- Palladium-catalyzed H-D exchange reaction under hydrothermal condition
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Alkenes and alkanes were converted into fully deuterium labelled ones by treatment with palladium on charcoal and deuterium oxide under hydrothermal condition. The simple method to get fully deuterium labelled compounds is easy to apply to various types of organic compounds.
- Matsubara, Seijiro,Yokota, Yutaka,Oshima, Koichiro
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- Discovery and mechanistic investigation of Pt-catalyzed oxidative homocoupling of benzene with PhI(OAc)2
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We present a Pt-catalyzed direct coupling of benzene to biphenyl. This catalytic reaction employs a cyclometalated platinum(ii) complex [PtMe(bhq)(SMe2)] (bhq = benzo[h]quinolate) with PhI(OAc)2 as an oxidant and does not require an acid, a co-catalyst or a solvent. The reaction kinetics and characterization of potential catalytic species are reported. The reaction is first-order in Pt and second-order in benzene, which implicates the second C-H activation step as rate-determining. A Pt(ii)/Pt(iv) catalytic cycle is suggested. The reaction commences by oxidation of the Pt(ii) complex to give the platinum(iv) species [Pt(bhq)(SMe2)(OAc)2](OAc) followed by C-H activation of benzene to afford the intermediate [PtPh(bhq)(SMe2)(OAc)](OAc) concurrently with the release of HOAc. A second benzene molecule reacts similarly to give the diphenyl intermediate [PtPh2(bhq)(SMe2)](OAc). C-C bond forming reductive elimination ensues to regenerate Pt(ii) and complete the catalytic cycle. The proposed mechanism has been examined by DFT computations, which provide support to experimental findings.
- Abu-Omar, Mahdi M.,Nabavizadeh, S. Masoud,Niroomand Hosseini, Fatemeh,Park, Chan,Wu, Guang
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- Synthesis, Characterization, and Comparative Theoretical Investigation of Dinitrogen-Bridged Group 6-Gold Heterobimetallic Complexes
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We have prepared and characterized a series of unprecedented group 6-group 11, N2-bridged, heterobimetallic [ML4(η1-N2)(μ-η1:η1-N2)Au(NHC)]+ complexes (M = Mo, W, L2 = diphosphine) by treatment of trans-[ML4(N2)2] with a cationic gold(I) complex [Au(NHC)]+. The adducts are very labile in solution and in the solid, especially in the case of molybdenum, and decomposition pathways are likely initiated by electron transfers from the zerovalent group 6 atom to gold. Spectroscopic and structural parameters point to the fact that the gold adducts are very similar to Lewis pairs formed out of strong main-group Lewis acids (LA) and low-valent, end-on dinitrogen complexes, with a bent M-N-N-Au motif. To verify how far the analogy goes, we computed the electronic structures of [W(depe)2(η1-N2)(μ-η1:η1-N2)AuNHC]+ (10W+) and [W(depe)2(η1-N2)(μ-η1:η1-N2)B(C6F5)3] (11W). A careful analysis of the frontier orbitals of both compounds shows that a filled orbital resulting from the combination of the π? orbital of the bridging N2 with a d orbital of the group 6 metal overlaps in 10W+ with an empty sd hybrid orbital at gold, whereas in 11W with an sp3 hybrid orbital at boron. The bent N-N-LA arrangement maximizes these interactions, providing a similar level of N2 push-pull activation in the two compounds. In the gold case, the HOMO-2 orbital is further delocalized to the empty carbenic p orbital, and an NBO analysis suggests an important electrostatic component in the μ-N2-[Au(NHC)]+ bond.
- Specklin, David,Coffinet, Ana?s,Vendier, Laure,Del Rosal, Iker,Dinoi, Chiara,Simonneau, Antoine
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- Perdeuteration of Deactivated Aryl Halides by H/D Exchange under Superelectrophile Catalysis
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Superelectrophilic silylium/arenium ions are shown to be highly effective H/D exchange promoters for the exhaustive deuteration of electron-deficient aryl halides. Several of the resulting perdeuterated aryl halides have been previously inaccessible with existing deuterium-labeling procedures. Using inexpensive C6D6as the deuterium source, excellent degrees of deuterium incorporation were achieved under ambient reaction conditions. Importantly, the perdeuteration remains unaffected on multigram scale, even at a reduced catalyst loading of 0.1 mol %. By this method, otherwise expensive or noncommercially available NMR solvents such as 1,2-dichloro- and 1,2-difluorobenzene can be prepared.
- He, Tao,Klare, Hendrik F. T.,Oestreich, Martin
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supporting information
p. 4734 - 4738
(2022/03/27)
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- Changes in ligand coordination mode induce bimetallic C-C coupling pathways
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Carbon-carbon coupling is one of the most powerful tools in the organic synthesis arsenal. Known methodologies primarily exploit monometallic Pd0/PdII catalytic mechanisms to give new C-C bonds. Bimetallic C-C coupling mechanisms that involve a PdI/PdII redox cycle, remain underexplored. Thus, a detailed mechnaistic understanding is imperative for the development of new bimetallic catalysts. Previously, a PdII-Me dimer (1) supported by L1, which has phosphine and 1-azaallyl donor groups, underwent reductive elimination to give ethane, a PdI dimer, a PdII monometallic complex, and Pd black. Herein, a comprehensive experimental and computational study of the reactivity of 1 is presented, which reveals that the versatile coordination chemistry of L1 promotes bimetallic C-C bond formation. The phosphine 1-azaallyl ligand adopts various bridging modes to maintain the bimetallic structure throughout the C-C bond forming mechanism, which involves intramolecular methyl transfer and 1,1-reductive elimination from one of the palladium atoms. The minor byproduct, methane, likely forms through a monometallic intermediate that is sensitive to solvent C-H activation. Overall, the capacity of L1 to adopt different coordination modes promotes the bimetallic C-C coupling channel through pathways that are unattainable with statically-coordinated ligands.
- Blacquiere, Johanna M.,Boyle, Paul D.,Jackman, Kyle M. K.,Liang, Guangchao,Zimmerman, Paul M.
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p. 3977 - 3991
(2022/03/31)
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- Efficient continuous-flow HD exchange reaction of aromatic nuclei in D2O/2-PrOH mixed solvent in a catalyst cartridge packed with platinum on carbon beads
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Herein, a continuous-flow deuteration methodology for various aromatic compounds is developed based on heterogeneous platinum-catalyzed hydrogen-deuterium exchange. The reaction entails the transfer of a substrate dissolved in a mixed solvent of 2-propanol and deuterium oxide into a catalyst cartridge packed with platinum on carbon beads (Pt/CB). Pt/ CB could be continuously used without significant deterioration of catalyst activity for at least 24 h. Deuteration proceeded within 60 s of the substrate solutions being passed through the Pt/CB layer in the Pt/CB-packed cartridge.
- Park, Kwihwan,Ito, Naoya,Yamada, Tsuyoshi,Sajiki, Hironao
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supporting information
p. 600 - 605
(2021/03/29)
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- Platinum on carbon-catalyzed H-D exchange reaction of aromatic nuclei due to isopropyl alcohol-mediated self- activation of platinum metal in deuterium oxide
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An efficient and simple deuteration method of arenes using the platinum on carbon-isopropyl alcohol-cyclohexane-deuterium oxide combination under hydrogen gas-free conditions was accomplished. Since the hydrogen-deuterium exchange reaction cannot be promoted without isopropyl alcohol, zerovalent platinum metal (on carbon) is self-activated by the in situ-generated very low amount of hydrogen or hydrogen-deuterium gas derived from isopropyl alcohol or isopropyl alcohol-d1. Deuterium-labeled compounds with high deuterium contents can be easily isolated by the filtration of platinum on carbon and simple extraction. The present hydrogen gas-free method is safe from the viewpoint of process chemistry and various arenes possessing a variety of reducible functionalities within the molecule could be effectively and directly deuterium-labeled without undesired reduction. Copyright
- Sawama, Yoshinari,Yamada, Tsuyoshi,Yabe, Yuki,Morita, Kosuke,Shibata, Kyoshiro,Shigetsura, Masahiro,Monguchi, Yasunari,Sajiki, Hironao
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supporting information
p. 1529 - 1534
(2013/06/27)
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- COMPOUND WITH TRIPHENYLAMINE STRUCTURE, AND ORGANIC ELECTROLUMINESCENT ELEMENT
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Problem to Be Solved: There is provided an organic compound of excellent characteristics that exhibits excellent hole-injecting/transporting performance and has an electron blocking ability and a highly stable thin-film state with excellent heat resistance. The compound is provided as a material of a high-efficiency, high-durability organic EL device, and is used to provide a high-efficiency, high-durability organic EL device. Solution: The compound of the present invention is an arylamine compound of general formula (1) or (2) having a triphenylamine structure. The arylamine compound is used as a constituent material of at least one organic layer in an organic electroluminescent device that includes a pair of electrodes, and one or more organic layers sandwiched between the pair of electrodes.
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Page/Page column 33
(2012/12/14)
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- Efficient and selective Pt/C-catalyzed H-D exchange reaction of aromatic rings
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An effective and applicable deuteration method for aromatic rings using Pt/C-D2O-H2 system was established. Especially, phenol was fully deuterated even at room temperature, and other electron-rich aromatic nuclei were efficiently deuterated under mild conditions. The scope and limitations of the presence method and its application to the synthesis of deuterium-labeled biologically active compounds and deuterium-labeled building blocks for practical multi-gram scale syntheses are reported. 2008 The Chemical Society of Japan.
- Ito, Nobuhiro,Esaki, Hiroyoshi,Maesawa, Tsuneaki,Imamiya, Eikoh,Maegawa, Tomohiro,Sajiki, Hironao
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experimental part
p. 278 - 286
(2009/03/12)
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- Aromatic ring favorable and efficient H-D exchange reaction catalyzed by Pt/C
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An effective and applicable Pt/C-catalyzed deuteration method of aromatic rings using D2O as a deuterium source under hydrogen atmosphere was developed. Five percent Pt/C would lead to quite effective H-D exchange results on the aromatic ring systems. The reaction is general for a variety of aromatic compounds including biologically active compounds.
- Sajiki, Hironao,Ito, Nobuhiro,Esaki, Hiroyoshi,Maesawa, Tsuneaki,Maegawa, Tomohiro,Hirota, Kosaku
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p. 6995 - 6998
(2007/10/03)
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- The extraordinary reactions of phenyldimethylsilyllithium with N,N-disubstituted amides
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The reactions of the silyllithium reagent with tertiary amides was discussed. The enediamines were easily isomerized from cis to trans, easily oxidized to dienediamines and were hydrolyzed to α-aminoketones. If the two equivalents of the silyllithium reagent were used, the product was an α-silylamine. The results show that each member of the homologous series of amides gives rise to a substantially different product.
- Buswell, Marina,Fleming, Ian,Ghosh, Usha,Mack, Stephen,Russell, Matthew,Clark, Barry P.
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p. 3006 - 3017
(2007/10/03)
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- Room Temperature Activation of Aromatic C-H Bonds by Non-Classical Ruthenium Hydride Complexes Containing Carbene Ligands
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Non-classical ruthenium hydride complexes are promising lead structures for the C-H bond activation and functionalization of aromatic compounds. In the present paper, the preparation and crystallographic characterisation of the first organo-metallic complexes bearing dihydrogen ligands and N-heterocyclic carbene ligands in the same coordination sphere are described. The mixed phosphine/ carbene complex [(IMes)Ru(H)2(H2) 2(PCy3)] (IMes = 1,3-dimesityl-1,3-dihydro-2H-imidazol-2- ylidene; 3a) shows a unique reactivity pattern in the inter- and intramolecular activation of C-H bonds. In particular, complex 3a effects a rapid and remarkably selective intermolecular activation of sp2 C-H bonds in simple aromatic compounds at room temperature.
- Giunta, Daniela,H?lscher, Markus,Lehmann, Christian W.,Mynott, Richard,Wirtz, Cornelia,Leitner, Walter
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p. 1139 - 1145
(2007/10/03)
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- Structural and Substituent Effect on (+.) vs. (+) Formation in Fast Atom Bombardment Mass Spectra of Simple Organic Compounds
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The peak intensity ratios of (+.) vs. (+) were measured in the fast atom bombardment (FAB) mass spectra of readily available test compounds with 3-nitrobenzyl alcohol as the matrix.For simple aromatic amines, the ratio increases as the ionization energy of the substrate decreases. 4-Subsituted benzophenones showed preferential formation of (+) ions, regardless of the nature of the substituents.This is probably due to the fact that the benzophenones have carbonyl groups which can form hydrogen bonds with the matrix molecule.The peak intensity ratio is roughly proportional to the Hammett ?+.Among 4-substituted biphenyls, both bromo and chloro substituents afforded abnormally high peak intensity ratios.The effects of the substituents in these compounds are discussed semi-quantitatively in terms of the Hammett correlation and the hard and soft acids and bases principle.The mechanism of ion formation in FAB and chemical ionization (CI) ion sources appeared to be different because some of the compounds studied showed an intense (+.) peak with a relatively weak (+) peak in FAB spectra but exhibited a strong (+) peak in ordinary CI spectra.
- Nakata, Hisao,Tanaka, Katsunori
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p. 283 - 288
(2007/10/02)
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- Kinetics and mechanism of biaryl reductive elimination from electron-poor [(C6F5)2PCH2CH2P(C 6F5)2]Pt(Ar)2 complexes
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The syntheses and elimination properties of electron-deficient (fluoroaryl)- and (fluoroalkyl)phosphine complexes of platinum are described. Treatment of (cod)PtCl2 with (C6F5)2PCH2CH2P(C 6F5)2 (dfppe) or (C2F5)2PCH2CH2P(C 2F5)2 (dfepe) at elevated temperatures gives the dichlorides (dfepe)PtCl2 (1) and (dfppe)PtCl2 (2) in high yield. The diaryls (dfppe)Pt(Ph)2 (3) and (dfppe)Pt(p-tol)2 (4) and the dialkyls (dfppe)Pt(Me)2 (5) and (dfepe)Pt(Me)2 (6) are prepared by metathesis of 1 or 2 with the appropriate Grignard reagent. Thermolysis of the diphenyl complex 3 cleanly yields biphenyl as the sole observed organic elimination product. No organic products derived from ancillary ligand degradation are observed. The fate of the released metal fragment is solvent-dependent, with the bis chelate (dfppe)2Pt (7) being the major product in noncoordinating aromatic solvents. The crystal structure of 7 has been determined. Crossover labeling studies for 3 and the regiospecific formation of 4,4′-dimethylbiphenyl from the thermolysis of 4 confirm that these elimination reactions proceed via an intramolecular 1,1′-coupling process. Elimination kinetics for 3 and 4 are conveniently followed by 1H NMR spectroscopy. Decomposition rates follow first-order behavior in all solvents examined and are independent of added phosphine concentration. The rate of biphenyl reductive elimination from 3 is found to be inversely proportional to solvent polarity, varying by almost a factor of 10 between benzene (ε = 2.28, k = [2.44 (5)] × 10-4 s-1) and DMSO (ε = 45.0, k = [2.50 (2)] × 10-5 s-1) media at 100°C. Entropies of activation obtained in benzene (ΔS? = -1.5 ± 1 eu) and DMSO (ΔS? = -1.7 ± 2 eu) are essentially equivalent and suggest that there is no significant solvent coordination along the elimination reaction coordinate. The mechanistic interpretation of these results and comparisons with prior group 10 elimination studies are discussed.
- Merwin, Richard K.,Schnabel, Richard C.,Koola, Johnson D.,Roddick, Dean M.
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p. 2972 - 2978
(2008/10/08)
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- A Linear Free Energy Relationship for an Equilibrium Isotope Effect
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The solution electron affinities of a series of monosubstituted phenyl-d5 benzenes relative to their perprotiated analogues were measured via electron paramagnetic resonance studies.The equilibrium constant for the electron transfer X-C6H5.- + X-C6D5 X-C6H5 + X-C6D5.-, where X = H, C6D5, CN, NO2, OCH3, tert-butyl, was found to be less than unity for all cases.However, this equilibrium constant is closer to unity for those systems where the substituent is electron withdrawing in nature, and it deviates further from unity for those systems that have an electron-donating group as the substituent.A linear free energy relationship was found, and the positive ρ value (0.34) is presumably due to the fact that there is a smaller excess charge and spin density from the antibonding electron in the area of the molecule where isotopic substitution takes place, for those systems where the ? value of the substituent is positive.
- Stevenson, Gerald R.,Wehrmann, Glenn C.,Reiter, Richard C.
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p. 901 - 905
(2007/10/02)
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- Aspects of the Chemistry of Donor Solvent Coal Dissolution Reactions. The Reduction of Benzophenone and the Diproportionation of Benzhydrol in Hydrocarbon Solvents at High Temperature
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The reduction of benzophenone by hydrogen donor molecules such as tetralin and dihydroanthracene to give diphenylmethane was investigated in the temperature range 300-400 deg C.Several lines of evidence indicate that the reaction occurs in three distinct stages.The first stage is a radical process which gives benzhydrol.In the second stage, this intermediate undergoes an SN reaction to produce water and bis(diphenylmethyl) ether.The ether disproportionates in a readily initiated, free radical chain reaction to give diphenylmethane and benzophenone.
- Choi, Chol-yoo,Stock, Leon M.
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p. 2871 - 2875
(2007/10/02)
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- Syntheses and Spectral Properties of several Branched-chain Polyphenyls containing 1,2,3-Trisubstituted Ring(s)
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Nine polyphenyls, including six new compound, 3'-phenyl-o-quaterphenyl (3), 2,6-diphenyl-m- (4), 2,6-diphenyl-p-terphenyl (5), 2,6,5'-triphenyl-m-terphenyl (6), 2',2''-diphenyl-m-quaterphenyl (8), and 2'-(phenyl-d5)-m-terphenyl (9), were synthesized by the Ullmann coupling reaction of aryl iodide(s) or by the Karash-type coupling reaction of deuterated aryl Grignard reagent with aryl iodide catalyzed by bis(acetylacetonato)-nickel(II).Infrared studies of the polyphenyls showed that the range 730-770 cm-1, generally accepted as the position of the C-H out-of-plane bending bands of phenyl rings, should be widened slightly to 730-781 cm-1.The high frequency bands were found to be correlated closely to the sterically overcrowded structure of terminal rings.Proton magnetic resonance spectral studies indicated that the characteristic spectral features of the polyphenyls containing 1,2,3-trisubstituted ring(s) were fully consistent with their conformational aspects deduced from stereomodels.Ultraviolet spectral data suggeted that the most probable conformation of the highly crowded 3',6''-diphenyl-o-quaterphenyl (1) is one in which the interplanar angles of the pivot bonds between the 1,2,3-trisubstituted ring and three benzene rings are rather smaller than those of the less crowded 2'-phenyl-m-terphenyl (2).Keywords - Ullmann reaction; nickel-complex-catalyzed cross-coupling; quaterphenyl; deuterated quaterphenyl; quinquephenyl; sexiphenyl; polyphenyl; IR; UV; 1H-NMR
- Ozasa, Shigeru,Fujioka, Yasuhiro,Kikutake, Jun-ichiro,Ibuki, Eiichi
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p. 1572 - 1581
(2007/10/02)
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- Mechanism of Thermal Decomposition of Tetra-aryltellurium Species
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Tetra-aryltellurium species decompose upon heating giving good yields of diaryl tellurides and biphenyls.Radical-scavenging experiments show that phenyl radicals are not intermediates in the formation of biphenyls.In contrast, cross-over experiments give mixed biphenyls as well as mixed diaryl tellurides, but these are formed by a statistical redistribution of organic groups giving mixed tetra-aryltellurium species which decompose thermally in an indiscrimate fashion.
- Glover, Stephen A.
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p. 1338 - 1344
(2007/10/02)
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- The formation and reactions of 9,10-phenanthryne and related arynes by pyrolytic reactions in the vapor phase
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The formation of 9,10-phenanthryne (5), 4-methyl-9,10-phenanthryne (7) and 9,10-benz(c)phenanthryne (9) by the thermal degradation of appropriate arenedicarboxylic acid anhydrides has been investigated by a combination of VLPP and mass spectrometry and by a co-pyrolysis of the anhydrides with benzene, hexadeuterobenzene and 1,3-butadiene. Compounds 5,7 and especially 9 are formed easily by VLPP at 700-900° from the anhydrides. The results indicate that 7 and 9 are less reactive by H-addition to the aryne bond than 5, benzyne or naphthalyne, respectively. The results of the co-pyrolysis experiments show that 5 and 9 react with benzene and 1,3-butadiene by H-abstraction and addition reactions, similar to 1,2-benzyne and 2,3-naphthalyne. However, the reactivity of the aryne in the H-abstraction reaction decreases and the selectivity for the addition reaction increases in the series 1,2-benzyne, 2,3-naphthalyne, 9,10-phenanthryne and 9,10benz(c)phenanthryne.
- Gruetzmacher, Hans-Fr.,Strabtmans, Udo
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p. 807 - 813
(2007/10/02)
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The synthesis of several phenyl-substituted and partially deuterated Schlenk's hydrocarbons and of deuterated tetracyclones is described. The paramagnetic species exhibit strong EPR triplet powder spectra on account of the dipolar interaction between the
- Hinrichs,Kurreck,Niemeier
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p. 315 - 320
(2007/10/12)
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