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...     

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.     

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.     

Infrared spectra and rotational isomerization of 1-bromo-3-methyl-2-butene

Infrared spectra obtained for the title compound, (CH₃)₂CCH. CH₂Br, have revealed the co-existence of two rotational isomeric forms in the fluid phases, the geometrical structures of which cannot be ascertained by use of vibrational spectroscopy alone. The energy ditterence between the two isomers was found to be 1.1 kcal mol⁻¹ (mean value) in the liquid state. Some of the i.r. fundamental bands were assigned using the characteristic absorption frequencies of localized group.     

The process of producing 2-methyl-2-butene by positional isomerization on sulfocation exchangers

The results of determination of composition and strength of the granules of nitrogen-phosphoric fertilizers containing 1.5 to 5.0% of P₂O₅, obtained by interaction of the mineralized mass of the phosphorites of Central Kyzylkum with the 70–90% solutions of ammonium nitrate at 110°C, are presented.     

Product yields of stabilized Criegee intermediates in the ozonolysis reactions of cis-2-butene, 2-methyl-2-butene,cyclopentene, and cyclohexene

Cavity ring-down spectroscopy(CRDS)was utilized in combination with chemical titration with sulfur dioxide(SO_2)to quantify stabilized Criegee intermediates(s CIs)produced at low pressures(4–20 Torr)in ozonolysis reactions of cis-2-butene,2-methyl-2-butene,cyclopentene,and cyclohexene.The yield of stabilized s CI,acetaldehyde oxide(CH_3CHOO),from cis-2-butene ozonolysis decreased with decreasing pressure and reached to 0.05±0.04 at the zero-pressure limit.The nonsymmetric alkene 2-methyl-2-butene produced two stabilized s CIs,CH_3CHOO and acetone oxide((CH_3)_2COO),and their total yield decreased with decreasing pressure and reached 0.01±0.03 at the zero-pressure limit.For cyclopentene and cyclohexene,the s CI yields were essentially constant near zero,as expected of endocyclic alkenes.The nascent yields of s CI of various alkenes are compared.     

Polymerization of 3-methyl-1-butene promoted by metallocene catalysts

3-Methyl-1-butene was polymerized in the presence of a number of homogeneous metallocene catalysts (co-catalyst methylalumoxane). Contrary to literature reports, it was found that even the simplest C₂-symmetric metallocenes promote the isotactic polymerization of this monomer with reasonable productivities. Quite surprisingly, a prevailingly isotactic polymer was also obtained in the presence of C_s-symmetric metallocenes, which are instead syndiotactic-specific in propene polymerization.     

The mechanism of 2-methylbutene-2 hydrohalogenation in solid phase

Complexes and reactions of 2-methylbutene-2 with hydrohalogen (HCl, HBr) have been studied in solid phase at 80–150 K. It has been found that 2-methylbutene-2 forms with HX complexes of 1:1 and 1:2 composition. Hydrohalogenation proceeds via the rearrangement of complex 2HX·C₅H₁₀ into complex of the addition product with HX. Kinetic equation depends on the reagents ratio. In excess of HX (1< HX:C₅H₁₀< 10) reaction can be described by the first order kinetic equation. If the ratio HX:C₅H₁₀ is more than 10, reaction is described by polychronous kinetic law. The effective activation energy of solid phase hydrohalogenation does not exceed 20 kJ/mole. The molecular mechanism of hydrohalogenation in solid phase has been proposed.     

Natural product chemistry. Part 158. Reactions of ethyl 4-hydroxy-1-methyl-3-quinolin-2(1H)-onecarboxylate with 1,4-dibromo-2-methyl-2-butene

Ethyl 4-hydroxy-1-methyl-3-quinolin-2(1H)-onecarboxylate ( 1 ) which is obtained conveniently by the condensation of N-methylisatoic anhydride with diethyl malonate [4], was reacted with 1,4-dibromo-2-methyl-butene ( 2 ) to give the main products 3 and 4 and the dimeric derivatives 5 and 6 .     

Ab initio studies of the allylic hydroxylation: DFT calculation on the reaction of 2-methyl-2-butene with selenium dioxide

The mechanism of the allylic oxidation of 2-methyl-2-butene with selenium dioxide has been investigated by ab initio quantum mechanics. Transition states for two major steps (an ene reaction and a [2,3]-sigmatropic rearrangement) of this reaction have been optimized by the B3LYP/6-311+G(d,p) method. A comparison of the energies of the transition states shows that the anti-endo and syn-endo approaches are the efficient routes in the ene reaction and the methyl (C4) group is sited in a pseudo-equatorial environment in cyclic transition states during the [2,3]-rearrangement. Calculations also show the kind of the terminal alkyl (C4) substituents may control (E)-selectivity in the formation of the allylic alcohols.     

Rate constants for the reaction of OH radicals with 2-methyl-2-butene over the temperature range 297–425 K

Absolute rate constants, k₂, for the reaction of OH radicals with 2-methyl-2-butene have been determined over the temperature range 297–425 K using a flash photolysis-resonance fluorescence technique. The Arrhenius expression obtained was k₂ = 3.6 × 10^?11 exp [(450 ± 400)/RT] cm³ molecule^?1 s^?1.