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Vibrationally Excited Hydrogen Halides : a Bibliography On
VI NBS SPECIAL PUBLICATION 392 J U.S. DEPARTMENT OF COMMERCE / National Bureau of Standards National Bureau of Standards Bldg. Library, _ E-01 Admin. OCT 1 1981 191023 / oO Vibrationally Excited Hydrogen Halides: A Bibliography on Chemical Kinetics of Chemiexcitation and Energy Transfer Processes (1958 through 1973) QC 100 • 1X57 no. 2te c l !14 c '- — | NATIONAL BUREAU OF STANDARDS The National Bureau of Standards' was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Institute for Computer Sciences and Technology, and the Office for Information Programs. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Meas- urement Services and the following divisions: Applied Mathematics — Electricity — Mechanics — Heat — Optical Physics — Nuclear Sciences" — Applied Radiation 2 — Quantum Electronics 1 — Electromagnetics 3 — Time 3 1 1 and Frequency — Laboratory Astrophysics — Cryogenics . -
Prebiological Evolution and the Metabolic Origins of Life
Prebiological Evolution and the Andrew J. Pratt* Metabolic Origins of Life University of Canterbury Keywords Abiogenesis, origin of life, metabolism, hydrothermal, iron Abstract The chemoton model of cells posits three subsystems: metabolism, compartmentalization, and information. A specific model for the prebiological evolution of a reproducing system with rudimentary versions of these three interdependent subsystems is presented. This is based on the initial emergence and reproduction of autocatalytic networks in hydrothermal microcompartments containing iron sulfide. The driving force for life was catalysis of the dissipation of the intrinsic redox gradient of the planet. The codependence of life on iron and phosphate provides chemical constraints on the ordering of prebiological evolution. The initial protometabolism was based on positive feedback loops associated with in situ carbon fixation in which the initial protometabolites modified the catalytic capacity and mobility of metal-based catalysts, especially iron-sulfur centers. A number of selection mechanisms, including catalytic efficiency and specificity, hydrolytic stability, and selective solubilization, are proposed as key determinants for autocatalytic reproduction exploited in protometabolic evolution. This evolutionary process led from autocatalytic networks within preexisting compartments to discrete, reproducing, mobile vesicular protocells with the capacity to use soluble sugar phosphates and hence the opportunity to develop nucleic acids. Fidelity of information transfer in the reproduction of these increasingly complex autocatalytic networks is a key selection pressure in prebiological evolution that eventually leads to the selection of nucleic acids as a digital information subsystem and hence the emergence of fully functional chemotons capable of Darwinian evolution. 1 Introduction: Chemoton Subsystems and Evolutionary Pathways Living cells are autocatalytic entities that harness redox energy via the selective catalysis of biochemical transformations. -
A Chemical Engineering Perspective on the Origins of Life
Processes 2015, 3, 309-338; doi:10.3390/pr3020309 processesOPEN ACCESS ISSN 2227-9717 www.mdpi.com/journal/processes Article A Chemical Engineering Perspective on the Origins of Life Martha A. Grover *, Christine Y. He, Ming-Chien Hsieh and Sheng-Sheng Yu School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Dr. NW, Atlanta, GA 30032, USA; E-Mails: [email protected] (C.Y.H.); [email protected] (M.-C.H.); [email protected] (S.-S.Y.) * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +1-404-894-2878 or +1-404-894-2866. Academic Editor: Michael Henson Received: 29 January 2015 / Accepted: 19 April 2015 / Published: 5 May 2015 Abstract: Atoms and molecules assemble into materials, with the material structure determining the properties and ultimate function. Human-made materials and systems have achieved great complexity, such as the integrated circuit and the modern airplane. However, they still do not rival the adaptivity and robustness of biological systems. Understanding the reaction and assembly of molecules on the early Earth is a scientific grand challenge, and also can elucidate the design principles underlying biological materials and systems. This research requires understanding of chemical reactions, thermodynamics, fluid mechanics, heat and mass transfer, optimization, and control. Thus, the discipline of chemical engineering can play a central role in advancing the field. In this paper, an overview of research in the origins field is given, with particular emphasis on the origin of biopolymers and the role of chemical engineering phenomena. A case study is presented to highlight the importance of the environment and its coupling to the chemistry. -
Carbon Kinetic Isotope Effect in the Oxidation of Methane by The
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 95, NO. D13, PAGES 22,455-22,462, DECEMBER 20, 1990 CarbonKinetic IsotopeEffect in the Oxidationof Methaneby the Hydroxyl Radical CttRISTOPHERA. CANTRELL,RICHARD E. SHE•, ANTHONY H. MCDANmL, JACK G. CALVERT, JAMESA. DAVIDSON,DAVID C. LOWEl, STANLEYC. TYLER,RALPH J. CICERONE2, AND JAMES P. GREENBERG AtmosphericKinetics and PhotochemistryGroup, AtmosphericChemistry Division, National Centerfor AtmosphericResearch, Boulder, Colorado The reactionof the hydroxylradical (HO) with the stablecafix)n isotopes of methanehas been studied as a functionof temperaturefrom 273 to 353 K. The measuredratio of the rate coefficientsfor reaction with•ZCHn relative to •3CH•(kn•/kn3) was 1.0054 (20.0009 at the95% confidence interval), independent of temperaturewithin the precisionof the measurement,over the rangestudied. The precisionof the present valueis muchimproved over that of previousstudies, and this resultprovides important constraints on the currentunderstanding of the cyclingof methanethrough the atmospherethrough the useof carbonisotope measurements. INTRODUCTION weightedaverage of the sourceratios must equal the atmospher- Methane (CH•) is an importanttrace gas in the atmosphere ic ratio, after correctionfor fractionationin any lossprocesses. [Wofsy,1976]. It is a key sink for the tropospherichydroxyl The primaryloss of CI-I4in the troposphereis the reactionwith radical. Methane contributesto greenhousewarming [Donner the hydroxylradical: and Ramanathan,1980]; its potentialwarming effects follow only CO2 and H20. Methaneis a primary sink for chlorine (R1) CHn + HO ---)CH3 + HzO atomsin the stratosphereand a majorsource of watervapor in the upper stratosphere. The concentrationof CI-I4 in the The rate coefficient for this reaction has been studied extensive- tropospherehas been increasing at a rateof approximately1% ly (seereview by Ravishankara[1988]), but dataindicating the per year, at leastover the pastdecade [Rasmussen and Khalil, effect of isotopesubstitution in methaneare scarce. -
Ubiquitous Argonium \(Arh+\) in the Diffuse Interstellar Medium: A
A&A 566, A29 (2014) Astronomy DOI: 10.1051/0004-6361/201423727 & c ESO 2014 Astrophysics Ubiquitous argonium (ArH+) in the diffuse interstellar medium: A molecular tracer of almost purely atomic gas P. Schilke1, D. A. Neufeld2, H. S. P. Müller1, C. Comito1, E. A. Bergin3, D. C. Lis4;5, M. Gerin6, J. H. Black7, M. Wolfire8, N. Indriolo2, J. C. Pearson9, K. M. Menten10, B. Winkel10, Á. Sánchez-Monge1, T. Möller1, B. Godard6, and E. Falgarone6 1 I. Physikalisches Institut der Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany e-mail: [email protected] 2 The Johns Hopkins University, Baltimore, MD 21218, USA 3 Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042, USA 4 California Institute of Technology, Pasadena, CA 91125, USA 5 Sorbonne Universités, Université Pierre et Marie Curie, Paris 6, CNRS, Observatoire de Paris, UMR 8112 LERMA, Paris, France 6 LERMA, CNRS UMR 8112, Observatoire de Paris & École Normale Supérieure, 24 rue Lhomond, 75005 Paris, France 7 Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden 8 Astronomy Department, University of Maryland, College Park, MD 20742, USA 9 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA 10 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany Received 28 February 2014 / Accepted 29 March 2014 ABSTRACT Aims. We describe the assignment of a previously unidentified interstellar absorption line to ArH+ and discuss its relevance in the + context of hydride absorption in diffuse gas with a low H2 fraction. -
Understanding the Bonding of Second Period Diatomic Molecules Spdf Vs MCAS
Understanding the Bonding of Second Period Diatomic Molecules Spdf vs MCAS By Joel M Williams (text and images © 2013) The html version with updates and higher resolution images is at the author’s website (click here) Abstract The current spdf and MO modeling of chemical molecules are well-established, but do so by continuing to assume that non-classical physics is operating. The MCAS electron orbital model is an alternate particulate model based on classical physics. This paper describes its application to the diatomic molecules of the second period of the periodic table. In doing so, it addresses their molecular electrostatics, bond strengths, and electron affinities. Particular attention is given to the anomalies of the carbon diatom. Questions are raised about the sensibleness of the spdf model’s spatial ability to contain two electrons on an axis between diatoms and its ability to form π-bonds from parallel p-orbitals located over the nuclei of each atom. Nitrogen, carbon monoxide, oxygen, and fluorine all have the same inter-nuclei bonding: all “triple bonds” of varying strength caused by different numbers of anti-bonding electrons. The spdf model was devised for single atoms by physicists and mathematicians. Kowtowing to them, chemists produce hybrid orbitals to explain how atoms could actually form molecules. Drawing these hybrids and meshing them on paper might look great, but, constrained to measured interatomic physical dimensions and electrostatic interactions, bonding based on the spdf-hybrids (sp, sp2, sp3) is illogical. To have even one electron occupy the “bond” region between the nuclei of diatomic molecules, at the expense of reduced coverage elsewhere, does not make sense for stable molecules. -
Questions ALKENES: REACTIONS with HYDROGEN HALIDES
Chemguide – questions ALKENES: REACTIONS WITH HYDROGEN HALIDES 1. State Markovnikov's Rule. 2. Show the structural formulae for the main product of each of the following addition reactions between various alkenes and a hydrogen halide. (This question is also testing your ability to write the structures for alkenes given their names. If you can't do that, get it sorted out before you continue!) a) ethene and hydrogen bromide b) but-2-ene and hydrogen chloride c) but-1-ene and hydrogen chloride d) propene and hydrogen iodide e) 2-methylbut-2-ene and hydrogen iodide f) but-1-ene and hydrogen bromide where everything is pure g) but-1-ene and hydrogen bromide in the presence of oxygen or organic peroxides 3. a) How does the rate of the reaction change as you go along the series HF – HCl – HBr – HI? b) Briefly explain the trend you have given in part (a). c) How does the rate of reaction change as you go from ethene to propene to 2-methylbut-2-ene? d) Alkyl groups (like methyl and ethyl groups) have a tendency to “push” electrons away from themselves towards the double bond. (i) How does this help to explain the way the attractiveness of the double bond varies from ethene to propene to 2-methylbut-2-ene? (ii) The mechanism for the reactions involves the formation of intermediate ions with the positive charge on a carbon atom (carbocations). The intermediate carbocations in these cases would be + + + CH CH CH CHCH CH CCH CH 3 2 3 3 3 2 3 CH3 Why does this help to explain the variation in reactivity that you should have given in part (c)? www.chemguide.co.uk. -
UNITED STATES PATENT of FICE 2,640,086 PROCESS for SEPARATING HYDROGEN FLUORIDE from CHLORODFLUORO METHANE Robert H
Patented May 26, 1953 2,640,086 UNITED STATES PATENT of FICE 2,640,086 PROCESS FOR SEPARATING HYDROGEN FLUORIDE FROM CHLORODFLUORO METHANE Robert H. Baldwin, Chadds Ford, Pa., assignor to E. H. du Pont de Nemours and Company, Wi inington, Del, a corporation of Delaware No Drawing. Application December 15, 1951, Serial No. 261,929 9 Claims. (C. 260-653) 2 This invention relates to a process for Sep These objects are accomplished essentially by arating hydrogen fluoride from monochlorodi Subjecting a mixture of hydrogen fluoride and fluoronethane, and more particularly, separat Inonochlorodifluoromethane in the liquid phase ing these components from the reaction mixture to temperatures below 0° C., preferably at about obtained in the fluorination of chloroform with -30° C. to -50° C., at either atmospheric or hydrogen fluoride, Super-atmospheric pressures, together with from In the fluorination of chloroform in the prest about 0.25 mol to about 2.5 mols of chloroform ence Of a Catalyst, a reaction mixture is pro per mol of chlorodifluoronethane contained in duced which consists essentially of HCl, HF, the mixture and separating an upper layer rich CHCIF2, CHCl2F, CHCls, and CHF3. A method O in HF from a lower organic layer. The proceSS of Separating these components is disclosed in is operative with mixtures containing up to 77% U. S. Patent No. 2,450,414 which involves sep by weight of HF. arating the components by a special fractional It has been found that chloroform is substan distillation under appropriate temperatures and tially immiscible With EIF at temperatures be pressures. -
Determination of Aluminium As Oxide
DETERMINATION OF ALUMINIUM AS OXIDE By William Blum CONTENTS Page I. Introduction 515 II. General principles 516 III. Historical 516 IV. Precipitation of aluminium hydroxide. 518 1. Hydrogen electrode studies 518 (a) The method 518 (b) Apparatus and solutions employed 518 (c) Results of hydrogen electrode experiments 519 (d) Conclusions from hydrogen electrode experiments 520 2. Selection of an indicator for denning the conditions of precipita- '. tion . 522 3. Factors affecting the form of the precipitate 524 4. Precipitation in the presence of iron 525 V. Washing the precipitate . 525 VI. Separation from other elements 526 VII. Ignition and weighing of the precipitate 528 1. Hygroscopicity of aluminium oxide 529 2. Temperature and time of ignition 529 3. Effect of ammonium chloride upon the ignition 531 VIII. Procedure recommended 532 IX. Confirmatory experiments 532 X. Conclusions '534 I. INTRODUCTION Although a considerable number of precipitants have been pro- posed for the determination of aluminium, direct precipitation of aluminium hydroxide by means of ammonium hydroxide, fol- lowed by ignition to oxide, is most commonly used, especially if no separation from iron is desired, in which latter case special methods must be employed. While the general principles involved in this determination are extremely simple, it has long been recog- nized that certain precautions in the precipitation, washing, and ignition are necessary if accurate results are to be obtained. While, however, most of these details have been studied and dis- cussed by numerous authors, it is noteworthy that few publica- tions or textbooks have taken account of all the factors. In the 515 ; 516 Bulletin of the Bureau of Standards [Voi.i3 present paper it seems desirable, therefore, to assemble the various recommendations and to consider their basis and their accuracy. -
Discharge Plasmas of Molecular Gases
/ J ¥4~r~~~: 'o j~ ~7 ~,~U;~I u t= ~]f~LL*~ ~~~~~~; 4. Isotope Separation in Discharge Plasmas of Molecular Gases EZOUBTCHENKO, Alexandre N.t, AKATSUKA Hiroshi and SUZUKI Masaaki Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo 152-8550, Japan (Received 25 December 1997) Abstract We review the theoretical principles and the experimental methods of isotope separation achieved through the use of discharge plasmas of molecular gases. Isotope separation has been accomplished in various plasma chemical reactions. It is experimentally and theoretically shown that a state of non- equilibrium in the plasmas, especially in the vibrational distribution functions, is essential for the isotope redistribution in the reagents and products. Examples of the reactions, together with the isotope separ- ation factors known up to the present time, are shown to separate isotopic species of carbon, nitrogen and oxygen molecules in the plasma phase, generated by glow discharge and microwave discharge. Keywords: isotope separation, vibrational nonequilibrium, glow discharge, microwave discharge, plasma chemistry 4.1 Introduction isotopic species will be redistributed between the rea- Plasmas generated by electric discharge of molecu- gents and the products. We can elaborate a new lar gases under moderate pressures (10 Torr < p < method of the plasma isotope separation for light ele- 200 Torr) are usually in a state of nonequilibrium. We ments . can define various temperatures according to the kine- There were a few experimental studies of isotope tics of various particles in such plasmas, for example, separation phenomena in the nonequilibrium electric electron temperature ( T*), gas translational temperature discharge. Semiokhin et al. measured C02 enrichment ( To), gas rotational temperature ( TR) and vibrational in i3C02 and 12C160180 with a separation factor a ~ temperature ( Tv), where the relationships T* > Tv ;~ 1.01 in the C02 Silent (barrier) discharge in the pres- TR- To usually hold. -
A Dicationic Iminophosphane Ying Kai Loh, Chitra Gurnani, Rakesh Ganguly, and Dragoslav Vidović*
A Dicationic Iminophosphane Ying Kai Loh, Chitra Gurnani, Rakesh Ganguly, and Dragoslav Vidović* Department of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371. Supporting Information Placeholder ABSTRACT: A novel dicationic system containing a PN frag- ment has been synthesized and structurally characterized. Accord- ing to the solid state analysis and theoretical investigation the dica- tionic iminophosphane resonance from is the most appropriate de- scription for the dication. However, the contribution from the phos- phorus mononitride resonance form is not negligible. Neutral two-eletron donor carbenes have proven to be quite versatile ligands for isolation of a wide variety of novel main group 1-4 species. Examples include diatomic allotropes (L-E2-L; L = car- bene, E = B, Si, Ge, P, As, etc)1a of boron, silicon, germanium, phosphorus, arsenic, etc.2-4 Nevertheless, these interesting mole- cules, among numerous other main group species, sparked a debate about the most appropriate way to describe bonding in these com- Figure 1. Recently isolated neutral (A) and radical cationic (B) 5,6 pounds. In particular, the arguments have been focused on phosphorus mononitrides, and general structure for carbones (C). whether the carbene moieties form typical covalent bonds or the Dipp = 2,6-diisopropylphenyl. use of dative bond analogy is also valid. The latest evidence showed that the L-E bonds for L-B2-L are quite strong suggesting a sub- stantial covalent character.6 However, Frenking argued that dative The overall synthesis of the target dication is summarized in bonds could be also very strong by the combination of -donation Scheme 1. -
The Distribution of the Hydroxyl Radical in the Troposphere Jack
The Distribution of the Hydroxyl Radical in the Troposphere By Jack Fishman Paul J. Crutzen Department of Atmospheric Science Colorado State University Fort Collins, Colorado THE DISTRIBUTION OF THE HYDROXYL RADICAL IN THE TROPOSPHERE by Jack Fishman and Paul J. Crutzen Preparation of this report has been financially supported by Environmental Protection Agency Grant No. R80492l-0l Department of Atmospheric Science Colorado State University Fort Collins, Colorado January, 1978 Atmospheric Science Paper No. 284 Abstract A quasi-steady state photochemical numerical model is developed to calculate a two-dimensional distribution of the hydroxyl (OH) radical in the troposphere. The diurnally, seasonally averaged globaJ 5 3 value of OH derived by this model is 3 x 10 cm- which is several times lower than the number computed previously by other models, but is in good agreement with the value inferred from the analysis of the tropospheric distribution of methyl chloroform. Likewise, the effects of the computed OH distribution on the tropospheric budgets of ozone and carbon monoxide are not inconsistent with this lower computed value. One important result of this research is the detailed analysis of the distribution of tropospheric ozone in the Southern Hemisphere. Our work shows that there is a considerable difference in the tropospheric ozone patterns of the two hemispheres and that through the analysis of the likely photochemistry occurring in the troposphere, a significant source of tropospheric ozone may exist in the Northern Hemisphere due to carbon monoxide oxidation. Future research efforts will be devoted to the meteorological dynamics of the two hemispheres to try to distinguish if these physical processes are similarly able to explain the interhemispheric differences in tropospheric ozone.