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Showing papers on "Cyclopropane published in 1984"


Journal ArticleDOI
TL;DR: In this article, the position of the cyclopropane ring on the aliphatic chain was identified by its odd mass and its separation of 13 mass units from ions in adjacent groups.
Abstract: Picolinyl esters of cyclopropane fatty acids produced characteristic mass spectra which enabled differentiation from isomeric monounsaturated acids by the presence of an abundant ion produced by formal cleavage through the cyclopropane ring. The mass of this ion indicated the position of the cyclopropane ring on the aliphatic chain and it could be identified by its odd mass and its separation of 13 mass units from ions in adjacent groups. Other major fragment ions arising from radical-induced cleavage of the chain following random hydrogen abstraction showed a 14 mass unit separation. This characteristic feature was also found in the mass spectra of bis-cyclopropane acids where each ring produced a characteristic ion of odd mass. Other features serving to differentiate cyclopropane acids from unsaturated acids were the abundant [M-1]+ ions and the presence of an ion at m/z 133. The nicotinyl derivatives of the corresponding cyclopropane alcohols showed analogous fragmentations. Mechanisms for the formation of the diagnostic ions are suggested.

72 citations


Journal ArticleDOI
TL;DR: In this paper, the structure of cristalline has been studied and the preconditioning of reactions successively de [(η 2 -N-trimethyl-2,2 butenyl-3 amino) (p-tolyl) carbene]-W(O) dont on etudie la structure cristaline
Abstract: Preparation par reactions successives de [(η 2 -N-trimethyl-2,2 butenyl-3 amino) (p-tolyl) carbene]-W(O) dont on etudie la structure cristalline

71 citations



Journal ArticleDOI
TL;DR: In this article, the authors investigated the degradability of propane, cyclopropane, propylene, propyne, and allene on the reconstructed Ir(110)•(1×2) surface.
Abstract: The dehydrogenation of propane, cyclopropane, propylene, propyne, and allene has been investigated on the reconstructed Ir(110)‐(1×2) surface. Annealing adlayers of these hydrocarbons (at low coverages) leads to the formation of surface hydrogen and hydrocarbon fragments of approximate stoichiometry C3H2. The importance of the β′2 adsite of hydrogen on this surface of Ir has been demonstrated further by poisoning studies with hydrogen, CO and surface carbon. The Ir(111) surface was found to dehydrogenate propylene but neither propane nor cyclopropane under the same reaction conditions, indicating a strong effect of surface geometry for the C–H bond activation of alkanes.

53 citations


Journal ArticleDOI
TL;DR: In this article, photolysis of pentacarbonyl pent-4-enyl (methoxy)carben tungsten at low temperature affords a new chelated alkene-carbene complex in which, according to an X-ray analysis, the alkene and the carbene functions are parallel, and which decomposes to give the expected cyclopropane.
Abstract: Photolysis of pentacarbonyl pent-4-enyl (methoxy)carben tungsten(4) at low temperature affords a new chelated alkene–carbene complex (5) in which, according to an X-ray analysis, the alkene and the carbene functions are parallel, and which decomposes to give the expected cyclopropane (7).

37 citations


Journal ArticleDOI
TL;DR: In this paper, the mass spectra of doubly charged ions of the hydrocarbon molecules ethene, difluorethene and cyclopropane have been measured.

36 citations


Journal ArticleDOI
TL;DR: In this article, a cyclopropane acetonitrile and trimethylsilyl-2 propene-2ol-1 were prepared for trimethyl silyl 2 propene 2ol.
Abstract: On prepare le trimethylsilyl-1 cyclopropane acetonitrile et le trimethylsilyl-1 cyclopropane carbaldehyde par cyclopropanation du trimethylsilyl-2 propene-2ol-1

31 citations


Journal ArticleDOI
TL;DR: In this paper, l'effet catalytique de BCl 3 sur l'isomerisation du cyclopropane is confirmed, and l'absence d'influence notable de Bcl 3 sur 3 autres reactions des hydrocarbures cycliques a des temperatures basses ou elevees: decompositions, deshydrogenation ou scission
Abstract: On confirme l'effet catalytique de BCl 3 sur l'isomerisation du cyclopropane. On met en evidence l'absence d'influence notable de BCl 3 sur 3 autres reactions des hydrocarbures cycliques a des temperatures basses ou elevees: decompositions, deshydrogenation ou scission

31 citations


Journal ArticleDOI
TL;DR: In this paper, the treatment of olefins bearing one electron-withdrawing substituent with cyclopropenone ketals under mild, thermal conditions provided cycloprobenone products.

29 citations


Journal ArticleDOI
TL;DR: In this article, the infrared spectra of cyclopropane have been obtained for the first time, and a two conformer (gauche/cis) fluid-phase equilibrium has been obtained, with only the gauche conformer remaining in the solid phase.
Abstract: The infrared spectra (4000–400 cm−1) of gaseous, liquid and solid (cyanomethyl) cyclopropane have been recorded for the first time. Additionally, the Raman spectra (3500–50 cm−1) of condensed phases of this substance have also been obtained. ‘Extra’ Q branches have been observed in the gas-phase infrared spectrum, and six liquid-phase Raman doublets (two of which are also seen in the infrared spectrum of the liquid) have also been observed, wherein one member of each doublet vanishes once the polycrystalline solid state spectrum is obtained. These data have been interpreted in terms of a two conformer (gauche/cis) fluid-phase equilibrium for (cyanomethyl)cyclopropane, with only the gauche conformer remaining in the solid phase. The temperature behavior of the 774/756 and 835/855 cm−1 liquid-phase Raman doublets yields an enthalpy difference between conformers of 0.72±0.10 kcal mol−1, with the gauche conformer the more stable. This ΔH value implies a room-temperature conformational equilibrium for (cyanomethyl)cyclopropane composed of 87% gauche and 13% cis rotamers in the liquid phase. In addition, a vibrational assignment for the 33 normal modes of (cyanomethyl)cyclopropane has been proposed, and it is in excellent agreement with the previously published vibrational assignments for three (halomethyl)cyclopropanes.

28 citations


Journal ArticleDOI
TL;DR: In this paper, the asymmetric synthesis of cyclopropane carboxylates, which are intermediates in the synthesis of photostable pyrethroid insecticides, by catalysed reaction of ethyl diazoacetate with halo-olefins is described.

Journal ArticleDOI
TL;DR: In this article, solidstate ESR studies showed that the trirnethylene radical cation undergoes rin,'', openina in the CFCI2C1.2C 1.

Journal ArticleDOI
TL;DR: In this paper, the ring-closed and ring-opened forms of a radical cation have been characterized by ESR spectroscopy, and the 1,1,2,2-tetracyclopropane (TMCP) was found to be stable in the ring closed form at 77/sup 0/K but rearranged to the ring opened form at 110/sup 1/K in the CF/sub 2/ClCFCl/ sub 2/ matrix.
Abstract: Results of a study in which both the ring-closed and ring-opened forms of a radical cation have been characterized by ESR spectroscopy are reported. The 1,1,2,2-tetracyclopropane (TMCP) radical cation was found to be stable in the ring-closed form at 77/sup 0/K but rearranged to the ring-opened form at 110/sup 0/K in the CF/sub 2/ClCFCl/sub 2/ matrix. The cation generated by radiolysis consisted of 15 almost evenly spaced components with a superimposed fine structure on at least 11 of these lines.

Journal ArticleDOI
TL;DR: Etude des spectres IR et Raman des composes cites dans 3 etats physiques differents as mentioned in this paper, i.e., IR and Raman, respectively.
Abstract: Etude des spectres IR et Raman des composes cites dans 3 etats physiques differents. Attribution des vibrations


Journal ArticleDOI
TL;DR: In this article, single crystal catalysts have been used to investigate the reaction of cyclopropane with hydrogen over clean and sulfided nickel surfaces, and significant differences in product formation rate are observed between the Ni(111 and the Ni (100) surfaces.
Abstract: Single crystal catalysts have been used to investigate the reaction of cyclopropane with hydrogen over clean and sulfided nickel surfaces. The apparatus used in these studies allows for catalyst preparation and surface characterization in ultrahigh vacuum (UHV) with an in vacuo transfer to a second UHV chamber designed for kinetics at elevated pressures. Kinetic studies on single crystals of nickel show the hydrogenolysis of cyclopropane to methane and ethane to be structure sensitive. Significant differences in product formation rate is observed between the Ni(111) and the Ni(100) surfaces. The open (100) surface demonstrates a much higher activity toward breaking carbon–carbon bonds than does the (111) surface. The sulfiding of both the Ni(111) and the Ni(100) surfaces significantly poisons the ability of both surfaces to cleave carbon–carbon bonds whereas the hydrogenation reaction to propane is only moderately attenuated.

Journal ArticleDOI
TL;DR: In this article, achimiques du bromo-7 norcarane avec les diphenylphosphure, Diphenylarseniure, and oxo-2 propanure are presented.
Abstract: Reactions photochimiques du bromo-7 norcarane avec les diphenylphosphure, diphenylarseniure et oxo-2 propanure




Journal ArticleDOI
TL;DR: The title reaction of 1-carbonyl substituted cyclopropanecarboxylates proceeds under C(1)-C(2) bond cleavage to produce γ-lactones as discussed by the authors.
Abstract: The title reaction of 1-carbonyl substituted cyclopropanecarboxylates proceeds under C(1)–C(2) bond cleavage to produce γ-lactones. Stereochemically, the reaction takes two pathways: (1) substrates with a cationstabilizing group like vinyl on C(2) give thermodynamically favored γ-lactones having the thermodynamically more stable arrangement of substituents irrespective of the configuration of the cyclopropane substrates, (2) substrates without such a cation-stabilizing group afford γ-lactones under ca. 70% inversion at C(2) reaction center.

Journal ArticleDOI
TL;DR: In this paper, the equilibrium geometries of the propane cation in its three lowest electronic states, 2B1, 2b2 and 2A1(C2v symmetry assumed), have been calculated by the UHF method within the ab initio MO-LCAO-SCF approximation.
Abstract: The equilibrium geometries of the propane cation in its three lowest electronic states, 2B1, 2B2 and 2A1(C2v symmetry assumed), have been calculated by the UHF method within the ab initio MO-LCAO-SCF approximation. The 2B1 state is predicted to be lowest in energy and the 2B2 and 2A1 states to be of almost the same energy, 12 kcal mol–1 above the 2B1 state. The isotropic hyperfine coupling constants have been calculated and compared with experimental data. The calculations confirm the e.s.r. identification of the 2B1 state, obtained in an SF6 matrix. The previous experimental assignment, 2B2, for the state obtained in Freon matrices was found to be ambiguous and an assignment to the 2A1 state can not be ruled out. Dipolar hyperfine coupling constants have been calculated for the 2B1, 2B2 and 2A1 states of the propane cation and for the 2A1 ground state of the cyclopropane cation. In the latter case, comparison with experimental data has been made with reasonable agreement. The equilibrium geometry agrees well with previous calculations. Complementary experimental data for the propane and cyclopropane cations are reported.


Journal ArticleDOI
TL;DR: In this article, it was shown that the probability of rearrangement in the complex is greater, the greater the dipole moment of the M species, since a larger dipole moments is associated with a deeper well depth for the ion/molecule complex, and hence, a lower energy for the transition state complex.

Journal ArticleDOI
TL;DR: In this article, the structure of cristalline has been studied and the preconditioning of reactions successively de [(η 2 -N-trimethyl-2,2 butenyl-3 amino) (p-tolyl) carbene]-W(O) dont on etudie la structure cristaline
Abstract: Preparation par reactions successives de [(η 2 -N-trimethyl-2,2 butenyl-3 amino) (p-tolyl) carbene]-W(O) dont on etudie la structure cristalline

Journal ArticleDOI
TL;DR: In this paper, electron drift velocities were measured over much larger temperature ranges than previously, and cyclopropane and ethene showed a Ramsauer-Townsend minimum of 0.08 eV and 0.07 eV, respectively.
Abstract: To check whether ethene and cyclopropane display a Ramsauer–Townsend minimum in their electron momentum transfer cross sections, electron drift velocities were measured over much larger temperature ranges than previously. Ethene: 130≤T(K)≤647, 0.25≲n(1025 molecule/m3)≲3.0. Cyclopropane: 185≤T(K)≤644, 0.13≲n(1025 molecule/m3)≲18. At 294 K vd at a given E/n was independent of n up to the highest n used. In both gases vd increases linearly with E/n up to ∼0.3 Td, then tends towards saturation at ∼4 Td. In ethene vsat is ∼17 km/s, and is ∼35 km/s in cyclopropane. The value of vsat in alkanes correlates with the inverse polarizability. Ethene has a Ramsauer–Townsend minimum in its momentum transfer cross section at 0.08 eV, and cyclopropane has one at 0.07 eV.

Journal ArticleDOI
TL;DR: Etude des conformations preferentielles de l'(aminomethyl) cyclopropane avec l'espoir de determiner quelles forces sont responsables of ces choix de conformations as discussed by the authors.
Abstract: Etude des conformations preferentielles de l'(aminomethyl) cyclopropane avec l'espoir de determiner quelles forces sont responsables de ces choix de conformations

Journal ArticleDOI
TL;DR: In this article, the effectiveness of the use of bromotris(triphenylphosphine)-rhodium(I), Br(P(C6H5)3)3Rh, as a homogeneous hydrogenation catalyst was evaluated and compared with the analogous chloro- and iodo-complexes.
Abstract: Various concentrations of cyclopropene fatty acids have been determined down to 0.2% by the use of gas liquid chromatographic (GLC) analysis of the methyl esters of fatty acids that have been quantitatively hydrogenated using a homogeneous transition metal complex catalyst. The effectiveness of the use of bromotris(triphenylphosphine)-rhodium(I), Br(P(C6H5)3)3Rh, as a homogeneous hydrogenation catalyst to convert the cyclopropene ring to a cyclopropane ring has been evaluated and compared with the analogous chloro- and iodo-complexes. The hydrogenation/GLC method of analysis has been compared with the method of titration with hydrogen bromide in benzene and with the method involving the use of high resolution nuclear magnetic resonance (NMR).

Journal ArticleDOI
TL;DR: In this paper, the reaction between cyclopropane and hydrogen atoms has been investigated in the temperature range from 628 to 779 K at a total argon pressure between 5.3 and 13.2 Torr using a discharge-flow system with gas-chromatographic product analysis.
Abstract: The reaction between cyclopropane and hydrogen atoms has been investigated in the temperature range from 628 to 779 K at a total argon pressure between 5.3 and 13.2 Torr using a discharge-flow system with gas-chromatographic product analysis. The measured products, methane, ethane, ethene, propane and propene, are shown to be consistent with a mechanism [graphic omitted] Measurement of kw permits evaluation of the rate constant for the abstraction process log(k1/cm3 mol–1 s–1)=(13.6 ± 1.0)–(48.5 ± 13.0 kJ mol–1/2.3RT) which is similar to that for the corresponding reaction of methane on account of the almost identical C—H bond strengths in the molecules.A composite function of the rate constants for addition to the two positions in propene is evaluated. It is shown that the flow rate of hydrogen atoms as measured by our previously described ethene titration technique gives values which are consistently only 80% of those evaluated by summation of the products of reaction with cyclopropane.

Journal ArticleDOI
TL;DR: In this paper, a synthesis of 2-selenenyl and sulfenyl 4-oxoesters based on Lewis acid promoted activation of methyl 2-trimethylsiloxy cyclopropanecarboxylates is reported.