A micro-review of the Baeyer-Villiger oxidation with recent (2012/2013) references from the literature; last updated on March 1 2013.
The Baeyer-Villiger Oxidation is a popular tool for the synthesis of esters and lactones.
See an animation at: http://www.harinchem.com/named_organic_reactions.html.
Please send feedback or questions through: http://www.harinchem.com/contactpage.aspx
The document discusses various types of molecular rearrangement reactions. It begins by defining rearrangement reactions as those where the atoms or groups in a molecule reshuffle to form a structural isomer of the original substance. Rearrangements are then classified as intermolecular or intramolecular. Several examples of nucleophilic rearrangements are provided, including carbonium ion rearrangements like the pinacol-pinacolone, Wagner-Meerwein, and benzillic acid rearrangements. Nitrogen deficiency rearrangements like the Schmidt, Curtius, Hoffmann, Beckmann, and Lossen rearrangements are also briefly described. The mechanisms and features of several important rearrangements are discussed in more detail.
There are five types of skeletal rearrangements: electron deficient, electron rich, radical, rearrangements on aromatic rings, and sigmatropic rearrangements. Molecular rearrangements involve the migration of a group from one atom to another within the same molecule. Examples include the Wagner-Meerwein rearrangement, pinacol-pinacolone rearrangement, and Cope rearrangement. Rearrangements are driven by stability of the carbocation intermediate or relief of ring strain.
The Baeyer-Villiger rearrangement involves the reaction of ketones with peroxy acids, resulting in the conversion of ketones to esters and cyclic ketones to lactones. A typical example is the reaction of acetophenone with perbenzoic acid to produce phenylacetate. The reaction proceeds through an anionotropic rearrangement where a group migrates from carbon to the electron-deficient oxygen. The Baeyer-Villiger rearrangement has applications in synthesizing lactones, anhydrides, and medicinal compounds.
Molecular Rearrangements of Organic Reactions ppsOMPRAKASH1973
This PPT is usefull for aspirants of JEE-IIT, CSIR-NET and UPSC exams in CHEMISTRY section. It is also usefull for grduates and Post graduates students of Indian Universities.
This document discusses classical and nonclassical carbocations. Nonclassical carbocations have charge delocalization from neighboring bonds like C=C pi bonds. The main difference is that classical carbocations have charge localized on one carbon, while nonclassical carbocations have charge delocalized by double or single bonds not in the allylic position. Examples like the norbornyl carbocation are given to show how neighboring double bonds can stabilize and delocalize charge through 3-center bonds. Reaction rates and product stereochemistry provide evidence for nonclassical intermediates. While some challenged this view, most chemists accept nonclassical interpretations of carbocation reactions.
The document summarizes the Favorskii and Wolff rearrangements. The Favorskii rearrangement involves the base-catalyzed rearrangement of cyclopropanones and α-halo ketones, forming carboxylic acid derivatives. It proceeds through the formation of an enolate intermediate and a cyclopropanone, which is then attacked by the nucleophile. The Wolff rearrangement can occur thermally, photochemically, or via transition metal catalysis, and involves 1,2-migration of substituents with the migratory aptitude of H > aryl > alkyl. Both rearrangements form a carbonyl group at the migration origin and involve migration of an electron-rich carbon terminus.
DIBAL-H is a commercially available selective reducing agent that can reduce esters and nitriles to the corresponding aldehydes. It is prepared by heating triisobutylaluminum, which induces beta hydride elimination to form DIBAL-H and isobutene. DIBAL-H selectively reduces esters to aldehydes at low temperatures through a tetrahedral intermediate. Hydrolytic workup of this intermediate then yields the desired aldehyde products. The document provides an introduction to DIBAL-H including its preparation, applications in organic synthesis, and how it differs from other reducing agents like LiAlH4.
The document discusses various types of molecular rearrangement reactions. It begins by defining rearrangement reactions as those where the atoms or groups in a molecule reshuffle to form a structural isomer of the original substance. Rearrangements are then classified as intermolecular or intramolecular. Several examples of nucleophilic rearrangements are provided, including carbonium ion rearrangements like the pinacol-pinacolone, Wagner-Meerwein, and benzillic acid rearrangements. Nitrogen deficiency rearrangements like the Schmidt, Curtius, Hoffmann, Beckmann, and Lossen rearrangements are also briefly described. The mechanisms and features of several important rearrangements are discussed in more detail.
There are five types of skeletal rearrangements: electron deficient, electron rich, radical, rearrangements on aromatic rings, and sigmatropic rearrangements. Molecular rearrangements involve the migration of a group from one atom to another within the same molecule. Examples include the Wagner-Meerwein rearrangement, pinacol-pinacolone rearrangement, and Cope rearrangement. Rearrangements are driven by stability of the carbocation intermediate or relief of ring strain.
The Baeyer-Villiger rearrangement involves the reaction of ketones with peroxy acids, resulting in the conversion of ketones to esters and cyclic ketones to lactones. A typical example is the reaction of acetophenone with perbenzoic acid to produce phenylacetate. The reaction proceeds through an anionotropic rearrangement where a group migrates from carbon to the electron-deficient oxygen. The Baeyer-Villiger rearrangement has applications in synthesizing lactones, anhydrides, and medicinal compounds.
Molecular Rearrangements of Organic Reactions ppsOMPRAKASH1973
This PPT is usefull for aspirants of JEE-IIT, CSIR-NET and UPSC exams in CHEMISTRY section. It is also usefull for grduates and Post graduates students of Indian Universities.
This document discusses classical and nonclassical carbocations. Nonclassical carbocations have charge delocalization from neighboring bonds like C=C pi bonds. The main difference is that classical carbocations have charge localized on one carbon, while nonclassical carbocations have charge delocalized by double or single bonds not in the allylic position. Examples like the norbornyl carbocation are given to show how neighboring double bonds can stabilize and delocalize charge through 3-center bonds. Reaction rates and product stereochemistry provide evidence for nonclassical intermediates. While some challenged this view, most chemists accept nonclassical interpretations of carbocation reactions.
The document summarizes the Favorskii and Wolff rearrangements. The Favorskii rearrangement involves the base-catalyzed rearrangement of cyclopropanones and α-halo ketones, forming carboxylic acid derivatives. It proceeds through the formation of an enolate intermediate and a cyclopropanone, which is then attacked by the nucleophile. The Wolff rearrangement can occur thermally, photochemically, or via transition metal catalysis, and involves 1,2-migration of substituents with the migratory aptitude of H > aryl > alkyl. Both rearrangements form a carbonyl group at the migration origin and involve migration of an electron-rich carbon terminus.
DIBAL-H is a commercially available selective reducing agent that can reduce esters and nitriles to the corresponding aldehydes. It is prepared by heating triisobutylaluminum, which induces beta hydride elimination to form DIBAL-H and isobutene. DIBAL-H selectively reduces esters to aldehydes at low temperatures through a tetrahedral intermediate. Hydrolytic workup of this intermediate then yields the desired aldehyde products. The document provides an introduction to DIBAL-H including its preparation, applications in organic synthesis, and how it differs from other reducing agents like LiAlH4.
The document discusses the Wagner-Meerwein rearrangement, a reaction first observed in 1899 where a carbocation is generated followed by a [1,2]-shift of an adjacent carbon-carbon bond to form a new carbocation. This reaction was not fully understood until 1922 when its ionic nature was revealed. The rearrangement involves the migration of hydrogen, alkyl, or aryl groups between carbocations and can involve multiple consecutive shifts. It can be initiated through various means to generate the initial carbocation and the migrating group retains its stereochemistry.
The document summarizes the Tiffeneau–Demjanov rearrangement reaction. It was discovered in the early 1900s by French chemist Marc Émile Pierre Adolphe Tiffeneau and Russian chemist Nikolay Yakovlevich Demyanov. The reaction involves treating 1-aminomethyl-cycloalkanol with nitrous acid to form an enlarged cycloketone through a 1,2-carbon migration. This ring expansion reaction is useful for increasing the size of amino-substituted cyclic compounds from four to eight-membered rings. The mechanism involves diazotization of the amine to form a diazonium ion that undergoes 1,2-alkyl shift accompanied by nitrogen loss to form
This is a brief introduction to the Baeyer-Villiger Oxidation/Rearrangement in the form of a micro-presentation.
The Baeyer-Villiger Oxidation is useful in the synthesis of esters and lactones. Consult the pdf file for more information.
You are encouraged to visit :
http://www.harinchem.com/named_organic_reactions.html to view a flash micro movie of the mechanism.
Please send feedback or questions through:
http://www.harinchem.com/contactpage.aspx.
The importance of lactone synthesis is underscored by its presence in diverse molecules of pharmacological significance, including statins (HMG CoA reductase inhibitors).
E1 &E2 mechanism, sandmeyer and benzyne mechanismlsk1976
The document discusses the Sandmeyer reaction, which is a type of radical-nucleophilic aromatic substitution reaction that replaces an amino group on an aromatic ring with different substituents. During the reaction, the amino group is converted to a diazonium salt that can then be transformed into various functional groups using a catalyst. It also describes the reaction of halobenzenes with potassium amide in liquid ammonia to yield aniline, which proceeds through an elimination-addition mechanism involving the elimination of an alpha hydrogen and addition of an amide anion to form an intermediate benzyne structure.
The document summarizes the dienone-phenol rearrangement, which is the acid- or base-catalyzed migration of alkyl groups in cyclohexadienones, resulting in highly substituted phenols. It was first described in 1893 for the rearrangement of santonin to desmotroposantonin under acidic conditions, but was more fully characterized in 1930. The rearrangement requires only moderately strong acids and is exothermic. It proceeds by a [1,3] sigmatropic migration of C-C bonds, which actually occurs through two subsequent [1,2] alkyl shifts. Depending on the migrating group, other rearrangements such as [1,2], [1,3], [
1. The von Richter reaction involves reacting aromatic nitro compounds with potassium cyanide, which results in the displacement of the nitro group and addition of a carboxyl group in the ortho position through cine substitution.
2. The reaction mechanism eluded chemists for almost 100 years before the currently accepted one was proposed.
3. This reaction is an example of cine aromatic nucleophilic substitution where the nitro group is replaced by a carboxylic group, which is always in the ortho position. However, the reaction has limited application and poor yields.
This slide is about the reagent named manganese dioxide which is an oxidative reagent for alcohols. Here you can learn briefly about the reagent and can improve your knowledge of organic chemistry. This slide is made by referring to many books and made easy for you to study. Hope you can understand it.
The Favorskii rearrangement is a rearrangement of cyclopropanones and α-halo ketones that leads to carboxylic acids or their derivatives. It involves the formation of an enolate away from the halogen that cyclizes to a cyclopropanone intermediate, which is then attacked by a nucleophile like hydroxide or an alkoxide base to yield an acid, ester, or amide through ring contraction. The reaction is useful for preparing carboxylic acids, esters, and amides.
The Paternò-Büchi reaction involves the photochemical reaction between a carbonyl compound and an alkene to form an oxetane ring. This reaction was first reported in 1909 by Paternò and Chieffi. Several mechanisms are possible, including those involving a diradical intermediate or photoinduced electron transfer. The reaction shows regioselectivity, site selectivity, and stereoselectivity that depend on factors such as the solvent, substituents on the carbonyl compound or alkene, and temperature. The Paternò-Büchi reaction has been used to synthesize various natural products and allows formation of oxetane rings, which are present in several biologically active compounds.
Protecting groups and deprotection- -OH, -COOH, C=O, -NH2 groups.SANTOSH KUMAR SAHOO
This document discusses various protecting groups used in organic synthesis. It begins by defining a protecting group as a molecular framework that is introduced onto a functional group to block its reactivity under reaction conditions needed for modifications elsewhere in the molecule. The document then summarizes several common protecting groups for hydroxyl, amine, and carboxylic acid functional groups including methyl, benzyl, and silyl ethers for alcohols as well as Boc, Fmoc, Cbz, and other carbamates for amines. It provides details on the formation and cleavage of each protecting group.
The document discusses the Diels-Alder reaction, which is a [4+2] cycloaddition reaction between a conjugated diene and a dienophile to form a six-membered ring. The reaction is initiated by heat and proceeds through a concerted mechanism. The reaction is stereospecific and favors the endo product. It has many applications including the synthesis of steroids, aromatic compounds, flame retardants, and pesticides.
1. Reaction mechanisms can be determined through various methods like identifying products, detecting intermediates through isolation, trapping or labeling studies, studying the effects of catalysts and acids, and performing kinetic studies.
2. Isotope labeling and crossover experiments involve using isotopically labeled reactants to determine whether reaction pathways are intra- or intermolecular. Kinetic isotope effects also provide information about which bonds are broken or formed in the rate-determining step.
3. Acid and base catalysis can indicate whether proton transfer is involved in the rate-determining step. General acid catalysis means proton transfer is rate-determining while specific catalysis means it is not.
The Wagner-Meerwein rearrangement is an organic reaction that converts an alcohol to an olefin using an acid catalyst. It involves the formation of a carbocation intermediate followed by a 1,2-shift of a group to form a more stable carbocation. This is then deprotonated to form the olefin product. It can be used to rearrange highly branched compounds and reduce ring strain in cyclic compounds. Examples include the rearrangement of neopentyl alcohols and bicyclic terpene derivatives.
IMPORTANT NAMED REACTIONS in Organic synthesis with Introduction, General Mechanism, and their synthetic application covering more than 20 named reactions in it.
The document discusses carbenes, which are molecules containing a neutral carbon atom with two unshared valence electrons. Carbenes can be classified as singlets or triplets based on their electronic structure. The document also describes the Wolff rearrangement, where α-diazoketones lose nitrogen to form reactive ketenes. Some applications of the Wolff rearrangement include the synthesis of carboxylic acid analogues, acid amides from carboxylic acids, and esters from carboxylic acids.
The presentation is prepared for lecture for the M. Sc Chemistry students studying under University of Madras (MER3A: Unit III). It is dealing with Aromaticity and Organic Photochemistry
The Barton reaction involves the photolysis of an alkyl nitrite to form a δ-nitroso alcohol which can dimerize or form an oxime. Sir Derek Barton discovered this reaction in 1960 and was awarded the Nobel Prize in Chemistry in 1969 for his work, including understanding the Barton Reaction. The reaction mechanism involves homolytic cleavage of the RO-NO bond, followed by δ-hydrogen abstraction, radical recombination, and tautomerization to form an oxime. An example provided is the Barton reaction of butyl nitrite to form a δ-nitroso butanol that can then dimerize or form an oxime. Applications include the synthesis of natural products like hormones and alkaloids.
The Claisen rearrangement is a thermal rearrangement reaction discovered by Rainer Ludwig Claisen in which the allyl group of a phenolic allyl ether migrates ortho to the phenol group. Key characteristics of the Claisen rearrangement are the inversion of the migrating allyl carbon and the intramolecular, unimolecular nature of the reaction. The mechanism involves a cyclic transition state that allows for migration to the ortho position, or para if both ortho positions are blocked.
This powerpoint is about the swern oxidation...It is used for the oxidaton of alcohol and inorder to avoid the chromium reagent. Follow me through youtube
CHE-MYSTERY
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This document presents a reaction mechanism for the atmospheric photochemical oxidation of benzene initiated by reaction with hydroxyl radicals. It develops an elementary reaction mechanism including 29 reactions and 26 species. Rate constants and thermodynamic parameters are analyzed using quantum Rice-Ramsperger-Kassel theory and group additivity techniques to determine equilibrium concentrations of reaction intermediates and product formation rates under atmospheric conditions. The mechanism accounts for important reaction intermediates like benzene-OH adducts and their reactions leading to ring-opening products such as dicarbonyl compounds.
The document discusses the Wagner-Meerwein rearrangement, a reaction first observed in 1899 where a carbocation is generated followed by a [1,2]-shift of an adjacent carbon-carbon bond to form a new carbocation. This reaction was not fully understood until 1922 when its ionic nature was revealed. The rearrangement involves the migration of hydrogen, alkyl, or aryl groups between carbocations and can involve multiple consecutive shifts. It can be initiated through various means to generate the initial carbocation and the migrating group retains its stereochemistry.
The document summarizes the Tiffeneau–Demjanov rearrangement reaction. It was discovered in the early 1900s by French chemist Marc Émile Pierre Adolphe Tiffeneau and Russian chemist Nikolay Yakovlevich Demyanov. The reaction involves treating 1-aminomethyl-cycloalkanol with nitrous acid to form an enlarged cycloketone through a 1,2-carbon migration. This ring expansion reaction is useful for increasing the size of amino-substituted cyclic compounds from four to eight-membered rings. The mechanism involves diazotization of the amine to form a diazonium ion that undergoes 1,2-alkyl shift accompanied by nitrogen loss to form
This is a brief introduction to the Baeyer-Villiger Oxidation/Rearrangement in the form of a micro-presentation.
The Baeyer-Villiger Oxidation is useful in the synthesis of esters and lactones. Consult the pdf file for more information.
You are encouraged to visit :
http://www.harinchem.com/named_organic_reactions.html to view a flash micro movie of the mechanism.
Please send feedback or questions through:
http://www.harinchem.com/contactpage.aspx.
The importance of lactone synthesis is underscored by its presence in diverse molecules of pharmacological significance, including statins (HMG CoA reductase inhibitors).
E1 &E2 mechanism, sandmeyer and benzyne mechanismlsk1976
The document discusses the Sandmeyer reaction, which is a type of radical-nucleophilic aromatic substitution reaction that replaces an amino group on an aromatic ring with different substituents. During the reaction, the amino group is converted to a diazonium salt that can then be transformed into various functional groups using a catalyst. It also describes the reaction of halobenzenes with potassium amide in liquid ammonia to yield aniline, which proceeds through an elimination-addition mechanism involving the elimination of an alpha hydrogen and addition of an amide anion to form an intermediate benzyne structure.
The document summarizes the dienone-phenol rearrangement, which is the acid- or base-catalyzed migration of alkyl groups in cyclohexadienones, resulting in highly substituted phenols. It was first described in 1893 for the rearrangement of santonin to desmotroposantonin under acidic conditions, but was more fully characterized in 1930. The rearrangement requires only moderately strong acids and is exothermic. It proceeds by a [1,3] sigmatropic migration of C-C bonds, which actually occurs through two subsequent [1,2] alkyl shifts. Depending on the migrating group, other rearrangements such as [1,2], [1,3], [
1. The von Richter reaction involves reacting aromatic nitro compounds with potassium cyanide, which results in the displacement of the nitro group and addition of a carboxyl group in the ortho position through cine substitution.
2. The reaction mechanism eluded chemists for almost 100 years before the currently accepted one was proposed.
3. This reaction is an example of cine aromatic nucleophilic substitution where the nitro group is replaced by a carboxylic group, which is always in the ortho position. However, the reaction has limited application and poor yields.
This slide is about the reagent named manganese dioxide which is an oxidative reagent for alcohols. Here you can learn briefly about the reagent and can improve your knowledge of organic chemistry. This slide is made by referring to many books and made easy for you to study. Hope you can understand it.
The Favorskii rearrangement is a rearrangement of cyclopropanones and α-halo ketones that leads to carboxylic acids or their derivatives. It involves the formation of an enolate away from the halogen that cyclizes to a cyclopropanone intermediate, which is then attacked by a nucleophile like hydroxide or an alkoxide base to yield an acid, ester, or amide through ring contraction. The reaction is useful for preparing carboxylic acids, esters, and amides.
The Paternò-Büchi reaction involves the photochemical reaction between a carbonyl compound and an alkene to form an oxetane ring. This reaction was first reported in 1909 by Paternò and Chieffi. Several mechanisms are possible, including those involving a diradical intermediate or photoinduced electron transfer. The reaction shows regioselectivity, site selectivity, and stereoselectivity that depend on factors such as the solvent, substituents on the carbonyl compound or alkene, and temperature. The Paternò-Büchi reaction has been used to synthesize various natural products and allows formation of oxetane rings, which are present in several biologically active compounds.
Protecting groups and deprotection- -OH, -COOH, C=O, -NH2 groups.SANTOSH KUMAR SAHOO
This document discusses various protecting groups used in organic synthesis. It begins by defining a protecting group as a molecular framework that is introduced onto a functional group to block its reactivity under reaction conditions needed for modifications elsewhere in the molecule. The document then summarizes several common protecting groups for hydroxyl, amine, and carboxylic acid functional groups including methyl, benzyl, and silyl ethers for alcohols as well as Boc, Fmoc, Cbz, and other carbamates for amines. It provides details on the formation and cleavage of each protecting group.
The document discusses the Diels-Alder reaction, which is a [4+2] cycloaddition reaction between a conjugated diene and a dienophile to form a six-membered ring. The reaction is initiated by heat and proceeds through a concerted mechanism. The reaction is stereospecific and favors the endo product. It has many applications including the synthesis of steroids, aromatic compounds, flame retardants, and pesticides.
1. Reaction mechanisms can be determined through various methods like identifying products, detecting intermediates through isolation, trapping or labeling studies, studying the effects of catalysts and acids, and performing kinetic studies.
2. Isotope labeling and crossover experiments involve using isotopically labeled reactants to determine whether reaction pathways are intra- or intermolecular. Kinetic isotope effects also provide information about which bonds are broken or formed in the rate-determining step.
3. Acid and base catalysis can indicate whether proton transfer is involved in the rate-determining step. General acid catalysis means proton transfer is rate-determining while specific catalysis means it is not.
The Wagner-Meerwein rearrangement is an organic reaction that converts an alcohol to an olefin using an acid catalyst. It involves the formation of a carbocation intermediate followed by a 1,2-shift of a group to form a more stable carbocation. This is then deprotonated to form the olefin product. It can be used to rearrange highly branched compounds and reduce ring strain in cyclic compounds. Examples include the rearrangement of neopentyl alcohols and bicyclic terpene derivatives.
IMPORTANT NAMED REACTIONS in Organic synthesis with Introduction, General Mechanism, and their synthetic application covering more than 20 named reactions in it.
The document discusses carbenes, which are molecules containing a neutral carbon atom with two unshared valence electrons. Carbenes can be classified as singlets or triplets based on their electronic structure. The document also describes the Wolff rearrangement, where α-diazoketones lose nitrogen to form reactive ketenes. Some applications of the Wolff rearrangement include the synthesis of carboxylic acid analogues, acid amides from carboxylic acids, and esters from carboxylic acids.
The presentation is prepared for lecture for the M. Sc Chemistry students studying under University of Madras (MER3A: Unit III). It is dealing with Aromaticity and Organic Photochemistry
The Barton reaction involves the photolysis of an alkyl nitrite to form a δ-nitroso alcohol which can dimerize or form an oxime. Sir Derek Barton discovered this reaction in 1960 and was awarded the Nobel Prize in Chemistry in 1969 for his work, including understanding the Barton Reaction. The reaction mechanism involves homolytic cleavage of the RO-NO bond, followed by δ-hydrogen abstraction, radical recombination, and tautomerization to form an oxime. An example provided is the Barton reaction of butyl nitrite to form a δ-nitroso butanol that can then dimerize or form an oxime. Applications include the synthesis of natural products like hormones and alkaloids.
The Claisen rearrangement is a thermal rearrangement reaction discovered by Rainer Ludwig Claisen in which the allyl group of a phenolic allyl ether migrates ortho to the phenol group. Key characteristics of the Claisen rearrangement are the inversion of the migrating allyl carbon and the intramolecular, unimolecular nature of the reaction. The mechanism involves a cyclic transition state that allows for migration to the ortho position, or para if both ortho positions are blocked.
This powerpoint is about the swern oxidation...It is used for the oxidaton of alcohol and inorder to avoid the chromium reagent. Follow me through youtube
CHE-MYSTERY
Subscribe and press bell button for notfcation
This document presents a reaction mechanism for the atmospheric photochemical oxidation of benzene initiated by reaction with hydroxyl radicals. It develops an elementary reaction mechanism including 29 reactions and 26 species. Rate constants and thermodynamic parameters are analyzed using quantum Rice-Ramsperger-Kassel theory and group additivity techniques to determine equilibrium concentrations of reaction intermediates and product formation rates under atmospheric conditions. The mechanism accounts for important reaction intermediates like benzene-OH adducts and their reactions leading to ring-opening products such as dicarbonyl compounds.
The document discusses bio-inspired catalysts for hydrogen production. It begins by noting the importance of hydrogen as an energy carrier and limitations of existing platinum-based catalysts. It then discusses how hydrogenase enzymes provide an efficient model but have limitations as well. Recent research has focused on developing bio-inspired catalysts that incorporate features of the hydrogenase active site and outer coordination sphere to improve catalytic efficiency. Some promising systems discussed include macrocyclic cobalt complexes and nickel bis(diphosphine) complexes containing amino acid groups to mimic the outer coordination sphere, which have shown activity under broader conditions than hydrogenases. Evaluation of catalytic performance focuses on turnover frequency and overpotential.
Another client, Ms. Dunham, has asked you to help her understand h.docxjustine1simpson78276
Another client, Ms. Dunham, has asked you to help her understand how her tax is computed. You need to provide Ms. Dunham with the following:
· An example of how to calculate the tax liability using the tax rate table and the tax rate formula for a taxpayer with taxable income of $55,000, filing status married filing jointly.
· An explanation of the marginal tax rate and average tax rates for this tax payer.
Be clear in our elaboration s that Ms. Dunham, a person with no business or tax background, can understand.
Kinetics of the Hydrolysis of
Atmospherically Relevant
Isoprene-Derived Hydroxy Epoxides
N E I L C . C O L E - F I L I P I A K ,
A L I S O N E . O ’ C O N N O R , A N D
M A T T H E W J . E L R O D *
Department of Chemistry and Biochemistry, 119 Woodland
Street, Oberlin College, Oberlin, Ohio 44074
Received June 4, 2010. Revised manuscript received July
16, 2010. Accepted July 19, 2010.
Isoprene (the most abundant nonmethane hydrocarbon
emitted into the atmosphere) is known to undergo oxidation to
2-methyl-1,2,3,4-butanetetraol, a hydrophilic compound
present in secondary organic aerosol (SOA) in the atmosphere.
Recent laboratory work has shown that gas phase hydroxy
epoxides are produced in the low NOx photooxidation of isoprene
and that these epoxides are likely to undergo efficient acid-
catalyzed hydrolysis on SOA to 2-methyl-1,2,3,4-butanetetraol at
typical SOA acidities. In order to confirm this hypothesis, the
specific hydroxy epoxides observed in the isoprene photooxidation
experiment (as well as several other related species) were
synthesized, and the hydrolysis kinetics of all species were
studied via nuclear magnetic resonance (NMR) techniques. It
was determined that the isoprene-derived hydroxy epoxides
should undergo efficient hydrolysis under atmospheric conditions,
particular on lower pH SOA. An empirical structure-reactivity
model was constructed that parametrized the hydrolysis
rate constants according to the carbon substitution pattern on
the epoxide ring and number of neighboring hydroxy functional
groups. Compared to the previously studied similar nonfunc-
tionalized epoxides, the presence of a hydroxy group at the R
position to the epoxy group was found to reduce the hydrolysis
rate constant by a factor of 20, and the presence of a hydroxy
group at the beta position to the epoxy group was found to
reduce the hydrolysis rate constant by a factor of 6.
Introduction
Because secondary organic aerosol (SOA) is known to play
a critical role in issues such as air pollution (1) and climate
change (2), there continues to be intense interest in the
formation mechanisms for these particles. Isoprene,
the dominant non-methane hydrocarbon emitted into the
atmosphere (3), has only recently been implicated in SOA
formation. In 2004, Claeys et al. identified 2-methyl-1,2,3,4-
butanetetraol in SOA found in air samples from the Amazon
and inferred that it must be an oxidation product of isoprene
(4). Several laboratory an.
ACETYLATION OF BENZYLIC ALCOHOLS OVER BiFeO3 (BFO), Bi0.86Sm0.07Eu0.07FeO3 (B...EDITOR IJCRCPS
BiFeO3 (BFO), Bi0.86Sm0.07Eu0.07FeO3 (BSEFO), and Bi0.86Sm0.07Cd0.07FeO3 (BSCFO) nanopowders were prepared by the sol-gel
combustion method and the catalytic performances were evaluated in acetylation reaction of benzyl alcohol. The physical chemical
properties of catalysts were characterized by using XRD, FT-IR, scanning electron microscope (SEM), EDX and BET surface.
Efficient acetylation of benzyl alcohol was carried out over all the nano powders using acetyl chloride/ acetonitrile at room
temperature. Among the nanopowders, BSCFO showed the highest catalytic performance and the yield of benzyl acetate was 89,
45, and 69 percent over BSCFO, BFO, and BSEFO, respectively. Partial substitution of Sm-Eu and Sm-Cd in bismuth ferrite
improved the catalytic performance and increased the specific surface area of the catalysts. A direct relationship was resulted
between catalytic performance and surface of catalysts, where BSCFO with the highest surface area (111m2/g) exhibited the
superior catalytic performance. The quantitative yield for acetate product was also resulted for acetylation of p-methyl benzyl
alcohol, p-nitro benzyl alcohol and p-chloro benzyl alcohol on BSCFO. The catalysts showed good reusability in the process. The
study confirmed the catalysts could be promising catalyst for acetylation of alcohols.
Keywords: Europium, Samarium, Bismuth ferrites, nano perovskite, doping, Acetylation, benzylic alcohols.
The role of protons in the epoxidation of olefins using metal catalysts and oxidants like H2O2 was studied. Three key findings:
1) Protons play an important role in cleaving the O-O bond of hydroperoxides to form reactive metal-oxo intermediates.
2) Protons increase the reactivity of these metal-oxo species towards olefins, facilitating epoxide formation.
3) Reactions performed with H2SO4 as a bronsted acid produced epoxides in higher yields and enantioselectivities compared to without acid. Isotopic labelling studies supported a metal-oxo intermediate.
Organic inorganic hybrid cobalt phthalocyanine/polyaniline as efficient catal...Pawan Kumar
Organic inorganic hybrid catalyst synthesized by doping of cobalt phthalocyanine (CoPc) on polyaniline
support (CoPc/PANI) exhibited higher activity for the oxidation of various alcohols to the corresponding
carbonyl compounds in high to excellent yield using molecular oxygen as oxidant and isobutyraldehyde
as a sacrificial agent. Notably, the synthesized catalyst was found to be truly heterogeneous in nature and
could be easily recovered, recycled for several recycling runs without loss of catalytic activity
Andrew Fielding's doctoral research focused on understanding the mechanism of O2 activation and catalysis by two similar catechol dioxygenases: Fe(II)-homoprotocatechuate 2,3-dioxygenase (Fe-HPCD) and Mn(II)-MndD. He prepared and characterized the cobalt-substituted variant of HPCD, which showed higher activity than Mn- or Fe-HPCD despite Co(II) being a poorer reducing agent. Using electron-poor substrate analogs, he was able to trap and characterize three O2 intermediates by EPR, providing new insights into dioxygenase mechanisms. Comparing the properties of different metal-substituted enzymes allowed full characterization
This document discusses research into synthesizing and characterizing isoprene hydroperoxides, which are atmospheric oxidation products of isoprene that can influence air quality and climate. The researchers developed a synthetic route to produce hydroperoxides via reactions of epoxides with peroxy nucleophiles. Preliminary results identified four potential hydroperoxide compounds via chromatography. However, only one, 3,4-isoprene hydroperoxide, was conclusively characterized with NMR. Future work will optimize purification methods and synthesize additional isoprene hydroperoxides to enable kinetic and gas phase studies of these compounds.
This document summarizes key aspects of palladium-catalyzed cross-coupling reactions, with a focus on the Heck reaction and its mechanisms and applications. The Heck reaction involves the coupling of alkenyl or aryl halides with alkenes, catalyzed by palladium. The mechanism proceeds through oxidative addition, transmetalation, and reductive elimination steps. The document discusses factors that determine regioselectivity and provides examples of the Heck reaction in total syntheses of natural products like dehydrotubifoline, capnellene, and taxol. It also describes domino and intramolecular Heck reactions and summarizes the related Stille coupling reaction.
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1. Baeyer-Villiger Oxidation
The Baeyer-Villiger oxidation, also known as the Baeyer-Villiger rearrangement, was first reported
on December 17, 1899 by Adolf Baeyer and Victor Villiger in Chemische Berichte. It is a popular
synthetic tool for the conversion of acyclic ketones to esters and cyclic ketones to lactones, of which
the latter are precursors to hydroxy acids and acyclic diols. Aromatic aldehydes bearing alkoxy
substituents can be converted to the corresponding fomates and phenols.
The original contribution of Baeyer and Villiger referred to the conversion of the cyclic ketones
menthone (1) and tetrahydrocarvone (2) to the respective lactones by monoperoxysulfuric acid,
also known as Caro’s acid:
O O
O
O O
O
H2SO5
H2SO5
(1)
(2)
Since then, the utility, regioselectivity and stereospecificity of the reaction has been extended by
new transition metal catalysts, zeolite based catalysts, alumina, mesoporous catalysts, enzymes
and the application of ultrasound. Metachloroperoxybenzoic acid (MCPBA), peroxybenzoic acid
(PBA), and trifluoroperoxyacetic acid (TFPAA) are among the most common peracids used. More
recent reagent systems include the magnesium salt of monoperoxyphthalic acid (MMPP), sodium
perborate,sodium percarbonate, hydrogen peroxide in the presence of boron trifluoride or
diselenides. Catalytic Baeyer-Villiger oxidations were feasible with methyltrioxorhenium and
hydrogen peroxide in the ionic liquid [bmim]BF4 . Oxone has been used to effect the oxidation in
[bmim]BF4. Potassium peroxomonosulfate supported on hydrated silica (‘reincarnated Caro’s
acid’) is also known; the reaction is more efficient when carried out in supercritical carbon dioxide.
Molecular oxygen has been used to effect a variety of Baeyer-Villiger oxidations at room
temperature. Recently introduced catalysts include pentafluorophenyl borates, mesoporous
zirconium phosphate and graphite.
Baeyer-Villiger monooxygenases have found increasing application through the development of
recombinant bacteria and fungi. The monoxygenases depend on flavin (FAD) as a cofactor and a
molecule such as NADPH or NADH to act as a reducing agent. Advantages associated with the
application of monoxygenases include high regioselectivity and enantioselectivity.
MCPBA preferentially yields the corresponding epoxide in the presence of a double bond, at low
temperature in an inert solvent without the presence of an acid catalyst. Application of
bis[trimethylsilyl] peroxide (BTSP) minimizes epoxide formation when an alkene is present. It was
demonstrated that BTSP can also be used as an effective reagent in the ionic liquid
1-n-butyl-3-methylimidazolium trifluoromethanesulfonate (bmimOTf). See page 14.
Base catalyzed rearrangements are less common. The mechanistically similar Dakin reaction is
generally conducted in basic conditions, leading to phenols and catechols from aromatic
aldehydes. See page 4 and compare with example 12 in page 7.
1
2. Mechanism
The most accepted mechanism is that proposed by Criegee, or a variation of it.
Salient features of the mechanism are.
1) Retention of stereochemistry by the migrating group.
2) Migration is concerted with the departure of the leaving group. The concerted step is rate
determining.
3) Migrating groups with greater electron donating power have correspondingly greater
migratory aptitude because of the increased ability to stabilize a positive charge in the
transition state. This renders stereoselectivity to the oxidation of unsymmetrical ketones.
The general order of migration is:
tertiary alkyl > cyclohexyl > secondary alkyl > benzyl > phenyl > primary alkyl > H
4) Migration is favored when the migrating (Rm
) group is antiperiplanar to the O-O bond of
the leaving group; this is known as the primary stereoelectronic effect. The antiperiplanar
alignment of the lone pair of electrons on oxygen with the migrating group is the
secondary stereoelectronic effect.
O
O
Rm
O
COR'
R
H
primary
secondary
4) Electron withdrawing groups on the peroxyacid and peroxide enhance the rate of
rearrangement.
The mechanism can be depicted as in Scheme (I):
R R
O
H
R R
O
H
O
O
R
OH
R
R
O
H
O
O
O
R
H
R OR
O
H
R OR
O
R R
O
H
O
O
O
R
H
Scheme I
Baeyer-Villiger oxidation of cyclohexanone is represented in Scheme II.
Schemes I and II provide general reaction mechanisms for acid catalyzed reactions.
2
3. O
H
O
H
O
R
O
O
H O
H
O O
O
R
O
O
H
O
O
H
Scheme II
Scheme III represents the rearrangement of the Criegee intermediate in a cyclical manner.
Rm
R
O
O H
O
O
R'
Scheme III
In the case of haloketones, migration tends to occur from the non-halogenated carbon.
Reactions conducted in non-polar solvents may follow a non-ionic mechanism; see additional
notes and references.
Baeyer-Villiger reaction of benzaldehydes often proceed by migration of the hydride ion instead of
the aryl group. In a study by Adejare, hydride ion migration occurred faster than phenyl ion migration
when the phenyl group had halogen substituents, resulting in the formation of carboxylic acid
instead of phenol; aromatic aldehydes possessing electron withdrawing groups have a strong
tendency to produce the corresponding carboxylic acids, in contrast to aromatic aldehyde(s) with
electron donating group(s).
Journal of Fluorine Chemistry (2000), 105, 107.
F
Br
CHO
F
Br
COOH
CH2Cl2, reflux
(74%)
MCPBA
3
4. A recent and interesting development is the selective transformation of both primary aliphatic
aldehydes and aromatic aldehydes to formates involving a hypervalent λ3
-bromane, by Ochiai.
The following pathway was proposed by Ochiai.
R
O
R'
H2O
R R'
HO OH
+
Br
CF3
F F
R'
R
OH
O
Br
F
Ar
ArBr
R'
O
OR
Br (III) Criegee intermediate
Journal of the American Chemical Society (2010), 32, 9236. See page 12 for corresponding
examples.
The Dakin reaction is portrayed here for comparison.
HO
O
R
H
O O
HO
R
O
O O
H
O
HO
O
R
OH
HO
H2O, OH
Recent examples of the Dakin reaction involving nucleophilic flavin catalysts are provided by
the publications of Chen and Foss in Organic Letters (2012), 14,11, 2806-2809.
An organometallic reaction proceeding through a mechanism similar to that of the Baeyer-Villiger
rearrangement was demonstrated by Periana, where an aryltrioxorhenium species was oxidized
to the corresponding phenol. Organometallics (2011),30, 2079.
Re
O
O
O
YO
YO = IO4, H2O2, PhIO4
Re
O
O OH
O Y
δ
δ
Examples follow; see pages 5-13.
4
5. Examples:
O
C6H13
O
O
C6H13
MMPP, NaHCO3
(1)
(2)
O
J. Org. Chem (1997), 62, 2633. 95%
O
O
O2, PhCHO
Fe2O3, 200
C
Angew. Chem. Int. Ed (1998), 37, 1198. 92%
MeOH
(3)
O
Na2CO3, H2O2, Ac2O O
O
))) 6h
Chemical Abstracts (1996), 123, 316192j. 84%
(4)
Tet. Lett (1977), 31, 2713. 69%
MCPBA
O
O
O
(5)
Cl
O
Cunninghamella echinulata Cl
OH
O
Tet. Lett (1997), 38,1195. > 99% ee
31%
(6)
O
CPMO O
O
CPMO = cyclopentanone monooxygenase
Chem. Commun (1996), 2333. 98% ee
quantitative
5
6. O
Me
O
O
Me
CHMO =cyclohexanone monooxygenase
J. Org. Chem (2003), 68, 6222. 99% ee
100% conversion
(7)
CHMO
(8)
O
*Engineered e.coli cells O
O
* E. coli cells that overexpress cyclohexanone monooxygenase
J. Org. Chem (2001), 66, 733. 48%
(9)
O
H2O2 (60%)
1 mol % catalyst
CF3CH2OH
O
O
J. Org. Chem (2001), 66, 2429 99%
Se
F3C
F3C
2
= catalyst
(10)
N
Cbz
H
H
O
H
Cl
N
Cbz
H
H
H
Cl
O
O
MCPBA
NaHCO3
CH2Cl2, rt, 30 min
J. Org. Chem (2002), 67, 3651. 85%, only product
6
7. (12)
CHO
OMe
O
OMe
O
OH
OMe
catalyst, H2O2
MeCN, 80 0
C, 7 h
87% total conversion
Beta-7 zeolite = catalyst
SnO2 content = 0 %; Si:Al ratio = 30 (mol/mol)
Journal of Catalysis (2004), 221, 67.
1% 95%
(11)
O
O
OH2O2 (35%), 1 mol % catalyst
CF3C6F11, (CH2)2Cl2
93%
Sn[N(SOCF17)2]4 = catalyst
25 0
C, 2h
Tet. Lett (2003), 44, 4977.
(13)
O
n
MCPBA
CH2Cl2, rt, 4d
O
x O
O
y
Macromolecules (2004), 37, 4484.
73%
ketone/ester = x/y = 82/18
(14)
O
catalyst, H2O2
t-BuOH, 650
C, 5h
60%
COOH
catalyst = 0.6 mol%
Se)2
Se)2
Syn. Comm (1999), 29, 2981.
7
8. (15)
O
Ph
5.2 eq. 30% H2O2
5 mol% catalyst
OTf
Se
2
catalyst = 5 mol %
O
O
Ph
Tet. Lett (2005), 46, 8665.
85%
CH2Cl2, RT, 24 h
(16)
O
O
O
hydr-Sio2.KHSO3
sc CO2
250 bar, 400
C
96%
J. Org. Chem (2006), 71, 6432.
(17)
O
O
O
PhCHO, O2
))) 2h, CCl4
87.7%
Chemical Eng. Journal (2006), 121, 63.
(18)
N
Ts
O
OBn
MCPBA, NaHCO3
O
N
O
Ts OBn
73%
Tet. Lett (2006), 47, 4865.
CH2Cl2
8
9. O
O
O
O
O
00
C, CH2Cl2, 1h
H H
H
COOMe
COOMe
(a)
(b)
TFPAA
a: b = 4: 1
75%
Steroids (2007), 72, 466.
(20)
Me
O
COOMeCbzHN
H
Me
O
COOMeCbzHN
H
Ph PhO
TFPAA
00
C, CH2Cl2, > 5 h
J. Org. Chem (2008), 73, 2633..
75%
(19)
COOMe
9
10. (21)
Ph
O O
Ph
O
CHCl3, 18h
H2O2, catalyst (10 mol%)
99%
ee = 88% R
Angewandte. Chem. Int. Ed (2008), 47, 2840.
catalyst:
O
X
P
O
OH
O
X = pyren-1-yl
X
(22)
O
HO HO
O OPenicillium lilacinum AM111
dehydroepiandrosterone (DHEA)
36 h
(85%)
Steroids (2008), 73, 441-1445.
(23)
O
OMe
OMeH
OMe
MCPBA, PTSA
CH2Cl2, rt
OMe
OMeH
OMe
O
O
75%
Tet. Lett (2010), 51, 93..
10
11. (24)
O
O
O
MCPBA, NaHCO3
CH2Cl2, 00
C, 30 min
O
O
60% 30%
+
Tet. Lett (2009), 50, 4519.
(25)
BnO
O
MCPBA
CH2Cl2, rt, 32h BnO OCOCH3
quantitative
Org. Lett (2010), 12, 508.
(26)
Me H
H
OH
Me
O
Me
O
Me
Me
Me H
H
OH
OAc
Me
O
Me
Me
1,2 DCE
rt, then 80 0
C, 48h
MCPBA (4 eq)
65%
JACS (2010), 132, 23, 8219.
11
12. (27)
aryl bromane (1.5 eq)
68%
JACS (2010), 132, 23, 9236.
CH3CH2CHO CH3CH2OCHO
H2O, CH2Cl2, 0 0
C
PhCHO PhOCHO
98%
aryl bromane:
Br
F F
CF3
O
Me O
O
Me
93%
+
O
O
Me
1%
(28)
Tet. Lett (2011), 52, 23, 458.
O
O
O
MCPBA (1.2 eq)
10 mol% CAN
CH2Cl2, 0 0
C to rt, 6h
75%
12
13. (29)
Tet. Lett (2012), 68, 9061-9068.
MCPBA, CHCl3O
Cl
C8H17
C8H17
O
O
Cl
p-TsOH, r.t, 16 days
+
O
Cl
H
H O
H
77 : 23
(30)
O
MCPBA
CH2Cl2, r.t, 2 days O
O
70%
Angewandte. Chem.Int. Ed (2012), 51, 2485-2488
(32)
98%%
J. Org. Chem (2013), 78, 93-103.
O
O
H
O
MMPP
O
O
H
O
O
(31)
O
O
O
catalyst (1 mol%)
30% H2O2 (1.1 eq)
77%
Angewandte Chemie International Edition (2012), 51,36, 9093-9096.
catalyst: LiB(C6F5)4.2.5Et2O
DCE (0.05M), 70 0
C
13
14. Additional Notes and References
An example of reversed regioselectivity was reported by Mikami and Yamanaka:
O
O
O
CF3
TFPAA ( 2.0 eq )
F3C
quantitative
O
O
CF3
not observed
rt, CH2Cl2, 16h
TFA ( 7.0 eq )
Organic Letters (2003),5, 25, 4803
Grein and Crudden published a study of the Baeyer-Villiger reaction of haloketones in the
Journal of Organic Chemistry (2006), 71, 861. The reaction mechanism is reviewed in
detail.
A scholarly review of the Baeyer-Villiger oxidation is given by Krow in volume 43 of
Organic Reactions (1993). Renz and Meunier provide an excellent complementary
discussion of historical aspects in the European Journal of Organic Chemistry (1999), 737-
750.
Mora-Diez and coauthors have argued against an ionic mechanism for Baeyer-Villiger
oxidations conducted in non polar solvents; an alternative mechanism is presented,
favoring concerted deprotonation during the addition and migration steps.
Organic and Biomolecular Chemistry (2009), 7, 3682.
Lactone synthesis was accomplished using methyltrioxorhenium/hydrogen peroxide in
N
N
BF4
the ionic liquid 1-n-butyl-3-methylimidazolium tetrafluoroborate[bmim]BF4, as reported in
Tetrahedron Letters (2003), 44, 8991.
Baeyer-Villiger oxidation of ketones with bis(trimethylsilyl) peroxide in the presence of
bmimOTf resulted in yields exceeding 70%, except for the oxidation of tetralone.
Green Chemistry (2009), 11, 279.
Chrobok’s group performed the oxidation with oxone (2KHSO5.KHSO4.K2SO4) in a variety
of ionic liquids; bmimBF4 and HmimOAc offered maximum yields (95-96%).
Tetrahedron (2010), 66, 6212.
14
15. The magnitude of the preference for antiperiplanar migration over gauche migration is
discussed by Radkiewicz-Poutsma in the Journal of Organic Chemistry (2004), 69, 7148.
Microwave accelerated Baeyer-Villiger synthesis of lactones was investigated by Ritter:
Tetrahedron (2006), 62, 4709.
Yamabe and Yamazaki recently discussed the role played by hydrogen bonds in the
rearrangement; their opinions are expressed in the Journal of Organic Chemistry (2007),
72, 3031.
Zeolite based catalysts and clay based catalysts for Baeyer-Villiger oxidation were
reviewed by Ruiz and Jimenez-Sanchidrian in Tetrahedron (2008), 64, 2011.
The mechanism of cyclohexanone monooxygenase is outlined in The Organic Chemistry of
Drug Action. Silverman, Richard B. (2002). Academic Press. ISBN 0-12-643731-9.
Enantioselectivities of recently isolated Baeyer-Villiger monooxygenases toward alkyl
substituted cyclohexanones are reviewed in Tetrahedron (2009), 65, 947 and
Chemical Reviews (2011), 111, 7, 4165.
The role of FAD (flavin adenine dinucleotide) in enzymically catalyzed Baeyer-Villiger
reactions is discussed by Walsh and Wencewicz in a recent review of flavoenzymes.
Natural Product Reports (2013), 30, 175-200.
Application of platinum (II) catalysts in conjunction with chelating diphosphines is
reviewed by Giorgio Strukul and co-authors in Coordination Chemistry Reviews (2010),
254, 646-660.
Lei and coworkers published an account of the use of silica supported sulfate acid
catalyst to effect the Baeyer-Villiger oxidation in excellent yields (86-100%).
Catalysis Communications (2011), 12, 798.
In addition to the examples given above (4, 10, 18, 23-26, 28-30), other citations of the
recent application of meta-chloroperoxybenzoic acid to implement the Baeyer-Villiger
oxidation are listed below.
Journal of Organic Chemistry (2011), 76, 1662.
Journal of Organic Chemistry (2011), 76, 2315.
Chemical Communications (2011), 47, 3745.
Tetrahedron (2012), 68, 47, 9612-9615.
Baeyer-Villiger oxidation at room temperature using molecular oxygen and benzaldehyde
over mesoporous zirconium phosphate was demonstrated by Sinhamapatra and Sinha.
Yields varied from 75% to 100% for the oxidation of alicyclic ketones. Similar yields were
reported when MCPBA was substituted for molecular oxygen.
Catalysis Science and Technology (2012), 2, 2375-2382.
Alegria's group showed that rhenium compounds were more active for the oxidation of
cyclic (4, 5 and 6-membered) rings than the acyclic ketones. Rhenium complexes bearing
N- or oxo-ligands were used. This is an example of homogenous catalysis.
Applied Catalysis A: General (2012), 443-44, 27-32.
(Copyright: HARINDRAN NAMASIVAYAM, 2002-2013)
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