T:Toxic;
74-83-9Relevant articles and documents
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Glew,Moelwyn-Hughes
, p. 150,152 (1953)
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Cope
, p. 1342,1345 (1934)
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Effect of 1-Butanol upon SN2 Reactions in Cationic Micelles. A Quantitative Treatment
Bertoncini, Clelia R. A.,Nome, Faruk,Cerichelli, Giorgio,Bunton, Clifford A.
, p. 5875 - 5878 (1990)
Observed first-order rate constants for reaction of methyl naphthalene-2-sulfonate (2-MeONs) with Br- in cetyltrimethylammonium and cetyltriethylammonium bromides (CTABr and CTEABr) are decreased by addition of 1-butanol.The inhibition can be treated quantitatively in terms of a pseudophase model in which the rate constant at the micellar surface follows the mole ratio of bound Br- to micellized surfactant and bound 1-BuOH.The second-order rate constants in the micellar pseudophase, kM, are independent of in the range 0-0.9 M.Conductometry and NMR line widths of 81Br- show that the alcohol reduces micellar binding of Br-, and spectral absorbance shows that binding of 2-MeONs is also reduced.
Concentration and medium micellar kinetic effects caused by morphological transitions
Graciani, Maria Del Mar,Rodriguez, Amalia,Martin, Victoria Isabel,Fernandez, Gaspar,Moya, Maria Luisa
, p. 18659 - 18668 (2010)
The reaction methyl naphthalene-2-sulfonate + Br- was investigated in several alkanediyl-α-ω-bis(dodecyldimethylammonium) bromide, 12-s-12,2Br- (with s = 2, 3, 4, 5, 6, 8, 10, 12), micellar solutions in the absence and in the presence of various additives. The additives were 1,2-propylene glycol, which remains in the bulk phase, N-decyl N-methylglucamide, MEGA10, which forms mixed micelles with the dimeric surfactants, and 1-butanol, which distributes between the aqueous and micellar phases. Information about the micellar reaction media was obtained by using conductivity and fluorescence measurements. In all cases, with the exception of water-1,2-prop 12-5-12,2Br- micellar solutions, with 30% weight percentage of the organic solvent, a sphere-to-rod transition takes place upon increasing surfactant concentration. In order to quantitatively explain the experimental data within the whole surfactant concentration range, a kinetic equation based on the pseudophase kinetic model was considered, together with the decrease in the micellar ionization degree accompanying micellar growth. However, theoretical predictions did not agree with the experimental kinetic data for surfactant concentrations above the morphological transition. An empirical kinetic equation was proposed in order to explain the data. It contains a parameter b which is assumed to account for the medium micellar kinetic effects caused by the morphological transition. The use of this empirical equation permits the quantitative rationalization of the kinetic micellar effects in the whole surfactant concentration range.
An Activated TiC–SiC Composite for Natural Gas Upgrading via Catalytic Oxyhalogenation
Zichittella, Guido,Puértolas, Bego?a,Siol, Sebastian,Paunovi?, Vladimir,Mitchell, Sharon,Pérez-Ramírez, Javier
, p. 1282 - 1290 (2018)
Alkane oxyhalogenation has emerged as an attractive catalytic route for selective natural gas functionalization to important commodity chemicals, such as methyl halides or olefins. However, few systems have been shown to be active and selective in these reactions. Here, we identify a novel and highly efficient TiC–SiC composite for methane and ethane oxyhalogenation. Detailed characterization elucidates the kinetics and mechanism of the selective activation under reaction conditions to yield TiO2–TiC–SiC. This catalyst outperforms bulk TiO2, one of the best reported catalysts, reaching up to 85 % selectivity and up to 3 times higher titanium-specific space-time-yield of methyl halides or ethylene. This is attributed to the fact that the active TiO2 phase generated in situ is embedded in the thermally conductive SiC matrix, facilitating heat dissipation thus improving selectivity control.
Kinetic Study of CH3 + HBr and CH3 + Br Reactions by Laser Photolysis-Transient Absorption over 1-100 Bar Pressure Range
Krasnoperov, Lev N.,Mehta, Kashyap
, p. 8008 - 8020 (1999)
Reactions of methyl radicals with hydrogen bromide CH3 + HBr -> CH4 + Br (1) and bromine atoms CH3 + Br -> CH3Br (2) were studied using excimer laser photolysis-transient UV spectroscopy at 297 +/- 3 K over the 1-100 bar buffer gas (He) pressure range. Methyl radicals were produced by 193 nm (ArF) laser photolysis of acetone, (CH3)2CO, and methyl bromide, CH3Br. Temporal profiles of methyl radicals were monitored by UV absorption at 216.51 nm (copper hollow cathode lamp with current boosting). The yield of acetyl radicals in photolysis of acetone at 193 nm was found to be less than 5 percent at 100 bar He based on the transient absorptions at 222.57 and 224.42 nm. The measured rate constants for reaction 1 are k1 = (2.9 +/-0.7)E-12, (3.8 +/- 1.5)E-12, and (3.4 +/- 1.3)E-12 cm3 molecule-1 s-1 at the buffer gas (He) pressures of 1.05, 11.2, and 101 bar, respectively. The rate data obtained in this study confirmed high values of the previous (low pressure) measurements and ruled out the possibility of interference of excited species. The measured rate constant is independent of pressure within the experimental error. The rate constant of reaction of methyl radicals with bromine atoms (2) was determined relative to the rate constant of methyl radical self reaction, CH3 + CH3 -> C2H6 (3) in experiments with photolysis of CH3Br: k2/k3 = 0.92 +/- 0.32, 1.15 +/- 0.30, and 1.65 +/- 0.26 at 1.05, 11.2, and 101 bar He, respectively. On the basis of the literature data for reaction 3, this yields k2 = (5.8 +/- 2.2)E-11, (7.4 +/- 2.2)E-11, (10.7 +/- 2.3)E-11, and (11.9 +/- 2.5) E-11 cm3 molecule-1 s-1 at 1 .05, 1 1.2, 101 bar (He), and in the high-pressure limit, respectively.
Study of the bromide ion reaction with methyl naphthalene-2-sulfonate in water-DMSO TTAB micellar solutions
Moya, Maria Luisa,Rodriguez, Amalia,Munoz, Maria,Del Mar Graciani, Maria,Fernandez, Gaspar
, p. 676 - 682 (2006)
The reaction of bromide ions with methyl naphthalene-2-sulfonate (MeNS) has been investigated in water-dimethyl sulfoxide, DMSO, tetradecyltrimethylammonium bromide, TTAB, micellar solutions, with the weight percentage of DMSO up to 50%. In order to quantitatively rationalize the micellar kinetic effects observed, conductivity, surface tension, and steady-state fluorescence measurements were used to get information about the micellar reaction media. Results showed that changes caused by the addition of different amounts of DMSO to TTAB aqueous micellar solutions are made evident from the kinetic micellar effects, these being a helpful tool to obtain information on the micellar reaction media in the presence of the added organic solvent. Copyright
Kinetics of Reactions of Halogenated Methyl Radicals with Hydrogen Iodide
Seetula, Jorma A.,Gutman, David
, p. 3626 - 3630 (1991)
The kinetics of the reactions of CH2I, CH2Br, CH2Cl, and CHCl2 with HI were studied in a tubular reactor coupled to a photoionization mass spectrometer.Rate constants were measured as a function of temperature (typically between 294 and 552 K) to determine Arrhenius parameters.For these and other R + HI reactions studied to date (i.e., those involving aklyl radicals), a linear free energy relationship was dicovered which correlates the large differences in reactivity among all these R + HI reactions with the inductive effect of the substitutent atoms or groups on the central carbon atom.
Carbon-Supported Bimetallic Ruthenium-Iridium Catalysts for Selective and Stable Hydrodebromination of Dibromomethane
Bonchev, Hristo,Mitchell, Sharon,Pérez-Ramírez, Javier,Saadun, Ali J.
, (2021/12/09)
Catalysts based on individual precious metals on carbon- and oxide-based carriers have shown remarkably selective behavior in the hydrodebromination of CH2Br2 to CH3Br, an important transformation within halogen-mediated methane upgrading processes. However, the high susceptibility of the active phase to coking and to sintering, which cannot be overcome by controlling the nuclearity of the metal species, hinders their practical implementation. Herein, a platform of carbon-supported Ir?Ru catalysts with distinct metal ratios at comparable metal nanoparticle size (ca. 1.0 nm) was adopted to systematically study the effects of a second metal on reactivity and stability. Catalytic tests reveal ruthenium-doped iridium nanoparticles as the first system that combines high CH3Br selectivity (up to 93 %) with unprecedented stability, outperforming any of the previously reported catalysts. This superior performance was rationalized by the intimate interaction between the two metals, forming ruthenium-poor surface alloys, which enable suppressing deactivation mechanisms as well as over hydrogenation/coking pathways.
Functionalization of RhIII-Me Bonds: Use of capping Arene Ligands to Facilitate Me-X Reductive Elimination
Gu, Shunyan,Chen, Junqi,Musgrave, Charles B.,Gehman, Zo? M.,Habgood, Laurel G.,Jia, Xiaofan,Dickie, Diane A.,Goddard, William A.,Gunnoe, T. Brent
, p. 1889 - 1906 (2021/05/29)
We show how to improve the yield of MeX from CH4 activation catalysts from 12% to 90% through the use of capping arene ligands. Four (FP)RhIII(Me)(TFA)2 {FP = capping arene ligands, including 8,8′-(1,2-phenylene)diquinoline (6-FP), 8,8′-(1,2-naphthalene)diquinoline (6-NPFP), 1,2-bis(N-7-azaindolyl)benzene (5-FP), and 1,2-bis(N-7-azaindolyl)naphthalene (5-NPFP)} complexes. These complexes and (dpe)RhIII(Me)(TFA)2 (dpe = 1,2-di-2-pyridylethane) were synthesized and tested for their performance in reductive elimination of MeX (X = TFA or halide). The FP ligands were used with the goal of blocking a coordination site to destabilize the RhIII complexes and facilitate MeX reductive elimination. On the basis of single-crystal X-ray diffraction studies, the 6-FP and 6-NPFP ligated Rh complexes have Rh-arene distances shorter than those of the 5-FP and 5-NPFP Rh complexes; thus, it is expected that the Rh-arene interactions are weaker for the 5-FP complexes than for the 6-FP complexes. Consistent with our hypothesis, the 5-FP and 5-NPFP RhIII complexes demonstrate improved performance (from 12% to ～60% yield) in the reductive elimination of MeX. The reductive elimination of MeX from (FP)RhIII(Me)(TFA)2 can be further improved by the use of chemical oxidants. For example, the addition of 2 equiv of AgOTf leads to 87(2)% yield of MeTFA and can be achieved in CD3CN at 90 °C using (5-FP)Rh(Me)(TFA)2.
