DOCSLIB.ORG

Detection of the Elusive Triazane Molecule (N3H5) in the Gas Phase

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Detection of the Elusive Triazane Molecule (N3H5) in the Gas Phase DOI:10.1002/cphc.201500560 Communications Detection of the Elusive Triazane Molecule (N3H5)inthe Gas Phase MarkoFçrstel,[a] PavloMaksyutenko,[a] BrantM.Jones,[a] Bing-Jian Sun,[b] Shih-Hua Chen,[b] Agnes. H.-H. Chang,*[b] and Ralf I. Kaiser*[a] We report the detection of triazane (N3H5)inthe gas phase. Tri- ful and only potential decompositionproducts of triazane azane is ahigher order nitrogen hydride of ammonia (NH3) (N3H5)—diazane (HNNH) and ammonia (NH3)—could be sam- [1c] [1d] and hydrazine (N2H4)offundamentalimportance for the un- pled. Finally,Fuji et al. made an effort to detect free tria- derstanding of the stability of single-bonded chains of nitro- zane in the microwave discharge of hydrazine, but only the + gen atomsand apotentialkey intermediate in hydrogen–nitro- lithium salt of triazane (LiN3H5 )and the triazane cation + gen chemistry. The experimental resultsalongwith electronic- (N3H5 )could be identified. Therefore, whether free triazane structurecalculations reveal that triazane presentsastable (N3H5)can surviveprompt dissociation in the gas phase has re- molecule with anitrogen–nitrogen bond length that is afew mained an unanswered question. This lack of experimental evi- picometers shorter than that of hydrazineand has alifetime dence on the stability of triazane has triggered substantial exceeding 6 2 msatasublimation temperature of 170 K. Tria- computational efforts.[1a,b] An evaluation of the thermodynamic Æ zane was synthesized throughirradiation of ammonia ice with stability, accounting for hydrogen bonding as well as hyper- energetic electrons and was detected in the gas phase upon conjugation effects, reveals three triazane conformers with C1 sublimation of the ice through soft vacuum ultraviolet (VUV) and Cs symmetries, which range in stability within 24 kJ 1 [1a,b] photoionization coupled with areflectron-time-of-flight mass molÀ . Accounting for potentialdecomposition pathways, spectrometer.Isotopic substitutionexperiments exploiting such as ammonia and diazene elimination, Schlegel and [1b] [D3]-ammonia ice confirmed the identificationthrough the de- Skancke concludedthat “there appears to be no low energy tection of its fully deuterated counterpart[D5]-triazane (N3D5). channels for the unimolecular decomposition of triazane” and that triazane represents a“promising candidate(s) for synthe- sis.” The triazane molecule (N3H5)has been long postulated to be Here, we report the experimental detection of the hitherto akey transientspecies in nitrogen–hydrogen chemistry and elusivetriazane molecule (N3H5)inthe gas phase. Our experi- has received considerable interest from the viewpoint of chem- ments are combined with ab initio electronic-structure calcula- ical bonding theory and as apromising high-energymaterial.[1] tions to verify the stability of triazane in the gas phase. The ex- Unlike carbon chemistry,the nitrogen–nitrogen single bond is periments were carriedout in an ultrahigh vacuum (UHV) sur- 11 [3] destabilized by the nonbonding electron pairs of the neighbor- face science machine operated at apressure of a3x10À torr. ing nitrogen atoms, resulting in significantly weaker nitrogen– Amorphous ices of ammonia (NH3)and [D3]-ammonia (ND3) 1 nitrogen single bonds(157–168kJmolÀ )compared to their were prepared in separate experiments with thicknesses of 1 carbon–carbon counterparts (345–355 kJmolÀ ). Consequently, 500 50 nm at 5.5 0.2 K. Nonequilibrium chemistry was in- Æ Æ single-bonded hydrides of nitrogen are extremelyrare and duced by irradiating these ices with energetic electrons (5 keV) only the methane (CH4)and ethane (C2H6)analoguesofnitro- for one hour at an averaged dose of 1.9 0.2 eV per molecule. Æ 1 gen—ammonia (NH3)and hydrazine (N2H4)—have been isolat- After irradiation, the ices were heated at arate of 0.5 KminÀ ed to date. The next higher homologue, triazane, wasreported (temperature-programmed desorption;TPD). During the TPD crystallographically in azeolite, where it was stabilized by com- process, the subliming neutralmolecules were first ionized 2+ [2] plexion to silver ions as Ag2(N3H5)3 . Attempts to isolate tria- through single vacuum ultraviolet (VUV) photon ionization at zane from triazanium sulfite salts, (N3H6)2SO3,were unsuccess- 10.49 eV,then mass resolved in areflectron time-of-flight mass spectrometer (Re-TOF), and eventually identified by their arrival [a] Dr.M.Fçrstel, Dr.P.Maksyutenko, Dr.B.M.Jones, Prof. Dr.R.I.Kaiser times through amultichannel plate (see the Supporting Department of Chemistry Information). University of Hawaii The mass spectra of the subliming molecules released from 2545 McCarthy Mall Honolulu,HI96822-2275 (USA) the irradiated ammonia ices are shown as afunction of tem- E-mail:[email protected] peratureinFigure 1. These spectra are dominated by the am- + [b] Dr.B.-J. Sun, Dr.S.-H. Chen, Prof. Dr.A.H.-H. Chang monia and[D3]-ammonia parentions at m/z=17 [NH3 ;ioniza- Department of Chemistry tion energy (IE)=10.07 0.02 eV] in the irradiated ammonia Æ NationalDong Hwa University ices shiftedby3to m/z=20 (ND +)inthe exposed [D ]-ammo- Shou-Feng,Hualien, 974(Taiwan) 3 3 E-mail:[email protected] nia samples (Figure 2). As the temperature rises, hydrazine Supporting Information for this article is available on the WWW under (N2H4)together with its deuterated counterpart (N2D4)are ob- http://dx.doi.org/10.1002/cphc.201500560. servable through their parent ions at m/z= 32 and 36 (IE= ChemPhysChem 2015, 16,3139 –3142 3139 2015 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim Communications ated, closed-shell nitrogen hydride. The molecularions at + + m/z=47 (N3H5 )and 52 (N3D5 )are stable in the ReTOF de- picting–based on the time-of-flight—life times of at least 30 Æ 1 ms; the stabilityofthe molecular ion is consistent with the study of Fuji et al. that identified the triazane cation in the mi- crowavedischargeofhydrazine. Finally,wewould like to out- line that the second ion peak and the shoulder of the TPD at + + m/z=48 (N3D3 )and 45 (N3H3 ), respectively,emerging at about 160 Kmight origin from N3D3/N3H3 isomers triazene (H2NNNH)and/or cyclotriazane (c-N3H3)togetherwith their deuterated counterparts. It is important to stress that we also conducted control ex- Figure 1. Reflectron time-of-flight (ReTOF) mass spectra as afunction of the periments, that is, experiments under identical conditions, but temperature of the newly formed products subliming into the gas phase from the irradiated ammonia ice measured at 10.49 eV.The signalofthe withoutirradiating the ices with energetic electrons. In these most abundant species at 17 (ammonia) was truncated to allow for abetter control studies, only ion signals derived from ammonia and representation of the data. [D3]-ammonia were observable.This demonstrates that the abovementioned products and the triazane molecule in partic- ular are aresult of the radiolysis of the ammonia ices, and not an artifact from the photolysis and/or ion–molecule reactions of the subliming ammonia. Therefore, our data provide com- pelling evidence that amolecule with the molecular formulae N3H5 (ammonia ice) and N3D5 ([D3]-ammonia ice) have been formed in the ices upon exposure to energetic electrons;these specieswere released into the gasphase upon sublimation and then ionizedbysingle-photon ionization. The calculated adiabatic IE of triazane was computed to be 7.7 0.1 eV,which Æ is well below the energy of the vacuum ultraviolet photon of 10.49 eV exploited to ionize the subliming molecules (see the Supporting Information).Considering the root-mean-square 1 Figure 2. Temperature desorption profiles of key species subliming from the velocityof310 msÀ of atriazane molecule subliming at 170 K irradiated ammonia (left) and [D3]-ammonia ices (right). Statistical error bars and the distance betweenthe ice and the photoionization are included in Panels (A)and (B) for the newly identified triazanemolecule. laser of 2mm, we determined alifetimeofthe subliming tria- Traces in blue show the signal from the irradiated sample and traces in red zane and [D5]-triazane molecules of at least 6 2and 7 2 ms, are those measured for the nonirradiated sample. Æ Æ respectively,and possibly much longer. 8.10 0.15 eV), respectively,asthey are released into the gas Æ phase with ion counts peakingat160 K. With increasing tem- + perature, we also observedsignal at m/z=30 (N2H2 ), 45 + + (N3H3 ), and 47 (N3H5 )along with their deuteratedcounter- + + + parts at m/z=32 (N2D2 ), 48 (N3D3 ), and 52 (N3D5 )peaking at about 170 K. Signals at m/z= 30 and45originate from ion- ized N H (IE=9.8 0.1 eV) and N H (IE=9.6 0.1 eV), respec- 2 2 Æ 3 3 Æ tively.Nomasses higher than 47 and 52 were observed for the irradiated ammonia and [D3]-ammonia ices, respectively.Itis important to stress that ionsignals depicting identical TPD profiles indicate that fragmentation of the molecules with the + highest mass may occur.Here, signals at m/z=17 (NH3 ), 30 + + (N2H2 ), and 45 (N3H3 ), the TPD profiles of which peak at + about 170 K, match the TPD profileofm/z= 47 (N3H5 ), thus indicating that the lower masses are fragments from amolecule that contains nitrogen andhydrogen atoms with amolecular weightof47, that is, triazane(N3H5). In case of [D3]-ammonia + ices, the fragment masses are shiftedtom/z=20 (ND3 ), 32 + + (N2D2 ), and 48 (N3D3 ), which, in turn, are fragments from [D ]-triazane (N D )upon photoionization. Note that m/z= 47 Figure 3. Structures of three conformersoftriazane, I–III,together with their 5 3 5 computed decomposition pathways of triazane. All energies are given in + + 1 (N3H5 )and 52 (N3D5 )cannot originate from higher masses, kJ molÀ .The molecular structures of the reactants,intermediates, products, as N3H5/N3D5 resembles the heaviest allowable fully hydrogen- and transitionstates are shown in Figure 4. ChemPhysChem 2015, 16,3139 –3142 www.chemphyschem.org 3140 2015 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim Communications Figure 4. Structures of reactant conformers (I–III), the intermediate (INT1), products, and transition states (TS1–TS4); bond lengths and angles are definedin pm and degrees, respectively.Also shown is the structure of the triazane ion.
Load more

Recommended publications
  • Triazene (H2NNNH) Or Triimide (HNHNNH) Markofçrstel,[A, D] Yetsedaw A
    DOI:10.1002/cphc.201600414 Articles On the Formation of N3H3 Isomers in Irradiated Ammonia Bearing Ices:Triazene (H2NNNH) or Triimide (HNHNNH) MarkoFçrstel,[a, d] Yetsedaw A. Tsegaw,[b] Pavlo Maksyutenko,[a, d] Alexander M. Mebel,[c] Wolfram Sander,[b] and Ralf I. Kaiser*[a, d] The remarkable versatility of triazenesinsynthesis, polymer theoretical studies with our novel detection scheme of photo- chemistry and pharmacology has led to numerousexperimen- ionization-driven reflectron time-of-flight mass spectroscopy tal and theoretical studies.Surprisingly,only very little is we can obtain information on the isomersoftriazene formed known aboutthe most fundamental triazene:the parentmole- in the films. Using isotopically labeled starting material, we can cule with the chemical formula N3H3.Here we observe molecu- additionally gain insightinthe formation pathways of the iso- lar,isolated N3H3 in the gas phase after it sublimes from ener- mers of N3H3 under investigation and identify the isomers getically processed ammonia and nitrogen films. Combining formedastriazene (H2NNNH) andpossibly triimide(HNHNNH). 1. Introduction During the last decades, triazenes—a class of organic mole- life time of at least 1mswas also inferred as an intermediate cules carrying the =N N=N moiety—have received substan- in the radiolysis of an aqueous solution of hydrazine based on À À tial attention both from the theoretical and organic chemistry asingle absorption feature at 230 nm.[6] The cyclic isomer of [1] communities. Derived from cis-and trans-triazene (HN=NNH2 ; triazene, cyclotriazane, was first reported crystallographically in Scheme1), the substituted counterparts have significant appli- zeolite A, where it was stabilized by asilver cation as [1a,c] [1d] + [7] + cations in synthetic chemistry, polymer science, and phar- Ag(N3H3) .
    [Show full text]
  • Durham E-Theses
    Durham E-Theses Halogenated diazines and triazines Wood, D. E. How to cite: Wood, D. E. (1978) Halogenated diazines and triazines, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/8324/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk UNIVERSITY OF Du'RKAM A THESIS entitled HALOGENATED DIAZINES AND TRIAZINES Submitted by D E. WOOD (Grey), B Sc (London) The copyright of this thesis rests with the author No quotation from it should be published without his prior written consent and information derived from it should be acknowledged A candidate for the degree of Doctor of Philosophy 19 78 sr i i > j J To my MoLhcr and FaLhcr WLLII Lh.inks for .ill LhaL Lhey have done ACKNOWLEDGEMLNTS I would like LO express my thanks Lo Professor R D Chambers i under whose guidance this research was undertaken, for considerable encouragement, advice and discussion Thanks are due to Dr R S Matthews for his expert advice with n in r.
    [Show full text]
  • Risto Laitinen/August 4, 2016 International Union of Pure and Applied Chemistry Division VIII Chemical Nomenclature and Structur
    Approved Minutes, Busan 2015 Risto Laitinen/August 4, 2016 International Union of Pure and Applied Chemistry Division VIII Chemical Nomenclature and Structure Representation Approved Minutes of Division Committee Meeting in Busan, Korea, 8–9 August, 2015 1. Welcome, introductory remarks and housekeeping announcements Karl-Heinz Hellwich (KHH) welcomed everybody to the meeting, extending a special welcome to those who were attending the Division Committee meeting for the first time. He described house rules and arrangements during the meeting. KHH also regretfully reported that it has come to his attention that since the Bangor meeting in August 2014, Prof. Derek Horton (Member, Division VIII task groups on Carbohydrate and Flavonoids nomenclature; Associate Member, IUBMB-IUPAC Joint Commission on Biochemical Nomenclature) and Dr. Libuse Goebels, Member of the former Commission on Nomenclature of Organic Chemistry) have passed away. The meeting attendees paid a tribute to their memory by a moment of silence. 2. Attendance and apologies Present: Karl-Heinz Hellwich (president, KHH) , Risto Laitinen (acting secretary, RSL), Richard Hartshorn (past-president, RMH), Michael Beckett (MAB), Alan Hutton (ATH), Gerry P. Moss (GPM), Michelle Rogers (MMR), Jiří Vohlídal (JV), Andrey Yerin (AY) Observers: Leah McEwen (part time, chair of proposed project, LME), Elisabeth Mansfield (task group chair, EM), Johan Scheers (young observer, day 1; JS), Prof. Kazuyuki Tatsumi (past- president of the union, part of day 2) Apologies: Ture Damhus (secretary, TD), Vefa Ahsen, Kirill Degtyarenko, Gernot Eller, Mohammed Abul Hashem, Phil Hodge (PH), Todd Lowary, József Nagy, Ebbe Nordlander (EN), Amélia Pilar Rauter (APR), Hinnerk Rey (HR), John Todd, Lidija Varga-Defterdarović.
    [Show full text]
  • I. MATRIX ISOLATION of 1,1-DIAZENES II. DISTANCE, TEMPERATURE, and DYNAMIC SOLVENT EFFECTS on ELECTRON TRANSFER REACTIONS Thesis
    I. MATRIX ISOLATION OF 1,1-DIAZENES II. DISTANCE, TEMPERATURE, AND DYNAMIC SOLVENT EFFECTS ON ELECTRON TRANSFER REACTIONS Thesis by James Edward Hanson In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 1990 (Submitted September 8, 1989) 11 © 1990 James Edward Hanson All rights Reserved ill Acknowledgements I would like to thank my advisor, Peter Dervan , for his enthusiasm and support during my studies at Caltech. I would also like to thank Professor John Hopfield for his availability when I needed assistance with the theoretical complexities of the electron transfer work. I am deeply indebted to Lutfur "Zeta" Khundkar and Joe Perry for their expert assistance and collaboration in making measurements and understanding the implications of the results. Al Sylwester was extremely helpful in my first year as I began to work on 1,1-diazenes, and Alvin Joran and Burt Leland made my transition to the electron transfer project relatively simple. I should also thank those in the Dervan group who helped me with synthetic problems, especially John Griffin and Warren Wade. I appreciated discussions with some of the electron transfer experts at Caltech: Professor Rudy Marcus, Dave Beratan, Jose Onuchic, Dave Malerba, and Tad Fox. There were many times when the men in the chemistry shops provided invaluable assistance--you guys are the best! There are many who made my stay at Caltech enjoyable--I'll remember skiing with John and Linda Griffin and Heinz Moser, basketball (and marathons!) with Dave Kaisaki, tennis with Erich Uffelmann, and late night conversations with Kevin Luebke.
    [Show full text]
  • Ger'g .Tyson Jr
    July 14, 1964 ' G. N. TYSON, JR 3,140,582 ROCKET PROPULSION METHOD USING BORON AND NITROGEN COMPOUNDS Filed April 14, 1959 Ger'g .Tyson Jr. INVENTOR. I", u .12) ATTORNEYS 3,l4,582 Patented July 14,, 1964 2 The nitrogen containing compound and the boron con 3,140,582 taining compound are reacted in such proportions that all ROCKET PROPULSION METHOD USING BORON of the nitrogen and all of the boron react to produce AND NOGEN COMPOUNDS boron nitride, the carbon is released as elemental carbon George N. Tyson, Jr., Claremont, Calif., assignor to Olin Mathieson Chemical Corporation, a corporation of and large volumes of hydrogen gas are produced. Virginia Nitrogen containing compounds which can be employed Filed Apr. 14, 1959, Ser. No. 806,396 as reactants include the saturated hydronitrogens such 20 Claims. (Cl. 60-354) as ammonia, hydrazine, triazane, tetrazane; the unsaturated hydronitrogens such as diimide, triazene, tetrazene, iso This invention relates to a method for producing large 10 tetrazene, ammonium azide, hydrazine azide, and hydra volumes of hot gases in a short period of time, which zoic acid; alkyl hydrazines such as methyl hydrazine, un large volumes of hot gases are useful for many purposes symmetrical dimethyl hydrazine, ethyl hydrazine, unsym including imparting thrust to jet propelled devices such metrical diethyl hydrazine; alkylamines including mixed al as rockets. kylamines such as methylamine, dimethylamine, trimeth Jet propelled devices are essentially of two types: those 15 ylamine, ethylamine, diethylamine, triethylarnine, methyl which depend upon an external source for a portion of ethyl amine, n-propylamine, isopropylamine, di-n-propyl the propellant, and those in which the propellant is en amine, tri-n-propylamine, methyl propyl amine, ethyl prop tirely contained within the device.
    [Show full text]
  • Ammonia a Very Important Molecule for Biological Organisms to Make Proteins Or Nucleic Acids
    Ammonia A very important molecule for biological organisms to make proteins or nucleic acids by QH, and Niloy Kumar Das Shahjalal Science & Technology University, Bangladesh Molecule of the Month - June 2013 Introduction Ammonia or azane is a compound of nitrogen and hydrogen with the formula NH3. It is a colorless gas with a characteristic pungent smell, which is very common in toilets sometime. It is used in industry and commerce, and also exists naturally in humans and in the environment. Ammonia is essential for many biological processes and serves as a precursor for amino acid and nucleotide synthesis. In the environment, ammonia is part of the nitrogen cycle and is produced in soil from bacterial processes. Ammonia is also produced naturally from decomposition of organic matter, including plants and animals. Sal Ammoniacus Sal ammoniac is a mineral composed of ammonium chloride. The Romans called the ammonium chloride deposits they collected from near the Temple of Jupiter Amun in ancient Libya 'sal ammoniacus' (salt of Amun) because of proximity to the nearby temple. It is the earliest known mineral source of ammonia. Fig: Sal ammoniac is a mineral Guano & saltpeter Later alternative sources of ammonia mineral were discovered. Guano and saltpeter played valuable roleas strategic commodity. Guano consists of ammonium oxalate and urate, phosphates, as well as some earth salts and impurities. Guano also has a high concentration of nitrates. Saltpeter is the mineral form of potassium nitrate (KNO3). Potassium and other nitrates are of great importance for use in fertilizers, and, historically, gunpowder. Fig: Guano is simply deposits of bird droppings Independence from mineral dependency Even though our atmosphere consists 78% nitrogen, atmospheric nitrogen is nutritionally unavailable to plants or animals because nitrogen molecules are held together by strong triple bonds.
    [Show full text]
  • Hydroxylamine-O -Sulfonic Acid — a Versatile Synthetic Reagent
    Hydroxylamine-O -sulfonic acid — a versatile synthetic reagent Raymond G. Wallacef School of Chemistry Brunei University Uxbridge, Middlesex UBS 3PH Great Britain imidazoli nones and related derivatives are time to these various modes of reaction. discussed in the review. Many of these The uses of HOSA as a reagent are organiz­ preparations can be carried out in high ed below according to the different syn­ yield, thetic transformations that it can bring about. Hydroxylamine-Osulfonic acid, NHj-OSOjH (abbreviated to HOSA in Probably by far the most well known this article) has become in recent years and explored reactions of HOSA are commercially available. Although much animation reactions, illustrating elec­ fruitful chemistry has been carried out us­ trophilic attack by HOSA, with amination ing HOSA, to this author's knowledge, on nitrogen being the most important, there has been no systematic review in although a significant number of English* of its use as a synthetic reagent. It animations on both carbon and sulfur have is a chemically interesting compound been reported, Amination on phosphorus because of the ability of the nitrogen center also occurs. to act in the role of both nucleophile and AMINATION electrophile, dependent on circumstances, Synopsis (a) At a nitrogen atom and thus it has proved to be a reagent of Hydroxylamine-0-sulfonic acid (0 Preparation of mono- and di- great synthetic versatility. (HOSA) has only recently become widely substituted hydrazines and trisubstituied commercially available despite the fact that H,N-Nu hydrazinium salts it has proved to be a valuable synthetic reagent in preparative organic chemistry.
    [Show full text]
  • Adapting Neural Machine Translation to Predict IUPAC Names from a Chemical Identifier
    Translating the molecules: adapting neural machine translation to predict IUPAC names from a chemical identifier Jennifer Handsel*,a, Brian Matthews‡,a, Nicola J. Knight‡,b, Simon J. Coles‡,b aScientific Computing Department, Science and Technology Facilities Council, Didcot, OX11 0FA, UK. bSchool of Chemistry, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK. KEYWORDS seq2seq, InChI, IUPAC, transformer, attention, GPU ABSTRACT We present a sequence-to-sequence machine learning model for predicting the IUPAC name of a chemical from its standard International Chemical Identifier (InChI). The model uses two stacks of transformers in an encoder-decoder architecture, a setup similar to the neural networks used in state-of-the-art machine translation. Unlike neural machine translation, which usually tokenizes input and output into words or sub-words, our model processes the InChI and predicts the 1 IUPAC name character by character. The model was trained on a dataset of 10 million InChI/IUPAC name pairs freely downloaded from the National Library of Medicine’s online PubChem service. Training took five days on a Tesla K80 GPU, and the model achieved test-set accuracies of 95% (character-level) and 91% (whole name). The model performed particularly well on organics, with the exception of macrocycles. The predictions were less accurate for inorganic compounds, with a character-level accuracy of 71%. This can be explained by inherent limitations in InChI for representing inorganics, as well as low coverage (1.4 %) of the training data. INTRODUCTION The International Union of Pure and Applied Chemistry (IUPAC) define nomenclature for both organic chemistry2 and inorganic chemistry.3 Their rules are comprehensive, but are difficult to apply to complicated molecules.
    [Show full text]
  • Reversing the Native Aerobic Oxidation Reactivity of Graphitic Carbon: Heterogeneous Metal-Free Alkene Hydrogenation
    Reversing the Native Aerobic Oxidation Reactivity of Graphitic Carbon: Heterogeneous Metal-Free Alkene Hydrogenation The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Murray, Alexander T. and Yogesh Surendranath. “Reversing the Native Aerobic Oxidation Reactivity of Graphitic Carbon: Heterogeneous Metal-Free Alkene Hydrogenation.” ACS Catalysis 7, 5 (April 2017): 3307–3312 © 2017 American Chemical Society As Published http://dx.doi.org/10.1021/acscatal.7b00395 Publisher American Chemical Society (ACS) Version Author's final manuscript Citable link http://hdl.handle.net/1721.1/115122 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. Reversing The Native Aerobic Oxidation Reactivity Of Graphitic Car- bon: Heterogeneous Metal-Free Alkene Hydrogenation Alexander T. Murray and Yogesh Surendranath* Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States. KEYWORDS Hydrogenation, Carbon Black, Carbocatalysis, Diimide, Alkene ABSTRACT: Commercially available carbon blacks serve as effective metal-free catalysts for the selective hydrogenation of car- bon-carbon multiple bonds under aerobic conditions using hydrazine as the terminal reductant. The reaction, which proceeds through a putative diimide intermediate, displays high tolerance to a variety of functional groups, including those sensitive to nu- cleophilic displacement by hydrazine, aerobic oxidation, or hydrazine-mediated reduction. Hydrazine chemisorbs strongly to the carbon surface, attenuating its native oxidative reactivity and allowing for selective hydrogenation. The catalytic sequence estab- lished here effectively umpolungs the reactivity of carbon, thereby enabling the use of this low cost material in selective reduction catalysis.
    [Show full text]
  • Diimide Reduction of Liquid Natural Rubber in Hydrazine Hydrate/Hydrogen Peroxide System: a Side Reaction Study
    Malaysian Journal of Analytical Sciences, Vol 22 No 6 (2018): 1023 - 1030 DOI: https://doi.org/10.17576/mjas-2018-2206-11 MALAYSIAN JOURNAL OF ANALYTICAL SCIENCES ISSN 1394 - 2506 Published by The Malaysian Analytical Sciences Society DIIMIDE REDUCTION OF LIQUID NATURAL RUBBER IN HYDRAZINE HYDRATE/HYDROGEN PEROXIDE SYSTEM: A SIDE REACTION STUDY (Penurunan Diimida Getah Asli Cecair dalam Sistem Hidrazin Hidrat/Hidrogen Peroksida: Kajian Tindak Balas Sampingan) Muhammad Jefri Mohd Yusof1, Nur Aidasyakirah Mohd Tahir1, Fazira Firdaus1, Siti Fairus M. Yusoff1,2* 1School of Chemical Sciences and Food Technology, Faculty of Science and Technology 2Polymer Research Centre, Faculty of Science and Technology Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia *Corresponding author: [email protected] Received: 27 July 2017; Accepted: 28 April 2018 Abstract Hydrogenation of liquid natural rubber (LNR) has been successfully accomplished via diimide reduction using hydrazine hydrate/hydrogen peroxide (HH/H2O2) system. Each parameter in the system was optimized to obtain maximum hydrogenation degree such as the mass of boric acid, mole ratio of HH: H2O2, reaction time and reaction temperature. As a result, the highest degree of hydrogenation was achieved at 91.2% using a molar ratio HH: H2O2 of 2:3, in the presence of boric acid as a promoter at 60 °C for 8 hours. In this research, we report on possible side reactions that led to lowering the hydrogenated rubber product. Reactivity of diimide species as well as decomposition of hydrogen peroxide were postulated based on literature reviews to be one of the factors hindering hydrogenation of LNR. The presence of side reactions such as degradation, cyclization, and crosslinking had been confirmed by gel permeation chromatography (GPC), 1H nuclear magnetic resonance (1H NMR), and swelling test, respectively.
    [Show full text]
  • Chapter 9 Hydrogen
    Chapter 9 Hydrogen Diborane, B2 H6• is the simplest member of a large class of compounds, the electron-deficient boron hydrid Like all boron hydrides, it has a positive standard free energy of formation, and so cannot be prepared direct from boron and hydrogen. The bridge B-H bonds are longer and weaker than the tenninal B-H bonds (13: vs. 1.19 A). 89.1 Reactions of hydrogen compounds? (a) Ca(s) + H2Cg) ~ CaH2Cs). This is the reaction of an active s-me: with hydrogen, which is the way that saline metal hydrides are prepared. (b) NH3(g) + BF)(g) ~ H)N-BF)(g). This is the reaction of a Lewis base and a Lewis acid. The product I Lewis acid-base complex. (c) LiOH(s) + H2(g) ~ NR. Although dihydrogen can behave as an oxidant (e.g., with Li to form LiH) or reductant (e.g., with O2 to form H20), it does not behave as a Br0nsted or Lewis acid or base. It does not r with strong bases, like LiOH, or with strong acids. 89.2 A procedure for making Et3MeSn? A possible procedure is as follows: ~ 2Et)SnH + 2Na 2Na+Et3Sn- + H2 Ja'Et3Sn- + CH3Br ~ Et3MeSn + NaBr 9.1 Where does Hydrogen fit in the periodic chart? (a) Hydrogen in group 1? Hydrogen has one vale electron like the group 1 metals and is stable as W, especially in aqueous media. The other group 1 m have one valence electron and are quite stable as ~ cations in solution and in the solid state as simple 1 salts.
    [Show full text]
  • Large Intermediates in Hydrazine Decomposition: a Theoretical Study of the N₃H₅ and N₄H₆ Potential Energy Surfaces
    Large Intermediates in Hydrazine Decomposition: A Theoretical Study of the N₃H₅ and N₄H₆ Potential Energy Surfaces The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Grinberg Dana, Alon et al. "Large Intermediates in Hydrazine Decomposition: A Theoretical Study of the N₃H₅ and N₄H₆ Potential Energy Surfaces." Journal of Physical Chemistry A 123, 22 (May 2019): 4679-4692 © 2019 American Chemical Society As Published http://dx.doi.org/10.1021/acs.jpca.9b02217 Publisher American Chemical Society (ACS) Version Author's final manuscript Citable link https://hdl.handle.net/1721.1/124015 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The Journal of Physical Chemistry This document is confidential and is proprietary to the American Chemical Society and its authors. Do not copy or disclose without written permission. If you have received this item in error, notify the sender and delete all copies. Large Intermediates in Hydrazine Decomposition: A Theoretical Study of the N3H5 and N4H6 Potential Energy Surfaces Journal: The Journal of Physical Chemistry Manuscript ID jp-2019-02217p.R1 Manuscript Type: Article Date Submitted by the n/a Author: Complete List of Authors: Grinberg Dana, Alon; Massachusetts Institute of Technology, Chemical Engineering Moore, Kevin; Argonne National Laboratory, Gas Phase Chemical Dynamics Jasper, Ahren; Argonne National Laboratory, Gas Phase Chemical Dynamics Green, William; Massachusetts Institute of Technology, Chemical Engineering ACS Paragon Plus Environment Page 1 of 60 The Journal of Physical Chemistry 1 2 3 4 5 Large Intermediates in Hydrazine Decomposition: A Theoretical Study of the 6 7 N3H5 and N4H6 Potential Energy Surfaces 8 9 1 2 2 1 10 Alon Grinberg Dana , Kevin B.
    [Show full text]