DOCSLIB.ORG

FIRE-SAFE POLYMERS and POLYMER COMPOSITES September 2004 6

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
FIRE-SAFE POLYMERS and POLYMER COMPOSITES September 2004 6 DOT/FAA/AR-04/11 Fire-Safe Polymers and Polymer Office of Aviation Research Washington, D.C. 20591 Composites September 2004 Final Report This document is available to the U.S. public through the National Technical Information Service (NTIS), Springfield, Virginia 22161. U.S. Department of Transportation Federal Aviation Administration NOTICE This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The United States Government assumes no liability for the contents or use thereof. The United States Government does not endorse products or manufacturers. Trade or manufacturer's names appear herein solely because they are considered essential to the objective of this report. This document does not constitute FAA certification policy. Consult your local FAA aircraft certification office as to its use. This report is available at the Federal Aviation Administration William J. Hughes Technical Center’s Full-Text Technical Reports page: actlibrary.act.faa.gov in Adobe Acrobat portable document format (PDF). Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. DOT/FAA/AR-04/11 4. Title and Subtitle 5. Report Date FIRE-SAFE POLYMERS AND POLYMER COMPOSITES September 2004 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Huiqing Zhang 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Polymer Science and Engineering University of Massachusetts Amhurst, MA 01003 11. Contract or Grant No. 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered U.S. Department of Transportation Federal Aviation Administration Office of Aviation Research 14. Sponsoring Agency Code Washington, DC 20591 ANM-110 15. Supplementary Notes The FAA William J. Hughes Technical Center COTR was Dr. Richard Lyon. Copyright by Huiqing Zhang 2003 All Rights Reserved 16. Abstract The intrinsic relationships between polymer structure, composition, and fire behavior have been explored to develop new fire-safe polymeric materials. Three milligram-scale methods (pyrolysis-combustion flow calorimetry (PCFC), simultaneous thermal analysis, and pyrolysis gas chromatography/mass spectrometry (GC/MS)) have been combined to fully characterize the thermal decomposition and flammability of polymers and polymer composites. Thermal stability, mass loss rate, char yield, and properties of decomposition volatiles were found to be the most important parameters in determining polymer flammability. Most polymers decompose by either an unzipping or a random chain scission mechanism with an endothermic decomposition of 100-900 J/g. Aromatic or heteroaromatic rings, conjugated double or triple bonds, and heteroatoms such as halogens, N, O, S, P, and Si, are the basic structural units for fire-resistant polymers. The flammability of polymers can also be successfully estimated by combining the pyrolysis GC/MS results or chemical structures with the thermogravimetric analysis. The thermal decomposition and flammability of two groups of inherently fire-resistant polymers—poly(hydroxyamide) (PHA) and its derivatives and bisphenol C (BPC II) polyarylates—have been systematically studied. PHA and most of its derivatives have extremely low heat release rates and very high char yields upon combustion. PHA and its halogen derivatives can completely cyclize into quasi-polybenzoxazole structures at low temperatures. However, the methoxy and phosphate derivatives show a very different behavior during decomposition and combustion. Molecular modeling shows that the formation of an enol intermediate is the rate-determining step in the thermal cyclization of PHA. BPC II-polyarylate is another extremely flame- resistant polymer. It can be used as an efficient flame-retardant agent in copolymers and blends. From the PCFC results, the total heat of combustion of these copolymers or blends changes linearly with composition, but the change of maximum heat release rates also depends on the chemical structure of the components. The flammability of various polymers and polymer composites measured by PCFC; cone calorimeter, ASTM E1354; and the Ohio State University (OSU) calorimeter, ASTM E906, were also compared. For pure polymers, there was a relatively good correlation between different methods. However, for polymer composites with inert fillers or flame-retardant additives, the OSU and cone calorimetries are more suitable evaluation methods. 17. Key Words 18. Distribution Statement Polymer, Fire, Flammability, Thermal analysis, Combustion This document is available to the public through the National Technical Information Service (NTIS), Springfield, Virginia 22161. 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 209 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized TABLE OF CONTENTS Page EXECUTIVE SUMMARY xix 1. FIRE AND POLYMERS 1-1 1.1 Introduction 1-1 1.2 Polymer Combustion Process 1-2 1.3 Standard Assessments and Tests 1-3 1.4 Flame-Retardant Chemistry 1-4 1.5 Inhibition of Polymer Combustion 1-5 1.5.1 Intrinsically Fire-Resistant Polymers 1-5 1.5.2 Flame-Retardant Additives 1-6 1.6 Thermal Decomposition Mechanisms of Polymers 1-11 1.7 Experimental Techniques for Thermal Decomposition of Polymers 1-12 2. QUANTATIVE MEASUREMENTS ON THE THERMAL DECOMPOSITION AND FLAMMABILITY OF POLYMERS 2-1 2.1 Introduction 2-1 2.2 Methodology of Flammability Calculations 2-2 2.2.1 Calculation of the Composition of the Volatiles 2-3 2.2.2 Calculation of Total Heat of Combustion and Heat Release Capacity of Polymers 2-4 2.3 Experimental 2-5 2.3.1 Pyrolysis GC/MS 2-5 2.3.2 Simultaneous Thermal Analysis 2-5 2.3.3 Pyrolysis-Combustion Flow Calorimeter 2-6 2.3.4 Materials 2-7 2.4 Results 2-8 2.4.1 Thermal Stability and Decomposition Process of Polymers 2-8 2.4.2 Thermal Decomposition Products of Polymers 2-13 2.4.3 Flammability 2-16 2.4.4 Bond Dissociation Energies of the Polymers 2-18 iii 2.4.5 Flammability Calculated by Pyrolysis GC/MS and STA Results 2-21 2.4.6 Flammability Estimated by Using Chemical Structure and TGA Results 2-22 2.5 Discussion 2-28 3. LOW FLAMMABILITY AND THERMAL DECOMPOSITION OF POLY (HYDROXYAMIDE) AND ITS DERIVATIVES 3-1 3.1 Introduction 3-1 3.2 Experimental 3-2 3.2.1 Materials 3-2 3.2.2 Film Preparation 3-3 3.2.3 Characterization 3-3 3.3 Results 3-3 3.3.1 Thermal Stability and Decomposition Process of PHAs 3-3 3.3.2 Flammability 3-10 3.3.3 Characterization of Chars by IR and Elemental Analysis 3-13 3.3.4 Identification of Volatiles by GC/MS 3-15 3.3.5 Thermal Decomposition Mechanisms 3-19 3.4 Discussion 3-23 4. FIRE-RESISTANT, UV/VISIBLE-SENSITIVE POLYARYLATES, COPOLYMERS, AND BLENDS 4-1 4.1 Introduction 4-1 4.2 Experimental 4-2 4.2.1 Materials 4-2 4.2.2 Characterization 4-2 4.3 Results 4-2 4.3.1 Flammability and Thermal Decomposition of BPA-Polyarylates 4-2 4.3.2 Thermal Decomposition and Flammability of Homopolyarylates 4-3 4.3.3 UV/Visible-Sensitive Chalcon II-Polyarylate 4-6 4.3.4 Thermal Decomposition and Flammability of Copolymers and Terpolymers 4-8 iv 4.3.5 Thermal Decomposition and Flammability of Blends 4-12 4.4 Discussion 4-15 5. EFFECTS OF FLAME-RETARDANT ADDITIVES AND CORRELATIONS AMONG PCFC, OSU, AND CONE CALORIMETERS 5-1 5.1 Introduction 5-1 5.2 Experimental 5-2 5.2.1 Test Samples 5-2 5.2.2 Sample Preparation 5-2 5.2.3 Characterization 5-2 5.3 Results 5-5 5.3.1 Poly(Methyl Methacrylate)/Clay Nanocomposites 5-5 5.3.2 Poly(Ether Ether Ketone) and Composites 5-7 5.3.3 Xydar and Its Composites 5-12 5.3.4 Polyphthalamides and Composites 5-17 5.3.5 Epoxy Resins With Phosphate Flame Retardants 5-28 5.3.6 Ignitability 5-32 5.3.7 Heat Release Rate 5-33 5.3.8 Correlation Between Different Flammability Tests 5-35 5.4 Discussion 5-39 6. STRUCTURE-COMPOSITION-FLAMMABILITY RELATIONSHIPS OF POLYMERS 6-1 6.1 Introduction 6-1 6.2 Experimental 6-1 6.2.1 Materials 6-1 6.2.2 Characterization 6-1 6.3 Chemical Structure 6-1 6.3.1 Main Chain—Polysulfones 6-1 6.3.2 Semiorganic Network Structure—Polycarbynes and Polysilynes 6-11 6.3.3 Substituents 6-14 6.3.4 Flame-Retardant Comonomers 6-20 6.4 Composition—Copolymers and Blends 6-26 6.4.1 Poly(Methyl Methacrylate)/Polystyrene Random Copolymers 6-26 6.4.2 Poly(Methyl Methacrylate)/Polystyrene Blends 6-26 v 6.5 Molecular Weight 6-28 6.5.1 Poly(Methyl Methacrylate) 6-28 6.5.2 Polystyrene 6-30 6.5.3 Poly(Ethylene Oxide) 6-32 6.5.4 Mechanisms of the Effects of the Molecular Weight 6-32 6.6 Free-Radical Scavenger—TEMPO 6-33 6.6.1 Polystyrene or PMMA/TEMPO Blends 6-34 6.6.2 The PMMA/PS Random Copolymers Initiated by TEMPO 6-34 6.7 Discussion 6-38 7. MOLECULAR MODELING OF THERMAL CYCLIZATION OF POLY(HYDROXYAMIDE) 7-1 7.1 Introduction 7-1 7.2 Previous Experimental Results 7-1 7.3 Results 7-3 7.4 Discussion 7-7 8. CONCLUSIONS AND RECOMMENDATIONS 8-1 8.1 Conclusions 8-1 8.1.1 Characterization of Thermal Decomposition and Flammability of Polymers 8-1 8.1.2 Inherently Fire-Resistant Polymers 8-2 8.1.3 Effects of Flame-Retardant Additives and Correlations Among Different Flammability Tests 8-4 8.1.4 Structure, Composition, and Flammability Relationships 8-5 8.1.5 Thermal Cyclization Mechanism of PHA 8-6 8.2 Recommendations 8-6 9 REFERENCES 9-1 10.
Load more

Recommended publications
  • A Facile Approach to Prepare Multiple Heteroatom-Doped Carbon
    www.nature.com/scientificreports OPEN A Facile Approach to Prepare Multiple Heteroatom-Doped Carbon Materials from Imine- Received: 17 November 2017 Accepted: 19 February 2018 Linked Porous Organic Polymers Published: xx xx xxxx Juan Yang, Min Xu, Jingyu Wang , Shangbin Jin & Bien Tan In this paper, we proposed a new strategy to prepare multiple heteroatom doped (N, P-doped) porous carbon materials with high surface area of ~1,535 m2 g−1 simply by pyrolysis of imine-linked porous organic polymers (POPs) synthesized via Schif base condensation. The strategy is simple without any post-processing and various heteroatoms could be involved. Scanning electron microscopy, Raman spectra, Nitrogen gas adsorption-desorption, X-ray photoelectron spectroscopy have been used to characterize the morphology, the structure and the composition of the materials. The multiple heteroatom doped porous carbon materials also display high electrocatalytic performance as exampled by the application in oxygen reduction, which showed the catalyst favors 4-electron transfer during the process, along with superior stability and higher tolerance to methanol as compared to the Pt/C. These results indicate the present method is promising for the preparation of multi-heteroatom doped carbon materials in the application of electrocatalysis. Porous organic polymers (POPs) are a type of organic polymers with large surface area, tunable skeleton and high stability1,2. Tey have attracted extensive attentions for broad applications in the felds of gas storage and separations, catalysis and energy storage3–5. Tere are many methodologies reported for the preparation of porous polymers6–10. Among them, Schif base reaction is one of the most versatile ways due to the facile, one-pot, catalyst-free, quantitative synthesis11.
    [Show full text]
  • Electron Ionization
    Chapter 6 Chapter 6 Electron Ionization I. Introduction ......................................................................................................317 II. Ionization Process............................................................................................317 III. Strategy for Data Interpretation......................................................................321 1. Assumptions 2. The Ionization Process IV. Types of Fragmentation Pathways.................................................................328 1. Sigma-Bond Cleavage 2. Homolytic or Radical-Site-Driven Cleavage 3. Heterolytic or Charge-Site-Driven Cleavage 4. Rearrangements A. Hydrogen-Shift Rearrangements B. Hydride-Shift Rearrangements V. Representative Fragmentations (Spectra) of Classes of Compounds.......... 344 1. Hydrocarbons A. Saturated Hydrocarbons 1) Straight-Chain Hydrocarbons 2) Branched Hydrocarbons 3) Cyclic Hydrocarbons B. Unsaturated C. Aromatic 2. Alkyl Halides 3. Oxygen-Containing Compounds A. Aliphatic Alcohols B. Aliphatic Ethers C. Aromatic Alcohols D. Cyclic Ethers E. Ketones and Aldehydes F. Aliphatic Acids and Esters G. Aromatic Acids and Esters 4. Nitrogen-Containing Compounds A. Aliphatic Amines B. Aromatic Compounds Containing Atoms of Nitrogen C. Heterocyclic Nitrogen-Containing Compounds D. Nitro Compounds E. Concluding Remarks on the Mass Spectra of Nitrogen-Containing Compounds 5. Multiple Heteroatoms or Heteroatoms and a Double Bond 6. Trimethylsilyl Derivative 7. Determining the Location of Double Bonds VI. Library
    [Show full text]
  • An Organic Chemist's Guide to Electrospray Mass Spectrometric
    molecules Review An Organic Chemist’s Guide to Electrospray Mass Spectrometric Structure Elucidation Arnold Steckel 1 and Gitta Schlosser 2,* 1 Hevesy György PhD School of Chemistry, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary; [email protected] 2 Department of Analytical Chemistry, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary * Correspondence: [email protected] Received: 16 January 2019; Accepted: 8 February 2019; Published: 10 February 2019 Abstract: Tandem mass spectrometry is an important tool for structure elucidation of natural and synthetic organic products. Fragmentation of odd electron ions (OE+) generated by electron ionization (EI) was extensively studied in the last few decades, however there are only a few systematic reviews available concerning the fragmentation of even-electron ions (EE+/EE−) produced by the currently most common ionization techniques, electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). This review summarizes the most important features of tandem mass spectra generated by collision-induced dissociation fragmentation and presents didactic examples for the unexperienced users. Keywords: tandem mass spectrometry; MS/MS fragmentation; collision-induced dissociation; CID; ESI; structure elucidation 1. Introduction Electron ionization (EI), a hard ionization technique, is the method of choice for analyses of small (<1000 Da), nonpolar, volatile compounds. As its name implies, the technique involves ionization by electrons with ~70 eV energy. This energy is high enough to yield very reproducible mass spectra with a large number of fragments. However, these spectra frequently lack the radical type molecular ions (M+) due to the high internal energy transferred to the precursors [1].
    [Show full text]
  • Heterocyclic Chemistrychemistry
    HeterocyclicHeterocyclic ChemistryChemistry Professor J. Stephen Clark Room C4-04 Email: [email protected] 2011 –2012 1 http://www.chem.gla.ac.uk/staff/stephenc/UndergraduateTeaching.html Recommended Reading • Heterocyclic Chemistry – J. A. Joule, K. Mills and G. F. Smith • Heterocyclic Chemistry (Oxford Primer Series) – T. Gilchrist • Aromatic Heterocyclic Chemistry – D. T. Davies 2 Course Summary Introduction • Definition of terms and classification of heterocycles • Functional group chemistry: imines, enamines, acetals, enols, and sulfur-containing groups Intermediates used for the construction of aromatic heterocycles • Synthesis of aromatic heterocycles • Carbon–heteroatom bond formation and choice of oxidation state • Examples of commonly used strategies for heterocycle synthesis Pyridines • General properties, electronic structure • Synthesis of pyridines • Electrophilic substitution of pyridines • Nucleophilic substitution of pyridines • Metallation of pyridines Pyridine derivatives • Structure and reactivity of oxy-pyridines, alkyl pyridines, pyridinium salts, and pyridine N-oxides Quinolines and isoquinolines • General properties and reactivity compared to pyridine • Electrophilic and nucleophilic substitution quinolines and isoquinolines 3 • General methods used for the synthesis of quinolines and isoquinolines Course Summary (cont) Five-membered aromatic heterocycles • General properties, structure and reactivity of pyrroles, furans and thiophenes • Methods and strategies for the synthesis of five-membered heteroaromatics
    [Show full text]
  • Hetero-Atom Containing Functional Polymers: Synthesis, Characterization and Applications
    University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 5-2017 Hetero-Atom Containing Functional Polymers: Synthesis, Characterization and Applications Hongbo Feng University of Tennessee, Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Polymer Chemistry Commons Recommended Citation Feng, Hongbo, "Hetero-Atom Containing Functional Polymers: Synthesis, Characterization and Applications. " PhD diss., University of Tennessee, 2017. https://trace.tennessee.edu/utk_graddiss/4397 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Hongbo Feng entitled "Hetero-Atom Containing Functional Polymers: Synthesis, Characterization and Applications." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Chemistry. Jimmy W. Mays, Major Professor We have read this dissertation and recommend its acceptance: Alexei Sokolov, Ziling Xue, Brian Long, Joshua Sangoro Accepted for the Council: Dixie L. Thompson Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Hetero-Atom Containing Functional Polymers: Synthesis, Characterization and Applications A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Hongbo Feng May 2017 Copyright © 2017 by Hongbo Feng.
    [Show full text]
  • Nomenclature of Heterocyclic Compounds
    Nomenclature of Heterocyclic Compounds Dr. Solomon Derese SCH 402 13 The IUPAC rules allow three nomenclatures. I. The Hantzsch-Widman Nomenclature. II. Common Names III. The Replacement Nomenclature Dr. Solomon Derese SCH 402 14 I. Hantzsch-Widman Nomenclature n = 1,2,3, …… The Hantzsch-Widman nomenclature is based on the type (Z) of the heteroatom; the ring size (n) and nature of the ring, whether it is saturated or unsaturated . This system of nomenclature applies to monocyclic three-to-ten-membered ring heterocycles. Dr. Solomon Derese SCH 402 15 I. Type of the heteroatom The type of heteroatom is indicated by a prefix as shown below for common hetreroatoms: Hetreroatom Prefix O Oxa N Aza S Thia P Phospha Dr. Solomon Derese SCH 402 16 II. Ring size (n) The ring size is indicated by a suffix according to Table I below. Some of the syllables are derived from Latin numerals, namely ir from tri, et from tetra, ep from hepta, oc from octa, on from nona, ec from deca. Table I: Stems to indicate the ring size of heterocycles Ring size Suffix Ring size Suffix 3 ir 7 ep 4 et 8 oc 5 ol 9 on Dr. Solomon Derese6 in SCH 40210 ec 17 The endings indicate the size and degree of unsaturation of the ring. Table II: Stems to indicate the ring size and degree of unsaturation of heterocycles Ring size Saturated Unsaturated Saturated (With Nitrogen) 3 -irane -irine -iridine 4 -etane -ete -etidine 5 -olane -ole -olidine 6 -inane -ine 7 -epane -epine 8 -ocane -ocine 9 -onane -onine 10 -ecane -ecine Dr.
    [Show full text]
  • IUPAC Nomenclature of Fused and Bridged Fused Ring Systems
    Pure &App/. Chern., Vol. 70, No. 1, pp. 143-216, 1998. Printed in Great Britain. Q 1998 IUPAC INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY ORGANIC CHEMISTRY DIVISION COMMISSION ON NOMENCLATURE OF ORGANIC CHEMISTRY (111.1) NOMENCLATURE OF FUSED AND BRIDGED FUSED RING SYSTEMS (IUPAC Recommendations 1998) Prepared for publication by G. P. MOSS Department of Chemistry, Queen Mary and Westfield College, Mile End Road, London, El 4NS, UK Membership of the Working Party (1982-1997): A. T. Balaban (Romania), A. J. Boulton (UK), P. M. Giles, Jr. (USA), E. W. Godly (UK), H. Gutmann (Switzerland), A. K. Ikizler (Turkey), M. V. Kisakiirek (Switzerland), S. P. Klesney (USA), N. Lozac’h (France), A. D. McNaught (UK), G. P. Moss (UK), J. Nyitrai (Hungary), W. H. Powell (USA), Ch. Schmitz (France), 0. Weissbach (Federal Republic of Germany) Membership of the Commission on Nomenclature of Organic Chemistry during the preparation of this document was as follows: Titular Members: 0. Achmatowicz (Poland) 1979-1987; J. Blackwood (USA) 1996; H. J. T. Bos (Netherlands) 1987-1995, Vice-chairman, 1991- ; J. R. Bull (Republic of South Africa) 1987-1993; F. Cozzi (Italy) 1996- ; H. A. Favre (Canada) 1989-, Chairman, 1991- ; P. M. Giles, Jr. (USA) 1989-1995; E. W. Godly (UK) 1987-1993, Secretary, 1989-1993; D. Hellwinkel (Federal Republic of Germany) 1979-1987, Vice-Chainnan, 1981-1987; B. J. Herold (Portugal) 1994- ; K. Hirayama (Japan) 1975-1983; M. V. Kisakiirek (Switzerland) 1994, Vice-chairman, 1996- ; A. D. McNaught (UK) 1979-1987; G. P. Moss (UK) 1977-1987, Chairman, 1981-1987, Vice-chairman, 1979-1981; R.
    [Show full text]
  • Physical Organic Chemistry
    Physical organic chemistry Edited by John Murphy Generated on 24 September 2021, 10:07 Imprint Beilstein Journal of Organic Chemistry www.bjoc.org ISSN 1860-5397 Email: [email protected] The Beilstein Journal of Organic Chemistry is published by the Beilstein-Institut zur Förderung der Chemischen Wissenschaften. This thematic issue, published in the Beilstein Beilstein-Institut zur Förderung der Journal of Organic Chemistry, is copyright the Chemischen Wissenschaften Beilstein-Institut zur Förderung der Chemischen Trakehner Straße 7–9 Wissenschaften. The copyright of the individual 60487 Frankfurt am Main articles in this document is the property of their Germany respective authors, subject to a Creative www.beilstein-institut.de Commons Attribution (CC-BY) license. Physical organic chemistry John A. Murphy Editorial Open Access Address: Beilstein J. Org. Chem. 2010, 6, 1025. WestCHEM, Department of Pure and Applied Chemistry, University of doi:10.3762/bjoc.6.116 Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, U.K Received: 01 November 2010 Email: Accepted: 01 November 2010 John A. Murphy - [email protected] Published: 03 November 2010 Guest Editor: J. Murphy © 2010 Murphy; licensee Beilstein-Institut. License and terms: see end of document. Physical organic chemistry – the study of the interplay between I am privileged to act as Guest Editor for this Thematic Series structure and reactivity in organic molecules – underpins of the Beilstein Journal of Organic Chemistry, and hope that organic chemistry, and we cannot imagine organic chemistry as you enjoy the papers that form this issue. I am grateful to the a subject without knowledge of mechanism and reactivity.
    [Show full text]
  • P-Containing Polycyclic Aromatic Hydrocarbons Rózsa Szűcs, Pierre-Antoine Bouit, Laszlo Nyulászi, Muriel Hissler
    P-containing Polycyclic Aromatic Hydrocarbons Rózsa Szűcs, Pierre-Antoine Bouit, Laszlo Nyulászi, Muriel Hissler To cite this version: Rózsa Szűcs, Pierre-Antoine Bouit, Laszlo Nyulászi, Muriel Hissler. P-containing Polycyclic Aromatic Hydrocarbons. ChemPhysChem, Wiley-VCH Verlag, 2017, 18 (19), pp.2618-2630. 10.1002/cphc.201700438. hal-01538723 HAL Id: hal-01538723 https://hal.archives-ouvertes.fr/hal-01538723 Submitted on 14 Jun 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. P-containing Polycyclic Aromatic Hydrocarbons Rózsa Szűcs,[a,b] Pierre-Antoine Bouit,*,[a] László Nyulászi,*,[b] Muriel Hissler*,[a] aromatic synthons using simple organic reactions (C-C cross- coupling, oxidations…). This method cannot be used to prepare micrometric graphene fragments, but it allows the preparation of well-defined molecules up to 10 nm (NGs or Graphene Abstract: Polycyclic Aromatic Hydrocarbons (PAHs) are highly NanoRibbons (GNRs)). In this field, pioneering work was appealing functional materials in the field of molecular performed by the group of K. Müllen during the 1990’s. They electronics. In particular, molecular engineering of these showed that with suitable polyaromatic precursors, the Scholl derivatives using organic chemistry is a powerful method to tune reaction can be used to “graphenize” large polyaromatic their properties from the point of view of the bandgap and frameworks.[ 5 ] They thus synthesized defect-free and soluble supramolecular assemblies.
    [Show full text]
  • Identify Similarities in Diverse Polycyclic Aromatic Hydrocarbons of Asphaltenes and Heavy Oils Revealed by Noncontact Atomic Fo
    Identify Similarities in Diverse Polycyclic Aromatic Hydrocarbons of Asphaltenes and Heavy Oils Revealed by Noncontact Atomic Force Microscopy: Aromaticity, Bonding, and Implications in Reactivity Yunlong Zhang [email protected] Corporate Strategic Research, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801 Heavy oils are enriched with polycyclic (or polynuclear) aromatic hydrocarbons (PAH or PNA), but characterization of their chemical structures has been a great challenge due to their tremendous diversity. Recently, with the advent of molecular imaging with noncontact Atomic Force Microscopy (nc-AFM), molecular structures of petroleum has been imaged and a diverse range of novel PAH structures was revealed. Understanding these structures will help to understand their chemical reactivities and the mechanisms of their formation or conversion. Studies on aromaticity and bonding provide means to recognize their intrinsic structural patterns which is crucial to reconcile a small number of structures from AFM and to predict infinite number of diverse molecules in bulk. Four types of PAH structures can be categorized according to their relative stability and reactivity, and it was found that the most and least stable types are rarely observed in AFM, with most molecules as intermediate types in a subtle balance of kinetic reactivity and thermodynamic stability. Local aromaticity was found maximized when possible for both alternant and nonalternant PAHs revealed by the aromaticity index NICS (Nucleus-Independent Chemical Shift) values. The unique role of five-membered rings in disrupting the electron distribution was recognized. Especially, the presence of partial double bonds in most petroleum PAHs was identified and their implications in the structure and reactivity of petroleum are discussed.
    [Show full text]
  • An Introduction to Heterocyclic Chemistry
    An Introduction to Heterocyclic Chemistry Reference: A Textbook of Organic Chemistry, Tewari and Vishnoi This is only the introduction part of the unit on heterocyclic chemistry. Please refer textbook for detailed information. Introduction Cyclic compound having only carbons as the ring members, such as benzene are called carbocyclic compounds. As only carbon forms the backbone of the ring, it is also a homocyclic compound. H H γ H H H H C C C C 4 β' C C β Heterocyclic Pyridine Carbocyclic Benzene 5 3 with one α' 6 2 α C C C 1 C Nitrogen Heteroatom C N H H H H H Figure 1: Structure of Homocyclic Benzene and Heterocyclic Pyridine In contrast, cyclic compounds having at least one atom other than carbon as ring members, (e.g. Pyridine with nitrogen replacing one of the carbon atom) may be termed as heterocyclic compounds . These atoms are termed as heteroatoms . The structure of benzene and pyridine are provided in figure 1 above. Nomenclature of Heterocyclic Compounds Heterocyclic compounds are popularly known by their common names. However, IUPAC has provided a systematic nomenclature with prefix and suffix as discussed below. According to IUPAC, the numbering starts with the heteroatom as shown in figure 1. According to common names, the greek letters, α, β, γ etc are followed as shown in figure 1. Order of Seniority Prefix Suffix 1 Oxa for oxygen 2 Thia for sulfur -ole for 5 membered rings 3 Aza for nitrogen -ine for 6 membered rings 4 Phoshpha for phosphorus -epine for 7 membered rings 5 Bora for boron Table 1: Nomenclature of Heterocyclic compounds When more than one heteroatom is present in a molecule, an order of seniority exists for the naming and numbering system, with the number preference given for oxygen first followed by 1 other atoms as shown.
    [Show full text]
  • Heteroatom-Doped Graphitic Carbon Catalysts for Efficient
    Perspective pubs.acs.org/acscatalysis Heteroatom-Doped Graphitic Carbon Catalysts for Efficient Electrocatalysis of Oxygen Reduction Reaction † Jintao Zhang and Liming Dai* Center of Advanced Science and Engineering for Carbon (Case4carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States ABSTRACT: The oxygen reduction reaction (ORR) plays an important role in renewable energy technologies, such as fuel cells and metal−air batteries. Along with the extensive research and development of nonprecious metal catalysts (NPMCs) to reduce/replace Pt for electrocatalytic reduction of oxygen, a new class of heteroatom-doped metal-free carbon catalysts has been recently developed, which, as alternative ORR catalysts, could dramatically reduce the cost and increase the efficiency of fuel cells and metal−air batteries. The improved catalytic performance of heteroatom-doped carbon ORR catalysts has been attributed to the doping-induced charge redistribution ff around the heteroatom dopants, which lowered the ORR potential and changed the O2 chemisorption mode to e ectively weaken the O−O bonding, facilitating ORR at the heteroatom-doped carbon electrodes. Subsequently, this new metal-free ORR mechanism was confirmed by numerous studies, and the same principle has been applied to the development of various other efficient catalysts for not only ORR in fuel cells but also oxygen evolution reaction (OER) in metal−air batteries and hydrogen evolution reaction (HER) in water-splitting systems. However, there are still some concerns about possible contributions of metal impurities to the ORR activities of these carbon catalysts. To avoid unnecessary confusion, therefore, it is important to clarify the situation.
    [Show full text]