DOCSLIB.ORG

Quantum-Chemical Modeling of The

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Quantum-Chemical Modeling of The Article Cite This: J. Phys. Chem. A 2018, 122, 1643−1657 pubs.acs.org/JPCA Quantum-Chemical Modeling of the First Steps of the Strecker Synthesis: From the Gas-Phase to Water Solvation Published as part of The Journal of Physical Chemistry virtual special issue “Manuel Yań̃ez and Otilia Mó Festschrift”. V. Riffet, G. Frison, and G. Bouchoux* LCM, CNRS, Ecole Polytechnique, UniversitéParis-Saclay, 91128 Palaiseau, France *S Supporting Information ABSTRACT: The two first steps of the Strecker synthesis of glycine, namely (a) addition of ammonia to formaldehyde to give aminomethanol and (b) its dehydration leading to methaneimine, is studied using high level quantum chemistry computations (G3B3). Water solvation is modeled by considering the effect of adding a discrete number of active or passive molecules of water (up to four) and by immersing the identified water-solute complexes in a conductor-like polarizable continuum solvent model. Activation of the reactants by protonation is also examined. Exhaustive search of microhydrated neutral and protonated aminomethanol has been performed using a combination of hierarchical and genealogical approaches. Critical energies associated with all the elementary reaction steps were estimated using the accurate G3B3 composite method thus providing benchmarks to discuss the possible occurrence of Strecker synthesis in prebiotic chemistry. 1. INTRODUCTION byproducts of this synthesis route) in carbonaceous chondrites The Strecker reaction1 is probably the most straightforward has been considered as an indication that the Strecker reaction has been involved in the formation of amino acids in the parent route from simple compounds such as ketone, aldehyde, 9,18,22 ammonia, and hydrogen cyanide to α-amino acids. For this bodies of this family of meteorites. Recently, laboratory − reason, it has been extensively studied2 and reviewed.3 5 experiments on interstellar ice analogues show that amino- Briefly, the Strecker synthesis proceeds through several methanol, HOCH2NH2, (in parallel with hydroxyacetonitrile, ∼ successive steps as depicted in Scheme 1: (a) addition of HOCH2CN) may be produced at low temperature (i.e., ammonia to an aldehyde RCHO giving rise to the 40K) from ices containing formaldehyde and ammonia.23,24 corresponding aminoalcohol RCH(OH)NH2, (b) dehydration Previous mechanistic studies of the Strecker reaction using of the later producing the imine RCHNH, then, (c) reaction of quantum chemical calculations have been devoted to step (a) in − the imine with hydrogen cyanide leading to formation of an α- the case R = H.25 31 Depending upon the theoretical level aminonitrile RCH(NH2)CN. Additionally, in aqueous solution, used, the computed critical energy for the formation of α −1 -aminonitrile formation is accompanied by a series of other H2NCH2OH was situated between 115 kJ mol and 200 kJ processes constituting a complex network of equilibrated mol−1 with respect to the reactants CH O+NH. The second 2 2 3 reactions from which emerge two noticeable irreversible step (b) has been predicted by theory to be more endothermic α − pathways: (d) the hydrolytic transformation leading to - than step (a) by ca. 40−60 kJ mol 1.27,29,30 Consideration of a amino acid, and (e) the reaction with CO2 giving hydantoins ̈ − 6 water solvent environment has been made by means of the through the Bucherer Berg reaction. isodensity surface polarizable model, IPCM, but without Occurrence of the abiotic formation of α-amino acids on the fi optimization of the geometry at this level, and inclusion of early Earth through Strecker synthesis was rst advocated by 26,28 7 one or two discrete water molecules or a 6 water ice Miller. This hypothesis has been retained by a number of 30 31 researchers who suggested that this pathway may be efficient in model and clusters including 4, 9, or 12 water molecules. In − many other environments in the Universe.8 19 Indeed, since its parallel, the reactivity of methaneimine with hydrogen cyanide (step (c), Scheme 1) has been studied both in vacuum and in reactants (hydrogen cyanide, ammonia, and aldehydes such as 32,33 30 formaldehyde and acetaldehyde) have been identified in aqueous solution or in ice environment. interstellar or circumstellar media,20,21 the occurrence of Strecker reaction can be conceivable as a synthetic pathway Received: October 24, 2017 in interstellar media, even in the gas-phase or on the surface of Revised: January 22, 2018 ice grains. Moreover, the presence of imino-diacids (usual Published: January 22, 2018 © 2018 American Chemical Society 1643 DOI: 10.1021/acs.jpca.7b10534 J. Phys. Chem. A 2018, 122, 1643−1657 The Journal of Physical Chemistry A Article Scheme 1. A Simplified View of the Strecker Synthesis of Amino Acids After consideration of these previous results, it appears that times do not bring any new minima. Finally, this procedure led (i) only a limited number of structures have been investigated to several hundred local minima. More precisely, 82 and 306 fi so far and that (ii) the level of theory used was not necessarily minima have been identi ed for (HOCH2NH2)(H2O)n and ffi + su cient to accurately describe the energetic aspects of these 102 and 216 minima for (HOCH2NH3 )(H2O)n with n = 3 and reactions. As a consequence, we propose here a large 4, respectively. All these minima, with up to 4 explicit water investigation at a uniform and high level of theory, including molecules, were obtained from MD simulations that do not optimization of the geometries in the solvent environment, in include any bulk water solvation effect. order to offer a realistic view of the considered systems. For this All structures B obtained from calculations detailed above purpose, we examine here the first steps (a) and (b) (A → B→ were optimized at the DFT level B3LYP using the double-ζ C, Scheme 1) of the Strecker synthesis of glycine (R = H, quality basis set 6-31G(d) and vibrational frequencies were Scheme 1) by quantum chemical calculations, using the calculated at the same DFT level to obtain enthalpies at 0 and 34 accurate composite methods G3B3. Starting from reactions 298 K using the Gaussian09 suite of programs.39 Among these −1 between isolated species CH2 O and NH3 in the gas phase, local minima, those situated in the first ca. 20 kJ mol potential we progressively examine the modifications brought by energy range (B3LYP/6-31G(d) level) were retained in order explicitly including several molecules of water acting as active to construct the potential energy profiles. At this stage, a catalysis and, further, a polarizable medium to mimic the bulk Darwinian tree is built on all minima identified in order to solvent or ice effects. Extensive explorations of the conforma- control that each generation of conformations involving n water tional spaces were done using methods that combine stationary − 50,35 molecule, Gn, is related to the previous generation Gn 1. and dynamic approaches developed in our group. Starting from the most stable structures B, all reaction routes Activation of the reactants by protonation both in the gas- toward reactant A and products C were investigated and the phase and in aqueous media is also considered. Conclusions as corresponding transition and final structures identified. The to whether the Strecker synthesis is a possible pathway leading search for the transition structures B → A and B → C was also to the primitive amino acids are drawn. done at the B3LYP/6-31G(d) level, and their connectivity to reactant and product was systematically controlled by IRC 2. COMPUTATIONAL METHODS calculations. Finally, energy computations were accurately 34 In order to construct the various potential energy profiles performed using the composite G3B3 method. presented in this work, geometries of the central structures B, It may be recalled that, in the G3B3 procedure, the + geometries of stable and transition structures are fully i.e., (HOCH2NH2)(H2O)n and (HOCH2NH3 )(H2O)n (n =0, 1, 2, 3, and 4), were first generated. For low n values, i.e., from 0 optimized with the hybrid functional B3LYP using the 6- to 2, structures B have been built manually, by identifying 31G(d) basis sets. The same level of theory is used (i) to fi calculate harmonic frequencies in order to obtain zero point hydrogen bond acceptor and donor sites able to xH2O molecules. If chemical intuition may be sufficient to explore energies and correction to enthalpies and (ii) to calculate exhaustively the conformational landscapes of structures B,itis entropies in the rigid-rotor harmonic oscillator approximation. not the case for the higher n values where molecular dynamic Improved energies are then obtained by making use of several (MD) simulation is necessary. For these last cases only (n > 2), successive more elaborated computations taking into account we used the methodology combining the hierarchical approach larger basis sets (6-31+G(d), 6-31G(2df,p), and G3large) and and the Darwin’s family tree building.51 Indeed, this method- larger electron correlation levels (MP2, MP4, and QCISD(T)). ology has already been used successfully to study the The final energy is calculated assuming additivity of the various microhydration of protonated Nα-acetylhistidine.35 For the contributions and including a higher-order correction (HLC) hierarchical approach, we used the Tinker molecular modeling to remove the remaining deficiencies in the energy calculations. package36 associated with the AMOEBA37,38 polarizable force The G3B3 method has been assessed on a test set of 299 fi eld. The parameters of the neutral CH2NH2 and CH2OH energies (enthalpies of formation, ionization energies, electron termination of ethylamine and ethanol allowed us to adjust the affinities, and proton affinities).34 The average absolute parameters of HOCH2NH2, respectively. In parallel, the deviations from experiments of these 299 energies are less + −1 parameters of HOCH2NH3 were adjusted on the basis of than 5 kJ mol .
Load more

Recommended publications
  • The Preparation and Reactions of Certain Quarternary Ammonium And
    THE PREPARATION AND REACTIONS OF CERTAIN QUATERNARY AMMONIUM AND RELATED COMPOUNDS By CARL L MICHAELIS A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA August, 1953 ACKNOWLEDGMENTS The author wishes to express his sincere appreci- ation for the valuable assistance and inspiring direction of Dr. George B. Butler. Special thanks are due Dr. and Mrs. Armin Gropp for the help and encouragement in carrying out this investi- gation. The author also wishes to express his appreciation for the assistance and advice so readily given him by his fellow students, graduate and undergraduate alike. \ ii TABLE OF CONTENTS Page ACKNOWLEDGMENTS ii TABLE OF CONTENTS iii INTRODUCTION 1 A. Review of Literature and Statement of Problem 1 EXPERIMENTAL 14 A. General Discussion 14 B. Procedure 18 DISCUSSION . 51 SUMMARY 62 BIBLIOGRAPHY 64 BIOGRAPHICAL ITEMS 66 COMMITTEE REPORT 67 iii INTRODUCTION The need for compounds of good adrenergic blooking activity has been the object of extensive investigation in recent years. In order to get a better idea of the nature of adrenergic blocking activity, it might be best to under- stand first how an adrenergic compound functions. Certain compounds like epinephrine or adrenaline, are powerful agents in stimulating the sympathetic nervous system, that part of the nervous system springing from the thoracic lumbar cord. The substance epinephrine is much like, if not identical to, the substance called sympathin, which is produced at the ending of a nerve in the smooth muscle or gland when a nerve is stimulated.
    [Show full text]
  • Important Features of the Potential Energy Surface of the Methylamine Plus O(1D) Reaction
    Physical Chemistry Chemical Physics Important Features of the Potential Energy Surface of the Methylamine Plus O(1D) Reaction Journal: Physical Chemistry Chemical Physics Manuscript ID CP-ART-09-2019-005039.R1 Article Type: Paper Date Submitted by the 17-Oct-2019 Author: Complete List of Authors: Wolf, Mark; University of Georgia , Center for Computational Quantum Chemsitry; Hoobler, Preston; Covenant College, Chemistry; University of Georgia Franklin College of Arts and Sciences, Center for Computational Quantum Chemistry Turney, Justin; University of Georgia, Center for Computational Chemistry Schaefer, Henry; University of Georgia, Computational Chemistry Page 1 of 13 Physical Chemistry Chemical Physics Journal Name Important Features of the Potential Energy Surface of the Methy- lamine Plus O(1D) Reaction † Mark E. Wolf, Preston R. Hoobler, Justin M. Turney, and Henry F. Schaefer III∗ This research presents an ab initio characterization of the potential energy surface for the methy- lamine plus 1D oxygen atom reaction, which may be relevant to interstellar chemistry. Ge- ometries and harmonic vibrational frequencies were determined for all stationary points at the CCSD(T)/aug-cc-pVTZ level of theory. The focal point method along with several additive correc- tions was used to obtain reliable CCSDT(Q)/CBS potential energy surface features. Extensive conformational analysis and intrinsic reaction coordinate computations were performed to ensure accurate chemical connectivity of the stationary points. Five minima were determined to be pos- sible products of this reaction and three novel transition states were found that were previously unreported or mislabeled in the literature. The pathways we present can be used to guide further searches for NH2 containing species in the interstellar medium.
    [Show full text]
  • Is the Reaction Between Formic Acid and Protonated Aminomethanol a Possible Source of Glycine Precursors in the Interstellar Medium?
    A&A 579, A125 (2015) Astronomy DOI: 10.1051/0004-6361/201526548 & c ESO 2015 Astrophysics Is the reaction between formic acid and protonated aminomethanol a possible source of glycine precursors in the interstellar medium? Pilar Redondo, Antonio Largo, and Carmen Barrientos Computational Chemistry Group, Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid, Spain e-mail: [predondo;alargo;cbb]@qf.uva.es Received 18 May 2015 / Accepted 28 May 2015 ABSTRACT Context. One of the most interesting questions in interstellar chemistry concerns whether we can detect the basic building blocks of proteins in astronomical sources. In ascertaining whether amino acids could be possible interstellar molecules, a crucial point is how they could be synthesized in the interstellar medium. Aims. We do a theoretical study of the ion-molecule reaction involving protonated aminomethanol and formic acid to establish its viability in space. This ion-molecule reaction has been proposed by other authors as a possible way to produce glycine in the interstellar medium. Methods. The relevant stationary points on the potential energy surface of the reaction between protonated aminomethanol and formic acid have been theoretically studied by using ab initio methods. The second-order Moller-Plesset level was employed, in conjunction with the correlation-consistent polarized valence triple-zeta (cc-pVTZ) basis set. In addition, the electronic energies were refined by means of single-point calculations at the CCSD(T) level (coupled cluster single and double excitation model augmented with a non-iterative treatment of triple excitations) on the MP2/cc-pVTZ geometries with the aug-cc-pVTZ basis set.
    [Show full text]
  • Reaction of Several Aminopyrimidines with Formaldehyde Gerald L
    JOURNAL OF RESEARCH of the National Bureau of Standards—A. Physics and Chemistry Vol. 66A, No. 1, January-February 1962 Reaction of Several Aminopyrimidines With Formaldehyde Gerald L. McLeod x (August 29, 1961) Formaldehyde has been shown to react with 2-aminopyrimidine (II) and 2-(methyl- amino)pyrimidine (V) at room temperature to give the corresponding methylol derivatives or the corresponding methylenebis(aminopyrimidines). The reaction of formaldehyde with 2-amino-4,6-dichloro-5-methylpyrimidine (VII) and also its failure to react with 2-(dimethylamino)pyrimidine (IX) are cited as evidence that the pyrimidine ring is not involved in the reaction. 1. Introduction methylol structure is supported by infrared analysis. The spectrum of 2-aminopyrimidine has two absorp- A number of investigations have been made on the tion bands near 3,320 and 3,170 cm"11 whichih are melamine-formaldehyde reaction, and several mech- 2 attributed to N—H asymmetric and symmetriy c anisms [1-5] have been suggested. The complex stretching modes [9]; the methylol compoundd, IIIIII, structures of the triamino-l,3,5-triazines made it shows one fairly broad band at 3,225 cm"1. The desirable to study simpler model compounds. A occurrence of both inter- and intra-molecular hydro- logical model compound, 2-amino-l,3,5~triazine (la), gen bonding in III could cause a lowering of the OH has been reported [6-8] not to give the usual amine stretching frequency, allowing it to overlap the reactions because it tautomerizes to the iminoid N—H stretching band. Treatment of the methylol structure (Ib).
    [Show full text]
  • OH and NH Stretching Vibrational Relaxation of Liquid Ethanolamine
    Z. Phys. Chem. 225 (2011) 913–926 / DOI 10.1524/zpch.2011.0125 © by Oldenbourg Wissenschaftsverlag, München OH and NH Stretching Vibrational Relaxation of Liquid Ethanolamine ∗ By Stephan Knop, Jörg Lindner, and Peter Vöhringer Lehrstuhl für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Wegelerstraße 12, 53115 Bonn, Germany Dedicated to Prof. Horst Hippler on the occasion of his 65th birthday (Received April 12, 2011; accepted in revised form May 30, 2011) Vibrational Relaxation / Liquid Dynamics / Hydrogen-Bonding / Ultrafast Spectroscopy Femtosecond mid-infrared pump-probe spectroscopy was carried out to obtain information about the dynamics of vibrational energy relaxation in liquid ethanolamine at room temperature and ambient pressure. Through partial deuteration it was possible to disentangle the dynamics resulting from the OH and the NH stretching modes that proceed independently and simultaneously in the hydrogen-bonded liquid following an ultrafast vibrational excitation by a resonant mid-infrared pulse. The OH-stretching vibrational lifetime was determined to be 450 fs while the NH-stretching lifetime was found to be 1.2 ps. This large difference in lifetimes highlights the importance of the hydrogen-donating and the hydrogen-accepting character of the vibrating groups that are engaged in hydrogen-bonding. 1. Introduction Vibrational energy relaxation (VER) in molecular liquids has attracted considerable attention of researchers devoted to exploring condensed phase chemical dynamics. As- sociated molecular liquids have been particularly attractive research targets because the influence of hydrogen bonding (H-bonding) on the timescales and molecular mechan- isms of the various vibrational dynamical phenomena remains until today only partially understood [1–3].
    [Show full text]
  • Formaldehyde and Methylamine Reactivity in Interstellar Ice Analogues As a Source of Molecular Complexity at Low Temperature V
    A&A 549, A40 (2013) Astronomy DOI: 10.1051/0004-6361/201219974 & c ESO 2012 Astrophysics Formaldehyde and methylamine reactivity in interstellar ice analogues as a source of molecular complexity at low temperature V. Vinogradoff, F. Duvernay, G. Danger, P. Theulé, F. Borget, and T. Chiavassa Université d’Aix-Marseille, Laboratoire de Physique des Interactions Ioniques et Moléculaires, UMR CNRS 7345, Centre de St-Jérôme, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France e-mail: [email protected] Received 9 July 2012 / Accepted 24 October 2012 ABSTRACT Context. Laboratory simulations on interstellar or cometary ice analogues are crucial to understand the formation of complex organic molecules that are detected in the interstellar medium (ISM). Results from this work give hints on physical and chemical processes occurring in space and can serve as a benchmark for dedicated space missions. Aims. The aim of this work is to consolidate the knowledge of ice evolution during the star formation process by investigating the influence of thermal reactions as a source of molecular complexity in the ISM. In this study, we are interested in the thermal reactivity between two interstellar molecules, formaldehyde (H2CO) and methylamine (CH3NH2) in water ice analogues. Methods. We used Fourier transform infrared spectroscopy, mass spectrometry, and B3LYP calculations to investigate the thermal reaction between formaldehyde and methylamine (14N and 15N) at low temperature in water ice analogues. Results. We demonstrate that methylamine and formaldehyde quickly react in water ice analogues for astronomically relevant tem- −1 peratures and form N-methylaminomethanol CH3NHCH2OH. The measured activation energy of this reaction, 1:1 ± 0:05 kJ mol (1:8 ± 0:08 kJ mol−1 with methylamine 15N), allows the reaction to proceed in interstellar ices, when the ices are gently warmed, as it occurs in young stellar objects, in photo-dissociation regions, or in comets.
    [Show full text]
  • Reaction of Several Aminopyrimidines with Formaldehyde
    JOURNAL OF RESEARCH of the National Bureau of Standards-A. Physics and Chemistry Vol. 66A, No. I, January- February 1962 I Reaction of Several Aminopyrimidines With Formaldehyde Gerald 1. McLeod 1 (August 29, 1961) Formaldehyde has been shown to react with 2-aminopyrimidine (II) a nd 2-(methyl­ amino)pyrimidine (V) at room temperature to give the corresponding methylol derivatives or the corresponding methylenebis(aminopyrimidines). The reaction of formaldehyde with 2-amino-4,6-dichloro-5-methylpyri rnidine (VII) and also its failure to react with 2-(dimethylamino)pyrimidine (IX) are cited as evidence that the pyrimidine ring is not invol ved in the reaction. 1. Introduction methylol strucLure is supported by infrared analysis. The spectrum of 2-aminopyrimidine has two absorp­ A number of investigations have been made on the tion bands near 3,320 and 3, 170 em- I which are melamine-formaldehyde reaction, and several mech­ attributed to N- H asymmetric and ymmetric anisms [1 - 5)2 have been suggested. The complex stretching modes [9] ; the methylol compound, III, structures of the triamino-1,3,5-triazines made it shows one fairly broad band at 3,225 cm- I • The desirable to stud y simpler model com pounds. A occurrence of both inter- and intra-molecular hydro­ logical model eompound, 2-amino-1 ,3, 5-triazine (Ia), gen bonding in III co uld cause a lowering of the OH has been reported [6-8] not to give the usuld amine stretching frequency, allowing it to overlap the reactions because it tautomerizes to the iminoid N- H stretching band.
    [Show full text]
  • Atmospheric Formation TELTEK
    1 Theoretical evaluation of the fate of harmful compounds post emission Claus J. Nielsen Centre for Theoretical and Computational Chemistry (CTCC) Department of Chemistry at the University of Oslo Norway. and Dirk Hoffmann and Hartmut Herrmann Leibniz-Institut für Troposphärenforschung Leipzig, Germany H&E TQP Amine Tel-Tek CCM project frame Kjølnes ring 30, Porsgrunn agreement 256430116 Norway contracts 256430117 and 256430118 Report 2210040-3 Tel-Tek project 2210040 September 2010 2 This page is intentionally left blank 2210040-3-WP2-Final-v2 3 Executive summary The present report presents a systematic survey of the atmospheric chemistry of amines and amine degradation products reported in the literature before August 1, 2010. The report encompasses the current knowledge on gas phase processes, phase transfer processes and aqueous phase processes, and includes best estimates of the atmospheric partitioning, fate and lifetimes of amines and amine degradation products in the Mongstad area. Assuming model estimates of Henry´s Law coefficients to describe equilibrium conditions it is predicted that unsubstituted alkylamines will primarily be oxidized in the gas phase, and that alkanolamines will primarily be oxidized in the atmospheric aqueous phase. Existing theoretical gas phase degradation schemes have been updated for methylamine, dimethylamine and trimethylamine, and the theoretical atmospheric aqueous phase chemistry of dimethylamine (DMA), monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), methyldiethanolamine (MDEA) and piperazine (PZ) has been developed. The study has uncovered serious gaps in the current knowledge concerning the fate of harmful compounds post emission from amine based CO2 capture plants. In particular the phase transfer processes are associated with large uncertainties.
    [Show full text]
  • Synthesis of the First Nitrogen-Heterocycles in Interstellar
    MNRAS 000,1–16 (2021) Preprint 11 June 2021 Compiled using MNRAS LATEX style file v3.0 Synthesis of the first nitrogen-heterocycles in interstellar ice analogs containing methylamine (CH3NH2) exposed to UV radiation: Formation of trimethylentriamine (TMT, c-(-CH2-NH)3) and hexamethylentetramine (HMT, (CH2)6N4). H. Carrascosa,1¢ C. González Díaz, 1 G. M. Muñoz Caro,1y P. C. Gómez,2 M. L. Sanz, 3 1Centro de Astrobiología (CSIC-INTA), Ctra. de Ajalvir, km 4, Torrejón de Ardoz, 28850 Madrid, Spain 2Dep. Química Física, Fac. Química, Univ. Complutense, 28040 Madrid, Spain 3Department of instrumental analysis and environmental chemistry, IQOG-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain Accepted XXX. Received YYY; in original form ZZZ ABSTRACT Hexamethylentetramine has drawn a lot of attention due to its potential to produce prebiotic species. This work aims to gain a better understanding in the chemical processes concerning methylamine under astrophysically relevant conditions. In particular, this work deeps into the formation of N-heterocycles in interstellar ice analogs exposed to UV radiation, which may lead to the formation of prebiotic species. Experimental simulations of interstellar ice analogs were carried out in ISAC. ISAC is an ultra-high vacuum chamber equipped with a cryostat, where gas and vapour species are frozen forming ice samples. Infrared and ultraviolet spectroscopy were used to monitor the solid phase, and quadrupole mass spectrometry served to measure the composition of the gas phase. The variety of species detected after UV irradiation of ices containing methylamine revealed the presence of 12 species which have been already detected in the ISM, being 4 of them typically classified as complex organic molecules: formamide (HCONH2), methyl cyanide (CH3CN), CH3NH and CH3CHNH.
    [Show full text]
  • Chemical Safety and Waste Management Manual
    Chemical Safety and Waste Management Manual University of Alabama at Birmingham Department of Occupational Health & Safety Chemical Safety Division 2002 EDITION 1. INTRODUCTION In a comparatively short time, the University of Alabama at Birmingham has gained significant recognition as a center of excellence for teaching, medical services and research programs. This is a highly commendable achievement and one that could not have been realized without the continued support and dedication of faculty, staff members, and employees. Similar unfailing cooperation and support are necessary for the institution to be equally successful in its development of a comprehensive occupational health and safety program for the protection of University personnel, students, and the surrounding community. An important part of this program is concerned with the safe and prudent handling of chemicals and their proper legal disposal as regulated by the Environmental Protection Agency (EPA) and the Alabama Department of Environmental Management (ADEM). Almost every laboratory and many allied and support personnel at UAB use chemicals in their daily activities. It is the purpose of this manual to describe the operation of the Chemical Safety Program and to provide guidance in establishing safe work practices for the use of chemicals. This program applies to all work operations at this University where employees may be exposed to hazardous substances under normal working conditions or during an emergency. The Chemical Safety and Waste Management Manual combines both the Chemical Hygiene Plan for laboratories and the Hazard Communication Program for maintenance, environmental services, and other support personnel. The Occupational Safety and Health Administration (OSHA) Hazard Communication Standard may be found at : http://www.osha- slc.gov/OshStd_data/1910_1200.html.
    [Show full text]
  • Studies Towards the Total Synthesis of Polyhydroxylated Pyrrolidine
    University of Wollongong Research Online University of Wollongong Thesis Collection University of Wollongong Thesis Collections 2012 Studies towards the total synthesis of polyhydroxylated pyrrolidine alkaloids isolated from the Japanese Paper Mulberry Broussonetia Kazinoki (Moraceae) Marc Etienne Bouillon University of Wollongong, [email protected] Recommended Citation Bouillon, Marc Etienne, Studies towards the total synthesis of polyhydroxylated pyrrolidine alkaloids isolated from the Japanese Paper Mulberry Broussonetia Kazinoki (Moraceae), Doctor of Philosophy thesis, School of Chemistry, University of Wollongong, 2012. http://ro.uow.edu.au/theses/3757 Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library: [email protected] Studies towards the Total Synthesis of Polyhydroxylated Pyrrolidine Alkaloids isolated from the Japanese Paper Mulberry Broussonetia kazinoki (Moraceae) Employing the Petasis borono-Mannich Reaction in the Synthesis of Cyclic Phytosphingosine Derivatives A thesis submitted in fulfilment of the requirements for the award of the degree of Doctor of Philosophy - PhD - from the University of Wollongong by Marc Etienne Bouillon Dipl.-Chem. Faculty of Science 2012 Declaration _____________________________________________________________________________ I hereby declare that the present thesis, submitted in fulfilment of the requirements for the award of Doctor of Philosophy in the Faculty of Science, University of Wollongong, is wholly my own work unless due reference is provided. This document has not been submitted for qualifications at any other academic institution. Marc Etienne Bouillon Wollongong, 09/01/2013 For My Parents “If you start something, you finish it. You don’t stop until you get it right. And if you don’t get it right, you start over again, And you keep on going as long as have to.
    [Show full text]
  • The Nitro-Mannich Reaction
    The Nitro-Mannich Reaction Adam Noble† and James C. Anderson,*,† †Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, U.K. CONTENTS 1. Introduction 3 2. Early Developments 5 2.1. The First Reports 6 2.2. Heterocycle Synthesis 16 2.3. Nitroalkene Synthesis 21 2.4. Synthesis of Dinitroamines 23 2.5. Reactions with Pre-Formed Imines 25 2.6. Conjugate Addition Nitro-Mannich Reactions 27 2.7. Reactions of Nitroesters 30 3. Non-Catalytic Examples 33 3.1. Base-Mediated Reactions 33 3.2. Reactions of α-Amido Sulfones 36 3.3. Auxiliary Controlled Stereoselective Reactions 40 3.4. Reformatsky-Type Reactions 43 3.5. Electrochemically Induced Reactions 45 1 4. Indirect Metal-Catalyzed Reactions 46 4.1. Racemic Reactions 46 4.2. Asymmetric Reactions 47 5. Direct Metal-Catalyzed Reactions 49 5.1. Racemic Reactions 50 5.2. Asymmetric Reactions 54 6. Organocatalytic Reactions 66 6.1. Racemic Reactions 66 6.2. Asymmetric Reactions 68 6.2.1. Urea/Thiourea Catalysts 68 6.2.2. Brønsted Acid Catalysts 79 6.2.3. Phase Transfer Catalysts 83 6.2.4. Brønsted Base Catalysts 88 7. Reactions of Ketimines 90 7.1. Racemic Reactions 90 7.2. Auxiliary Controlled Reactions 92 7.3. Catalytic Asymmetric Reactions 94 8. Reactions of α-Nitroesters 96 9. Reactions of α-Nitrophosphonates 103 10. Conjugate Addition Nitro-Mannich Reactions 106 10.1. Organocatalytic Reactions with Carbon Nucleophiles 106 10.2. Reactions with Organometallic Nucleophiles 111 10.3. Aza-Morita-Baylis-Hillman Reactions 114 10.4. Synthesis of 3-Nitrochromene Derivatives 117 2 10.5.
    [Show full text]