION OF SONOCHEMICAL RADIATIONS
 Low frequency – high power ultra sound (20-100 KHz)
 High frequency - medium power ultrasound ( 100 KHz
–1MHz)
 High frequency- low power ultrasound
(1-10MHz)
61

62. APPLICATIONS OF SONOCHEMISTRY
 Emulsification
 Refining
 Pasteurization
 Soldering
 Dispersion
 Degassing of Liquids
 Organic Chemical transformations
62

63. ULTRASOUND RADIATIONS WORKS THROUGH
CAVITATIONS
 Cavitations is nothing but the formation of gas bubbles in liquid
that occurs when pressure within liquid drops significantly below
vapour pressure of liquid
 When sound passes through the liquid it consists of expansion
and compression waves that causes formation, growth, rapid
recompression of vapour bubble in liquid
 The implosive bubble collapse generates localized heating and
associate high energy ( 4000-5000K, 100 to 150 atm) 63

64. ORGANIC TRANSFORMATIONS USING ULTRASOUND
RADIATIONS
 Esterification
 Saponification
 Hydrolysis
64
RCOOH + R-OH RCOOR'
H2SO4,rt
))))))))
COOCH3 COOH
-
OH/ H2O
)))))) ,60 min.
Ar CN Ar COOH
-
OH/ H2O
)))))) ,60 min.

65. 65
 Substitution
 Alkylations
 Oxidation
R Cl
O
R CN
O
KCN, MeCN
)))))))) 50 C
N
H
N
CH3
MeI / KOH / PhCH3
PEG methyl ether
20o
C, 30 min ))))))
R1 R2
OH KMnO4 / Hexane
rt , ))))))) R1 R2
O

66. 66
 Hydroboration
 Coupling Reactions
 Friedal Craft acylation Reaction
BH3.SMe2, THF
1 hr )))))))
B
3
Br Li , THF
)))))))
OH
OMe
MeO
R
Pr2NH , AlCl3 , Et2O
CH3COCl ))))
OH
OMe
MeO
R
O

67. OUR WORK IN THIS AREA
67

68. SONOCHEMICAL CONDENSATION OF THIOUREA WITH 3-FORMYL
CHROMONES
68
O
O
CHO
R1
R2
R3
H2N NH2
S
Alc. KOH
)))))) 15min
O
N
R1
R2
R3
NH
S
OH

69. COMPARATIVE STUDY OF CONDENSATION 3-
FORMYL CHROMONE WITH THIOUREA
69
Sr.No. R1 R2 R3 Ultrasound Conventional
Time
(min)
Yield
(%)
Time
(min)
Yield
(%)
4a H H Cl 10 84 180 56
4b H H F 10 78 180 50
4c H H Me 12 85 180 51
4d H Me Cl 15 78 180 60

70. 70
Ultrasound assisted green synthesis of bis(indol-3-yl)methanes catalyzed
by 1-hexenesulphonic acid sodium salt
R. S. Joshi and C. H. Gill
Ultrasonic Sonochemistry, 17 (2010), 298–300
N
H
R H
O
N
H
N
H
R
2
1-Hexenesulphonic
acid sodium salt
Water, ))))))

71. 71
Ultrasound promoted greener approach to synthesize α-hydroxy
phosphonates catalyzed by potassium dihydrogen phosphate
under solvent-free condition
P. G. Mandhane and C.H.Gill
Tetrahedron letters 51 (2010) 1490–1492
O
H
R ))))))), r.t.
P
O
HO
R
KH2PO4
P
OEt
OEt
EtO
OEt
EtO

72. 72