green chemistry microwave assisted organometallic reaction l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Green Chemistry: Microwave Assisted Organometallic Reaction PowerPoint Presentation
Download Presentation
Green Chemistry: Microwave Assisted Organometallic Reaction

Loading in 2 Seconds...

play fullscreen
1 / 118

Green Chemistry: Microwave Assisted Organometallic Reaction - PowerPoint PPT Presentation


  • 1263 Views
  • Uploaded on

Green Chemistry: Microwave Assisted Organometallic Reaction. Green Chemistry. To promote innovative chemical technologies that reduce or eliminate the use or generation of hazardous substances in the design, manufacture, and use of chemical products. What does the Chemical Industry do for us?.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Green Chemistry: Microwave Assisted Organometallic Reaction' - arleen


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
green chemistry
Green Chemistry

To promote innovative chemical technologies that reduce or eliminate the use or generation of hazardous substances in the design, manufacture, and use of chemical products.

green chemistry4
Green chemistry

is about

  • Waste Minimisation at Source
  • Use of Catalysts in place of Reagents
  • Using Non-Toxic Reagents
  • Use of Renewable Resources
  • Improved Atom Efficiency
  • Use of Solvent Free or Recyclable Environmentally Benign Solvent systems
green chemistry responsibility
Green Chemistry = Responsibility

Why is there no ‘Green Geology’ or ‘Green Astronomy’?

Because chemistry is the science that introduces new substances into the world and we have a responsibility for their impact in the world.”

- Ronald Breslow

green chemistry is also called
Green Chemistry is also called…
  • A new approach to designing chemicals and chemical transformations that are beneficial for human health and the environment
  • An innovative way to design molecules and chemical transformations for sustainability
    • Meeting the needs of the current generation without compromising the ability of future generations to meet their own needs
  • Benign by design
  • Pollution prevention at the molecular level
what is green chemistry
What is Green Chemistry?
  • Green chemistry is the study of how to design chemical products and processes in ways that are sustainable and not harmful for humans and the environment.
  • Three components: catalysis, solvents, non-toxic
  • 12 principles of green chemistry
green chemistry is about
Green Chemistry Is About...

Waste

Materials

Hazard

Reducing

Risk

Energy

Cost

why do we need green chemistry
Why do we need Green Chemistry ?
  • Chemistry is a very prominent part of our daily lives.
  • Chemical developments also bring new environmental problems and harmful unexpected side effects, which result in the need for ‘greener’ chemical products.
  • A famous example is the pesticide DDT.
the 12 principles of green chemistry 7 12
The 12 Principles of Green Chemistry (7-12)
  • 7 Use of Renewable Feedstocks
    • A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.
  • 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.
  • 9 Catalysis
    • Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
  • 10 Design for Degradation
    • 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.
  • 11 Real-time Analysis for Pollution Prevention
    • Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances.
  • 12 Inherently Safer Chemistry for Accident Prevention
    • 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.
what is green
What is “Green”?
  • Sustainable
  • Kinder and gentler to people and the planet
conventional heating vs alternative energy source
Conventional Heating vs Alternative Energy Source
  • Conventional Heating
  • Bunsen burner
  • Oil bath
  • Heating mantle
  • Alternative Energy Sources
  • Microwave
  • Ultrasound
  • Sunlight / UV
  • Electonchemistry
clean chemical synthesis using alternative reaction methods
Clean Chemical Synthesis UsingAlternative Reaction Methods
  • Alternative Energy Sources
  • Microwave
  • Ultrasound
  • Sunlight / UV
  • AlternativeReactionMedia/Solvent-free
  • Supercritical Fluids
  • Ionic Liquids
  • Water
  • Polyethylene glycol (PEG)
  • Solvent free
slide18

History or how it all began…

  • While fire is now rarely used in synthetic chemistry, it was not until Robert Bunsen invented the burner in 1855 that the energy from this heat source could be applied
  • There is some controversy about the origins of the microwave power cavity called the magnetron – the high-power generator of microwave power.

The British were particularly forward-looking in deploying radar for air defense with a system called Chain Home which began operation in 1937.

Originally operating at 22 MHz, frequencies increased to 55 MHz.

1921 was published by A.W. Hull the earliest description of the magnetron, a diode with a cylindrical anode

1940 It was developed practically by Randall and Booth at the University of Birmingham in England ; they verified their first microwave transmissions: 500 W at 3 GHz.

A prototype was brought to the United States in September of that year to define an agreement whereby United States industrial capability would undertake the development of microwave radar.

1940 the Radiation Laboratory was established at the Massachusetts Institute of Technology to exploit microwave radar. More than 40 types of tube would be produced, particularly in the S-band (i.e. 300 MHz). The growth of microwave radar is linked with Raytheon Company and P.L. Spencer who found the key to mass production.

slide19

History or how it all began…

  • 1946 Dr. Percy Spencer-the magnetron inventor; he has found a variety of technical applications in the chemical and related industries since the 1950s, in particular in the food-processing, drying, and polymer
  • surprisingly, microwave heating has only been implemented in organic synthesis since the mid-1980s.
  • Today, a large body of work on microwave-assisted synthesis exists in the published and patent literature.
  • Many review articles, several books and information on the world-wide-web already provide extensive coverage of the subject.
slide20
1969 “ Carrying out chemical reactions using microwave energy ” J.W. Vanderhoff – Dow Chemical Company US 3,432,413
  • 1986 “The Use of Microwave Ovens for Rapid Organic Synthesis” Gedye, R. N. et alTetrahedron Lett. 1986, 27, 279
  • 1986 “Application of Commercial Microwave Ovens to Organic Synthesis” Giguere, R. J. and Majetich, G. Tetrahedron Lett. 1986, 27, 4945
energy use in conventional chemical processes
Energy Use in ConventionalChemical Processes
  • Heating
  • Stirring
  • Piping
  • Transporting
  • Cooling
problem of conventional heating
Problem of Conventional Heating
  • You heat what you don’t want to heat.
  • Solvents for reactions, apparatus: heated up and cool it down.
  • Double energy penalty without any apparent “benefit”.
energy consumptions
Energy Consumptions

Three ways to get the reaction done, but different energy bills to pay

microwaves
Microwaves
  • MW reactors operate at 2.45 GHz.
  • Electric field oscillates at 4.9 x 109 times/sec – 10oC/sec heating rate.
electromagnetic spectrum
Electromagnetic Spectrum

Neas, E.; Collins, M. Introduction to Microwave Sample Preparation: Theory and Practice, 1988, p. 8.

schematic of a microwave
Schematic of a Microwave

E= electric field

H= magnetic field

l= wavelength (12.2 cm for 2450 MHz)

c= speed of light (300,000 km/s)

microwaves application in heating food
Microwaves Application in Heating Food

1946: Original patent (P. L. Spencer)

1947: First commercial oven

1955: Home models

1967: Desktop model

1975: U.S. sales exceed gas ranges

1976: 60% of U.S. households have

microwave ovens

spectrum electromagnetic
Spectrum Electromagnetic
  • Electric field component
  • Responsible for dielectric heating
  • Dipolar polarization
  • Conduction
  • Magnetic field component
microwaves dipolar rotation
Microwaves – Dipolar Rotation
  • Polar molecules have intermolecular forces which give any motion of the molecule some inertia.
  • Under a very high frequency electric field, the polar molecule will attempt to follow the field, but intermolecular inertia stops any significant motion before the field has reversed, and no net motion results.
  • If the frequency of field oscillation is very low, then the molecules will be polarized uniformly, and no random motion results.
  • In the intermediate case, the frequency of the field will be such that the molecules will be almost, but not quite, able to keep in phase with the field polarity.
  • In this case, the random motion resulting as molecules jostle to attempt in vain to follow the field provides strong agitation and intense heating of the sample.
  • At 2.45 GHz the field oscillates 4.9 x 109 times/s which can lead to heating

rates of 10 °C per second when powerful waves are used

mw heating mechanism
MW Heating Mechanism

Continuous electric

field

Alternating electric field

Withhigh frequency

Noconstraint

  • Two mechanisms:
  • Dipolar rotation / polarization
  • Ionic Conduction mechanism
microwave dielectric heating mechanisms
Microwave Dielectric HeatingMechanisms

Conduction Mechanism

Dipolar Polarization

Mechanism

Dipolar molecules try to

align to an oscillating field

by rotation

Ions in solution will move

by the applied electric

field

Mingos, D. M. P. et al., Chem. Soc. Rev. 1991, 20, 1 and 1998, 27, 213

microwave vs oil bath heating
Microwave vs Oil-bath Heating

J.-S. Schanche, Mol. Diversity 2003, 7, 293.

www.personalchemistry.-com; www.biotage.com.

conventional heating by conduction
Conventional Heating byConduction

Conductive

heat

Heating by

convection

currents

Slow and

energy

inefficient

process

temperature on the outside surface is

in excess of the boiling point of liquid

direct heating by microwave irradiation
Direct Heating by MicrowaveIrradiation
  • Solvent/reagent
  • absorbs MW energy
  • Vessel wall transparent to MW
  • Direct in-core heating
  • Instant on-off

Inverted temperature gradients!

microwave ovens
Microwave Ovens

Cooking Food!

Cooking Chemistry ???

Household MW ovens

The Use of Microwave Ovens for Rapid Organic Synthesis R. Gedye et al., Tetrahedron Lett. 1986, 27, 279.

publications on mw assisted organic synthesis
Publications on MW-AssistedOrganic Synthesis

7 Synthetic Journals: J.Org.Chem.,Org.Lett.,Tetrahedron Lett.,Tetrahedron, Synth.Commun., Synlett, Synthesis

All Journals (Full Text): Dedicated instruments only (Anton Paar, Biotage, CEM, Milestone, Prolabo)

industrial chemical applications of microwave heating
Industrial /Chemical / Applications of Microwave Heating

Food Processing

+ Defrosting

+ Drying / roasting / baking

+ Pasteurization

Plasma

+ Semiconductors

Waste Remediation

+ Sewage treatment

Drying Industry

+ Wood, fibers, textiles

+ Pharmaceuticals

+ Brick / concrete walls

Analytical Chemistry

+ Digestion

+ Extraction

+ Ashing

Polymer Chemistry

+ Rubber curing, vulcanization

+ Polymerization

Biochemistry / Pathology

+ Protein hydrolysis

+ PCR, proteomics

+ Tissue fixation

+ Histoprocessing

Ceramics/Materials

+ Alumina sintering

+ Welding, smelting, gluing

Medical

+ Diathermy, tumor detection

+ Blood warming

+ Sterilization (Anthrax)

+ Drying of catheters

books on microwave assisted synthesis
Books on Microwave-Assisted Synthesis

(ACS Professional Reference Book) H. M. Kingston, S. J. Haswell (eds.)

Hayes, B. L.,

CEM Publishing,

Matthews, NC,

2002

Microwaves in Organic and Medicinal Chemistry

Kappe, C. O. and Stadler, A.

Wiley-VCH, Weinheim, 2005, ISBN: 3-527-31210-2

410 pages, ca 1000 references,

􀂃 Fundamentals of Microwave Application

􀂃 Alternative Laboratory Microwave

Instruments

􀂃 Chemistry Applications

􀂃 Biochemistry Applications

􀂃 Laboratory Microwave Safety

books on microwave assisted synthesis44
Books on Microwave-Assisted Synthesis

Lidstöm, P.;

Tierney, J. P.

(Eds.),

Blackwell

Scientific,

2005

Loupy Andre (Ed.)

Wiley-VCH, Weinheim, 2003, ISBN: 3-527-30514-9

523 pages, 2000 refs.

Book (2 volumes) Wiley-VCHA.

Loupy edit

Second Edition

(2006) 22 Chapters

books on microwave assisted synthesis45
Books on Microwave-Assisted Synthesis

Practical Microwave Synthesis for Organic Chemists - Strategies, Instruments, and Protocols 

Edition - 2009, X, 310 Pages, Hardcover, Monograph

Astra Zeneca Research

Foundation Kavitha Printers,

Bangalore, India, 2002

azrefi@astrazeneca.com

monomodal instrument
Monomodal instrument

Piccoli volumi processabili

- Onde Stazionarie (Hot Spots)

- Difficoltà nello Scale-up

+ Alta densità d’energia

Images adapted from: C.O. Kappe, A. Stadler: Microwaves in Organic and Medicinal Chemistry, Wiley, 2005

multimodal instrument
Multimodal instrument

+ Alta densità d’energia (maggior potenza disponibile)

+ Maggiori volumi processabili (cavità a MW più grande)

+ No Onde Stazionarie (No Hot-spots)

+ Semplice Scale-up

- Volume minimo processabile

thermal effects
Thermal Effects
  • More efficient energetic coupling of solvent with microwaves promotes higher rate of temperature increase
  • • Inverted heat transfer, volumetric
  • • “Hot spots” in monomode microwaves
  • • Selective on properties of material (solvents, catalysts, reagents, intermediates, products, susceptors)
hydrolysis of benzamide
Hydrolysis of benzamide

R. Gedye, F. Smith, K. Westaway, H. Ali, L. Baldisera, L. Laberge, J. Rousell, Tetrahedron Lett. 1986, 27, 279–282. R. J. Giguere, T. L. Bray, S. M. Duncan,

G. Majetich, Tetrahedron Lett. 1986, 27, 4945–4958.

thermal: 1 h, 90 % yield (reflux)

MW: 10 min, 99 % yield (sealed vessel)

The first reports on the use of microwave heating to accelerate organic chemical transformations (MAOS) were published by the groups of Richard Gedye (and Raymond J. Giguere/George Majetich in 1986. In those early days, experiments were typically carried out in sealed Teflon or glass vessels in a domestic household microwave oven without any temperature or pressure measurements. The results were often violent explosions due to the rapid uncontrolled heating of organic solvents under closed-vessel conditions.

solvent free reactions or solid solid reactions
Solvent-free Reactions or Solid-Solid Reactions

“No reaction proceeds without solvent”

Aristotle

Green chemistry

enabled advancement

Solventless syntheses

solvent free organic synthesis
Solvent-free Organic Synthesis

Chemical Synthesis w i t h o u t t h e u s e o f solvents has developed

i n t o a p o w e r f u l

m e t h o d o l o g y a s i t reduces the amount of toxic waste produced and therefore becomes less harmful to the

e n v i r o n m e n t

solvent free organic synthesis57
Solvent-free Organic Synthesis
  • Clean and efficient synthesis
  • Economic and environmental impact
  • Fast reaction kinetics

Best solvent is no solvent!

slide60
Towards

benign

synthesis

with

remarkable

Versatility

G. W. V. Cave, C. L.

Raston, J. L. Scott

Chem.Commun.

2001, 2159

solid state general oxidation with with urea h 2 o 2 complex
Solid-State General Oxidation with with Urea H2O2 Complex

R. S. Varma and K. P. Naiker, Org. Letters, 1999, 1, 189.

solvent free oxidative preparation of heterocycles
Solvent-free Oxidative Preparation of Heterocycles

Kumar, Chandra Sekhar, Dhillon, Rao, and Varma,Green Chem., 2004, 6, 156-157.

solvent free synthesis of keto keto sulfones ketones
Solvent-free Synthesis of ß-Keto Keto Sulfones Ketones

Kumar, Sundaree, Rao and Varma,Tetrahedron Letters, 2006, 47, 4197-4199.

solvent free reduction
Solvent-free Reduction

F. Toda et al. Angew. Chem. Int. Ed. Engl., 1989, 28, 320and Chem. Commun., 1989, 1245.

carbon carbon bond formation
Carbon-Carbon Bond Formation

Toda, Tanada, Iwata, J. Org. Chem., 1989, 54, 3007.

solventless photo coupling and photo rearangements
Solventless Photo Coupling and Photo Rearangements

Y. Ito, S. Endo, J. Am. Chem. Soc. 1997, 119, 5974.

Shin, Keating, Maribay, J. Am. Chem. Soc. 1996, 118, 7626.

solvent free condensation
Solvent - Free Condensation

Z. Gross, et al., Org. Letters, 1999, 1, 599.

solid state preparation of dumb bell shaped c120
Solid-State Preparationof Dumb-bell-shaped C120

Wang, Komatsu, Murata, Shiro, Nature 1997, 387, 583

advantages of solid mineral supports alumina silica and clay
Advantages of Solid Mineral Supports(Alumina, Silica and Clay)
  • Good dispersion of active (reagent) site can lead to significant improvement of reactivity–large surface area.
  • The constraints of the (molecular dimensions) pores and the characteristics of the surface adsorption can lead to useful improvement in reaction selectivity.
  • Solids are generally easier and safer to handle than liquids or gaseous reagents.
  • Inexpensive, recyclable and environmentally benign nature.
solid supported solventless reactions
Solid-supported Solventless Reactions
  • Microwave irradiation of solventless reactions with inorganic mineral supports such as alumina, silica, or clays have resulted in faster reactions with higher yields with simplified separation.

R. S. Varma, Tetrahedron, 2002, 58, 1235.

R. S. Varma, Green Chem., 1999, 1, 43.

supported reactions using microwaves
Supported ReactionsUsing Microwaves

E. Gutterrez, A. Loupy, G. Bram, E. Ruiz-Hitzky, Tetrahedron Lett. 1989, 30, 945.

microwave assisted deacetylation on alumina
Microwave-Assisted Deacetylationon Alumina

Varma et al.: J. Chem. Soc., Perkin Trans. 1, 999 (1993)

deprotection of benzyl esters via microwave thermolysis
Deprotection of Benzyl Esters viaMicrowave Thermolysis

A practical alternative to traditional catalytic hydrogenation

Varma et al.: Tetrahedron Lett., 34, 4603 (1993)

slide74
Solid State Deoximation with Ammonium Persulfate-Silica gel Regeneration of Carbonyl Compounds Using Microwaves

Varma, Meshram: Tetrahedron Lett., 38, 5427 (1997)

slide75
Solid State Cleavage of Semicarbazones/Phenylhydrazones with Amm.Persulfate–Clay using Microwave and Ultrasonic Irradiation

Varma, Meshram: Tetrahedron Lett., 38, 7973 (1997)

solid supported solvent free oxidation under mw
Solid Supported Solvent-freeOxidation under MW

Varma et al., Tetrahedron Lett., 1997, 38, 2043 and 7823

solvent free reduction using mw
Solvent-free Reduction Using MW

Chemoselective reduction of trans-cinnamaldehyde: olefinic moiety remains intact and the aldehyde functionality is reduced in a facile reaction.

Varma et al., Tetrahedron Lett., 1997, 38, 4337

hydrodechlorination under continuous mw
Hydrodechlorination under continuous MW

Pillai, Sahle-Demessie, Varma: Green Chemistry, 6, 295 (2004)

synthesis of heterocyclic compounds
Synthesis of Heterocyclic Compounds

Varma et al.: J. Chem. Soc. Perkin Trans 1, 4093 (1998)

Varma, J. Heterocycl. Chem., 36, 1565 (1999)

indolizines
INDOLIZINES
  • Heterocyclic systems, 10- p electronics
  • Structure of many naturals alkaloids : (-) slaframine, (-) dendroprimine, indalozine, coniceine
  • Key intermediates in indolizidines, bisindolizines, ciclofans, ciclazines synthesis- biologic actives compounds
why interest for indolizinic products
Why interest for indolizinic products

Strong fluorescent properties

luminiscent products

  • Potentially fluorescents marker
  • Potentially laser“scintillaters”
  • Strong inhibitors for lipid peroxydation (15-lipooxygenase inhibitors )
  • Biologic actives products
  • Ligands for estrogen receptors
  • Possible inhibitory activity for phospholipase A2
  • “Calcium-entry” blockers
  • Bioorg. & Med. Chem. Lett., 16, 59, 2006
  • Tetrahedron, 61, 4643, 2005
  • Bioorg. & Med. Chem., 10, 2905, 2002
  • J. Org. Chem., 69, 2332, 2004
  • Dyes and Pigments, 46, 23, 2000
  • J. of Luminiscence, 82, 155, 1999
indolizines by irradiation with microwaves in mcr
Indolizines by irradiation with microwaves, in MCR

U. Bora, A. Saikia, R. C. Boruah – Organic Lett., 5 (4), 435, 2003;

Asymmetric indolizines, by irradiation with microwaves, in MCR

A. Rotaru, I. Druţă, T. Oeser, T. Muller – Helv. Chim. Acta, 88, 1798, 2005;

synthesis of new indolizines
Synthesis of new indolizines
  • [3+2] dipolarcycloaddition of symmetrical or non-symmetrical 4,4’-bipyridinium-methyne-ylids with actives alkynes, symmetrical or non-symmetrical :
  • I. Druţă, R. Dinică, E. Bâcu, I. Humelnicu – Tetrahedron, 54, 10811, 1998
  • R. Dinică, C. Pettinari – Heterocycl. Comm., 07(4), 381, 2001
  • A. V. Rotaru, R. P. Dănac, I. Druţă – J. Heterocyclic Chem., 41, 893, 2004
  • A. Rotaru, I. Druţă, T. Oeser, T. Muller – Helv. Chim. Acta, 88, 1798, 2005
synthesis of new substituted pyridinium indolizines
Synthesis of new substituted pyridinium-indolizines
  • Indolizinic cycloadducts using like dipolarophile 4-nitro-phenyl propiolate
monoindolizine synthesis in solid phase under microwaves
Monoindolizine synthesis in solid phase, under microwaves

Reaction conditions and the yelds for synthesized compounds (12a-d)

  • B. Furdui, R. Dinică, I. Druţă, M. Demeunynck –Synthesis, 16, 2640, 2006
benefits of mw assisted reactions
Benefits of MW-Assisted Reactions
  • Higher temperatures (superheating / sealed vessels)
  • 􀂉 Faster reactions, higher yields, any solvent (bp)
  • 􀂉 Absolute control over reaction parameters
  • 􀂉 Selective heating/activation of catalysts, specific effects
  • 􀂉 Energy efficient, rapid energy transfer
  • 􀂉 Can do things that you can not do conventionally
  • 􀂉 Automation / parallel synthesis – combichem
mw assisted solvent free three component coupling formation of propargylamines
MW-Assisted Solvent-free Three Component Coupling:Formation of Propargylamines

Ju, Li and Varma, QSAR & Combinatorial Science, 2004, 23, 891

solvent free synthesis of ionic liquids
Solvent-free Synthesis of Ionic Liquids

Varma, Namboodiri, Chem. Commun., 2001, 643.

Varma, Namboodiri, Pure Appl. Chem., 2001, 73, 1307.

Namboodiri, Varma, Chem. Commun., 2002, 342.

mw synthesis of tetrahalideindate iii based il
MW Synthesis ofTetrahalideindate(III)-based IL

Kim and Varma. J. Org. Chem., 2005, 70, 7882.

peg a biodegradable solvent
PEG, a Biodegradable “Solvent”
  • 􀂾 PEG has been applied in bioseparations.
  • 􀂾 PEG is on the FDA’s GRAS list, (compounds Generally
  • Recognized as Safe) and has been approved by the FDA for
  • Internal consumption.
  • 􀂾 PEG is weakly, immunogenic, a factor which has enabled
  • the development of PEG–protein conjugates as drugs.
  • 􀂾 Aqueous solutions of PEG are biocompatible and are
  • utilized in tissue culture media and for organ preservation.
  • 􀂾 PEGs are nonvolatile
  • 􀂾 PEG has low flammability
  • 􀂾 PEG is biodegradable

J. Chen, S. K. Spear, J. G. Huddleston, R.D. Rogers, Green Chem.. 2005, 7, 64.

suzuki cross coupling reaction in peg accelerated by microwaves
Suzuki Cross-Coupling Reactionin PEG Accelerated by Microwaves

V. Namboodiri, R. S. Varma: Green Chemistry, 2001, 3, 146.

advantages of present approach
Advantages of Present Approach
  • PEG offers a convenient recyclable reaction medium
  • Good substitute for volatile organic solvents
  • The microwave heating offers a rapid and clean alternative at high solid concentration and reduces the reaction times from hours to minutes
  • The recyclability of the catalyst makes the reaction economically and potentially viable for commercial applications
water as a cleaner solvent
Water as a “cleaner” solvent
  • Water is not a popular choice of solvent,
  • reactivity in heterogeneous aqueous media is
  • not very well understood
  • But It brings biochemistry and organic
  • chemistry closer together in the beneficial use
  • of water as the reaction medium, it is abundant,
  • inexpensive and clean.
cu i catalyzed click chemistry
Cu (I) Catalyzed Click Chemistry

P. Appukkuttan, W. Dehaen, V. V. Fokin, E. Van der Eycken.

Org. Lett. 2004, 6, 4223.

n alkylation of amines using alkyl halides
N-alkylation of Aminesusing Alkyl Halides

Ju, Y.; Varma, R. S., Green Chem. 2004, 6, 219-221.

aqueous n alkylation of amines using microwave irradiation
Aqueous N-alkylation of Aminesusing Microwave Irradiation

Ju, Y.; Varma, R. S., Green Chem. 2004, 6, 219-221.

mw synthesis of n aryl azacycloalkanes
MW Synthesis of N-Aryl Azacycloalkanes

Ju; Varma, Tetrahedron. Lett., 2005, 46, 6011.

Ju; Varma, J. Org. Chem., 2006, 71, 135.

designing a greener synthesis
Designing a “greener” synthesis
  • Plan!
  • Maximize convergence
  • Consider using renewable starting materials
  • Avoid super toxic reagents
  • Strive for high atom economy
    • Use catalytic over stoichiometric
    • Avoid auxiliaries and protecting groups
  • Consider greener solvents
  • Minimize number of purifications
take aways
Take Aways
  • “Green chemistry” is not so far away from what we do everyday
    • High yields
    • Minimal number of steps
    • Minimize number of purifications
  • Green principles to keep in mind
    • Strive for atom economy
    • Consider the toxicity and necessity of reagents and solvents
green chemistry opportunities
Green Chemistry Opportunities

Conferences

    • Annual ACS Green Chemistry and Engineering Conference
    • Annual Gordon Conferenece, Green Chemistry
  • Funding
    • PRF green chemistry grants
    • NSF green chemistry grants
    • EPA funding
conclusion
Conclusion

Green chemistryNot a solution to all environmental problems But the most fundamental approach to preventing pollution.

slide114
Today, a large body of work on microwave-assisted synthesis exists in the published and patent literature.
  • Many review articles, several books and information on the world-wide-web already provide extensive coverage of the subject.
lead references
Lead References
  • Lidström, P.; Tierney, J.P.; Wathey, B.; Westman, J. Tetrahedron 2001, 57, 9225
  • Hayes, Brittany, L. Microwave Synthesis. Chemistry at the Speed of Light. North Carolina: CEM Publishing, 2002.
  • Tierney, J.P., and P. Lidström, ed. Microwave Assisted Organic Synthesis. Oxford: Blackwell Publishing Ltd, 2005.
  • de la Hoz, A.; Diaz-Ortiz, A.; Moreno, A. Chem. Soc. Rev. 2005, 34, 164.
lead references reviews
Lead Referencesreviews

A. Loupy, A. Petit, J. Hamelin, F. Texier- Boullet, P. Jacquault, D. Math_, Synthesis1998, 1213–1234; R. S. Varma, Green Chem. 1999, 43–55; M. Kidawi, Pure Appl. Chem. 2001, 73, 147–151; R. S. Varma, Pure Appl. Chem. 2001, 73, 193–198; R. S. Varma, Tetrahedron 2002, 58, 1235–1255; R. S. Varma, Advances in Green Chemistry: Chemical Syntheses Using Microwave Irradiation, Kavitha Printers, Bangalore, 2002. A. K. Bose, B. K. Banik, N. Lavlinskaia, M. Jayaraman, M. S. Manhas, Chemtech 1997, 27, 18–24; A. K. Bose, M. S. Manhas, S. N. Ganguly, A. H. Sharma, B. K. Banik, Synthesis 2002, 1578–1591. C. R. Strauss, R. W. Trainor, Aust. J. Chem. 1995, 48, 1665–1692; C. R. Strauss, Aust. J. Chem. 1999, 52, 83–96; C. R. Strauss,

references books
References books
  • Microwaves in Combinatorial and High-Throughput Synthesis (Ed.: C. O. Kappe), Kluwer, Dordrecht, 2003 (a special issue of Mol. Diversity 2003, 7, pp 95–307);
  • Stadler, C. O. Kappe, Microwave-Assisted Organic Synthesis (Eds.: P. Lidstr_m, J. P. Tierney), Blackwell Publishing, Oxford, 2005 (Chapter 7).
  • Loupy (Ed.), Microwaves in Organic Synthesis, Wiley-VCH, Weinheim, 2002.
  • B. L. Hayes, Microwave Synthesis: Chemistry at the Speed of Light, CEM Publishing, Matthews, NC, 2002.
  • P. Lidstrom, J. P. Tierney (Eds.), Microwave- Assisted Organic Synthesis, Blackwell Publishing, Oxford, 2005.
  • For online resources on microwave-assisted organic synthesis (MAOS), see: www.maos.net.
thank
THANK

YOU

FOR YOUR ATTENTION!

118