DOCSLIB.ORG

Dissociative Ionization and Thermal Decomposition of Cyclopentanone Johani.M.Pastoors,[A] Andras Bodi,[B] Patrickhemberger,[B] and Jordy Bouwman*[A, C]

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dissociative Ionization and Thermal Decomposition of Cyclopentanone Johani.M.Pastoors,[A] Andras Bodi,[B] Patrickhemberger,[B] and Jordy Bouwman*[A, C] DOI:10.1002/chem.201702376 Full Paper & Reaction Mechanisms |Hot Paper| Dissociative Ionization and Thermal Decomposition of Cyclopentanone JohanI.M.Pastoors,[a] Andras Bodi,[b] PatrickHemberger,[b] and Jordy Bouwman*[a, c] Abstract: Despitethe growing use of renewable and sus- out areversebarrieropen up to oxopropenyl and cyclopro- tainable biofuels in transportation,their combustion chemis- panonecations by ethyl-radical loss and asecond ethene- try is poorly understood, limiting our efforts to reduce harm- loss channel, respectively.Astatistical Rice–Ramsperger– ful emissions. Here we report on the (dissociative) ionization Kassel–Marcus model is employed to test the viability of this and the thermaldecomposition mechanism of cyclopenta- mechanism. Thepyrolysis of cyclopentanone is studied at none, studied using imaging photoelectron photoion coinci- temperatures ranging from about 800 to 1100 K. Closed- dence spectroscopy.The fragmentation of the ions is domi- shell pyrolysis products,namely 1,3-butadiene, ketene, pro- nated by loss of CO, C2H4,and C2H5,leadingtodaughter pyne, allene, and ethene, are identified based on their pho- + ions at m/z 56 and 55. Exploring the C5H8OC potential toion mass-selected threshold photoelectron spectrum.Fur- energy surface reveals hydrogen tunneling to play an impor- thermore, reactiveradical species such as allyl, propargyl, tant role in low-energydecarbonylation and probably also in and methyl are found. Areaction mechanism is derived in- the ethene-loss processes, yielding 1-butene and methylke- corporating both stable and reactive species, which were tene cations, respectively.Athigher energies,pathways with- not predicted in prior computational studies. Introduction tion that can be produced from furfural,[3,4] which in turn is produced industriallybyacidic hydrolysis of hemicellulose, a In general, biofuelsare renewable and often sustainable alter- major constituent of plant matter,[5] or,alternatively,through natives to fossil fuels, whichcan also mitigate harmful emis- pyrolysis of biomass.[6] Cyclopentanone also serves as aprecur- sions.[1] In particular, more and more research focusesonfuels sor for other, high-density,fuels,[7] which are suitable for use in derived from waste biomass.While fossil fuels are typically airplanes. Athorough understanding of the unimolecular dis- composed of mostlycarbon and hydrogen, biofuels also con- sociation of cyclopentanone is crucial to accurately model its tain oxygen in the form of hydroxyl (e.g.,ethanol), carboxyl, al- combustion. dehyde, or ketone functional groups.[2] Their varying composi- The pyrolysis of cyclic ketoneshas been studied in some tion leads to differing combustion chemistry,whichneeds to detail. Employing fractional product condensation and IR spec- be thoroughly understood. troscopic analysis, Johnson and Walters[8] found 2-cyclopenten- One of numerouspossible classes of biofuel molecules are 1-one,1-butene, ethene, carbon monoxide, and hydrogen as [9] ketones. Cyclopentanone is acyclic ketone of C5H8Ocomposi- cyclopentanone pyrolysis products. Delles et al. performed similar experiments and reported the formation of 4-pentenal [a] J. I. M. Pastoors, Dr.J.Bouwman in addition to products reported by Johnson and Walters.[8] Radboud University,Institute for Molecules and Materials Several low-molecular-weight species were observed in agas FELIX Laboratory,Toernooiveld 7c, 6525 ED Nijmegen (The Netherlands) E-mail:[email protected] chromatogram of the reactionmixture, but could not be as- [10] [b] Dr.A.Bodi,Dr. P. Hemberger signed. Porterfield et al. studied the pyrolysis of another cy- Laboratoryfor Synchrotron Radiation and Femtochemistry cloketone, cyclohexanone (C6H10O), using flash pyrolysis in Paul Scherrer Institute, 5232 Villigen (Switzerland) combination with photoionization mass spectrometry and [c] Dr.J.Bouwman matrixisolation Fouriertransform infrared (FTIR) spectroscopy. Presentaddress:Sackler Laboratoryfor Astrophysics They reported that methylvinyl ketone and ethene are formed Leiden Observatory,Leiden University,P.O. Box 9513 2300 RA Leiden (The Netherlands) through keto–enol tautomerization followed by aretro-Diels– Supporting information and the ORCID identification numbers for the Alder reaction. Furthermore, they argued that the other detect- authors of this article can be found under https://doi.org/10.1002/ ed products, among which ketene (C2H2O), are formed by chem.201702376. meansofa, b,org C Cbond cleavage followed by rearrange- À 2017 The Authors. Published by Wiley-VCH Verlag GmbH&Co. KGaA. mentsofthe thus formed diradicals. This is an open access article under the terms of Creative Commons Attri- Cyclopentanone pyrolysis has also been addressed computa- bution NonCommercialLicense, whichpermitsuse, distributionand repro- [11] duction in any medium, provided the original work is properlycited and is tionally.Zaras et al. characterized the energetics of the uni- not used for commercial purposes. molecular dissociation of cyclopentanone using the composite Chem. Eur.J.2017, 23,13131 –13140 13131 2017 The Authors. Published by Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim Full Paper G3B3 method. They considered C Cscissionreactions, among Threshold photoelectron spectrum À other possible channels,and only found products formed from reactions initiatedbya-cleavage, despite the fact that b-cleav- The cyclopentanone cation has C2 symmetry and the highest age was determinedtobelower in energy.The computational occupied molecular orbital(HOMO), shown togetherwith the results on the neutralcyclopentanone potential energy surface mass-selected threshold photoelectronspectrum in Figure 1, (PES) were employed to calculate rate constants of the initial isomerization steps over the 800–2000 Ktemperature range by using Rice–Ramsperger–Kassel–Marcus(RRKM) modeling. They concludedthat the main products are C2H4 +CO and the rate constantssuggest that keto–enol isomerization plays apivotal role in the formation of other products, namely cyclopente- none, 1,3-butadiene, and acetylene. Wang et al.[12] performedacombined theoretical and experi- mental study on the dissociative photoionization of cyclopen- + tanone, providing adetailed C5H8OC PES. Experiments were performed using afemtosecond laser to induce dissociative ionization and time-of-flight(TOF) mass spectrometry for de- tection of fragments. Based on quantumchemical computa- tions, rates and branching fractions were derived by RRKM modeling. Figure 1. Threshold photoelectron spectrum of cyclopentanone (connected Literature data to validate the theoretical computations on blue circles)displayed togetherwith aFranck–Condon simulation of the cyclopentanone dissociation are scarce. In prior experimental spectrum (green). The inset showsthe highest occupied molecular orbital on cyclopentanone. pyrolysis studies, product specieswere assigned offline after condensation, introducing the possibility of secondary reac- tions and inherently imposing uncertainties on the actual un- has antibondingcharacter along the C=Obond and bonding derlyingformation mechanism of the detected products.More- character along the! two (O=)C Cbonds. Upon ionization À over,thesestudies were not sensitive to reactive intermediates, through the X˜ + 2B X˜ 1Atransition, electron densityisremoved which could provide important clues to the overall chemistry. from the HOMO,leadingtoa0.02 contraction of the C=O Furthermore, single-photon dissociative ionization data em- bond and a0.03 elongation of the two (O=)C Cbonds, as À ploying parent-ion internal energy selection are not available. predicted by B3LYP/6–311 ++G(d,p) geometry optimizationof However,such data can be used to quantify bond dissociation the neutraland ionic ground state. The measured spectrum re- energiesonthe cationic surface accurately,and provide details veals astrong resonance at (9.27 0.02) eV,whichisinagree- Æ on the underlying dissociation mechanism,[13] relevant for un- ment with the ionization potentialfor cyclopentanone of derstanding and modeling, for example, mass spectra.[14] (9.25 0.02) eV reportedbyChadwick et al.[16] The simulated Æ Here we report on an experimentalstudy of the (dissocia- spectrum matches the resonances in the measured spectrum tive) ionization and pyrolysis of cyclopentanone, using thresh- very well. Three major features at 9.30, 9.36 and 9.43 eV can be 1 old photoelectron photoion coincidence spectroscopy (TPEPI- assigned to aCH2 rocking motion (260 cmÀ ), aCC(=O) C [15] 1 À À CO). The pyrolysis products are sampled directly from the stretching vibration (776 cmÀ )and acombination of C=Oand 1 pyrolysis reactor and are identified by comparing their thresh- aC C(=O) Cstretch (1268 cmÀ ). À À old photoelectron spectra to data availablefrom the literature. Apyrolysis mechanism is proposed and discussed in light of Dissociative ionization the recent findings on cyclohexanonepyrolysis. The experi- mental findings on the dissociativeionization are rationalized The dissociative photoionization of cyclopentanone has been by hydrogen tunneling and amodel is constructed to test the studied to distinguish dissociative ionization products from viability of this fragmentation mechanism. thermaldecomposition products.[17] Furthermore, it is interest- ing to compare and contrastthe fragmentation processes in the neutralmolecule, induced by heat in the microreactor,and in the ion, broughtabout by the excess energyofanionizing Results vacuum ultraviolet (VUV) photon.Inthe breakdowndiagram in Figure
Load more

Recommended publications
  • Cyclopentane Synthesis
    Cyclopentane Synthesis Dan O’Malley Baran Group Meeting Cyclopentane Synthesis Group Meeting O'Malley 2/9/2005 This presentation is broken down into the following catagories. Some reactions either fit more than one Students of organic chemistry are taught a number of reactions for the synthesis of category or do not fit easily into any of them. Efforts have been made to place all such reactions in the cyclohexanes at a very early stage of their careers. Techniques for the creation of cyclopentanes, most appropriate category. however, are generally taught at a much later stage and are rarely given the same detailed treatment. This may be the result of the fact that there are no equivalents of reactions such as the Diels-Alder and I. General Information Robinson Annulation in terms of generality, extent of use, and historical importance. This may, in turn, II. Ionic Reactions be caused by the fact that the cyclopentane is an inherintly "umpoled" functionality, as illustrated below. III. Metal Mediated Reactions IV. Radical Reactions FG V. Pericyclic and Pseudo-pericyclic Reactions VI. Ring Expansion and Contraction Reactions I. General Information This situation is further exacerbated by the general lack of cheaply available cyclopentane compounds Baldwin's rules in the chiral pool; wheras a number of cyclohexane terpenes are readily available for elaboration, there Baldwin has divided ring closure reactions into those that are "favored" and those that are "disfavored". are no analogous cylcopentane natural products. Cyclopentanes are however, present in many Those that are disfavored are not always impossible, but are frequently much more difficult to effect.
    [Show full text]
  • Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy Petr Klan,́*,†,‡ Tomaś̌solomek,̌ †,‡ Christian G
    Review pubs.acs.org/CR Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy Petr Klan,́*,†,‡ Tomaś̌Solomek,̌ †,‡ Christian G. Bochet,§ Aurelień Blanc,∥ Richard Givens,⊥ Marina Rubina,⊥ Vladimir Popik,# Alexey Kostikov,# and Jakob Wirz∇ † Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic ‡ Research Centre for Toxic Compounds in the Environment, Faculty of Science, Masaryk University, Kamenice 3, 625 00 Brno, Czech Republic § Department of Chemistry, University of Fribourg, Chemin du Museé 9, CH-1700 Fribourg, Switzerland ∥ Institut de Chimie, University of Strasbourg, 4 rue Blaise Pascal, 67000 Strasbourg, France ⊥ Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, 5010 Malott Hall, Lawrence, Kansas 66045, United States # Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States ∇ Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland 7.3. Arylsulfonyl Group 160 7.4. Ketones: 1,5- and 1,6-Hydrogen Abstraction 160 7.5. Carbanion-Mediated Groups 160 7.6. Sisyl and Other Silicon-Based Groups 161 7.7. 2-Hydroxycinnamyl Groups 161 7.8. α-Keto Amides, α,β-Unsaturated Anilides, CONTENTS and Methyl(phenyl)thiocarbamic Acid 162 7.9. Thiochromone S,S-Dioxide 162 1. Introduction 119 7.10. 2-Pyrrolidino-1,4-Benzoquinone Group 162 2. Arylcarbonylmethyl Groups 121 7.11. Triazine and Arylmethyleneimino Groups 162 2.1. Phenacyl and Other Related Arylcarbonyl- 7.12. Xanthene and Pyronin Groups 163 methyl Groups 121 o 7.13. Retro-Cycloaddition Reactions 163 2.2. -Alkylphenacyl Groups 123 8. Sensitized Release 163 2.3. p-Hydroxyphenacyl Groups 125 p 8.1.
    [Show full text]
  • Screening Values for Non-Carcinogenic Hanford Waste Tank Vapor Chemicals That Lack Established Occupational Exposure Limits
    PNNL-15640 Screening Values for Non-Carcinogenic Hanford Waste Tank Vapor Chemicals that Lack Established Occupational Exposure Limits TS Poet TJ Mast JL Huckaby February 2006 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. PACIFIC NORTHWEST NATIONAL LABORATORY operated by BATTELLE for the UNITED STATES DEPARTMENT OF ENERGY under Contract DE-AC05-76RL01830 Printed in the United States of America Available to DOE and DOE contractors from the Office of Scientific and Technical Information, P.O. Box 62, Oak Ridge, TN 37831-0062; ph: (865) 576-8401 fax: (865) 576-5728 email: [email protected] Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm This document was printed on recycled paper.
    [Show full text]
  • Carboxylic Acids and Their Derivatives
    8 CARBOXY A lmost all of the basic types of reactions now have been covered: addition, elimination, substitution, and rearrangement by polar, radical, and concerted mechanisms. Indeed, if you have been looking for similarities, you will have seen that most of the reactions discussed in the preceding three chapters are variations on basic types we have discussed earlier. Furthermore, most of the basic structural effects that determine chemical reactivity also have been covered in previous chapters: bond energies, steric hindrance, electronega- tivity, electron delocalization, hydrogen bonding, solvation, and conforma- tional influences. You might well ask what is left. The answer is, a great deal- but now we will be concerned mostly with putting concepts together, moving from the simple to the complex. For example, in this chapter we will be trying to under- stand the ways that carboxylic acids, which possess the -c' functional \ group, are similar to and different from alcohols, which have the OH group, and aldehydes and ketones, which have C=O bonds. Subsequently we will look at acids that also possess OH or NH, sub- stituent groups (or both) and develop a rationale for the behavior of these combinations in terms of effects we already have discussed. Insofar as pos- sible, you should try to do this yourself whenever you encounter a substance with a new set of combinations of functional groups on its molecules. You often will be in error (as many experts will be), because even if you take Carboxylic Acids and Their Derivatives 789 account of all of the structural effects, as well as the possible reactions or inter- actions, the overall result of these frequently is very difficult to judge in advance.
    [Show full text]
  • Aldehydes, Ketones and Carboxylic Acids
    1212Unit Objectives AldehydesAldehydesAldehydesAldehydes,,,,,, KKKKKKeeeeeetonestonestonestonestonestones After studying this Unit, you will be able to andandandandandand CarboxylicCarboxylicCarboxylicCarboxylicCarboxylicCarboxylic • write the common and IUPAC names of aldehydes, ketones and carboxylic acids; AAAAAAcidscidscidscidscidscids • write the structures of the compounds containing functional groups namely carbonyl and carboxyl groups; Carbonyl compounds are of utmost importance to organic chemistry. They are constituents of fabrics, flavourings, plastics • describe the important methods and drugs. of preparation and reactions of these classes of compounds; In the previous Unit, you have studied organic • correlate physical properties and compounds with functional groups containing carbon- chemical reactions of aldehydes, oxygen single bond. In this Unit, we will study about the ketones and carboxylic acids, organic compounds containing carbon-oxygen double with their structures; bond (>C=O) called carbonyl group, which is one of the • explain the mechanism of a few most important functional groups in organic chemistry. selected reactions of aldehydes and ketones; In aldehydes, the carbonyl group is bonded to a carbon and hydrogen while in the ketones, it is bonded • understand various factors to two carbon atoms. The carbonyl compounds in which affecting the acidity of carboxylic carbon of carbonyl group is bonded to carbon or acids and their reactions; hydrogen and oxygen of hydroxyl moiety (-OH) are • describe the uses of aldehydes, known as carboxylic acids, while in compounds where ketones and carboxylic acids. carbon is attached to carbon or hydrogen and nitrogen of -NH2 moiety or to halogens are called amides and acyl halides respectively. Esters and anhydrides are derivatives of carboxylic acids. The general formulas of these classes of compounds are given below: 2021–22 Aldehydes, ketones and carboxylic acids are widespread in plants and animal kingdom.
    [Show full text]
  • ABSTRACT JANG, YUJIN. Synthesis of 1-Sulfonylcyclopropanols and Their Application in New Chemical Transformations As Powerful Cy
    ABSTRACT JANG, YUJIN. Synthesis of 1-Sulfonylcyclopropanols and Their Application in New Chemical Transformations as Powerful Cyclopropanone Equivalents. (Under the direction of Dr. Vincent Lindsay). Cyclopropanone, a notoriously strained cycloalkanone (Baeyer strain ca. 49 kcal/mol), is a promising three carbon building block in organic synthesis where all three C–C bonds are labile, and can be readily involved in ring-opening or ring-expansion. Despite its tremendous potential as a strained reagent, the difficulties associated with its handling and storage have precluded its widespread use in organic synthesis. For these reasons, a majority of cyclopropanone chemistry in the literature involves the use of equivalents such as hemiketals that can equilibrate to the parent ketone in situ via base-induced α-elimination. Although the classical hemiketals are suitable in some reactions, a number of potential transformations are still inaccessible, as harsh conditions are often required to generate cyclopropanone due to the poor leaving group ability of alkoxides and the immense strain generated in the process. In order to elevate the chemistry of cyclopropanones as common building blocks in synthesis, well-behaved cyclopropanone precursors are highly demanded. Here, we describe the efficient and convenient synthesis and application of unsubstituted 1-sulfonylcyclopropanols as powerful cyclopropanone equivalents. By tuning the electronic and steric nature of leaving group, a variety 1-sulfonylcyclopropanols were furnished, and the relative propensity of their equilibration to cyclopropanone was investigated in a novel pyrazole substitution reaction. With this well-behaved class of surrogates, we explored the C–C bond activation of this strained cycloalkanone in the presence of transition metals and organocatalysts.
    [Show full text]
  • Nucleophilic Addition to the Carbonyl Group 6
    Nucleophilic addition to the carbonyl group 6 Connections Building on Arriving at Looking forward to • Functional groups, especially the C=O • How and why the C=O group reacts • Additions of organometallic group ch2 with nucleophiles reagents ch9 • Identifying the functional groups in a • Explaining the reactivity of the C=O • Substitution reactions of the C=O molecule spectroscopically ch3 group using molecular orbitals and curly group’s oxygen atom ch11 • How molecular orbitals explain arrows • How the C=O group in derivatives of molecular shapes and functional • What sorts of molecules can be made by carboxylic acids promotes substitution groups ch4 reactions of C=O groups reactions ch10 • How, and why, molecules react together • How acid or base catalysts improve the • C=O groups with an adjacent double and using curly arrows to describe reactivity of the C=O group bond ch22 reactions ch5 Molecular orbitals explain the reactivity of the carbonyl group We are now going to leave to one side most of the reactions you met in the last chapter—we will come back to them all again later in the book. In this chapter we are going to concentrate on just one of them—probably the simplest of all organic reactions—the addition of a nucleo- phile to a carbonyl group. The carbonyl group, as found in aldehydes, ketones, and many other compounds, is without doubt the most important functional group in organic chemis- try, and that is another reason why we have chosen it as our fi rst topic for more detailed study. You met nucleophilic addition to a carbonyl group on pp.
    [Show full text]
  • Photochemical Reactions of Cyclohexanone: Mechanisms and Dynamics Published As Part of the Journal of Physical Chemistry a Virtual Special Issue “Mark S
    Article pubs.acs.org/JPCA Photochemical Reactions of Cyclohexanone: Mechanisms and Dynamics Published as part of The Journal of Physical Chemistry A virtual special issue “Mark S. Gordon Festschrift”. † ‡ † ‡ Dorit Shemesh, Sergey A. Nizkorodov, and R. Benny Gerber*, , † Institute of Chemistry and The Fritz Haber Research Center, The Hebrew University, Jerusalem 91904, Israel ‡ Department of Chemistry, University of California, Irvine, California 92697, United States *S Supporting Information ABSTRACT: Photochemistry of carbonyl compounds is of major importance in atmospheric and organic chemistry. The photochemistry of cyclohexanone is studied here using on-the- fly molecular dynamics simulations on a semiempirical multi- reference configuration interaction potential-energy surface to predict the distribution of photoproducts and time scales for their formation. Rich photochemistry is predicted to occur on a picosecond time scale following the photoexcitation of cyclo- hexanone to the first singlet excited state. The main findings include: (1) Reaction channels found experimentally are confirmed by the theoretical simulations, and a new reaction channel is predicted. (2) The majority (87%) of the reactive trajectories start with a ring opening via C−Cα bond cleavage, supporting observations of previous studies. (3) Mechanistic details, time scales, and yields are predicted for all reaction channels. These benchmark results shed light on the photochemistry of isolated carbonyl compounds in the atmosphere and can be extended in the future to photochemistry of more complex atmospherically relevant carbonyl compounds in both gaseous and condensed-phase environments. I. INTRODUCTION representative examples are given), acetaldehyde,8 propanal,9 10 11 The photochemistry of carbonyl compounds is an important butanal and its derivatives, heptanal, and other small − 12 topic in organic and atmospheric chemistry.1 3 Atmospheric aldehydes.
    [Show full text]
  • Calculations 273 Absolute Asymmetric Synthesis 634, 635 Absolute
    1317 Index A activation enthalpy 23, 39, 188, 195–196, 204, 205, 206, aaptosine 358, 359 217, 339, 341, 345, 370, 393, 398, 411, 412, 443, 444, ab initio Hartree–Fock (HF) calculations 273 452, 453, 462, 465, 500, 697, 728 absolute asymmetric synthesis 634, 635 activation entropy 39, 188, 190, 192–196, 198, 369, 500, absolute electronegativity 37 689, 695, 872 absolute hardness 37–39, 839 activation entropy and reaction mechanism absolute softness 37 – Cope rearrangement 195 absorbance 616 – gas phase – – homolysis and radical combination 192–193 absorption complex 624, 667 – – isomerizations 193–194 absorption on crystalline quartz 44 – neighboring group directing effects 197 acetaldehyde 15, 18, 60, 66, 70, 80, 82, 86, 145, 146, 147, – retro-carbonyl-ene reaction 195–197 195, 197, 223, 514, 551, 619, 683, 686, 697, 732, 797, activation parameters 819, 855, 920, 921, 1168 – Curtin–Hammett principle 190–192 acetamide 62, 66, 82, 89, 619 – temperature effect, two parallel reactions 190 acetic acid 12, 13, 49, 60, 87, 89, 151, 373, 503, 619, 650, acyclic ,-and,-enones 60, 642 699, 800, 808, 900, 1030, 1032–1034, 1050 acyclic alkylaminocarbene 439 acetic anhydride 12, 61, 216, 619, 802, 1033 acyclic diene 55, 468, 633, 1126 acetone 15, 25, 35, 36, 60, 70, 80, 85, 86, 88, 90, 122, acyclic 1,3-dienes 55, 697, 698 143, 146–148, 153, 203, 210, 213, 224, 226, 229–232, acyclic dithiosilylene 448 373, 374, 382, 383, 412, 413, 435, 619, 622, 623, 628, acyclic peroxides 729 633, 637, 638, 641, 656, 662, 669, 671, 682, 685, 686, (1,2)-acyloxy shifts
    [Show full text]
  • Study on the Fate of Pharmaceuticals in Aqueous Media: Synthesis, Characterization and Detection of Biotic and Abiotic Transform
    Study on the fate of pharmaceuticals in aqueous media : synthesis, characterization and detection of biotic and abiotic transformation products using electrochemical advanced oxidation processes and bioconversions Hugo Olvera Vargas To cite this version: Hugo Olvera Vargas. Study on the fate of pharmaceuticals in aqueous media : synthesis, character- ization and detection of biotic and abiotic transformation products using electrochemical advanced oxidation processes and bioconversions. Biodiversity and Ecology. Université Paris-Est; Erasmus Mundus EteCoS3, 2014. English. NNT : 2014PEST1179. tel-01207532 HAL Id: tel-01207532 https://tel.archives-ouvertes.fr/tel-01207532 Submitted on 1 Oct 2015 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. Joint PhD degree in Environmental Technology Docteur de l’Université Paris-Est Spécialité : Sciences et Techniques de l’Environnement Dottore di Ricerca in Tecnologie Ambientali Degree of Doctor in Environmental Technology Thèse – Tesi di Dottorato – PhD thesis Hugo Olvera-Vargas Study on the Fate of Pharmaceuticals in Aqueous Media: Synthesis, Characterization and Detection of Biotic and Abiotic Transformation Products using Electrochemical Advanced Oxidation Processes and Bioconversions To be defended on December the 17th, 2014 In front of the PhD committee Prof. Marco Panizza Reviewer Prof.
    [Show full text]
  • Molecular Modeling Experiment
    (004:141) Experiment #11 MOLECULAR MODELING: AROMATIC RESONANCE EFFECTS IN CYCLIC KETONES Goal: In this experim ent, you will us e computational chemistry to probe the effects of aromaticity upon bond strengths and lengths. The vibrational spectral frequencies for a variety of cyclic ketones will b e predicted using m olecular orbital methods, and the trends in bond length and C=O stretching frequency will be com pared to expectations based on resonance theory and aromaticity models. If you wish you may work in groups of two or three, and share the results of your computations. Discuss th e results am ongst yourselves, but each person must write up and submit his or her own report. For the calculations, use the PC SPART AN ‘02 com puter program (Wavefunction Inc.) on PCs in the Chemistry Department (locations will be announced). You will draw and calculate properties of each of the molecules shown below: O O O O O O 1 (004:141) Experiment #11 Background Principles of Resonance Kekulé structural formulas are essential tools for understanding organic chem istry. However, the structures of som e compounds and ions cannot be represented by a single formula. For example, sulfur dioxide (SO2) and nitric acid (HNO3) may each be described by two equivalent formulas (equations 1 & 2). For clarity the two am biguous bonds to oxygen are given different colors in these formulas. If only one formula for sulfur dioxide were correct and accurate, then the double bond to oxygen would be shorter and stronger than the single bond. Since experim ental evidence indicates that this molecule is bent (bond angle 120°) and has equal lengths of sulfur-oxygen bonds (1.432 Å), a single formula is inadequate, and the actual structure resembles an average of the two form ulas.
    [Show full text]
  • A Study Op the Kinetics Op Hydrolysis Op
    A STUDY OP THE KINETICS OP HYDROLYSIS OP CYCLOALKANONE DIALKYL KETALS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By WALTER THOMAS REICHLE, B.S. The Ohio State University 1958 Approved by: Adviser Department of Chemistry ACKNOWLEDGMENTS I I wish to express my deep apprecia­ tion for the guidance, help, and advice which I have received from Dr. Harold Shechter during the course of this investi­ gation. I am grateful to the General Electric Company and the National Science Foundation for fellowship funds. I also wish to thank the taxpayers of the State of Ohio and those of the United States of America for their liberal, indirect aid. ii DEDICATED To H.S.S. and My Wife, for the many lonely hours. iii TABLE OP CONTENTS Page I, INTRODUCTION ................................ 1 II. THE MECHANISMS OP THE HYDROLYSIS OF ACETALS AND K E T A L S ..................... 4 III. DISCUSSION OF RESULTS OF THE PRESENT INVESTIGATION ................. 19 The Kinetics of Hydrolysis of Homologous Cyclanone Dimethyl K e t a l s .......... 19 The Effect of the Alcohol Groups on the Rates of Hydrolysis of Cyciobutanone, Cyclopentanone, and Cyclohexanone Dialkyl Ketals ........ 33 The Effect of Alkyl Groups on the Rates of Hydrolysis of Methyl Ring-substituted Cyciobutanone, Cyclopentanone, and Cyclohexanone Dimethyl K e t a l s ......................... 43 Free Energy Relationships of Reactions of Cyclic Molecules .......... 58 IV, EXPERIMENTAL Constant Temperature B a t h ............... 6? Temperature Measurements ................. 68 Miscellaneous ............................ 69 Kinetic Procedure ....................... 71 Calculations .............................. 75 Special Calculations for the Hydrolysis of the Ten-membered Ketal .
    [Show full text]