F:Flammable;
540-54-5Relevant articles and documents
LASER-INITIATED FREE-RADICAL CHLORINATION OF PROPANE IN AMORPHOUS THIN FILMS: TEMPERATURE DEPENDENCE FROM 15 TO 77 K
Sedlacek, Arthur J.,Wight, Charles A.
, p. 2821 - 2824 (1988)
The free-radical chlorination of propane, deposited as a thin amorphous film, has been investigated at temperatures ranging from 15 to 77 K.Reactions are initiated by pulsed laser photolysis of chlorine molecules at 308 nm.Product yields and branching ration are characterized by Fourier transform infrared absorption spectroscopy.The inherent reactivity of chlorine atoms toward secondary versus primary hydrogens (when corrected for the greater number of primary sites) decreases from 17:1 at 77 K to 2.3:1 at 60 K and below.Over the same temperature range the quantum yield is observed to increase from 0.12+/-0.02 to 0.70+/-0.06.These results reflect the onset of translationally excited (hot) chlorine atom reactions.
Solute-solvent interactions in liquid noble gases as probed by the conformational equilibrium of some 1,2-disubstituted ethanes
Herrebout,Van der Veken
, p. 9671 - 9677 (1996)
Using variable-temperature infrared spectroscopy, the enthalpy difference between the trans and gauche conformers of 1-chloro-2-fluoroethane, 1,2-dichloroethane, and 1-chloropropane has been determined in the gas phase and in solutions of liquefied krypton and xenon. Using a simple reaction field model, the changes in the enthalpy difference between vapor phase and solution are quantitatively explained as the result of weak dipole-induced dipole interactions appearing between the solute molecules and the surrounding noble gas atoms.
Chlorine Atom/Benzene System. 1. The Role of the 6-Chlorocyclohexadienyl Radical
Skell, Philip S.,Baxter, Harry N.,Tanko, James M.,Chebolu, Venkatasuryanarayana
, p. 6300 - 6311 (1986)
The concept of radical reactivity mediated by solvation has rested mainly on the alteration of Cl. properties by aromatic solvents.For this reason, the full scope of the benzene/Cl. system has been reexamined to evaluate the discription of that system based largely on a ?-complex (solvation).At the present time, the ?-complex description rests narrowly on the assignment of a 490-nm absorption, which, even if correct, could not provide an unambiguous structure assignment.Results are presenteed which described the selectivities in alkane substitutions as a function of the concentrations of both benzene and the alkane.Selectivities increase with decreasing alkane concentrations, reaching a plateau below 0.1 M alkane.The change in selectivity is the result of variable contributions of both a low- and a high-selectivity intermediate, LSI and HSI, respectively.The observed selectivity at a given and is the consequence of a unique / ratio.A range of substrates and their effect of DMB selectivity were studied, and from these results details regarding the chemistry of the HSI were extracted.Several features of the LSI/HSI equilibrating system are realized. (1) Reaction of alkyl radicals with Cl2 in benzene produces the LSI, (2) the LSI does not exhibit the characteristics of free chlorine atom, and (3) at alkane concentrations and , added reagents (T) which react with CCH, such as maleic anhydride (MA) or Cl2, bring about an increase in the LSI/HSI ratio.Low-selectivity hydrogen abstractions (LSI function) are best ascribed to a mixture of chlorine atom and chlorine atom/benzene ?-complex.The chemistry of CCH is as follows: (1) loss of the ipso H to O2 yielding PhCl and HO2., (2) reactions of Cl2 or (3) maleic anhydride with the aromatic nucleus of CCH resulting in additions to the ring, (4) the transfer of Cl to alkenes, and (5) the highly selective retardation of rates of reaction with alkanes producing alkyl radicals, HCl, and benzene.The results of a kinetic analysis, accounting for the effect of , , and CCH trapping agents (T), are presented.For CCH, the following reactivity order is established: maleic anhydride (6) > trans-dichloroethene(5) > 2,3-dimethylbutane (2) > pentane (1) > Cl2 > neopentane ( 2 (27) > 1 .These properties can be rationalized with canonical structures for CCH wherein spin density at carbon, chlorine, and the ipso hydrogen makes contributions to the hybrid.
Formation of C3H6 from the reaction C3H7 + O2 between 450 and 550 K
Kaiser
, p. 5903 - 5906 (1998)
The generation of C3H6 from the reaction C3H7 + O2 (1) has been investigated as a function both of temperature (450-550 K) at constant density (5.5 × 1018 molecules/cm3) and of pressure (55-550 Torr) at 490 K. The experiments were carried out by UV irradiation of mixtures of C3H8, Cl2, and O2 to generate propyl radicals. C3H8, C3H6, and C3H7Cl were monitored by gas chromatographic analysis. The propylene yield is 0.7% at 450 K. Based on these measurements and previous data at 298 K, the propylene yield has an apparent activation energy which is less than 2.5 kcal mol-1 below 450 K. Beginning near 450 K, the yield increases rapidly with an apparent activation energy of ～32 kcal mol-1, similar to previous observations on the generation of C2H4 from the reaction C2H5 + O2. At 490 K, the propylene yield from reaction 1 depends inversely on total pressure (YC3H6 ∝ P -0.6) between 55 and 550 Torr, while the overall value of k1 has a much smaller pressure dependence (P0.18). These observations show that above 450 K propylene is formed via reaction 1 through an excited propylperoxy adduct which can be stabilized by collision as was observed at 298 K.
Free radical chlorination of alkanes in supercritical carbon dioxide: The chlorine atom cage effect as a probe for enhanced cage effects in supercritical fluid solvents
Fletcher, Beth,Suleman, N. Kamrudin,Tanko
, p. 11839 - 11844 (1998)
The chlorine atom cage effect was used as a highly sensitive probe for studying the effect of viscosity and the possible role of solvent clusters on cage lifetimes and reactivity for reactions carried out in supercritical fluid solvents. These experiments were conducted in supercritical carbon dioxide (SC-CO2, 40 °C, at various pressures) with parallel experiments in conventional solvents and in the gas phase. The results of these experiments provide no indication of an enhanced cage effect near the critical point in SC-CO2 solvent. The magnitude of the cage effect observed in SC-CO2 at all pressures examined is well within what is anticipated on the basis of extrapolations from conventional solvents.
Controlling the Lewis Acidity and Polymerizing Effectively Prevent Frustrated Lewis Pairs from Deactivation in the Hydrogenation of Terminal Alkynes
Geng, Jiao,Hu, Xingbang,Liu, Qiang,Wu, Youting,Yang, Liu,Yao, Chenfei
, p. 3685 - 3690 (2021/05/31)
Two strategies were reported to prevent the deactivation of Frustrated Lewis pairs (FLPs) in the hydrogenation of terminal alkynes: reducing the Lewis acidity and polymerizing the Lewis acid. A polymeric Lewis acid (P-BPh3) with high stability was designed and synthesized. Excellent conversion (up to 99%) and selectivity can be achieved in the hydrogenation of terminal alkynes catalyzed by P-BPh3. This catalytic system works quite well for different substrates. In addition, the P-BPh3 can be easily recycled.
Iron-Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers
Biberger, Tobias,Makai, Szabolcs,Lian, Zhong,Morandi, Bill
supporting information, p. 6940 - 6944 (2018/05/14)
Among all metathesis reactions known to date in organic chemistry, the metathesis of multiple bonds such as alkenes and alkynes has evolved into one of the most powerful methods to construct molecular complexity. In contrast, metathesis reactions involving single bonds are scarce and far less developed, particularly in the context of synthetically valuable ring-closing reactions. Herein, we report an iron-catalyzed ring-closing metathesis of aliphatic ethers for the synthesis of substituted tetrahydropyrans and tetrahydrofurans, as well as morpholines and polycyclic ethers. This transformation is enabled by a simple iron catalyst and likely proceeds via cyclic oxonium intermediates.
Facile one-step synthesis of palladium tellurium alloy nanorods
Mariappan, Kadarkaraisamy,Varapragasam, Shelton J.P.,Hansen, Matthew R.,Rasalingam, Shivatharsiny,Alaparthi, Madhubabu,Sykes, Andrew G.
, p. 251 - 256 (2018/05/23)
A palladium-tellurium binary alloy nanomaterial was synthesized by a one-pot reaction of bis(4-methoxyphenyltelluro)methane [(4-CH3O-C6H4Te)2CH2](1) and allylpalladium (II)chloride dimer [(η3-C3H5)2Pd2(μ-Cl2)] (2) in 1:1 ratio using methylene chloride as solvent at ambient conditions. In addition to the Pd20Te7 alloy nanomaterial (3) generated, a palliadum (II) tellurolate complex [PdC1(μ-TeC6H4-OCH3)Te(C6H4-OCH3)2]2 (6), and other organic and organotellurim compounds were isolated as byproducts using column chromatography. The palladium-tellurium binary alloy nanomaterial and other byproducts from the reaction were characterized by powder X-ray diffraction (PXRD), NMR, GC-MS, transmission electron microscopy (TEM), and single crystal X-ray diffractions (XRD) methods. The palladium-tellurium binary alloy nanomaterial was obtained as single-phase Pd20Te7 nanorods, under mild conditions. TEM results indicated that the nanorods are less than 15 nm in diameter and range from 40 to 200 nm in length. A nanomaterial mixture was isolated with two binary-phases Pd20Te7 and Pd10Te3 when benzene was used as solvent. Compound 6 was successfully tested for catalytic activity for the Heck Reaction and produced a mixture of PdTe2 with Pd13Te3 nanomaterials as byproducts.
Catalytic Olefin Hydrosilations Mediated by Ruthenium η3-H2Si σ Complexes of Primary and Secondary Silanes
Lipke, Mark C.,Poradowski, Marie-Noelle,Raynaud, Christophe,Eisenstein, Odile,Tilley, T. Don
, p. 11513 - 11523 (2018/11/23)
Unambiguous examples of η3-H2SiH(R) complexes featuring a terminal Si-H bond have been prepared and examined as possible intermediates in olefin hydrosilation. These species were generated by displacement of the secondary silane ligands in [PhBPPh3]RuH[η3-H2SiMePh] (1b) (PhBPPh3 = PhB(CH2PPh2)3- by primary silanes RSiH3 to generate [PhBPPh3]RuH[η3-H2SiH(R)] (R = Cy (1d), CH2CH2Ph (1e), Trip = 2,4,6-iPr3C6H2 (1f)). Complexes 1d and 1e were characterized in solution, whereas 1f was isolated and studied in detail. Complex 1b is not a competent precatalyst for the hydrosilation of 1-hexene with CySiH3, whereas comparable conditions gave reasonable yields for the selective anti-Markovnikov hydrosilations of Cl3SiCH2CH=CH2 (89%), p-chlorostyrene (73%), and allyl chloride (70%). The 1H NMR spectrum of 1f collected at -30 °C displays a downfield signal (δ = 8.26 ppm) for the terminal Si-H bond that suggests electronic similarities between 1f and cationic silylene dihydrides [Cp?(iPr3P)Ru(H)2=SiH(R)]+ that mediate olefin hydrosilations via the direct insertion of the C=C bond into the terminal Si-H bond. However, further mechanistic considerations, including results on the hydrosilation of p-chlorostyrene with the secondary silane Et2SiH2 and [PhBPPh3]RuH[η3-H2SiEt2] (1a) as the catalyst, indicate that an insertion mechanism involving a Ru-H (rather than a Si-H) group is possible. DFT investigations of the hydrosilation of several olefins with CySiH3 using 1d as the catalyst reveal a preferred pathway involving olefin insertion into a Ru-H bond followed by migration of the resulting alkyl group to the silicon atom of an η3-H2SiH(Cy) ligand. The latter process occurs via an unusual transition state in which a Ru-H-Si linkage acts as a pivot point to facilitate a Si-H bond cleavage/Si-C bond formation step that is otherwise similar to those involving the kite-shaped four-center transition states of σ-bond metathesis. Direct insertion into the Si-H bond is the next lowest accessible pathway.
Propane chlorination over ruthenium oxychloride catalysts
Testova,Shalygin,Maksimov,Paukshtis,Parmon
, p. 428 - 433 (2015/08/04)
The gas-phase chlorination of propane over different catalysts, including those containing ruthenium oxychlorides as the active component, has been investigated. The propylene and chlorine-containing product formation selectivities in propane chlorination at 150-450°C in a fixed-bed flow reactor have been determined.
