Temperature dependence of the rate constants of the reactions of oxygen atoms with trans-2-butene,cis-2-butene, 2-methylpropene, 2-methyl-2-butene,and 2,3-dimethyl-2-butene

The kinetics of the reactions of ground state oxygen atoms with trans-2-butene, cis-2-butene, 2-methylpropene, 2-methyl-2-butene, and 2,3-dimethyl-2-butene was investigated in the temperature range 200 to 370K. In this range, the rate constants are (in units 10^?11 cm³ s^?1): (1.1 ± 0.1) exp[+(180 ± 24)K/T]; (0.98 ± 0.09) exp[+(149 ± 23)K/T]; (1.14 ± 0.13) exp[+(128 ± 33)K/T]; (2.34 ± 0.16) exp[+(250 ± 16)K/T]; and (3.31 ± 0.50) exp[+(257 ± 36)K/T], respectively. The atoms were generated by the H₂ laser photolysis of NO and detected by the time resolved chemiluminescence in the presence of NO. The concentrations of the O(³P) atoms were kept so low that secondary reactions with products are unimportant. © 1995 John Wiley & Sons, Inc.     

Solid-phase hydrohalogenation of 2-methyl-2-butene

Complex formation between 2-methyl-2-butene and hydrogen halides (HX, X=Cl, Br) and the hydrohalogenation reaction was studied in the solid phase in the range of 80–150°K by IR spectroscopy. It was shown that 2-methyl-2-butene forms 11 and 12 complexes with HX. The hydrohalogenation reaction is realized by rearrangement of the 12 complex into a complex of the hydrohalogenation product with HX. The kinetics of the transformation depend on the ratio of the reagents. With an excess of the olefin the reaction is described by a kinetic equation of first order with respect to the complex of the initial reagents up to 60–80% conversion; with an excess of HX it is described by an equation of polychronous kinetics. The effective activation energy of the solid-phase halogenation of 2-methyl-2-butene is not greater than 20 kJ/mole. A molecular mechanism of addition to olefins in the solid phase is examined.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 1, pp. 34–40, January–February, 1987.     

Vapour–liquid equilibrium for the ethyl ethanoate + 1-butene, +cis-2-butene, +trans-2-butene, +2-methylpropene, +n-butane and +2-methylpropane

Isothermal vapour–liquid equilibrium was measured for ethyl ethanoate + 1-butene, +cis-2-butene, +trans-2-butene, +2-methylpropene, +n-butane and +2-methylpropane at 318.4 K with an automated static total pressure measurement apparatus. The experimental data was correlated with the Wilson activity coefficient model. A good agreement between the experiments and the model was achieved. All six binary systems exhibited positive deviation from Raoult's law.     

Vibrational assignment and rotational isomerism of 2-chloro-1-butene and 2-bromo-1-butene

Infrared spectra were obtained for 2-chloro-l-butene and 2-bromo-l-butene that show the presence of trans and gauche rotamers in both compounds. Vibrational assignments were made with the aid of normal coordinate calculations that utilized a thirty-eight parameter valence force field.     

在Pt/Al2O3催化剂上丁烷及顺、反-2-丁烯深度氧化催化剂的有效因子

用玻璃外循环无梯度反应器研究在Pt/Al₂O₃催化剂上丁烷、反-2-丁烯及顺-2-丁烯深度氧化的内扩散影响.测出催化剂有效因子η为0.42～1.27,并随反应温度升高而下降.用Runge-Kutta法计算氧在催化剂孔内压力分布,孔中心氧分压y₀随内扩散影响加大而下降,在420℃y₀如趋于零.     

2-甲基-2-丁烯乳液氯化反应的研究

研究了温度、时间、紫外光照射等对天然胶乳小分子模型物(2-甲基-2-丁烯乳液)氯化反应的影响,结果表明,在有紫外光照的条件下的氯化反应速率要快于无紫外光照的;温度对氯化反应有着一定影响,在50℃以下,随温度升高产物的氯含量越高,在50℃以上,对产物的氯含量的影响不大;当温度50℃,时间达到7个小时的产物的氯含量能达到6...     

Photodissociation of 1-bromo-2-butene, 4-bromo-1-butene, and cyclopropylmethyl bromide at 234 nm studied using velocity map imaging

We present photofragment imaging experiments to characterize potential photolytic precursors of three C4H7 radical isomers: 1-methylallyl, cyclopropylmethyl, and 3-buten-1-yl radicals. The experiments use 2+1 resonance enhanced multiphoton ionization (REMPI) with velocity map imaging to state-selectively detect the Br(2P(3/2)) and Br(2P(1/2)) atoms as a function of their recoil velocity imparted upon photodissociation of 1-bromo-2-butene, cyclopropylmethyl bromide, and 4-bromo-1-butene at 234 nm as well as the angular distributions of the photofragments. Energy and momentum conservation allows the internal energy distribution of the nascent momentum-matched radicals to be derived. The radicals are detected with single photon photoionization at 157 nm. In the case of the 1-methylallyl radical the photoionization cross section is expected to be independent of internal energy in the range of 7-30 kcal/mol. Thus, comparison of the product recoil kinetic energy distribution derived from the measurement of the 1-methylallyl velocity distribution, detecting the radicals with 157 nm photoionization, with a linear combination of the Br atom recoil kinetic energy distributions allows us to derive reliable REMPI line strength ratios for the detection of Br atoms and to test the assumption that the photoionization cross section does not strongly depend on the internal energy of the radical. This line strength ratio is then used to determine the branching to the Br(2P(3/2)) and Br(2P(1/2)) product channels for the other two photolytic systems and to determine the internal energy distribution of their momentum-matched radicals. (We also revisit earlier work on the photodissociation of cyclobutyl bromide which detected the Br atoms and momentum-matched cyclobutyl radicals.) This allows us to test whether the 157 nm photoionization of these radicals is insensitive to internal energy for the distribution of total internal (vibrational+rotational) energy produced. We find that 157 nm photoionization of cyclopropylmethyl radicals is relatively insensitive to internal energy, while 3-buten-1-yl radicals show a photoionization cross section that is markedly dependent on internal energy with the lowest internal energy radicals not efficiently detected by photoionization at 157 nm. We present electronic structure calculations of the radicals and their cations to understand the experimental results.     

High pressure isomerization of 1,4-bis(methylthio)hexafluoro-2-butene to-1-butene

The complete bond migration of the internal olefinic bond of trans-1,4-bis(methythio)hexafluoro-2-butene(I) under high pressure to the terminal olefinic bond to form cis- and trans-1,4-bis(methylthio)hexafluoro-1-butene(II) is described. The Teflon-lined high pressure cell maintains a constant pressure at 16,000 atm and 180 to 200°C for 24 hours. The cis- and trans-II are elucidated from gas chromatography-mass spectroscopy, which shows two identical parent ions at m/e value of 255(C₆H₆F₆S₂⁺), but at different elution times. The ¹⁹FNMR data of the isomeric products are summarized. Elemental analysis of II is verified by double focussing high resolution mass spectrometer.     

The Radiation Polymerization of 4-Methyl-1-pentene, 2-Methyl-1-butene,and 2,3-Dimethyl-1-butene under Conditions of Extreme Dryness

The γ-ray initiated polymerization of 4-methyl-1-pentene, 2-methyl-1-butene, and 2,3-dimethyl-1-butene has been studied under conditions of extreme dryness. Only low yields of oily low molecular weight polymers were obtained. It is suggested that the low propagation rate constants are responsible for the results obtained.     

Processes of synthesis of 1-butene from 2-butene by the positional isomerization on sulfocation exchangers

Obtaining of individual 1-butene and 2-butenes from the butane-butene fractions can be processed sufficiently effectively by combining positional isomerization of alkenes on the sulfocation exchanger catalysts and careful rectification. At 50–60°C is reached the equilibrium with the ratio of the sum of 2-butenes to 1-butene ～20:1. The relatively high-boiling 2-butenes are enough completely separated by rectification of 1-butene, and isobutane from the harmful impurities (butadiene and isobutene). The reverse isomerization of the purified 2-butene into 1-butene with the continuous distillation of the latter makes it possible to obtain pure 1-butene with a very low prime cost.     

Thiosulfonium ions. Methylthiolation of 3-methylthio-1-butene and cis- and trans-1-methylthio-2-butene

Whereas sulfenyl reagents commonly add to carbon double bonds, addition to sulfur of 3-methylthio-1-butene precedes attack at carbon to give allylic thiosulfonium ions that form reversibly and which rearrange rapidly to $\text{trans}$-2-butenyl analogs. Likewise, rearrangement of $\text{cis}$- to $\text{trans}$-1-methylthio-2-butene occurs by way of thiosulfonium ions.     

Polyethers. I. Polymerization of 2-methyl-2-butene oxide

2-Methyl-2-butene oxide (2,3-epoxy-2-methylbutane) was polymerized with modified alkylaluminum initiators a t low temperatures to a high-melting, crystalline, film-forming polymer. High yields and comparatively high molecular weights were obtained with Al(i-Bu)₃?xH₂O initiators in inert diluents. When such initiators were modified with acetylacetone they became ineffective. Ammonia could be substituted for water in formulating an active initiator. Attempts to prepare an active initiator in the presence of the monomer were unsuccessful indicsting competition with the water for Al(i-Bu)₃. Thermal decomposition of the polymer produced methyl isopropyl ketone with some pivaldehyde.     

Chiral anilines: development of C2-symmetric, late-transition metal catalysts for isoselective 2-butene polymerization

Chiral nickel catalysts were synthesized and used for the isoselective polymerization of trans-2-butene.     

Thermal isomerization of cis- or trans-2-butene. The unimolecular elimination of hydrogen from cis-2-butene around 500°C

An analytical and kinetic study of the thermal reaction of cis- or trans-2-butene has been performed in a static system over the temperature range of 480–550°C and at a low extent of reaction and initial pressures of 10–100 torr. The rate constant of the unimolecular cis–trans isomerization of cis-2-butene, determined under the conditions (2.3 RT in cal/mole) is in good agreement with previous measurements made at lower pressures. A comparison between the formation rates of hydrogen from the thermal reactions of cis- and trans-2 butene around 500°C leads to the rate constant value (2.3 RT in cal/mole) for the unimolecular 1,4? hydrogen elimination from cis? 2? butene.