DOCSLIB.ORG

Efficient and Sustainable Laccase-Catalyzed Iodination of P

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Efficient and Sustainable Laccase-Catalyzed Iodination of P RSC Advances View Article Online PAPER View Journal | View Issue Efficient and sustainable laccase-catalyzed iodination of p-substituted phenols using KI as Cite this: RSC Adv.,2019,9, 19549 iodine source and aerial O2 as oxidant† Mark Sdahl, Jurgen¨ Conrad, Christina Braunberger and Uwe Beifuss * Received 4th April 2019 The laccase-catalyzed iodination of p-hydroxyarylcarbonyl- and p-hydroxyarylcarboxylic acid derivatives Accepted 27th May 2019 using KI as iodine source and aerial oxygen as the oxidant delivers the corresponding iodophenols in DOI: 10.1039/c9ra02541c a highly efficient and sustainable manner with yields up to 93% on a preparative scale under mild rsc.li/rsc-advances reaction conditions. Introduction For the preparation of iodophenols the electrophilic aromatic substitution is also the most widely used method. For The iodophenol moiety represents an important structural this purpose, phenols are reacted (a) with iodination agents like Creative Commons Attribution-NonCommercial 3.0 Unported Licence. 11a 11b 11c 11d 11e 11f motif for many of the nearly 200 iodine-containing natural NIS, PyICl, TICA, BMPDCI, IPy2BF4, BTMA ICl2, 1 11g 11h 11i 11j products known so far. Typical examples include the cytotoxic I2, I2-amine complex, I2/AgNO3, or I2/KI, (b) with I2 in 12a tyramine derivative iodocionin (I) from the Mediterranean combination with an oxidant, such as (n-BuPPh3)2S2O8, 2a 0 12b 12c 12d 12e 12f ascidian Ciona edwardsii, the cytotoxic 6 -iodoaureol (II) from HIO3, K2FeO4/K10, H2O2, O2/NaNO2 or TICA/SiO2, (c) the sponge Smenospongia sp.,2b the antibiotic cyclic depsipep- with an iodide in combination with an oxidant such as NaO- 2c 13a 13b 13c 13d 13e 13f 13g tide miuraenamide B (III) from the myxobacterial SMH-27-4 Cl, NaClO2, H2O2, KClO3, NaIO4, oxone, KIO3, 2d 13h 13i 13j and the thyroid hormones triiodothyronine (IV) and thyroxin DMSO, H2SO4 or tert-butylhypochlorite. (V) (Fig. 1).2d The most prominent non-natural biologically Most of these methods have a number of serious disadvan- This article is licensed under a active iodophenol is amiodarone (VI)3 which is widely used as tages. Among them are the use of more than equimolar an antiarrhythmic drug in the treatment of ventricular and amounts of iodination agents and/or oxidants. Many of the supraventricular tachyarrhythmias. Iodoaromatics in general reagents employed are acutely toxic, corrosive, explosive and Open Access Article. Published on 21 June 2019. Downloaded 10/2/2021 6:58:20 AM. and iodophenols in particular are important substrates for Pd- catalyzed cross couplings,4 such as the Sonogashira-coupling,5a the carbonylative Sonogashira-coupling,5b the Negishi-cou- pling,5c the Suzuki–Miyaura-coupling5d and related reactions,5e Stille-,5f Hiyama-5g and Heck-couplings.5h Iodophenols can also be used as substrates for the preparation of organometallics, such as Grignard reagents, under suitable conditions.6 This is why the development of selective, efficient and environmentally benign methods for the preparation of iodoaromatics in general and iodophenols in particular is of the greatest importance. Over the years, a number of methods have been developed for the preparation of iodoaromatics.7 Without doubt, the most popular is the electrophilic aromatic substitution. Among the classical methods are also the Sandmeyer reaction,8 the ortho- lithiation/halogenation9 and the Hunsdiecker reaction.10 Recently, the synthesis of iodoaromatics has been achieved by methods which are based on sp2 C–H activation.7b Bioorganische Chemie, Institut fur¨ Chemie, Universitat¨ Hohenheim, Garbenstr. 30, Stuttgart, D-70599, Germany. E-mail: [email protected]; Fax: +49 711 459 22951; Tel: +49 711 459 22171 † Electronic supplementary information (ESI) available: Experimental data and copies of the 1H NMR and 13C NMR spectra. See DOI: 10.1039/c9ra02541c Fig. 1 Important iodinated phenolic compounds. This journal is © The Royal Society of Chemistry 2019 RSC Adv.,2019,9, 19549–19559 | 19549 View Article Online RSC Advances Paper oxidizing, while others are commercially not available, expen- accompanied by the reduction of O2 to H2O, which is the only sive or difficult to prepare. In addition, many iodinations have byproduct of laccase-catalyzed reactions. Laccases with low to be performed in highly volatile and/or toxic organic solvents. (0.4–0.5 mV), medium (0.5–0.6 mV) and high (0.7–0.8 mV) redox 20a–c Most electrophilic aromatic substitutions with I2 or iodide as potentials are known. By using laccase/mediator systems the iodine source can only be run successfully in the presence of substrate scope of laccase-catalyzed oxidations can be signi- heavy metal reagents and/or strong oxidants. All methods which cantly widened.19,20d Among the transformations that can be make use of I2 as iodine source suffer from the fact, that only catalyzed by laccases on a semi preparative or preparative scale 21a one iodine atom ends up in the product of the electrophilic are oxidations of several functional groups (CH3 / CHO, 21b 21c aromatic substitution while the other remains unused in the CH2OH / CHO, CH2OH / CO2H, CH2NH2 / CHO/ 21d reaction medium. Clearly, this results in lower values of atom CO2H ), the transformation of 1,4-dihydropyridines to pyr- economy.14 Approaches which are based on the combination of idines21e and oxidative couplings of phenols21f–i and related 21j 21k I2 and iodides, respectively, as the iodine source, with sustain- substrates as well as thiophenols. The oxidation of cate- 12e 12d,13c able oxidants, such as O2 or H2O2, are oen hampered by chols and hydroquinones is also known. The resulting o- and p- their restricted substrate scope12d,e or by the fact that they benzoquinones can be intercepted in different reactions like require highly acidic conditions.12e,13c As a result, there is great 1,4-additions and Diels–Alder reactions. This approach demand for iodination methods which are not only highly provides not only access to simple 1,4-adducts22 but also to selective and efficient but also fulll the requirements of different carbo- and heterocycles.23 sustainable chemistry in order to protect the environment. Here we show for the rst time, that the laccase-catalyzed Over the last few years, a keen interest in oxidative haloge- iodination of a wide range of p-substituted phenolic nations, which allow for the use of halides as halogen sources substrates delivers the iodinated products in a highly chemo- instead of the halogens themselves, has emerged.7d With selective manner on a preparative scale; the dimerization could respect to sustainability, transition metal- and enzyme- be completely suppressed. Moreover, we will show that the Creative Commons Attribution-NonCommercial 3.0 Unported Licence. catalyzed transformations using H2O2 or O2 as oxidants are laccase-catalyzed iodination can be developed to a sustainable particularly attractive. Enzyme-catalyzed oxidative halogena- iodination method. tions with H2O2 as oxidant are usually catalyzed by less specic heme- and vanadium-dependent haloperoxidases, while oxida- Results and discussion tive halogenations with O2 are mainly catalyzed by more substrate specic avin-dependent halogenases and non-iron Reaction condition optimization 15 O2-dependant halogenases. In this context, studies towards Motivated by our interest in using laccases as catalysts in the regioselective bromination and chlorination catalyzed by preparative organic chemistry we wondered whether it would be FAD-dependant tryptophan halogenases16a deserve to be possible to develop a selective, efficient, atom economic and This article is licensed under a mentioned since they can be performed on a preparative sca- sustainable iodination of aromatics on a preparative useful le.16b In contrast, enzyme-catalyzed iodinations have received scale based on the laccase-catalyzed oxidation of alkali iodides only marginal attention so far. It is known that oxidative to iodine using aerial oxygen as oxidant. 17a–c Open Access Article. Published on 21 June 2019. Downloaded 10/2/2021 6:58:20 AM. iodinations can be catalyzed by lactoperoxidases, a chlor- The optimization of the reaction conditions was performed operoxidase17d and a horseradish peroxidase.17e However, as using the iodination of vanillin (1a) to 4-hydroxy-3-iodo-5- good as nothing is known concerning substrate specicity, methoxybenzaldehyde (2a) as a model reaction since vanillin substrate scope, selectivity, efficiency, scalability and sustain- is a natural product that is manufactured from biomass by ability of these reactions. First observations concerning the means of an established industrial process on a large scale.24 laccase-catalyzed oxidation of iodide to iodine can be traced Against the background of our experience in the eld of laccase- back to the reports of Xu17f and Amachi et al.17g Later, Ihssen catalyzed transformations, equimolar amounts of 1a and KI et al. have reported on the laccase-catalyzed iodination of were stirred with catalytic amounts (225 U) of T. versicolor lac- phenolic compounds.17h However, a closer look at their results case in the presence of aerial oxygen in acetate buffer (pH reveals that their method does not allow for the chemoselective 5) : DMSO ¼ 9 : 1 for 48 h at rt (Table 1, entry 1). Under these iodination of phenols on a preparative useful scale. In most conditions, the desired iodination product 2a was formed in cases, the formation of the iodophenols was accompanied by only 7% yield. The main product was the dimer 6,60-dihydroxy- the formation of products resulting from oxidative dimeriza- 5,50-dimethoxy-[1,10-biphenyl]-3,30-dicarbaldehyde (divanillin) tion. Structure and yields of the iodinated products are difficult (3a). However, the formation of 3a was not surprising, since the to evaluate since they were not isolated in pure form. Moreover, laccase-catalyzed oxidative dimerization of 1a is known to the scope of the method was not studied. deliver 3a.21f Under the conditions presented in Scheme 1, we Laccases (benzenediol:oxygen oxidoreductase, EC 1.10.3.3) isolated 3a in 91% yield (Scheme 1).
Load more

Recommended publications
  • The Degradation of Carboxylic Acid Salts by Means of Halogen the Hunsdieceerreaction Robert G
    THE DEGRADATION OF CARBOXYLIC ACID SALTS BY MEANS OF HALOGEN THE HUNSDIECEERREACTION ROBERT G. JOHNSON Department of Chemistry, Xavier University, Cincinnati 7, Ohio AND ROBERT K. INGHAM Department of Chemistry, Ohio University, Athens, Ohio Received November 17, 1966 CONTENTS I. Introduction.. ...... 11. Synthetic applicatio A. Aliphatic halides B. Alicyclic halides. C. Aromatic halides D. Heterocyclic hali 111. Materials and methods ....................................... 248 IV. Mechanisms., ...... V. Related reactions. ....... ......................................... 259 VI. Summary.. ......... VII. References.. ................................................................. 263 VIII. Addendum. ........................... .. 268 I. INTRODUCTION The degradation of a carboxylic acid salt in anhydrous medium by means of halogen to a halide of one less carbon atom than the original acid can be ex- pressed by the equation: RCOOM + Xz -+ RX + COz + MX Largely because of the extensive contributions of the Hunsdieckers (96, 97, 98, 99, 100, 101, 102) to our knowledge of this reaction, many chemists refer to the reaction under discussion as the “Hunsdiecker reaction.” Others designate the reaction by the names “silver salt reaction” or “silver salt-halogen reac- tion.” It has been proposed (95) that the name “Borodine reaction” be used, in recognition of the discovery of the reaction by Borodine (33). The authors of a recent book (179) incorrectly name this reaction M the Simonini reaction. The reviewers favor the use of “Hunsdiecker reaction,” if a name is to be given to this reaction, because of the many instances of the use of this termi- nology already in the literature and because of the large amount of developmental work carried out by the Hunsdieckers. The often-used descriptive names are contraindicated by the fact that the reaction is successful with salts other than silver salts, halogens other than bromine can be used, and the reaction of salts 219 220 ROBERT G.
    [Show full text]
  • Organic Seminar Abstracts
    L I B RA FLY OF THE U N IVERSITY OF 1LLI NOIS Q.54-1 Ii£s 1964/65 ,t.l P Return this book on or before the Latest Date stamped below. Theft, mutilation, and underlining of books are reasons for disciplinary action and may result in dismissal from the University. University of Illinois Library OCfcfcsrm L161— O-1096 Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/organicsemi1964651univ s ORGANIC SEMINAR ABSTRACTS 196^-65 Semester I Department of Chemistry and Chemical Engineering University of Illinois ' / SEMINAR TOPICS I Semester I96U-I965 f"/ ( Orientation in Sodium and Potassium Metalations of Aromatic Compounds Earl G. Alley 1 Structure of Cyclopropane Virgil Weiss 9 Vinylidenes and Vinylidenecarbenes Joseph C. Catlin 17 Diazene Intermediates James A. Bonham 25 Perfluoroalkyl and Polyfluoroalkyl Carbanions J. David Angerer 3^ Free Radical Additions to Allenes Raymond Feldt 43 The Structure and Biosynthesis of Quassin Richard A. Larson 52 The Decomposition of Perester Compounds Thomas Sharpe 61 The Reaction of Di-t -Butyl Peroxide with Simple Alkyl, Benzyl and Cyclic Ethers R. L. Keener 70 Rearrangements and Solvolysis in Some Allylic Systems Jack Timberlake 79 Longifolene QQ Michael A. Lintner 00 Hydrogenation ! Homogeneous Catalytic Robert Y. Ning 9° c c Total Synthesis of ( -) -Emetime R. Lambert 1* Paracyclophanes Ping C. Huang 112 Mechanism of the Thermal Rearrangement of Cyclopropane George Su 121 Some Recent Studies of the Photochemistry of Cross -Conjugated Cyclohexadienones Elizabeth McLeister 130 The Hammett Acidity Function R. P. Quirk 139 Homoaromaticity Roger A.
    [Show full text]
  • Swager for the Degree of California Institute
    PRECURSOR ROUTES TO CONDUCTING POLYMERS FROM THE RING-OPENING METATHESIS POLYMERIZATION OF CYCLIC OLEFINS Thesis by Timothy Manning Swager In Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 1988 (Submitted May 16, 1988) I a ELECTRONS TALK TO ME! Oh elusive electron how can I set thee free? I’ll unlock your chains just show me the key. Should I destroy your captors those localized bonds? Or would you like something else should I search beyond? I want to let you run and move about with ease. And you may travel in pairs or alone if you please. Lead me the way to that magic superconductive state. And I will do my best to try to accommodate. I’ll build you a band of whatever width you desire. And with my friend polymer chemistry I’ll fashion you a wire. You hold the secrets that can make the world a better place. And I have become curious and decided to join the chase. Oh magnificent electrons hear my plea I have come to set you free. Timothy M. Swager 1988 11 ACKNOWLEDGMENTS First and foremost, I want to thank my wife and best friend Anne for her undaunting support and companionship. I cannot imagine life without her and her influence has made me a happier and stronger person. To my research advisor Bob Grubbs, I owe considerable gratitude and thanks. His guidance will have lasting influence over my career as a chemist. Bob has allowed me to chase many pipe dreams in his laboratory, yet given me the necessary guidance to keep my research on course.
    [Show full text]
  • 5.2. Related Mechanisms of Halogen Chemistry a Large Variety of Organic
    5.2. Related mechanisms of halogen chemistry A large variety of organic reactions involving different halogen species is known within the basic organic chemistry literature (e.g. March, 1992). Those reactions can be divided into two groups: carbon skeleton affecting and functionality modifying reactions. The halogen species discussed here are the species which are supposed to be present during the molecular halogen photochemical experiments: X2, HOX and HX, where X is chlorine or bromine. XO radicals formed by the rapid reactions of halogen atoms with ozone are considered to be unreactive against the organic precursors and to be converted to HOX via reaction with HO2, thus keeping the levels low (Mellouki et al., 1994; Bedjanian et al., 2001). The chosen precursors for the SOA represent different structural elements like an aliphatic structure with ring strain, comprising primary, secondary and tertiary C-H bonds, and an olefinic double bond (α- pinene) and substituted aromatic/phenolic structures (catechol and its methyl-ether modification guaiacol), where ring opening upon oxidation and possibly aldol condensation lead to further olefinic and conjugated structures. Those different organic precursors result in a different chemical structure of the related SOA. The SOA is considered to be still highly reactive and thus will offer a different chemical environment for RHS chemistry. The change of carbon-hydrogen bonds, observed by long-path FTIR spectroscopy upon halogenation (Fig. 4), can be related to the abstraction reaction of H atoms by chlorine atoms from C-H bonds of the methyl groups of the carbon structure (2A). (2A) Molecular chlorine might then react with the aliphatic radical in the well-known chain propagation of photochlorination according to equation (2B) in the initial phase of chlorine injection.
    [Show full text]
  • ABSTRACT ZHANG, JINYUAN. Study of Bridge Effects on Electronic Coupling of Donor- Bridge-Acceptor Biradical Complexes
    ABSTRACT ZHANG, JINYUAN. Study of Bridge Effects on Electronic Coupling of Donor- Bridge-Acceptor Biradical Complexes. (Under the direction of Dr. David Shultz). A series of Donor-Bridge-Acceptor (D-B-A) (D: S=1/2 ortho-semiquinonate, SQ; A: S=1/2 nitronlynitroxide, NN) biradical complexes featuring different bridges were synthesized to serve as ground state analogues of charge separated excited states as well as molecular analogs of single-molecule break junction devices. The aim is to elucidate bridge-mediated electronic structure contributions to electronic coupling. The study of biradicals with sterically hindered para-phenylene bridges and an “Aviram-Ratner” (bicycle[2.2.2]octane) bridge allowed for an experimentally- determined evaluation of torsionally dependent (π) and torsionally independent (σ) contributions to the electronic and exchange couplings at parity of donor, acceptor and donor-acceptor distance. The torsional dependence was illustrated using a 3-dimensional, “Ramachandran-type” plot that related D-B torsion and B-A torsions to both electronic and exchange couplings. Biradicals with asymmetric thiophene-pyridine bridges were used to study a bridge’s ability to affect current rectification in a molecular electronic device. Our approach uses McConnell’s electronic coupling theory and Nitzan’s correlation of electronic coupling with conductance (= resistance-1). Within the framework of our model, exchange coupling parameters of the biradicals were used to estimate rectification ratios of the unsymmetric bridge. This study showed that the intra-bridge torsion angles and the unexpected symmetry of the bridge LUMO conspired to create a small rectification ratio. However, the “biradical approach” is quite effective to derive key structure-property relationships that allow insight into the choice of bridge fragments for molecular rectification.
    [Show full text]
  • Carboxylic Acids a Carbonyl with One OH Attached Is Called a Carboxylic
    Carboxylic Acids A carbonyl with one OH attached is called a carboxylic acid One important property of carboxylic acids is the acidity O O pKa ~4-5 B B H H3C OH H3C O Acetic acid carboxylate Upon deprotonation a carboxylate is formed Carboxylic Acids Nomenclature There are two important guidelines to know about carboxylic acids: 1) The carboxylic acid has the highest priority in naming 2) In common names, the point of substitution is labeled by the Greek letter counting from the carbonyl " O OH # ! This naming is common practice amongst organic chemists, e,g, substitution at α-carbon Carboxylic Acids Examples O Br O OH OH (E)-2-pentenoic acid 3-bromo-2-methylpentanoic acid Or β-bromo-α-methylpentanoic acid (common) CO2H Cl Trans-2-chlorocyclohexanecarboxylic acid Carboxylic Acids Many carboxylic acids have a common name Aromatic rings have a number of these common names CO2H CO2H CO2H Benzoic acid Phthalic acid -As do many dicarboxylic acids O O HO OH Malonic acid (IUPAC: Propanediodic acid) Carboxylic Acids Due to the ability to resonate a lone pair of electrons on oxygen with the carbonyl, the structure of an acid has two preferred conformations O O H O O H s-cis s-trans The s-cis conformer also allows an acid to form a dimer in solution with two hydrogen bonds O H O O H O This hydrogen bonding causes a higher melting point and boiling point compared to compounds of similar molecular weight Carboxylic Acids As noted in the name, carboxylic acids are relatively acidic organic compounds The acidity is rationalized by the ability to resonate
    [Show full text]
  • Decarboxylative Fluorination of Aliphatic Carboxylic Acids Via Photoredox Catalysis Sandrine Ventre,† Filip R
    Communication pubs.acs.org/JACS Decarboxylative Fluorination of Aliphatic Carboxylic Acids via Photoredox Catalysis Sandrine Ventre,† Filip R. Petronijevic,† and David W. C. MacMillan* Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544, United States *S Supporting Information ABSTRACT: The direct conversion of aliphatic carbox- ylic acids to the corresponding alkyl fluorides has been achieved via visible light-promoted photoredox catalysis. This operationally simple, redox-neutral fluorination method is amenable to a wide variety of carboxylic acids. Photon-induced oxidation of carboxylates leads to the formation of carboxyl radicals, which upon rapid CO2- extrusion and F• transfer from a fluorinating reagent yield the desired fluoroalkanes with high efficiency. Experimen- tal evidence indicates that an oxidative quenching pathway is operable in this broadly applicable fluorination protocol. he capacity of fluorine atoms to engender a variety of useful T properties in pharmaceuticals, agrochemicals, and perform- ance materials has driven significant research efforts toward the − invention of novel fluorination reactions.1 3 Over the past two decades, significant progress has been made toward the production of sp2 C−F bonds;4 however, catalytic methods for − sp3 C−F formation have only recently become available.5 8 In particular, metal-mediated radical C−H abstraction/fluorination protocols have been developed to form tertiary aliphatic,6 7 8 benzylic, as well as allylic C−F centers, a strategy that is protocol for the photon-mediated decarboxylative fluorination founded upon the selective functionalization of weak C−H of sp3-carbon-bearing carboxylic acids, using a blue LED light bonds. Despite these important advances, the development of a source and a commercial photocatalyst (eq 2).
    [Show full text]
  • Pdf, 1022.16 Kb
    Original Article The Development and Implementation of Innovative Learning Resource with Guided Projects for the Teaching of Carboxylic Acid Topic Jamalum Purba1, Manihar Situmorang2,*, Ramlan Silaban1 1Department of Chemistry Education, Graduate Study Program, Universitas Negeri Medan (State University of Medan), Medan, North Sumatra, INDONESIA. 2Department of Chemistry, Faculty of Mathematics and Naturas Science, Universitas Negeri Medan (State University of Medan), Medan, North Sumatra, INDONESIA. ABSTRACT Background: The development of good learning resources in line with current technology to facilitate active learning has become a trend in education. An innovative learning material is believed to be able to motivate the students to learn and to improving students’ skills for chemistry and pharmacy students to handle chemical reaction. Objectives: The study aimed to enact an innovative learning material with guided project to be implemented as learning resources to improve student’s performance in organic chemistry. Materials and Methods: This study was carried out at Universitas Negeri Medan with the involvement of 180 chemistry students in the Department of Chemistry. It consisted of the development and standardization of an innovative learning package with guided project and implementing it for the teaching of carboxylic acid topic. Results and Conclusion: An innovative learning package with project contextual example related to carboxylic acid topic has been developed in a systematic order and the projects were provided to guide the students to become independent learners. The learning package was easy to follow and guided the students to do scientific investigations. The guide projects integrated in the learning package facilitated the students to gain deeper understanding of organic chemistry concept, be able to set their own project to keep the students engage in curiosity and problem solving and develop students’ skills on planning, actions and reporting the project results.
    [Show full text]
  • Advanced Organic Synthesis
    Advanced Organic Synthesis METHODS AND TECHNIQUES RICHARD S. MONSON DEPARTMENT OF CHEMISTRY CALIFORNIA STATE COLLEGE, HAYWARD HAYWARD, CALIFORNIA ACADEMIC PRESS New York and London COPYRIGHT © 1971, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED NO PART OF THIS BOOK MAY BE REPRODUCED IN ANY FORN BY PHOTOSTAT, MICROFILM, RETRIEVAL SYSTEM, OR ANY OTHER MEANS, WITHOUT WRITTEN PERMISSION FROM THE PUBLISHERS. ACADEMIC PRESS, INC. Ill Fifth Avenue, New York, New York 10003 United Kingdom Edition published by ACADEMIC PRESS, INC. (LONDON) LTD. Berkeley Square House, London WlX 6BA LIBRARY OF CONGRESS CATALOG CARD NUMBER: 75-165531 PRINTED IN THE UNITED STATES OF AMERICA Contents Preface xi I. FUNCTIONAL GROUP MODIFICATIONS 1. Chemical Oxidations I. Chromium Trioxide Oxidation 3 II. Periodate-Permanganate Cleavage of Olefins 5 III. Free Radical Oxidation of an Allylic Position 7 IV. Epoxidation of Olefins 8 V. Baeyer-Villiger Oxidation of Ketones 9 VI. Lead Tetraacetate Oxidation of Cycloalkanols 11 VII. Photolytic Conversion of Cyclohexane to Cyclohexanone Oxime 11 VIII. Oxidation of Ethers to Esters 12 IX. Partial Oxidation of an Aliphatic Side Chain 13 X. Bisdecarboxylation with Lead Tetraacetate 14 XI. Oxidation with Selenium Dioxide 15 References 16 2. Hydride and Related Reductions I. Reduction by Lithium Aluminum Hydride 18 II. Mixed Hydride Reduction 20 III. Reduction with Iridium-Containing Catalysts 22 IV. Reduction of Conjugated Alkenes with Chromium (H) Sulfate 23 References 24 3. Dissolving Metal Reductions I. Reduction by Lithium-Amine 25 II. Reduction by Lithium-Ethylenediamine 26 III. Reduction of a,/MJnsaturated Ketones by Lithium-Ammonia 27 IV. Reduction of a,/9-Unsaturated Ketones in Hexamethylphosphoric Triamide ...
    [Show full text]
  • Facing the Music: How Original Was Borodin's Chemistry?
    Chemistry for Everyone Facing the Music: How Original Was Borodin’s Chemistry? Michael D. Gordin Department of History, Princeton University, Princeton, NJ 08544; [email protected] Aleksandr Porfir’evich Borodin (1833–1887) was a re- Markovnikov (1838–1904, of the eponymous rule), or F. K. markable individual. Born illegitimate in St. Petersburg, Rus- Beilstein (1838–1906, of the indispensable Handbuch). Al- sia, to a Russified nobleman from the Caucasus and his maid, though Borodin began the 1860s as one of the more prom- he was educated in that city as a medical doctor at the ising young chemists of his generation—a reputation based Medico–Surgical Academy (later home to Ivan Pavlov), stud- on some striking research while he was abroad at Heidelberg ied abroad on a postdoctoral trip in Heidelberg (1859–1862), and Pisa—for a variety of reasons his research programs began a career teaching at his alma mater in 1862, lobbied dwindled largely on their own (and certainly not, as has been for higher education for women, and along the way man- claimed, due to subterfuge and priority theft by foreigners— aged to compose two and a half symphonies, roughly twenty although issues of priority were raised and continue to be songs, two string quartets, a symphonic poem (“On the pressing issues for chemists internationally today). Borodin Steppes of Central Asia”), and an unfinished operatic mas- seems to have left active chemical research owing to a dimi- terpiece, Prince Igor. (The music for the latter formed the nution of interest and an increasing desire to devote his time basis for the score of the Tony-award-winning Kismet.) Al- to other issues.
    [Show full text]
  • Centre for Chemical Sciences School of Basic and Applied Sciences Central University of Punjab Mansa Road Bathinda – 151001
    Course Structure and Syllabus M.Sc. Chemistry (CBCS) (SEMESTER: I - IV) (FOR NEW ADMISSION) Examinations: 2016-17 Centre for Chemical Sciences School of Basic and Applied Sciences Central University of Punjab Mansa Road Bathinda – 151001 Page 1 of 63 Centre for Chemical Sciences M.Sc. Chemistry SEMESTER 1 S. Paper Code Course Title Cour L T P Cr Weightage (%) E No. se Type A B C D 1 CHL.501 Chemical Biology FC 2 - - 2 10 15 15 10 50 (Non-medical group) CHL502 Chemical Mathematics (Medical group) 3 CHL.503 Analytical Chemistry CC 4 1 - 4 25 25 25 25 100 and Instrumental Methods 4 CHL.504 Inorganic Chemistry-1 CC 4 1 - 4 25 25 25 25 100 5 CHL.506 Organic Chemistry-I CC 4 1 - 4 25 25 25 25 100 6 CHL.508 Physical Chemistry-I CC 4 1 - 4 25 25 25 25 100 7 CHP.505 Practical Inorganic CC - - 4 2 - - - - 50 Chemistry-1 8 CHP.507 Practical Organic CC - - 4 2 - - - - 50 Chemistry-I 9 XXX Inter-Disciplinary EC 2 - - 2 10 15 15 10 50 Course (ID) (Opt any one from other Departments) Total 20 4 8 24 600 FC: Foundation Course, CC: Core Course, EC: Elective Course A: Surprise Tests (minimum three): Based on Objective Type Tests B: Mid-Semester Test – I: Based on Subjective Type Test C: Mid-Semester Test – II: Based on Subjective Type Test D: End-Term Exam (Final): Online Objective Type Test E: Total Marks L: Lectures T: Tutorial P: Practical Cr: Credits Page 2 of 63 SEMESTER 2 S.
    [Show full text]
  • Lecture 21 Free-Radical Reactions I
    NPTEL – Chemistry – Principles of Organic Synthesis Lecture 21 Free-Radical Reactions I 9.1 Principles Free radicals may be defined as the species that contain one or more unpaired electrons. They are generally less stable and react in fraction of seconds with another species. 9.1.1 Formation of Free Radicals Three general methods are used for the generation of free radicals. 9.1.1.1 Thermal Generation Two types of compounds dissociate to give free-radicals at moderate temperature: (i) compounds that have an intrinsically weak bond such as dialkyl peroixides (DO-O = 155 KJ mol-1), and (ii) compounds that, on fragmentation, form strongly bonded products, such as AIBN which releases N2. O. O heat 2 O heat . NC N 2 + N N CN CN 2 9.1.1.2 Photochemical Generation Light can bring the fragmentation of a compound if the wavelength of the light is correspond both to an energy greater than that of the bond to be cleaved, and to an electronic excitation of the molecule concerned. This procedure is suitable for the formation of alkoxy radicals from alkyl nitrite or hypochlorites. light N . RO O RO + NO light RO Cl RO . + Cl . Joint initiative of IITs and IISc – Funded by MHRD Page 1 of 22 NPTEL – Chemistry – Principles of Organic Synthesis 9.1.1.3 Redox Generation Covalent bonds may be broken by electron transfer process either by accepting an electron from a donor or donating an electron to an acceptor. O EtO OEt R OEt R . OEt dimerization R Na . + R R R O O O Na O OH In the second group, the acceptor is generally a transition-metal-ion in a high-valence state.
    [Show full text]