Green Chemistry

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Green Chemistry
Dr. C. H. GILL. (Prof. Head) Dept. of
Chemistry, Dr. Babasaheb Ambedkar Marathwada
University, Aurangabad. chgill50_at_yahoo.com
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GREEN CHEMISTRY
GREEN CHEMISTRY

PREVENTING POLLUTION SUSTAINING THE EARTH
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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.

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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
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• Scarcity of natural resources occur due to their
  huge consumption

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Why Chemical Manufacturing is Essential ?

• Requirements of essential commodities on a
  very large scale such as-
• Synthetic Fibers
• Plastic
• Pharmaceuticals
• Dyes
• Fertilizers
• Pesticides

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The Need of Green Chemistry is due to Adverse
Effect of Global Warming
Deplication of Earth
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Forthcoming situation
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Green Chemistry Is About...
Waste
Materials
Hazard
Reducing
Risk
Energy
Environmental Impact
COST
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Some Aspects of Green Chemistry
Catalysis
Safer Reactions Reagents
Solvent Replacement
Separation Processes
Green Chemistry
Use of Renewable Feedstocks
Energy Efficiency
Waste Minimisation
Process Intensification
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PREVENTING WASTES

• Design experiments to Reduce or eliminate waste.
• Incorporate materials used in a process into the
  final product.

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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

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What is Atom Economy?


Mass of Product Atom
economy 100 ? ----------------------

Mass of Reactants
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Example

98 Atom economy 100 ?
-------------- 44.1
78 144
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Atom Uneconomic Reactions

• Example-

• Substitution
• Elimination
• Wittig
• Grignard

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Substitution Reaction (Atom Un-economic)

120.5 Atom economy 100 ?
--------- 54.5
102119 SO2 and HCl are
unwanted by products reducing the overall atom
economy.
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Substitution Reaction(Atom Un-economic)

120.5 Atom economy 100
? ----------- 54.5
102119 SO2 and
HCl are unwanted by products reducing the overall
atom economy.
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Elimination Reactions

56 Atom economy
100 ? ----------- 45.9
122
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Atom Economic Reactions

• Example-

• Rearrangement
• Addition
• Diels-Alder
• Other Concerted reactions.
• ( Pericyclic)

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Rearrangements
Ex. Claisen Rearrangement

134 Atom economy 100 ?
------ 100
134
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Addition Reactions
Atom Economy 100

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Diels Alder Reactions
Atom Economy 100
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Solvents and Green Chemistry
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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.

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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.

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Solvent alternatives

• Use of solvent less reactions
• Use of non-organic solvents
• Processing technology

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Advantages to Solvent lessOrganic 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.

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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.

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Potassium dihydrogen phosphate an inexpensive
reagent for the solvent-free, one-pot synthesis
of a-aminophosphonates Ratnadeep S. Joshi, and
Charansingh H. Gill Green Chemistry letters
Reviews 2010, 3(3), 191-194.
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Chemoselective acylation of amines, thiols and
phenols using 2,4,6-triacyloxy-1,3,5 triazine
(TAT) as a new and effective reagent under mild
condition. Somnath S. Gholap and Charansingh H.
Gill J. Indian Chem. Soc. 2009, 86, 179-182
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Ammonium metavanadate an efficient catalyst for
synthesis of ?- hydroxyphosphates S. S. Sonar
and C. H .GillArkivoc ii, (2009), 138-148
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Synthesis of 1,5-benzodiazepines using silica
perchloric acid An effective reusable
heterogeneous catalyst under mild
condition.Somnath S. Gholap and C. H
.GillRasayan Journal of chemistry 1(2), (2008),
331-336
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SILICA DICHLOROPHOSPHATE SiO2-POCl2 AS A
EXPEDITIOUS REUSABLE CATALYST FOR THE SYNTHESIS
OF BIS-(INDOLYL) METHANES UNDER SOLVENTFREE
CONDITIONS Charansingh H. Gill and Somnath S.
Gholap Bulletin of the catalysis Society of
India, 8 (2009) 126-130
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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.

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Use of non-organic solvents

• Water

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Organic Reactions in Aqueous Media

• WaterIsnt that bad for my organic reaction?

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Organic Reactions in Aqueous Media

• Most of the worlds chemistry occur in aqueous
  media.

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Why Water?

• Cost - water is the worlds cheapest solvent.
• Safety doesnt get any safer than water.
• Some reactions work better in water.

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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.

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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
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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.

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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

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MICROWAVE
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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.

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• 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.

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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

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Microwave Induced Synthesis of
3-methyl-4-(Chromon-3-yl)-methylene-1-Phenyl
Pyrazolin-5(4H) ones with Alumina Support and in
Solvent free Conditions B.K.Karale and
C.H.Gill Synthetic Communications, 32(4),
(2002), 497.
Stereochemistry determined by NOE
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One Pot Synthesis of Substituted
1,2,4-Triazolo 1,21,2pyrimido
6,5-b-quinoline and Its Antibacterial
Activity Ratnadeep S. Joshi and Charansingh H.
Gill Bulletin of Korean Chemical Society, 31(8),
(2010), 2341-2344
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Thiamine hydrochloride (VB1) promoted one-pot
synthesis of 2,4,5-triphenyl-1H-imidazole using
microwave irradiation Priyanka G. Mandhane and
C.H.Gill Chinese Chemical Letter
(doi10.1016/j.cclet.2010.11.021)
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Microwave Induced Synthesis of Flavones N.R.Dalvi
and C.H.Gill Chemistry an Indian Journal, 1(8),
582-83, 2004
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Microwave Assisted Improved Method for the
Synthesis of Pyrazole Containing
2,4,-Disubstituted Oxazole-5-one and their
Antimicrobial Activity N. D. Argade and
C.H.Gill E-Journal of Chemistry, 5(1), January
2008, 120-129
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Limitations of Microwave

• The boiling points of solvents are reached
  rapidly, leading to fire and explosions.
• Absence of measurement and control of temperature.

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What is Sonochemistry?

• Study of chemical changes that occur in
  presence of sound or ultra-sound.

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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

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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)

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Applications of Sonochemistry

• Emulsification
• Refining
• Pasteurization
• Soldering
• Dispersion
• Degassing of Liquids
• Organic Chemical transformations

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Ultrasound assisted green synthesis of
bis(indol-3-yl)methanes catalyzed by
1-hexenesulphonic acid sodium salt Ratnadeep S.
Joshi and C.H.Gill Ultrasonics Sonochemistry, 17
(2010) 298300
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Ultrasound promoted greener approach to
synthesize a-hydroxy phosphonates catalyzed by
potassium dihydrogen phosphate under solvent-free
condition Priyanka G. Mandhane and
C.H.Gill Tetrahedron letters 51 (2010) 14901492
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Tetrabutylammonium Fluoride (TBAF) Catalysed
Synthesis of 2-Arylbenzimidazole in Water under
Ultrasound Irradiation Ratnadeep S. Joshi and
C.H.Gill J. Chin. Chem. Soc., 57(6), 2010, 1-4
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An efficient synthesis of 3,4-dihydropyrimidin-2
(1H)-ones catalyzed by thiamine hydrochloride in
water under ultrasound irradiation Priyanka G.
Mandhane and C.H.Gill Tetrahedron letters 51
(2010) 3138-3140
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Development of practical methodologies for the
synthesis of novel 3(4-oxo-4H-chromen-3-yl)acrylic
acid hydrazides Ratnadeep S. Joshi and
C.H.Gill Ultrasonics Sonochemistry, (DOI
10.1016/j.ultsonch.2010.11.001)
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Ultrasonic Promoted Synthesis and Antibacterial
Screening of Some Novel Piperidine Incorporated
a-Aminophosphonates  Priyanka G. Mandhane and
C.H.Gill Phosphorus, Sulfur, and Silicon, 186,
2011, 149158
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An efficient synthesis of some novel
3-(5-phenyl-1,3,4-oxadiazol-2-yl)pyridine
derivatives catalyzed by ammonium metavanadate in
ethanol under ultrasound irradiation Priyanka G.
Mandhane and C.H.Gill Bulletin of the Catalysis
Society of India, 9 (2010)120-126
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Synthesis of 1-(2-Hydroxy-phenyl)-3-piperidin-1-y
l-propenone by Ultrasonic Irradiation N.R.Dalvi
and C.H.Gill Synthetic Communications
371421-1424, (2006)
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Thank You