Durham E-Theses
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
The Ins and Outs of Dechlorination
The Ins and Outs of Dechlorination If you plan on using a municipal water supply for chlorine is added to water, it will first react with growing fish you will require a dechlorination step any reducing agents, including any ammonia that in your water treatment process. Most municipal may be present. Hypochlorous acid reacts with water systems use chlorine or chloramine (a com- ammonia to form chloramines as follows: bination of chlorine and ammonia) to render the water safe for human consumption. While rela- HOCL + NH3 _ H2O + NH2Cl (monochloramine) tively harmless to humans in minute amounts, HOCL + NH2Cl _ H2O + NHCl2 (dichloramine) chlorine can be deadly to fish. In order to under- HOCL + NHCl2 _ H2O + NCl3 (trichloramine) BY: CARLA MACQUARRIE stand how to dechlorinate water, there must first AND SEAN WILTON be an understanding of how and why chlorine is The formation of chloramines is also dependent used as a disinfecting agent. on pH and temperature, as well as on the concen- tration of ammonia. With the added presence of Chlorine is water soluble gas (7160 mg/L these chloramines, the available chlorine is at 20°C and 1atm) that hydrolyzes rapidly referred to as combined available chlorine (CAC). to form hypochlorous acid (HOCl). This When these reactions are complete, residual reaction forms the basis for the applica- chlorine will accumulate, either in the form of FAC tion of chlorine as a disinfectant and oxi- or CAC. Total residual chlorine refers to the sum of dant as follows: the free and combined forms of residual chlorine. As a disinfectant, the FAC component is more Cl2 + H20 —> HOCl + H+ + Cl- effective than the CAC – this is because chlo- ramines are considered to have only a moderate The by-product, hypochlorous acid(HOCl) biocidal activity against bacteria and a low bioci- ionizes to produce the hypochlorite (OCl-) dal activity against viruses and cysts. -
Hypochlorous Acid Handling
Hypochlorous Acid Handling 1 Identification of Petitioned Substance 2 Chemical Names: Hypochlorous acid, CAS Numbers: 7790-92-3 3 hypochloric(I) acid, chloranol, 4 hydroxidochlorine 10 Other Codes: European Community 11 Number-22757, IUPAC-Hypochlorous acid 5 Other Name: Hydrogen hypochlorite, 6 Chlorine hydroxide List other codes: PubChem CID 24341 7 Trade Names: Bleach, Sodium hypochlorite, InChI Key: QWPPOHNGKGFGJK- 8 Calcium hypochlorite, Sterilox, hypochlorite, UHFFFAOYSA-N 9 NVC-10 UNII: 712K4CDC10 12 Summary of Petitioned Use 13 A petition has been received from a stakeholder requesting that hypochlorous acid (also referred 14 to as electrolyzed water (EW)) be added to the list of synthetic substances allowed for use in 15 organic production and handling (7 CFR §§ 205.600-606). Specifically, the petition concerns the 16 formation of hypochlorous acid at the anode of an electrolysis apparatus designed for its 17 production from a brine solution. This active ingredient is aqueous hypochlorous acid which acts 18 as an oxidizing agent. The petitioner plans use hypochlorous acid as a sanitizer and antimicrobial 19 agent for the production and handling of organic products. The petition also requests to resolve a 20 difference in interpretation of allowed substances for chlorine materials on the National List of 21 Allowed and Prohibited Substances that contain the active ingredient hypochlorous acid (NOP- 22 PM 14-3 Electrolyzed water). 23 The NOP has issued NOP 5026 “Guidance, the use of Chlorine Materials in Organic Production 24 and Handling.” This guidance document clarifies the use of chlorine materials in organic 25 production and handling to align the National List with the November, 1995 NOSB 26 recommendation on chlorine materials which read: 27 “Allowed for disinfecting and sanitizing food contact surfaces. -
Bimetallic Catalyst Catalyzed Carbonylation of Methanol to Acetic Acid
materials Article Study on Rh(I)/Ru(III) Bimetallic Catalyst Catalyzed Carbonylation of Methanol to Acetic Acid Shasha Zhang 1, Wenxin Ji 1,2,*, Ning Feng 2, Liping Lan 1, Yuanyuan Li 1,2 and Yulong Ma 1,2 1 College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China; [email protected] (S.Z.); [email protected] (L.L.); [email protected] (Y.L.); [email protected] (Y.M.) 2 State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, Yinchuan 750021, China; [email protected] * Correspondence: [email protected]; Tel.: +86-135-1957-9989; Fax: +86-951-206-2323 Received: 13 July 2020; Accepted: 3 September 2020; Published: 11 September 2020 Abstract: In this study, a Rh(I)/Ru(III) catalyst with a bimetallic space structure was designed and synthesized. The interaction between the metals of the bimetallic catalyst and the structure of the bridged dimer can effectively reduce the steric hindrance effect and help speed up the reaction rate while ensuring the stability of the catalyst. X-ray photoelectron spectroscopy (XPS) results show that rhodium accepts electrons from chlorine, thereby increasing the electron-rich nature of rhodium and improving the catalytic activity. This promotes the nucleophilic reaction of the catalyst with methyl iodide and reduces the reaction energy barrier. The methanol carbonylation performance of the Rh/Ru catalyst was evaluated, and the results show that the conversion rate of methyl acetate and the yield of acetic acid are 96.0% under certain conditions. Furthermore, during the catalysis, no precipitate is formed and the amount of water is greatly reduced. -
Advances in the Carbonylation of Aryl Halides Using Palladium Catalysts
FIRST SOLVIAS SCIENCE DAY 684 CHIMIA 2001,55, No.9 Chimia 55 (2001) 684--687 © Schweizerische Chemische Gesellschaft ISSN 0009-4293 Advances in the Carbonylation of Aryl Halides Using Palladium Catalysts Matthias Bellera* and Adriano F. Indoleseb Abstract: The palladium-catalyzed carbonylation of aryl halides is shown to be a versatile tool for the synthesis of various benzoic and heteroaromatic acid derivatives. Recent developments from our laboratories in this area are presented. Keywords: Benzoic acid derivatives· Carbonylation . Homogeneous catalysis· Palladium Introduction From a general point of view the leav- Elegant work by researchers from ing group of the aryl-X derivative is for- Hoffmann-La Roche also demonstrated Palladium-catalyzed carbonylation reac- mally replaced by a nucleophile with in- the industrial applicability of such a reac- tions of aryl-X compounds leading to corporation of one or two molecules of tion in the commercial process for carboxylic acid derivatives were estab- CO (Scheme I). In addition to aryl-, hete- Lazabemide, a monamine oxidase B in- lished in the mid-seventies by the pio- ro-aryl-, vinyl-, allyl- und benzyl-X com- hibitor. In this process the aminocar- neering work of Heck and co-workers pounds can also serve as starting materi- bonylation of the commercially available [1]. Since that time these reactions have als in these carbonylations [2]. Two ex- 2,5-dichloropyridine with ethylenedi- found a number of applications in organ- amples for carbonylation reactions of ben- amine is performed with a Pd/dppp cata- ic synthesis, and even some industrial zyl-X applied on an industrial scale for lyst with comparably high catalyst pro- processes (see below) have been realized. -
39 Transition Metal Ketenes Laura M. Babcock Literature Seminar March 19, 1985 the Mechanism of Fischer-Tropsch Catalysis Is
39 Transition Metal Ketenes Laura M. Babcock Literature Seminar March 19, 1985 The mechanism of Fischer-Tropsch catalysis is presently believed to pro ceed via reactions involving methylene species on metal surfaces [1]. Muetterties, Herrmann, and Katzer [2] have suggested that carbonyl carbene coupling to form an intermediate ketene complex is one reaction path which could lead to oxygen-containing products. Support for these ketene inter mediates arises from the ever increasing number of isolable, transition metal ketene complexes and their subsequent reactivity. Transition metal ketenes have been observed in several different bonding arrangements. C ,0 and C ,C 'TT-bonding to one or two metal centers have been reported. Terminal, MRC~C=O, and µ cluster bridged ketene complexes are 3 also known. There are three primary methods for synthesizing transition metal ketenes. Substitution reactions bind a ketene to the metal center by displacement of a weakly Mund ligand [ 3]. Dehydrohalogena tion, a general synthetic route to ketene complexes of zr ·and Ti, involves proton abstraction from the acyl~halo complex followed by displacement of the halogen by the ketene oxygen [4]. Insertion of a carbonyl into the metal carbon bond of a methylene ligand is, however, the most common method for preparing metal ketenes [5]. CO insertion into other alkylidenes and alkylidynes has been observed as well, Fig. 1. L3bellng and reactivity studies on several systems 0s(C0)4 a . /~ . (CO).,ps 0s(C014 \ c-cI H2 'o Fig. 1 2 PMe3 _ e"'-t,,,_h=-=e_,__r__ b. 40°C indicate that both internal c~rbene-carbonyl coupling [5b,c,6] and insertion of external carbon monoxide [7] are possible pathways for the formation of metal ketenes. -
Warning: the Following Lecture Contains Graphic Images
What the новичок (Novichok)? Why Chemical Warfare Agents Are More Relevant Than Ever Matt Sztajnkrycer, MD PHD Professor of Emergency Medicine, Mayo Clinic Medical Toxicologist, Minnesota Poison Control System Medical Director, RFD Chemical Assessment Team @NoobieMatt #ITLS2018 Disclosures In accordance with the Accreditation Council for Continuing Medical Education (ACCME) Standards, the American Nurses Credentialing Center’s Commission (ANCC) and the Commission on Accreditation for Pre-Hospital Continuing Education (CAPCE), states presenters must disclose the existence of significant financial interests in or relationships with manufacturers or commercial products that may have a direct interest in the subject matter of the presentation, and relationships with the commercial supporter of this CME activity. The presenter does not consider that it will influence their presentation. Dr. Sztajnkrycer does not have a significant financial relationship to report. Dr. Sztajnkrycer is on the Editorial Board of International Trauma Life Support. Specific CW Agents Classes of Chemical Agents: The Big 5 The “A” List Pulmonary Agents Phosgene Oxime, Chlorine Vesicants Mustard, Phosgene Blood Agents CN Nerve Agents G, V, Novel, T Incapacitating Agents Thinking Outside the Box - An Abbreviated List Ammonia Fluorine Chlorine Acrylonitrile Hydrogen Sulfide Phosphine Methyl Isocyanate Dibotane Hydrogen Selenide Allyl Alcohol Sulfur Dioxide TDI Acrolein Nitric Acid Arsine Hydrazine Compound 1080/1081 Nitrogen Dioxide Tetramine (TETS) Ethylene Oxide Chlorine Leaks Phosphine Chlorine Common Toxic Industrial Chemical (“TIC”). Why use it in war/terror? Chlorine Density of 3.21 g/L. Heavier than air (1.28 g/L) sinks. Concentrates in low-lying areas. Like basements and underground bunkers. Reacts with water: Hypochlorous acid (HClO) Hydrochloric acid (HCl). -
ACETIC ACID and ACETIC ANHYDRIDE (November 1994)
Abstract Process Economics Program Report 37B ACETIC ACID AND ACETIC ANHYDRIDE (November 1994) This Report presents preliminary process designs and estimated economics for the manufacture of acetic acid and acetic anhydride by carbonylation technology. The three processes evaluated in this report include Monsanto’s low pressure carbonylation of methanol process (BP Chemical acquired licensing rights to this process in 1985), Eastman’s process for carbonylation of methyl acetate to produce acetic anhydride (methanol added to the reaction mixture results in the coproduction of acetic acid in this process), and a process based on BP Chemical patents that coproduces acetic acid and acetic anhydride via carbonylation of methyl acetate in the presence of water. Both the Eastman and BP Chemical processes are back– integrated into the manufacture of the methyl acetate feedstock from methanol and acetic acid. We have included a discussion of other commercialized acetic acid and acetic anhydride processes as well as potential new processes. A list of the world’s acetic acid and acetic anhydride producers along with their estimated plant capacities and a description of the major acetic acid and acetic anhydride markets are also included in this Report. This Report will be useful to producers of acetic acid and acetic anhydride, as well as to producers of methanol and downstream products such as vinyl acetate monomer. PEP’93 MKG CONTENTS 1 INTRODUCTION 1-1 2 SUMMARY 2-1 GENERAL ASPECTS 2-1 ECONOMIC ASPECTS 2-1 TECHNICAL ASPECTS 2-3 Low Pressure Carbonylation -
Active Chlorine Released from Hypochlorous Acid
Regulation (EU) No 528/2012 concerning the making available on the market and use of biocidal products Evaluation of active substances Assessment Report ★ ★ ★ ★ * ★ * ★★ Active chlorine released from hypochlorous acid Product-type 1 (Human hygiene) July 2020 Slovak Republic Active chlorine released from Product-type 1 July 2020 hypochlorous acid CONTENTS 1. STATEMENT OF SUBJECT MATTER AND PURPOSE............................... 4 1.1. Procedure followed................................................................................................... 4 1.2. Purpose of the assessment report............................................................................ 4 2. OVERALL SUMMARY AND CONCLUSIONS............................................ 5 2.1. Presentation of the Active Substance.......................................................................5 2.1.1. Identity, Physico-Chemical Properties & Methods of Analysis..................................... 5 2.1.2. Intended Uses and Efficacy..................................................................................... 9 2.1.3. Classification and Labelling.................................................................................... 10 2.2. Summary of the Risk Assessment............................................................................10 2.2.1. Human Health Risk Assessment............................................................................. 10 2.2.1.1. Hazard identification and effects assessment.................................................... 10 2.2.1.2. -
Organometallic Chemistry Chemistry
OrganometallicOrganometallic Chemistry Chemistry Worawan Bhanthumnavin Department of Chemistry Chulalongkorn University Bangkok 10330, Thailand Given as part of the 6th semester organic chemistry course at the University of Regensburg (May 2008) Under the ASEM-DUO Thailand 2007 exchange program organoboron, organosilicon Organoboron compounds • Revise: what organoboron have you seen before? boranes Organoboron compounds • vast array of C-C-forming reactions involving organoborons • Here: focus on transfer reactions of C moieties from boron to an adjacent C. Examples: transfer of CO, CN, carbanions derived from dichloromethyl methyl ether and dichloromethane, and allyl groups in reactions of allylic boranes with aldehydes. Preparations Reaction of Organoborons Carbonylation • reaction of organoboranes with carbon monoxide [(–):C≡O:(+) ], which is an ylide, gives rise to 3 possible rearrangements. • Depending on reaction conditions, single, double, and triple migrations of groups may occur leading, after appropriate workup, to a variety of aldehydes and ketones as well as primary, secondary, and tertiary alcohols. Reaction of Organoborons Carbonylation Synthesis of Aldehydes and Primary Alcohols • Addition of CO to trialkylboranes leads to the formation of an ate-complex (structure A). Subsequent migration of an R group to the CO ligand yields intermediate B. In the presence of a mild reducing agent, such as lithium trimethoxyaluminum hydride or potassium triisopropoxyborohydride, B is converted to the mono-migration product C. Reaction of Organoborons Carbonylation Synthesis of Aldehydes and Primary Alcohols • Oxidation (H2O2) of C furnishes the corresponding aldehyde. On the other hand, treatment of C with LiAlH4 followed by oxidative workup produces the primary alcohol. Reaction of Organoborons Carbonylation Synthesis of Aldehydes and Primary Alcohols • To maximize utilization of valuable alkyl groups, alkenes used for the transfer reaction are hydroborated with 9-BBN. -
Nitroxyl (Hno) and Carbonylnitrenes
INVESTIGATION OF REACTIVE INTERMEDIATES: NITROXYL (HNO) AND CARBONYLNITRENES by Tyler A. Chavez A dissertation submitted to the Johns Hopkins University in conformity with the requirements for the degree of Doctor of Philosophy Baltimore, Maryland February 2016 © 2016 Tyler A. Chavez All rights reserved Abstract Membrane inlet mass spectrometry (MIMS) is a well-established method used to detect gases dissolved in solution through the use of a semipermeable hydrophobic membrane that allows the dissolved gases, but not the liquid phase, to enter a mass spectrometer. Interest in the unique biological activity of azanone (nitroxyl, HNO) has highlighted the need for new sensitive and direct detection methods. Recently, MIMS has been shown to be a viable method for HNO detection with nanomolar sensitivity under physiologically relevant conditions (Chapter 2). In addition, this technique has been used to explore potential biological pathways to HNO production (Chapter 3). Nitrenes are reactive intermediates containing neutral, monovalent nitrogen atoms. In contrast to alky- and arylnitrenes, carbonylnitrenes are typically ground state singlets. In joint synthesis, anion photoelectron spectroscopic, and computational work we studied the three nitrenes, benzoylnitrene, acetylnitrene, and trifluoroacetylnitrene, with the purpose of determining the singlet-triplet splitting (ΔEST = ES – ET) in each case (Chapter 7). Further, triplet ethoxycarbonylnitrene and triplet t-butyloxycarbonylnitrene have been observed following photolysis of sulfilimine precursors by time-resolved infrared (TRIR) spectroscopy (Chapter 6). The observed growth kinetics of nitrene products suggest a contribution from both the triplet and singlet nitrene, with the contribution from the singlet becoming more prevalent in polar solvents. Advisor: Professor John P. Toscano Readers: Professor Kenneth D. -
Metal Carbonyls
MODULE 1: METAL CARBONYLS Key words: Carbon monoxide; transition metal complexes; ligand substitution reactions; mononuclear carbonyls; dinuclear carbonyls; polynuclear carbonyls; catalytic activity; Monsanto process; Collman’s reagent; effective atomic number; 18-electron rule V. D. Bhatt / Selected topics in coordination chemistry / 2 MODULE 1: METAL CARBONYLS LECTURE #1 1. INTRODUCTION: Justus von Liebig attempted initial experiments on reaction of carbon monoxide with metals in 1834. However, it was demonstrated later that the compound he claimed to be potassium carbonyl was not a metal carbonyl at all. After the synthesis of [PtCl2(CO)2] and [PtCl2(CO)]2 reported by Schutzenberger (1868) followed by [Ni(CO)4] reported by Mond et al (1890), Hieber prepared numerous compounds containing metal and carbon monoxide. Compounds having at least one bond between carbon and metal are known as organometallic compounds. Metal carbonyls are the transition metal complexes of carbon monoxide containing metal-carbon bond. Lone pair of electrons are available on both carbon and oxygen atoms of carbon monoxide ligand. However, as the carbon atoms donate electrons to the metal, these complexes are named as carbonyls. A variety of such complexes such as mono nuclear, poly nuclear, homoleptic and mixed ligand are known. These compounds are widely studied due to industrial importance, catalytic properties and structural interest. V. D. Bhatt / Selected topics in coordination chemistry / 3 Carbon monoxide is one of the most important π- acceptor ligand. Because of its π- acidity, carbon monoxide can stabilize zero formal oxidation state of metals in carbonyl complexes. 2. SYNTHESIS OF METAL CARBONYLS Following are some of the general methods of preparation of metal carbonyls. -
Action of Hypochlorous Acid on Polymeric Components of Cartilage
Action of Hypochlorous Acid on Polymeric Components of Cartilage. Use of 13C NMR Spectroscopy Jürgen Schiller, Jürgen Arnhold and Klaus Arnold Institut für Medizinische Physik und Biophysik, Medizinische Fakultät, Universität Leipzig, Liebigstraße 27, D-04103 Leipzig, Bundesrepublik Deutschland Z. Naturforsch. 50c, 721-728 (1995); received May 29/June 21, 1995 Hypochlorous Acid, Cartilage, Chondroitinsulphate, Carbon NMR Spectroscopy It is a well known fact that neutrophil-derived hypochlorous acid plays an important role in cartilage destruction during rheumatoid arthritis. It has been shown by 'H NMR spectro scopy in a previous paper (Schiller et al. (1994), Biol. Chem. Hoppe-Seyler 375, 167-172) that sodium hypochlorite affects primarily the N-acetyl side chains of polymeric carbohydrates of cartilage like chondroitinsulphate and hyaluronic acid. An instable intermediate, likely to be a chloramine, is involved in these processes. The present paper deals with the application of carbon NMR spectroscopy for the study of these degradation processes, because carbon NMR gives the opportunity to detect changes on the single sugar ring carbons. Although it was not possible to prove the involvement of an intermediate, because of its fast hydrolysis, we were able to show that the reaction between sodium hypochlorite and N-acetylglucos- amine affects mainly the side chain, accompanied by the formation of acetate. The application of a large excess of sodium hypochlorite leads to a breakdown of the carbohydrate ring under the formation of formiate. Introduction model experiments (Baker et al., 1988; Kowanko Rheumatic diseases are characterized by a mas et al., 1989). Whereas a loss of viscosity of hyal sive damage of components of the extracellular uronic acid solutions is observed with small matrix and an enhancement of the number of amounts of hypochlorous acid, higher concentra polymorphonuclear leukocytes (PMNs) in the in tions lead to a breakdown of the polymer chains flamed joint (Zvaifler, 1973; Brown, 1988).