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.     

Reaction of stabilized Criegee intermediates from ozonolysis of limonene with sulfur dioxide: ab initio and DFT study

The mechanism of the reaction of the sulfur dioxide (SO(2)) with four stabilized Criegee intermediates (stabCI-CH(3)-OO, stabCI-OO, stabCIx-OO, and stabCH(2)OO) produced via the ozonolysis of limonene have been investigated using ab initio and DFT (density functional theory) methods. It has been shown that the intermediate adduct formed by the initiation of these reactions may be followed by two different reaction pathways such as H migration reaction to form carboxylic acids and rearrangement of oxygen to produce the sulfur trioxide (SO(3)) from the terminal oxygen of the COO group and SO(2). We found that the reaction of stabCI-OO and stabCH(2)OO with SO(2) can occur via both the aforementioned scenarios, whereas that of stabCI-CH(3)-OO and stabCIx-OO with SO(2) is limited to the second pathway only due to the absence of migrating H atoms. It has been shown that at the CCSD(T)/6-31G(d) + CF level of theory the activation energies of six reaction pathways are in the range of 14.18-22.59 kcal mol(-1), with the reaction between stabCIx-OO and SO(2) as the most favorable pathway of 14.18 kcal mol(-1) activation energy and that the reaction of stabCI-OO and stabCH(2)OO with SO(2) occurs mainly via the second reaction path. The thermochemical analysis of the reaction between SO(2) and stabilized Criegee intermediates indicates that the reaction of SO(2) and stabilized Criegee intermediates formed from the exocyclic primary ozonide decomposition is the main pathway of the SO(3) formation. This is likely to explain the large (~100%) difference in the production rate in the favor of the exocyclic compounds observed in recent experiments on the formation of H(2)SO(4) from exocyclic and endocyclic compounds.     

The reactions of the Criegee intermediate CH3 CHOO in the gas-phase ozonolysis of 2-butene isomers

Ozonolysis of cis- and trans-2-butene isomers were carried out in a 570 l spherical glass vessel in 730 torr synthetic air at 295 ± 3 K. The initial concentrations were 5 to 10 ppmv for the isomers and 2 to 5 ppmv for ozone. Quantitative yields were determined by FTIR spectroscopy for CH₃CHO, HCHO, CH₄, CH₃OH, CO, and CO₂. By means of computational subtraction of the spectral contribution of the identified products from the product spectra, residual spectra have been obtained. Formation of 2-butene ozonide, propene ozonide, and l-hydroperoxyethyl formate CH₃CH(OOH)(SINGLE BOND)O(SINGLE BOND)CH(O) have been identified in the residual spectra. These products have been shown to be formed in the reactions of the Criegee intermediate CH₃CHOO with CH₃CHO, HCHO, and HCOOH, respectively. Mechanistic implications and atmospheric relevance of these observations are discussed. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 461–468, 1997.     

Computational study of the reaction between biogenic stabilized Criegee intermediates and sulfuric acid

We have postulated a mechanism for the reaction of sulfuric acid with stabilized Criegee intermediates (sCIs). We have computed Gibbs free energies for the reaction of sulfuric acid with two biogenic sCIs and three smaller model species. We have also calculated Gibbs free energies for two competing sink reactions. Due to the large size of the biogenic sCIs, the computations have been performed at the relatively modest B3LYP/6-31G(d,p) and B3LYP/6-311+G(2d,p) levels. However, single-point RI-CC2/def2-QZVPP calculations for the (CH3)(2)COO model species are in good agreement with the B3LYP results. The reaction is found to be strongly exothermic for all studied species. Activation barrier calculations on the (CH3)(2)COO model species further indicate that the reaction with sulfuric acid may proceed significantly faster than the sink reaction with water. If the same applies to the biogenic sCIs, the proposed reactions could account for some part of the organically assisted new particle formation events observed in the atmosphere.     

在氯化亚锡存在下2,3-二甲基-2-丁烯与乙酐的催化酰化反应

一种新的催化剂,SnCl2·2H2O,已用于2,3-二甲基-2-丁烯与乙酐的酰化反应来制备高产率的3,3,4-三甲基-4-戊烯-2-酮 (TMP). 发现SnCl2·2H2O是室温下2,3-二甲基-2-丁烯与乙酐进行酰化反应的有效催化剂. 考察了催化剂用量、乙酐用量、反应时间和溶剂的加入等因素对该酰化反应的影响. 发现当催化剂/2,3-二甲基-2-丁烯摩尔比在0.30/1和 0.60/1之间、反应时间为2 h时,所得酰化产品的产率最高. 该酰化反应进行到完全所需的时间取决于催化剂用量和乙酐用量. 在需要加入溶剂的情况下,二氯甲烷或氯仿是一种合适的溶剂.     

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.     

在H3PO4存在下2,3-二甲基-2-丁烯与乙酐的酰化反应

在H3PO4存在下进行了2，3－二甲基－2－丁烯与乙酐的酰化反应，结果表明，H3PO4是室温下催化2，3－二甲基－2－丁烯与乙酐酰化反应的有效催化剂，在H3PO4存在下，酰化产物的收率主要取决于：（a)H3PO4的用量，（b)乙酐的用量；（c)反应温度和（d)反应时间，在适宜反应条件下，所得3，3，4－三甲基－4－戊烯－2－酮（TMP）约为99％，另外还发现，反应体系中加入少量乙酸，不会明显减少酰化产物的收率，乙酐的纯度，反应物的加入顺序对该反应几乎没有任何影响，在有和没有溶剂CH2Cl2的条件下所得酰化产物的收率是可比的。     

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.     

Linear-reactor-infrared-matrix and microwave spectroscopy of the cis-2-butene gas-phase ozonolysis

Investigation of the formation of complex products in the gas-phase ozonolysis of cis,-2-butene by linear-reactor-infrared-matrix and linear-reactor-microwave spectroscopy is reported. The following species have been unequivocally detected: secondary 2-butene ozonide, acetic acid, peracetic acid, glycolaldehyde, dimethyl ketene, the simple and mixed anhydrides of formic and acetic acid, 2,3-epoxybutane and 2-butanone, besides polyatomic products already known. In contrast, the primary ozonide has been detectable neither by LR.-MW. nor by LR.-IR. Observation of both stereoisomeric epoxides and kinetic modelling are used to support the intermediate formation of the O'Neal-Blumstein radical CH₃CH(O₂)CH(O)CH₃ and the existence of a reaction channel in which the two carbon atoms of the C, C double bond of the olefin remain connected. As the dominant reaction path a mechanism with a Criegee type split into methyldioxirane (ethylidene peroxide) and acetaldehyde is considered and subsequently proposed to explain formation of many complex products by either unimolecular or bimolecular processes of the peroxide. For the reactions considered, thermochemical estimates of reaction enthalpies and activation data are included. Kinetic modelling for a partial reaction mechanism involving at least two different paths of decay of the O'Neal-Blumstein biradical into Criegee-type intermediates and the 2, 3-epoxybutanes is discussed.     

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.     

Exciplex and radical ion intermediates in the photochemical reaction of 9-cyanophenanthrene with 2,3-dimethyl-2-butene

The photochemical reaction of 9-cyanophenanthrene and 2,3-dimethyl-2-butene, first reported by Mizuno, Pac and Sakurai, has been reinvestigated. The formation of a [2+2]-cycloadduct via a singlet exciplex is the exclusive reaction in the nonpolar solvents benzene and ethyl acetate. Photochemical behavior in polar solvents is far more complicated than previously reported. Mechanisms consistent with the effects of solvent polarity, methanol concentration, methanol deuteration, and light intensity upon product yields are proposed. Formation of a 9-cyanophenthrene anion radical and 2,3-dimethyl-2-butene cation radical is the primary photoinitiated process in polar solvent. The cation radical can undergo deprotonation to yield an allyl radical or nucleophilic attack by methanol to yield a methoxyalkyl radical. Covalent bonding of these radicals and the 9-cyanophenanthrene anion radical gives rise to the acyclic adducts obtained in polar solvents. The anion radical can also be protonated, leading ultimately to the formation of 9,10-dihydro-9-cyanophenanthrene.     

2,3-二甲基-2-丁烯酰化合成3,3,4-三甲基-4-戊烯-2-酮的负载ZnCl2固体催化剂

研究了负载ZnCl2的固体催化剂在2，3-二甲基-2-丁烯与乙酐酰化合成3，3，4-三甲基-4-戊烯-2-酮反应中的催化活性。结果表明，K10粘土是最好的载体，但是HY沸石、Synclyst S13(一种无定型的酸性固体)、硅胶和氧化铝也都是制备负载ZnCl2的固体催化剂的有效载体。ZnCl2的负载量和改性方法都影响负载ZnCl2的固体催化剂的催化活性。     

Synthesis of 1,4-Bis(dimethylamino)-2,3-dibromo-2-butene and Its Quaternary Derivatives

Alkylation of 1,4-bis(dimethylamino)-2,3-dibromo-2-butene yielded its previously inaccessible quaternary analogs.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 5, 2005, pp. 768–770.Original Russian Text Copyright © 2005 by Saakyan, Gyul’nazaryan, Markaryan, Kocharyan, Panosyan, Karapetyan.     

ESR study of pressure and temperature dependence of free-radical decay in poly(vinyl chloride)

Gamma-irradiated poly(vinyl chloride) was annealed at various temperatures (80 to 140°C) and pressures (0.1 to 800 MN m^?2). Rate constants and activation volumes of free-radical decay were determined from the changes of the electron spin resonance (ESR) spectra before and after annealing. The pressure and temperature dependence of the rate constant is compared with the pressure and temperature dependence of the mechanical relaxation parameters. The correlation between the kinetics of radical reactions and the kinetics of the molecular motions in the α-relaxation region is discussed.     

Lifetime and quenching rate constants for a flourescent excited state of tetramethylethylene (2,3-dimethyl-2-butene)

The collisionless lifetime of a flourescent excited state of tetramethylethylene (TME) vapor when excited at 235 nm is 20.8±0.9 ns and the self-quenching rate constant is (2.97±0.01) × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹. The rate constants for quenching of TME vapor by O₂, benzene. CCl₄, Xe, N₂ and CH₄ are also repeated. In the vapor phase, the lifetime strongly depends on the excitation energy. The lifetime of liquid TME is 10±2 ns at 25±2°C.     

Synthesis and Structure of 2,3-Bis(5-tert-butyl-2-methoxyphenyl)buta-1,3-diene by Bromine Elimination of (Z)-1,4-Dibromo-2,3-bis(5-tert-butyl-2-methoxyphenyl)-2-butene

2,3-Bis(5-tert-butyl-2-methoxyphenyl)buta-1,3-diene was prepared by bromination of (Z)- and (E)-2,3-bis(5-tert-butyl-2-methoxyphenyl)-2-butene followed by treatment with zinc powder in a mixture of CH₂Cl₂ and acetic acid, which was converted to the corresponding o-terphenyl skeleton by the condensation with dimethyl acetylenedicarboxylate followed by oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone.     

萘甲腈和2,3-二甲基丁烯-2-光环加成反应:三氟醋酸的效应

在低转光解情况下,1-萘甲腈(1-NpCN)和2,3-二甲基丁烯-2(DMB)在环已烷或苯中的光环加成反应主要得到环丁烷3,但2-NpCN主要得到氨杂环丁烯6和少量的环丁烷5,三氟醋酸(TFA)量增加抑制1-NpCN和DMB的光环加成反应,表明TFA与基态及单激发态1-NpCN生成非光反应的复合物,它也淬灭^*(1-NpCN-DMB)激基复合物.在低浓度范围(0.1M以下)TFA加速2-NpCN和DMB光环加成反应,但在高浓度范围(大于0.1M)时又抑制反应.这些结果被解析如下:^*(2-NpCN-DMB)激基复合物和TFA反应增加5和6的得率,反之,是由于生成非光反应的基态复合物及淬灭单激发态2-NpCN.在非极性溶剂中二种单激发态萘甲腈生成TFA激基复合物的萤光与母体^*NpCN萤光区域几乎相同.     

2,3-二甲基-4-(2,2,2-三氟乙氧基)吡啶-1-氧化物的合成

以2,3-二甲基-4-硝基吡啶-1-氧化物为原料,合成兰索拉唑中间体2,3-二甲基-4-(2,2,2-三氟乙氧基)吡啶-1-氧化物（2）,其结构经¹H NMR确证。研究了溶剂、催化剂、碱和反应时间等因素对2收率的影响。结果表明：在最优反应条件(乙腈作溶剂,三氟乙醇2.0 eq.,碳酸钾2.5 eq.,在1 mol%TBAB水溶液中反应10 h)下,2收率超过85%。将实验规模放大到100 g级,工艺稳定。