bài giảng sự xúc tác và hóa học xanh

12/14/2012
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ĐẠI HỌC BÀ RỊA – VŨNG TÀU
SỰ XÚC TÁC VÀ HÓA HỌC XANH
Diệp Khanh
KHOAHÓA HỌC VÀ CÔNG NGHỆ THỰC PHẨM
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
PRINCIPLES OF GREEN CHEMISTRY
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
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Agent Orange (2,3,7,8-TCDD):

2,4-D
2,4–dichlorop henox yacetic acid
2,4,5-T
2,4,5-trichlorophenox yacetic acid
2,3,7,8-TCDD
2,3,7,8-t etrachlorodibenzodioxin
↓
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
Phản ứng hình thành Chất độc màu da cam (Orange agence)
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
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What is green chemistry?
The design of chemical products &
processes that reduce or eliminate the use
or generation of hazardous substances
Discovery & application of new chemistry /
technology leading to prevention /
reduction of environmental, health & safety
impacts at source
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
History
• Early 1990’s
Green Chemistry gained its current standing as a scientific discipline as well as
practical means to pollution prevention as the result of collaboration between
the US government, Industry, and Academia. In the early 1990's, Paul Anastas,
who was then the chief of the Industrial Chemistry Branch at the US EPA,

moved forward the concept of Green Chemistry
• Mid 1990's
Paul Anastas and John Warner developed the 12 Principles of Green Chemistry:
a framework to help us think about how to prevent pollution when inventing
new chemicals and materials. Paul Anastas and John Warner's work as
founders of a new field called Green Chemistry, based on the productive
collaboration of government and industry, was just beginning.
• 1993
A white paper entitled "Chemistry for a Clean World," published by the
European Community's Chemistry Council in June, attracted a great deal of
attention in Europe.
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
•
1995
President Bill Clinton established the Presidential Green Chemistry Challenge
Awards to recognize chemical technologies that incorporate the principles of
sustainable chemistry into chemical design, manufacture and use.
•
1996
The first Presidential Green Chemistry Challenge Awards winners were
announced. The awards increased awareness of Green Chemistry in industry
and government by annually acknowledging individuals, groups, and
organizations in academia, industry, and the government for their innovations
in cleaner, cheaper, smarter chemistry. This remains the only award given by
the President of the United States specifically for work in chemistry.
•
1997
After more than a year of planning by individuals from industry, government,
and academia, the Green Chemistry Institute (GCI) was incorporated in 1997
as a not-for-profit 501(c)3 corporation — devoted to promoting and advancing

green chemistry.
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• 1998
John Warner and Paul Anastas published the seminal book Green Chemistry:
Theory and Practice, which gave a precise definition to Green Chemistry and
enumerated the Twelve Principles fundamental to the science. The definition and
principles have become the generally accepted guidelines for Green Chemistry.
Since it was first published, the book has been re-printed in several languages.
• 1999
Great Britain's Royal Society of Chemistry publishes an international scientific
journal entitled Green Chemistry bimonthly; the first issue was published in
February 1999. The majority of the synthesis and process journals focus on papers
related to this topic.
• 2001
GCI joined the American Chemical Society (ACS) in an increased effort to address
global issues at the intersection of chemistry and the environment.
• 2006
The International Union of Pure and Applied Chemistry, formed a special
subcommittee on Green Chemistry and launched a bi-annual international
conference. The first was held in Germany, the second in Russia, and the 2010
conference was slated for Canada.
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• 2007
John Warner returned to industry to develop green technologies, partnering with
Jim Babcock to found the first company completely dedicated to developing green
chemistry technologies, the Warner Babcock Institute for Green Chemistry. The
Institute was created with the mission to develop nontoxic, environmentally benign,

and sustainable technological solutions for society.
Simultaneously, John Warner founded a non-profit foundation, Beyond Benign, to
promote K-12 science education and community outreach.
• 2009
In May 2009, President Barack Obama nominated Paul Anastas to lead the U.S.
Environmental Protection Agency's (EPA's) Office of Research and Development.
The nomination is a decisive achievement for the adoption and advancement of the
principles of Green Chemistry.
• Today
The United States is just one of many countries that have green chemistry
programs, centers, and educational initiatives. Others include Australia, China,
Germany, India, Italy, the Netherlands, Spain, and the United Kingdom, to mention
but a few.
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The 12 principles of Green Chemistry
(Paul Anastas & John Warner)
Prevention
It is better to prevent waste than to treat or clean up waste
after it has been created.
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
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Atom Economy:Example
Less Hazardous Chemical Syntheses
Wherever practicable, synthetic methods should be
designed to use and generate substances that possess
little or no toxicity to human health and the
environment.
Designing Safer Chemicals
Chemical products should be designed to effect their
desired function while minimizing their toxicity
Atom Economy = (137/275) X 100 = 50%
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Safer Solvents and Auxiliaries
The use of auxiliary substances (e.g., solvents,
separation agents, etc.) should be made unnecessary
wherever possible and innocuous when used
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Design for Energy Efficiency
Energy requirements of chemical processes should be
recognized for their environmental and economic
impacts and should be minimized. If possible,
synthetic methods should be conducted at ambient
temperature and pressure.
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM

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Use of Renewable Feedstocks
A raw material or feedstock should be renewable
rather than depleting whenever technically and
economically practicable.
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Reduce Derivatives
Unnecessary derivatization (use of blocking groups,
protection/ deprotection, temporary modification of
physical/chemical processes) should be minimized or
avoided if possible, because such steps require
additional reagents and can generate waste.
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
Catalysis
Catalytic reagents (as selective as possible)
are superior to stoichiometric reagents.
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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.
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
My Waste, My responsibility

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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.
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Condensed Principles of green chemistry
(Samantha Tang, Richard Smith and Martyn Poliakoff )
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 Inherently Safer Chemistry for Accident Prevention
Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for
chemical accidents, including releases, explosions, and fires.
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The Twelve Principles of Gre en Chemistry*
1.Prevention
It is better to prevent waste than to treat or clean up waste after it has been created.
2.Atom Economy
Synthetic methods should be desig ned to maximize the incorporation of all materials used in the process into the
final product.
3.Less Hazardous Chemical Syntheses
Wherever practicable, synthetic methods should be designed to use and gene rate substances that possess little or
no toxicity to human health and the environment.
4.Designing Safer Chemicals
Chemical products should be desig ned to eff ect their desired function while minimizing their toxicity.
5.Safer Solvents and Auxiliaries
The use of auxiliary substances (e.g., solve nts, separation agents, e tc.) should be made unnecessary whereve r
possible and innocuous when used.

6.Design for Energy Efficiency
Energy requirements of chemical processes should be recognized for their environmental and economic impacts
and should be minimize d. If possible, synthetic methods should be conducted at ambient temperature and
pressure.
7.Use of Renewable Feedstocks
A raw material or fe edstock should be renewable rather than depleting whenever tec hnically and e conomically
practicable.
8.Reduce Derivatives
Unnecessary de rivatization (use of blocking groups, prote ction/ deprotection, temporary modification of
physical/chemical processes) should be minimized or a voided if possible, because such steps require additional
reagents and can gene rate waste.
9.Catalysis
Catalytic reag ents (as selective as possible) are superior to stoichiometric reagents.
10.Design for Degradation
Chemical products should be desig ned 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 ne ed to be further developed to allow for re al-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 minimize the potential
for chemical accidents, including release s, explosions, and fires
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The Twelve Principles of Gre en Engineer ing*
Inhere nt Rather Than Circumstantial
Designer s need to strive to ensure that all materials and ene rgy inputs and outputs are as inherently
nonhazardous as possible.
Preve ntion Instead of Treatment
It is better to preve nt waste than to treat or clean up waste afte r it is formed.

Design for Separation
Separation and purification operations should be desig ned to minimize energ y consumption and materials use.
Maximize Efficiency
Products, processes, and sy stems should be designe d to maximize mass, e nergy , space, and time efficiency .
Output-Pulled Versus Input-Pushed
Products, processes, and sy stems should be "output pulled" rather than "input pushed" through the use of
energ y and materials.
Conserve Complexity
Embedded e ntropy and complexity must be viewed as an inve stment when making design choices on rec ycle,
reuse, or beneficial disposition.
Durability Rather T han Immortality
Targe ted durability, not immortality, should be a de sign goal.
Meet Ne ed, Minimize Excess
Design for unnece ssary capacity or capability (e .g., "one size fits all") solutions should be considered a design
flaw.
Minimize Material Diversity
Material diversity in multicomponent products should be minimized to promote disassembly a nd value
retention.
Integrate Mater ial and Energy Flows
Design of products, proce sses, and systems must i nclude integration and interconnectivity with available
energ y and materials flows.
Design for Comme rcial "Afterlife"
Products, processes, and sy stems should be designe d for performance in a commercial "afterlife."
Renewable Rather Than Depleting
Material and ener gy inputs should be rene wable rather than depleting.
* Anastas, P.T., and Zimmerman, J.B., "Desig n through the Twelve Principles of Green Engineering", Env. Sci.
and Te ch., 37, 5, 94A -101A, 2003.
Green chemistry is about:
Waste
Materials

Hazard
Reducing Risk
Energy
Environmental
Impact
COST
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In Brief, GREEN CHEMISTRY is





Efficient use of (preferably renewable) raw materials,
Elimination of wasteful byproducts,
Avoiding use of toxic/hazardous reagents and solvents,
Use of safer final (biodegradable) products, and
Increasing energy efficiency.
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Two considerations that dominated green
chemistry are:
A. Maximum atom utilization,
B. The minimum waste produced (E-Factor).
The waste includes byproducts, reagents,
solvent loss and even fuel.
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SỰ XÚC TÁC VÀ HÓA HỌC XANH
Why is catalysis important in making industrial

processes more efficient and economically profitable?
•Catalytic reagents reduce the energy of the
transition state, thereby reducing the energy input
required for a process.
•Catalysts are required in small quantities.
•The regeneration and reversibility of catalysts are
good for green processes.
2
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No
catalyst
With
catalyst
3
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With catalyst: Less energy, less toxic reagents, less waste
4
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E factor
Solution to reduce waste?
In simple form, it defined as:
(Chemicals in (kg) - Desired product (kg) ) / Total product (kg)
The enormous waste in different segments of industry are shown in the table below.
Catalyst
Stoichiometric
reagents

M. Lancaste r, “G re en Che mistr y : An Introducto ry Text, Roy.Soc.Chem., cambridg e, 2002 .
A higher Efactor → more waste → greater negative
environmental effect
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
Atom efficiency / economy
No
cataly
st
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Atom efficiency (economy)
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Classical aromatic chemistry
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Non-classical aromatic chemistry
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Two ways to hydroquinone
< 1kg waste / kg
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Supported catalyst
Solid supports: polymer haysilica
15

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Using solid catalyst
Heterogeneous Catalysts
•Low Selectivity
•Difficult to Functionalize
•Ill-defined catalytic species
•Limited Range of Reactions
•Problems of Leaching
•Ease of Recycle
•Preferred Industrially
Catalyst separation by
filtration / centrifugation
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Using Soid catalyst
Reused catalyst
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Using homogeneous catalyst
•More waste
•More energy consumed
•Less possibility to recycle and
reuse

•Product contaminated with toxic
metals
•More toxic solvents involved
Catalyst separation by column
chromatography / distillation / extraction
Using homogeneous catalyst
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
Homogeneous Friedel-Crafts acylation
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22
21
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Heteromogeneous Friedel-Crafts acylation
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Homogeneoussynthesis of 2,6-dichlorobenzonitrile
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Heterogeneous synthesis of 2,6-dichlorobenzonitrile – less waste
25
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Soluble polymer-supported catalyst
•Temperature-dependent phase separation
Catalyst
• Solvent-dependent phase separation
• PEG: soluble in DMF, DCM but insoluble in ether, iPrOH
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
Biocatalysts
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Advantages of biocatalysis
▪One area where organic chemists are still
struggling: chirality !!!
▪Biocatalysts: predominantly suited for optically
pure stereo-isomers
▪ Essential for drugs & agrochemicals
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Chemo-selectivity:
•Other chemically sensitive functional groups → still survive with enzyme
•Biocatalytic conditions → cleaner / greener still
•Side-reactions avoided → advantageous for product purifications
•Enzyme → react on a single type of functional group only
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM

Q factor
Another important parameter is the extent of harmfulness of
the waste. For example, sodium sulphate as a waste is
certainly far less harmful than a cyanide waste. A new term
environment quotient (Q) has been coined to emphasize this
difference and some number has been arbitrarily assigned to
different wastes according to their extent of their harmful
effect.
R. A. Sheldon, Che mtech., 38, (1994).
O
23
+
C2H2
HZSM-5
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Catalysis with acidic zeolites
Similarly, propylbenzene could be manufactured using a 3-dimensional
dealuminated mordenite (3-DDM) catalyst
+
dealuminated
mordenite
Si/Al = 100-1000
Dealumination enabled to obtain very high Si:Al ratio (up to 1000). In these
form, the micropores of mordenite were connected through mesopores (5-
10 nm).
K.Tanabe and W.F. Holderich, Appl .Catal.A General, 181,399 (1999 ).
1. ALKYLATION: Mobil-Badger Process (Polyalkylation is suppressed)
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
Naphthalene is dialkylated with propene over 3-DDM. The product is used in
making the carboxylic acid that is an important monomer for making Plastics.

+
+
(CH3CO)2O
Acylation with heterogeneous catalysis ismuch more difficult because of the polarity
difference of the substrate and the acylating reagent that makes it difficult to achieve
Favourable adsorption ratio of the two. This could be achieved by the use of H-Beta.
O
G.R. Meima, G.S. Lee and J.M. Garces, in “Fine Chemicals Through heteroge neous
Catalysis (Ed. R.A. Sheldon, Wile-VCH, Weinheim, 2001.
Acylation
A. Vogt and A. Pfenning er, EP0701987A1, 1996 to Uetikon AG.
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
.
Hydroxyalkylaton using zeolites is difficult because of unfavourable
adsorption ratio of the reagent and the substrate. This difficulty is avoided
by having the aromatic and the epoxide functions in the same molecule
H-ZSM-5
or H-Beta
O
J.A. Elings, R.S. Downing and R.A. Sheldon, Stud.Surf.Sci.Catal, 105, 1125 (1997).
Ce3+ exchanged Y zeolite could catalyze toluene and xylenes using with higher
carboxylic acids showing that free carboxylic acids can be used in acylation.
O
R
+ RCO2H
B. Chiche, A. Finiels, C. Gauthier, P. Genes te, J. Graille and D. Pioch, J. Org. Chem., 51, 2128 (1986).
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
Forma tion of N-heterocycles by intermolecular
cyclization is catalyz ed b y a cidic zeo lites.
Synthesis of pyridine and pic oline from a

mixture of a ceta ldehyde, formaldehyde an d
ammonia in presence of H-ZSM-5 is an
example.
N N
NH2H2N
N
+
Pd
N
H
CH3CHO + HCHO + NH3
H-ZSM-5
H-ZSM-5
Si :Al > 1000 ,350oC
vap.phase
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
W. F. Holderich et al. in “Fine Chemicals
through Catalysis”, pp.217-231, Wiley-
VCH, (2001)
M.J.Burk et. Al., J. Org. Chem., 64, 3290 (1999)
Beckmann rearrangement
produces 2 kg 0f a mmon. sulfate
per kg of product
sulfuric a cid
NOH
Sumitomo
NH
conventio nal
NOH
Cl

H+
NHCH3
NH2
+ (MeO)2CO + MeOH + CO2
Cs-X
+ H2O
Soc.Chem.Commun., 1005 (1995).
24
TS-1 or
ZSM-5
O
H
TS-1 ZSM-5
conv. 100% 99%
select. 98% 97-100%
Epoxidereaarangement( key stepinthemanufactureofmany intermediates in
thefinechemicalindustry. Traditionalmethodusedstoichiometric Lewis acids
or bases.
O
G. P. Heitmann, G. Dahlhoff
and W.F.Holderich, J.Catal,
186,, 12 (1999)
Traditional method for preparing 2,6-dichlorobenzonitrile uses stoichiometric Amonts of
chlorine, HCN an d POCl3 with atom efficiency 31%. The new process W as developed uses
zeollite cat alysts Eur.Pa t.Appl. EP94898 8 (1999)
+ Cl2
Cl Cl
Cl
Cl
Cl

Cl Cl Cl
CN
Cl
ad sorption i n
faujas ite
Cl
NH3 + O2
ca talyst
35 0-45 0 oC
Ag-H-Mo r
350 oC
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Oxidation
Traditional methods of oxidation in organic chemistry uses stoichometric reagents (salts of manganese and
chromium. The new chemistry tries to use molecular oxygen or hydrogen peroxide. TiO2 supported on silica was
not effective with hydrogen peroxide because the water produced gets strongly adsorbedo on silica. TS-1 has
been used successfully because this titanium substituted silicalite-1 is hydrophobic. Phenol is converted with
hydrogen peroxide to a mixture of hydroquinone and catechol. Rhone-Poulenc Process uses perchloric acid and
phosphoric acid whereas Enichem process uses TS-1. A comparision Is given here
Comparision of phenol conversion processes
Process ( catalyst) Rhone-Poulenc (H3PO4 ,HClO4)
Phenol conversion (%) 5
Enichem (TS-1)
25
Selectivityon phenol 80 90
Catechol/hydroquinone 2.3 1
HO
TS-1 is also called a redox molecular sieve an d can be used as a catalys t fo r ma ny oxidations with hyd rog en
per oxide. In pre sence of TS-1, ammoni a and hydr oge n pe roxide forms in -sit u hydr oxylam ine which re acts
O

with a ke tone.An example is:
TS- 1
+ NH3 + H2O2
HO
NHCOCH3
Beckmann rearrange ment
A. Corma, L.T. Neme th,
M. Rench and S. Valencia,
Nature, 412, 423 (2001).
O
O
1 eq . H2O2 O
0.66mol% Sn-Beta
dioxane, 90 oC
A lrg e number of bulk chem icals are produced by usin g m olecula r oxygen eithe r in the liquid
or in th e vapour phase rea ction. S0me of these ar e:
Benzene/et hene to styr ene, p-xylene to terephthalic acid, for mald ehyd e to methan ol, Ethene
to ethene o xide, n-bu tane to aceti c acid, pro pene to acr yloni trile, n-butane to Maleic anh ydride,
o-xylene to phthalic an hydr ide, isobute ne to methy l methacrylate etc.
Molecular oxuy gen is a s pin triple t and its dire ct rea ction to a organic singlet com pound is
spin for bidden. To overcome this, th e tri plet is allowe d to re act with p arameg netic Metal ions
forming a superoxo-metal complex tha t for ms a vari ety of meta l-oxyg en specie s.
Use of catalytic r oute to select ive oxida tion in pres ence of sever al fu nctional gr oups is A big
challe nge .
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
K. Iwayama, S. Yamakawa, M. Kato and H. Okino, Eur. Pat. Appl. EP948988 (1999) to Toray
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
Bayer- Villiger Oxidation (conversion of ketone or an aldehyde to the ester)
The peracid undergoes a nucleophylic attack on the carbonyl group givimg an inetrmediate. In the next step, a
concerted migration of one of the alkyl groups takes place releasing the Carboxylate anion. The reaction is widely

used in organic chemistry. Zeolite beta containing 1.4 wt% of tin is a good catalyst using hydrogen peroxide.
aromatics.
CHO COOEt
+ NCCH2CO2Et Na-X
CN
Chemicals thro ugh Hetero. Catal.,
Cormma and S. Iborra in “Fine
309 (2001).
K-Y
CN CN
+ MeOH
K.R. Kloestra, H. van Bekku m, Chem.
SIDE CHAIN ALKYLATIONS
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
HO
KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
par aceta mol
Basic zeolites
Coma ratt ively much less at tentio n has been paid to basic zeol ites. Zeol ites can be made basic by 1.Exchange
of pr oton s with alkali o r rare ear th ions or 2 . by depos iting nano-par ticles of alkali or alka li earth oxid es in the
pores. The b asic si tes are weak. They can be u sed to gener ate C-C bond in the sid e chain s of subs tituted
12/14/2012
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KHOAHÓAHỌC VÀ CÔNG NGHỆTHỰC PHẨM
You too, can make a contribution to green chemistry by
taking a small pledge, when you do your chemistry
practicals.
Reduce Waste: Use as little of the chemicals you
need.
Increase Safety: Don't pour hazardous substances

down the sink, dispose it through the correct methods.
Be Efficient: Work out the reaction carefully in your
notebook before you do it in the lab.
Save Energy: If your reaction needs heating or cooling,
do it for the minimum time needed.
If you follow the pledge, you'll not only have a greener
experience, but a safer and more scientific one too.