DOCSLIB.ORG

Catalytic Systems Based on Cp2zrx2 (X = Cl, H), Organoaluminum

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Catalytic Systems Based on Cp2zrx2 (X = Cl, H), Organoaluminum catalysts Article Catalytic Systems Based on Cp2ZrX2 (X = Cl, H), Organoaluminum Compounds and Perfluorophenylboranes: Role of Zr,Zr- and Zr,Al-Hydride Intermediates in Alkene Dimerization and Oligomerization Lyudmila V. Parfenova 1,* , Pavel V. Kovyazin 1, Almira Kh. Bikmeeva 1 and Eldar R. Palatov 2 1 Institute of Petrochemistry and Catalysis of Russian Academy of Sciences, Prospekt Oktyabrya, 141, 450075 Ufa, Russia; [email protected] (P.V.K.); [email protected] (A.K.B.) 2 Bashkir State University, st. Zaki Validi, 32, 450076 Ufa, Russia; [email protected] * Correspondence: [email protected]; Tel.: +7-347-284-3527 i i Abstract: The activity and chemoselectivity of the Cp2ZrCl2-XAlBu 2 (X = H, Bu ) and [Cp2ZrH2]2- ClAlEt2 catalytic systems activated by (Ph3C)[B(C6F5)4] or B(C6F5)3 were studied in reactions with 1-hexene. The activation of the systems by B(C6F5)3 resulted in the selective formation of head- to-tail alkene dimers in up to 93% yields. NMR studies of the reactions of Zr complexes with organoaluminum compounds (OACs) and boron activators showed the formation of Zr,Zr- and Zr,Al-hydride intermediates, for which diffusion coefficients, hydrodynamic radii, and volumes were estimated using the diffusion ordered spectroscopy DOSY. Bis-zirconium hydride clusters of type x[Cp ZrH ·Cp ZrHCl·ClAlR ]·yRnAl(C F ) − were found to be the key intermediates of alkene 2 2 2 2 6 5 3 n dimerization, whereas cationic Zr,Al-hydrides led to the formation of oligomers. Citation: Parfenova, L.V.; Kovyazin, P.V.; Bikmeeva, A.K.; Palatov, E.R. Keywords: zirconocene; metal hydrides; alkene dimerization; nuclear magnetic resonance Catalytic Systems Based on Cp2ZrX2 (X = Cl, H), Organoaluminum Compounds and Perfluorophenylboranes: Role of 1. Introduction Zr,Zr- and Zr,Al-Hydride Among the catalytic methods for alkene di-, oligo-, and polymerization, approaches Intermediates in Alkene Dimerization that use Ziegler–Natta-type catalytic systems, based on metallocenes or post-metallocenes, and Oligomerization. Catalysts 2021, 11, 39. https://doi.org/10.3390/ typically Group 4 transition metal complexes, in combination with organoaluminum catal11010039 or organoboron activators, have great potential for development [1–5]. Apart from the + − known action of alkyl cations [(L2MAlk) X ] as polymer chain growth centers, the idea + − Received: 10 December 2020 of the participation of [(L2MH) X ]-type hydride complexes as catalytic active species Accepted: 27 December 2020 in the reactions of alkene di-, oligo-, and polymerization has been repeatedly pointed Published: 31 December 2020 out [2,4,6–15]. This assumption follows both from the structure of the reaction prod- ucts (the presence of vinylidene terminal groups, arising upon chain termination via b-H Publisher’s Note: MDPI stays neu- elimination, which generates intermediates with M–H bond) and from the fact that the tral with regard to jurisdictional clai- efficiency of catalytic systems increases upon the introduction of hydride-generating ad- i ms in published maps and institutio- ditives such as AlBu 3 [13,16–25]. Moreover, there are several studies on the synthesis nal affiliations. and identification of catalytically active hydride Zr,B-complexes (Scheme1). For exam- + − + − ple, complexes [Cp’2ZrH] [MeB(C6F5)3] and [Cp’2ZrH] [HB(C6F5)3] were found to be active in the ethylene and propylene polymerization [26,27]. Additionally, hydride complexes [Cp0 Zr H ][B(C F R) ] (R = F, SiPri ), highly active initiators for the isobutene Copyright: © 2020 by the authors. Li- 4 2 3 6 4 4 3 censee MDPI, Basel, Switzerland. homopolymerization and isobutene–isoprene copolymerization, were described [28]. This article is an open access article A number of Zr borohydride complexes were prepared by Piers et al. by the reaction distributed under the terms and con- of alkylzirconocenes with HB(C6F5)2 [29–31]. The complexes were found to be active in ditions of the Creative Commons At- ethylene polymerization provided that additional alkylation with MAO takes place [30]. tribution (CC BY) license (https:// Zr,B-hydride complexes were also obtained in the reaction of rac-ethylenebis(4,5,6,7- i creativecommons.org/licenses/by/ tetrahydro-1-indenyl)]zirconium difluoride with HAlBu 2 and B(C6F5)3 [32,33]. The acti- i 4.0/). vation of hafnocenes with AlBu 3/(Ph3C)[B(C6F5)4] yielded hydrido-bridged species of Catalysts 2021, 11, 39. https://doi.org/10.3390/catal11010039 https://www.mdpi.com/journal/catalysts Catalysts 2021, 11, 39 2 of 16 i + i + the type [LHf(µ-H)2AlBu 2] or [LHf(µ-H)2Al(H)Bu ] , which were more active in alkene polymerizations than methyl-bridged heterobinuclear intermediates [LHf(µ-Me)2Al(µ- Me)2][MeMAO] and [LHf(µ-Me)2Al(µ-Me)2][B(C6F5)4][34]. Conversely, the formation of a + + – similar intermediate, [Cp2Zr(µ-H)2AlMe2] , observed in the [Cp2Zr(µ-Me)2AlMe2] [B(C6F5)4] -1-alkene system by electrospray ionization mass spectrometry (ESI-MS), is interpreted as a pathway for catalyst deactivation [35]. The reaction of zirconocenes with excess i AlBu 3 and boron activators gave an oily product that contained hydride complexes [LZr(µ- i H)(µ-C4H7)-AlBu 2][B(C6F5)4][36,37], which were proposed as the thermodynamic sink of the catalyst in alkene polymerization [37]. As a result of studying the polymerization reactions in the presence of dialkyl ansa-complexes [Me2C(Cp)IndMMe2] (M = Zr; Hf), activated with B(C6F5)3, hydride intermediates Me2C(Cp)IndMMe(µ-H)B(C6F5)3, which were unreactive towards monomer insertion and, therefore, represented dormant states, were found [38]. Modification of Zr,Al-hydride complexes Cp’2ZrH3AlH2 (Cp’ = C5Me5, C5H4SiMe3) by B(C6F5)3 was accompanied by the formation of di- or polynuclear metal- Catalysts 2020, 10, x FOR PEER REVIEW 2 of 17 locenium ion pairs containing terminal and bridging counteranions HB(C6F5)3, appearing due to hydride abstraction, which showed the ability to polymerize ethylene [39]. Het- found to be active in the ethylene and propylene polymerization [26,27].i Ad- i erometallic complexes formed in the reactions of L2ZrCl2 with XAlBu 2 (X = H, Cl, Bu )[40] ditionally, hydride complexes [Cp′4Zr2H3][B(C6F4R)4] (R = F, SiPri3), highly ac- being transformed into the cationic species by [Ph C][B(C F ) )] also become capable of tive initiators for the isobutene homopolymerization3 and isobutene–isoprene6 5 4 alkene polymerization [10,11]. copolymerization, were described [28]. c + - [Cp'2ZrH] [HB(C6F5)3] b + - a [Cp'2ZrH] [MeB(C6F5)3] - t [B(C6F4R)4] - Cp' = Me5C5, Bu 2C5H3 [B(C6F4R)4] c b 5 T. Marks, 1992, 1994 Cp' = η -C5H3SiMe3 i R = F, SiPr 3 a M. Bochmann, 1999 - - W. E. Piers, 1995-1998 R = Cl, Me, Ph - [B(C6F5)4] 5 L = Ph2C[(fluorenyl)(η -C5H4)] M = Zr; Hf P. Arndt; U. Rosenthal, 2003, 2006 C. Gotz, 2002 Ab. Al-Humydi; Sc. Collins, 2005 - - - [B(C6F5)4] [B(C6F5)4] [B(C6F5)4] M= Zr; Hf 5 2 2 2 η 5 4 5 L = Me Si(1-indenyl) ; Me C[(fluorenyl)( -C H )]; L = EBI, EBTHI, Me2C(1-indenyl)2, Me4C2(η -C5H4)2, 5 2 η 5 4 5 Ph C[(fluorenyl)( -C H )]; 2 η 5 4 2 2 2 5 3 2 [Me Si( -C H ) , [(Me Si) (C H ) , C2H4[(fluorenyl)(5,6-C3H6-2-MeInd)] 5 5 n 5 5 η -C5H5, η -C5H4 Bu, η -C5H4SiMe3, η -1,2-Me2C5H3 H.-H. Brintzinger, 2011 K.P. Bryliakov, M. Bochmann, 2008 - [B(C6F5)4] 2[HB(C6F5)3] n H. S. Zijlstra, S. Collins and J. S. McIndoe, 2020 L = CpMe5; BuCp; Me3SiCp R. Gonzalez-Hernandez, Sc. Collins, 2006 SchemeScheme 1. 1.Examples Examples of of Zr(Hf),B-hydride Zr(Hf),B-hydride complexes. complexes. OurA number recent of study Zr borohydride was concerned complexes with the were structure, prepared dynamics, by Piers et andal. by reactivity of i hydridethe reaction complexes of alkylzirconocenes generated in with the followingHB(C6F5)2 [29–31]. systems: The L2 complexesZrCl2-XAlBu were2 (X = H, Cl, i i Bufound)[41 –to45 be] and active [Cp in2ZrH ethylene2]2-ClAlR polymeri2 (R =zation Et, Bu provided)-methylaluminoxane that additional (MMAO-12) alkyl- [46,47] ation with МАО takes place [30]. Zr,B-hydride complexes were also obtained in the reaction of rac-ethylenebis(4,5,6,7-tetrahydro-1-indenyl)]zirconium difluoride with HAlBui2 and B(C6F5)3 [32,33]. The activation of hafnocenes with AlBui3/(Ph3C)[B(С6F5)4] yielded hydrido-bridged species of the type [LHf(µ-H)2AlBui2]+ or [LHf(µ-H)2Al(H)Bui]+, which were more active in al- kene polymerizations than methyl-bridged heterobinuclear intermediates [LHf(µ-Me)2Al(µ-Me)2][MeMAO] and [LHf(µ-Me)2Al(µ-Me)2][B(C6F5)4] [34]. Conversely, the formation of a similar intermediate, [Cp2Zr(µ-H)2AlMe2]+, observed in the [Cp2Zr(µ-Me)2AlMe2]+[B(C6F5)4]--1-alkene system by elec- trospray ionization mass spectrometry (ESI-MS), is interpreted as a pathway for catalyst deactivation [35]. The reaction of zirconocenes with excess AlBui3 and boron activators gave an oily product that contained hydride complexes [LZr(µ-H)(µ-C4H7)-AlBui2][B(C6F5)4] [36,37], which were proposed as the thermodynamic sink of the catalyst in alkene polymerization [37]. As a result of studying the polymerization reactions in the presence of dialkyl ansa-com- plexes [Me2C(Cp)IndMMe2] (M = Zr; Hf), activated with B(C6F5)3, hydride in- Catalysts 2020, 10, x FOR PEER REVIEW 3 of 17 termediates Me2C(Cp)IndMMe(µ-H)B(C6F5)3, which were unreactive to- wards monomer insertion and, therefore, represented dormant states, were found [38]. Modification of Zr,Al-hydride complexes Cp’2ZrH3AlH2 (Cp’ = C5Me5, C5H4SiMe3) by B(C6F5)3 was accompanied by the formation of di- or polynuclear metallocenium ion pairs containing terminal and bridging coun- teranions HB(C6F5)3, appearing due to hydride abstraction, which showed the ability to polymerize ethylene [39].
Load more

Recommended publications
  • LIGHT METAL BOROHYDRIDES and Mg-BASED HYDRIDES for HYDROGEN STORAGE
    LIGHT METAL BOROHYDRIDES AND Mg-BASED HYDRIDES FOR HYDROGEN STORAGE by SHENG GUO A thesis submitted to the University of Birmingham for the degree of DOCTOR OF PHILOSOPHY School of Metallurgy and Materials College of Engineering and Physical Sciences University of Birmingham December 2014 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. Synopsis This work has investigated structural and compositional changes in LiBH4, Mg(BH4)2, Ca(BH4)2, LiBH4-Ca(BH4)2 during heating. The crystal and vibrational structures of these borohydrides/composites were characterized using lab-based X-ray diffraction (XRD) and Raman spectroscopy, with particular attention to the frequency/width changes of Raman vibrations of different polymorphs of borohydrides. The thermal stability and decomposition pathway of the borohydrides was studied in great detail mainly using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), in/ex situ XRD and Raman measurements, whilst the gaseous products during heating were monitored using a mass spectrometry (MS). Hydrogen is the main decomposition gaseous product from all of these compounds, but in some cases a very small amount of diborane release was also detected.
    [Show full text]
  • NNL TSL Evaluations for Yttrium Hydride and Hexagonal Ice
    NNL TSL Evaluations for Yttrium Hydride and Hexagonal Ice Michael Zerkle and Jesse Holmes Naval Nuclear Laboratory Cross Section Evaluation Working Group Meeting November 14-16, 2016 Brookhaven National Laboratory The Naval Nuclear Laboratory is operated for the U.S. Department of Energy and the U.S. Department of the Navy by Bechtel Marine Propulsion Corporation, a wholly owned subsidiary of Bechtel National, Inc. NNL TSL Evaluations Material MAT H(YH2) 5 Y(YH2) 55 H(ice-Ih) 10 O(ice-Ih) 50 2 YH2 Background • Yttrium hydride (YH2) is an advanced high temperature moderator • Superior hydrogen density (NH) at elevated temperatures • Keinert (1971) proposed H(YH2) TSL based on simple analytic frequency distributions • Debye-type for acoustic mode • Gaussian-type for optical mode • Higher-fidelity TSLs for H(YH2) and Y(YH2) developed using first- principles calculations • Density Functional Theory (DFT) to calculate interatomic Hellman- Feynman forces for crystal structure Hydrogen in metallic Zr, Ce, Y and Ca in equilibrium with 1 atm H at various temperatures. • Lattice Dynamics (LD) to determine 2 dispersion relations and phonon (Source: Metal Hydrides, Academic Press, p. 442, 1968) density of states (DOS) -22 NH is number of hydrogen atoms/cc x 10 3 Ab Initio Calculation of Phonon Spectra 4 YH2 Structure and Lattice Dynamics • YH2 has a CaF2 type FCC structure • 12 atoms • 4 Y atoms (blue) at vertices and faces of unit cell • 8 H atoms (grey) in tetrahedral holes between Y atoms • Dispersion relations (at right) • Well separated acoustical and optical modes • Lower branches are acoustical modes mainly due to heavy Y atom vibrations • Higher branches are optical modes mainly due to light H atom vibrations 5 YH2 Phonon Density of States 6 YH2 Phonon Density of States High resolution inelastic neutron scattering spectra from Udovic shows similar structure for YH2 centered on 0.127 eV.
    [Show full text]
  • This Thesis Has Been Submitted in Fulfilment of the Requirements for a Postgraduate Degree (E.G
    This thesis has been submitted in fulfilment of the requirements for a postgraduate degree (e.g. PhD, MPhil, DClinPsychol) at the University of Edinburgh. Please note the following terms and conditions of use: • This work is protected by copyright and other intellectual property rights, which are retained by the thesis author, unless otherwise stated. • A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. • This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author. • The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author. • When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given. Development of Novel Metal-Catalysed Methods for the Transformation of Ynamides Thesis Submitted in Accordance with the Requirements of The University of Edinburgh for the Degree of Doctor of Philosophy By Donna L. Smith Supervised by Dr. Hon Wai Lam School of Chemistry College of Science and Engineering 2013 Declaration I hereby declare that, except where specific reference is made to other sources, the work contained within this thesis is the original work of my own research since the registration of the PhD degree in September 2009, and any collaboration is clearly indicated. This thesis has been composed by myself and has not been submitted, in whole or part, for any other degree, diploma or other qualification. Donna L. Smith 2 Abstract I. Rhodium-Catalysed Carbometalation of Ynamides using Organoboron Reagents As an expansion of existing procedures for the carbometalation of ynamides, it was discovered that [Rh(cod)(MeCN)2]BF4 successfully promotes the carbometalation of ynamides with organoboron reagents.
    [Show full text]
  • Research Report Fürstner 2017-2019 603.42 Kb
    Research Programs – Organometallic Chemistry 2.4 Advances in Metal-Carbene Chemistry Department of Organometallic Chemistry by Alois Fürstner ABSTRACT: The major lines of research in this Department continue to be: (i) alkyne metathesis, (ii) iron catalyzed C-C-bond formation, (iii) π-acid catalysis using platinum, gold and rhodium complexes, and (iv) unorthodox catalytic addition reactions. All areas are prospering, including the application of the in-house methodology to target-oriented synthesis; yet, it was the field of ruthenium-catalyzed addition chem- istry which led to the most perplexing and (hopefully) significant results. For the unexpected intervention of discrete metal carbenes as reac- tive intermediates, the major findings in this area are discussed together with our recent contributions to the related field of rhodium carbene chemistry. Ruthenium. cis-Delivery of H2 to a π-system of an unsaturated cal outcome is astounding, if one considers that conventional trans- substrate is the canonical course of metal catalyzed hydrogenation hydroboration is the textbook example for a cis-addition process via reactions. This stereochemical paradigm remained basically unchal- a four-membered transition state under frontier-orbital control. All lenged since the pioneering work of Sabatier until our group re- newly discovered trans-hydrometalation reactions break this fun- ported the semi-reduction of internal alkynes with the aid of damental stereochemical rule; importantly, they are robust, distin- [Cp*Ru]-based catalysts. The reaction clearly violates this funda- guished by excellent functional group compatibility, and have mental rule and affords E-alkenes by direct trans-hydrogenation already stood the test of natural product synthesis in a number of (Scheme 1).
    [Show full text]
  • Catalytic Enantioselective Carbon-Carbon Bond Formation Using Cycloisomerization Reactions
    View Online / Journal Homepage / Table of Contents for this issue Chemical Science Dynamic Article LinksC< Cite this: Chem. Sci., 2012, 3, 2899 www.rsc.org/chemicalscience MINIREVIEW Catalytic enantioselective carbon-carbon bond formation using cycloisomerization reactions Iain D. G. Watsona and F. Dean Toste*b Received 30th April 2012, Accepted 7th June 2012 DOI: 10.1039/c2sc20542d This review describes important recent advancements in asymmetric cycloisomerization reactions. A wide variety of catalytic and asymmetric strategies have been applied to these reactions over the past twenty years. Cycloisomerization reactions have the ability to produce diverse polycyclic compounds in excellent yields and selectivity. They constitute a powerful and efficient strategy for asymmetric carbon- carbon bond formation in cyclic compounds. Enyne and related olefin cyclizations comprise the majority of reactions of this type and important advances have recently occurred in this area. However, significant changes have also occurred in the area of classical cyclization as well as intramolecular hydroacylation and C–H activation initiated cyclization and these will also be described. 1 Introduction The purpose of this review is to describe important new advances in asymmetric cycloisomerization reactions. In partic- The synthesis of rings is central to the art of organic synthesis. ular, this review will focus on enantioselective carbon-carbon Cyclic compounds abound in chemistry, from strained three bond forming cycloisomerizations. Many aspects of cyclo- membered rings to macrocyclic monsters. A common synthetic isomerization reactions have already been reviewed,3 including challenge is the creation of a ring within a certain target mechanistic4 and asymmetric aspects of the reaction.5 This compound.
    [Show full text]
  • EI-ICHI NEGISHI Herbert C
    MAGICAL POWER OF TRANSITION METALS: PAST, PRESENT, AND FUTURE Nobel Lecture, December 8, 2010 by EI-ICHI NEGISHI Herbert C. Brown Laboratories of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907-2084, U.S.A. Not long ago, the primary goal of the synthesis of complex natural products and related compounds of biological and medicinal interest was to be able to synthesize them, preferably before anyone else. While this still remains a very important goal, a number of today’s top-notch synthetic chemists must feel and even think that, given ample resources and time, they are capable of synthesizing virtually all natural products and many analogues thereof. Accepting this notion, what would then be the major goals of organic synthesis in the twenty-first century? One thing appears to be unmistakably certain. Namely, we will always need, perhaps increasingly so with time, the uniquely creative field of synthetic organic and organometallic chemistry to prepare both new and existing organic compounds for the benefit and well-being of mankind. It then seems reasonably clear that, in addition to the question of what compounds to synthesize, that of how best to synthesize them will become increasingly important. As some may have said, the primary goal would then shift from aiming to be the first to synthesize a given compound to seeking its ultimately satisfactory or “last synthesis”. If one carefully goes over various aspects of organic synthetic methodology, one would soon note how primitive and limited it had been until rather recently, or perhaps even today. For the sake of argument, we may propose here that the ultimate goal of organic synthesis is “to be able to synthesize any desired and fundamentally synthesizable organic compounds (a) in high yields, (b) efficiently (in as few steps as possible, for example), (c) selectively, preferably all in t98–99% selectivity, (d) economically, and (e) safely, abbreviated hereafter as the y(es)2 manner.” with or without catalyst R1M + R2X R1R2 + MX R1, R2: carbon groups.
    [Show full text]
  • Transition Metal Hydrides That Mediate Catalytic Hydrogen Atom Transfers
    Transition Metal Hydrides that Mediate Catalytic Hydrogen Atom Transfers Deven P. Estes Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences COLUMBIA UNIVERSITY 2014 © 2014 Deven P. Estes All Rights Reserved ABSTRACT Transition Metal Hydrides that Mediate Catalytic Hydrogen Atom Transfers Deven P. Estes Radical cyclizations are important reactions in organic chemistry. However, they are seldom used industrially due to their reliance on neurotoxic trialkyltin hydride. Many substitutes for tin hydrides have been developed but none have provided a general solution to the problem. Transition metal hydrides with weak M–H bonds can generate carbon centered radicals by hydrogen atom transfer (HAT) to olefins. This metal to olefin hydrogen atom transfer (MOHAT) reaction has been postulated as the initial step in many hydrogenation and hydroformylation reactions. The Norton group has shown MOHAT can mediate radical cyclizations of α,ω dienes to form five and six membered rings. The reaction can be done catalytically if 1) the product metalloradical reacts with hydrogen gas to reform the hydride and 2) the hydride can perform MOHAT reactions. The Norton group has shown that both CpCr(CO)3H and Co(dmgBF2)2(H2O)2 can catalyze radical cyclizations. However, both have significant draw backs. In an effort to improve the catalytic efficiency of these reactions we have studied several potential catalyst candidates to test their viability as radical cyclization catalysts. I investigate the hydride CpFe(CO)2H (FpH). FpH has been shown to transfer hydrogen atoms to dienes and styrenes. I measured the Fe–H bond dissociation free energy (BDFE) to be 63 kcal/mol (much higher than previously thought) and showed that this hydride is not a good candidate for catalytic radical cyclizations.
    [Show full text]
  • Fuel Geometry Options for a Moderated Low-Enriched Uranium Kilowatt-Class Space Nuclear Reactor T ⁎ Leonardo De Holanda Mencarinia,B,Jeffrey C
    Nuclear Engineering and Design 340 (2018) 122–132 Contents lists available at ScienceDirect Nuclear Engineering and Design journal homepage: www.elsevier.com/locate/nucengdes Fuel geometry options for a moderated low-enriched uranium kilowatt-class space nuclear reactor T ⁎ Leonardo de Holanda Mencarinia,b,Jeffrey C. Kinga, a Nuclear Science and Engineering Program, Colorado School of Mines (CSM), 1500 Illinois St, Hill Hall, 80401 Golden, CO, USA b Subdivisão de Dados Nucleares - Instituto de Estudos Avançados (IEAv), Trevo Coronel Aviador José Alberto Albano do Amarante, n 1, 12228-001 São José dos Campos, SP, Brazil ABSTRACT A LEU-fueled space reactor would avoid the security concerns inherent with Highly Enriched Uranium (HEU) fuel and could be attractive to signatory countries of the Non-Proliferation Treaty (NPT) or commercial interests. The HEU-fueled Kilowatt Reactor Using Stirling Technology (KRUSTY) serves as a basis for a similar reactor fueled with LEU fuel. Based on MCNP6™ neutronics performance estimates, the size of a 5 kWe reactor fueled with 19.75 wt% enriched uranium-10 wt% molybdenum alloy fuel is adjusted to match the excess reactivity of KRUSTY. Then, zirconium hydride moderator is added to the core in four different configurations (a homogeneous fuel/moderator mixture and spherical, disc, and helical fuel geometries) to reduce the mass of uranium required to produce the same excess reactivity, decreasing the size of the reactor. The lowest mass reactor with a given moderator represents a balance between the reflector thickness and core diameter needed to maintain the multiplication factor equal to 1.035, with a H/D ratio of 1.81.
    [Show full text]
  • Delayed Hydride Cracking in Zirconium Alloys in Pressure Tube Nuclear Reactors
    IAEA-TECDOC-1410 Delayed hydride cracking in zirconium alloys in pressure tube nuclear reactors Final report of a coordinated research project 1998–2002 October 2004 IAEA-TECDOC-1410 Delayed hydride cracking in zirconium alloys in pressure tube nuclear reactors Final report of a coordinated research project 1998–2002 October 2004 The originating Section of this publication in the IAEA was: Nuclear Power Technology Development Section International Atomic Energy Agency Wagramer Strasse 5 P.O. Box 100 A-1400 Vienna, Austria DELAYED HYDRIDE CRACKING IN ZIRCONIUM ALLOYS IN PRESSURE TUBE NUCLEAR REACTORS IAEA, VIENNA, 2004 IAEA-TECDOC-1410 ISBN 92–0–110504–5 ISSN 1011–4289 © IAEA, 2004 Printed by the IAEA in Austria October 2004 FOREWORD This report documents the work performed in the Coordinated Research Project (CRP) on Hydrogen and Hydride Degradation of the Mechanical and Physical Properties of Zirconium Alloys. The Project consisted of hydriding samples of Zr-2.5 Nb pressure tube materials used in CANDU-type and RBMK reactors, the measurement of delayed hydride cracking (DHC) rates under specified conditions, and analysis of hydrogen concentrations. The project was overseen by a supervisory group of experts in the field who provided advice and assistance to the participants as required. All of the research work undertaken as part of the CRP is described in this report, which includes a review of the state of the art in understanding crack propagation by DHC and details of the experimental procedures that produced the most consistent set of DHC rates reported in an international round-robin exercise to this date. All of the participants and many of their co-workers in the laboratories involved in the CRP contributed results and material used in the drafting of this report, which contains compilations of all of the results, their analysis, discussions of their interpretation and conclusions and recommendations for further work.
    [Show full text]
  • NETS 2020 Template
    بÀƵƧǘȁǞƧƊǶ §ȲȌǐȲƊǿ ƊƧDzɈȌɈǘƵwȌȌȁƊȁƮȌȁ ɈȌwƊȲȺɈǘȲȌɐǐǘƊƮɨƊȁƧǞȁǐ خȁɐƧǶƵƊȲɈƵƧǘȁȌǶȌǐǞƵȺƊȁƮ ǞȁȁȌɨƊɈǞȌȁ ǞȺ ȺȯȌȁȺȌȲƵƮ Ʀɯ ɈǘƵ ƊDz ªǞƮǐƵ yƊɈǞȌȁƊǶ ׁׂ׀ׂ y0À² ÀǘǞȺ ƧȌȁǏƵȲƵȁƧƵ خׁׂ׀ׂ ةɈǘ׀׃ƊȁƮ ɩǞǶǶƦƵ ǘƵǶƮ ǏȲȌǿȯȲǞǶ ׂ׆ɈǘٌةmƊƦȌȲƊɈȌȲɯ ɩǞǶǶ ƦƵ ǘƵǶƮ ɨǞȲɈɐƊǶǶɯ ȺȌ ɈǘƊɈ ɈǘƵ ƵȁɈǞȲƵ y0À² خƧȌǿǿɐȁǞɈɯǿƊɯȯƊȲɈǞƧǞȯƊɈƵǞȁɈǘǞȺƵɮƧǞɈǞȁǐǿƵƵɈǞȁǐ ǐȌɨخȌȲȁǶخخׁׂ׀ȁƵɈȺׂششبǘɈɈȯȺ Nuclear and Emerging Technologies for Space Sponsored by Oak Ridge National Laboratory, April 26th-30th, 2021. Available online at https://nets2021.ornl.gov Table of Contents Table of Contents .................................................................................................................................................... 1 Thanks to the NETS2021 Sponsors! ...................................................................................................................... 2 Nuclear and Emerging Technologies for Space 2021 – Schedule at a Glance ................................................. 3 Nuclear and Emerging Technologies for Space 2021 – Technical Sessions and Panels By Track ............... 6 Nuclear and Emerging Technologies for Space 2021 – Lightning Talk Final Program ................................... 8 Nuclear and Emerging Technologies for Space 2021 – Track 1 Final Program ............................................. 11 Nuclear and Emerging Technologies for Space 2021 – Track 2 Final Program ............................................. 14 Nuclear and Emerging Technologies for Space 2021 – Track 3 Final Program ............................................. 18
    [Show full text]
  • Safe Hydroformylation of Aliphatic Alkene in a Flow Reactor
    International Journal of Organic Chemistry, 2018, 8, 135-141 http://www.scirp.org/journal/ijoc ISSN Online: 2161-4695 ISSN Print: 2161-4687 Safe Hydroformylation of Aliphatic Alkene in a Flow Reactor Hisashi Masui, Eiki Honda, Sakura Niitsu, Mitsuru Shoji, Takashi Takahashi* Department of Pharmaceutical Sciences, Yokohama University of Pharmacy, Yokohama, Japan How to cite this paper: Masui, H., Honda, Abstract E., Niitsu, S., Shoji, M. and Takahashi, T. (2018) Safe Hydroformylation of Aliphatic Despite hydroformylation being a very efficient method for the transforma- Alkene in a Flow Reactor. International tion of alkenes, it is not commonly employed in laboratories owing to the Journal of Organic Chemistry, 8, 135-141. flammable/toxic nature of hydrogen and carbon monoxide gases and the ne- https://doi.org/10.4236/ijoc.2018.81009 cessity of high-pressure equipment in a batch system. Flow chemistry often Received: November 30, 2017 raises the safety profiles against high-pressure and toxic gases because the Accepted: March 6, 2018 diameter of the flow reactor is small. Herein, we show that aliphatic alkenes Published: March 9, 2018 can be safely hydroformylated in a flow reactor. In our flow method, although Copyright © 2018 by authors and the target hydroformylated product was obtained in a low yield (19%), toxic Scientific Research Publishing Inc. gases were safely treated using a flow reactor. Better yields could possibly be This work is licensed under the Creative achieved by recycling of the unreacted alkene. Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Keywords Open Access Hydroformylation, Flow Synthesis, Alkene, Carbon Monoxide, Aldehyde 1.
    [Show full text]
  • Transition Metals for Organic Synthesis
    Matthias Beller, Carsten Bolm Transition Metals for Organic Synthesis Building Blocks and Fine Chemicals © WILEY-VCH Weinheim • New York • Chichester • Brisbane • Singapore • Toronto Contents Volume 1 1 General 1 1.1 Basic Aspects of Organic Synthesis with Transition Metals (Barry M. Trost) 3 1.1.1 Chemoselectivity 4 1.1.2 Regioselectivity 6 1.1.3 Diastereoselectivity 7 1.1.4 Enantioselectivity 9 1.1.5 Atom Economy 10 1.1.6 Conclusion 11 References 12 1.2 Concepts for the Use of Transition Metals in Industrial Fine Chemical Synthesis (Wilhelm Keim) 14 1.2.1 General Principles 14 1.2.2 Use of Transition Metals in Fine Chemical Synthesis .... 15 1.2.3 Why are Transition Metals used in Fine Chemical Synthesis? 21 1.2.4 Considerations for the Future 22 References 22 2 Transition Metal-catalyzed Reactions 23 2.1 New Opportunities in Hydroformylation: Selected Syntheses of Intermediates and Fine Chemicals (Carlo Botteghi, Mauro Marchetti, Stefano Paganelli) ... 25 2.1.1 Introduction 25 2.1.2 Building Blocks for Pharmaceutical and Natural Products . 26 2.1.3 Building Blocks for Agrochemicals 40 2.1.4 Concluding Remarks 43 References 45 viii Contents 2.2 Hydrocarboxylation and Hydroesterification Reactions Catalyzed by Transition Metal Complexes (Bassam El Ali, Howard Alper) 49 2.2.1 Introduction 49 2.2.2 Intermolecular Hydrocarboxylation and Hydroesterification of Unsaturated Substrates 49 2.2.2.1 Hydrocarboxylation of Alkenes 49 2.2.2.2 Hydroesterification of Alkenes 53 2.2.2.3 Hydrocarboxylation and Hydroesterification of Allenes and Dienes
    [Show full text]