四氯化碳制备二氯卡宾反应机理的理论研究

四氯化碳制备二氯卡宾反应机理的理论研究李来才（四川师范大学化学系成都６１００６６）关键词四氯化碳反应途径过滤态ＭＮＤＯ方法中图分类号Ｏ６２１．１４６二氯卡宾是有机合成中一个重要的试剂。目前制备二氯卡宾的方法有多种［１－３］，但Ｍａｋｃ－ｓｚａ［４］报...     

Reaction of Some Alkenols with Tetrachloromethane

Summary.  The reaction of some alkenols with tetrachloromethane in the presence of a radical initiator was investigated. Regarding the effects of structural features of the starting alkenol (number and position of methyl substituents at the double bond and at the carbinol carbon atom, constitutional relationship between the double bond and the hydroxyl group) there are two possible competing reactions: addition and cyclization. In the case of the simplest alkenols (without substituents and with a more remote double bond) addition occurs; mono- and disubstituted secondary and tertiary Δ⁴- and Δ⁵-alkenols cyclize in high yields to give the corresponding cyclic ethers. Received March 17, 2000. Accepted (revised) May 31, 2000     

某些Lewis碱与CCl4和CHCl3在298.15K的过量体积

在298.15 K下用连续稀释膨胀计或振动管密度计测量了二甲基甲酰胺(DMF)、二甲基乙酰胺(DMA)、N-甲基吡咯烷酮(NMP)、γ-丁内酯(γ-BL)、二甲基亚砜(DMSO)分别与四氯化碳和三氯甲烷构成的二元系的过量体积。除DMSO+CHCl_2二元系的V~(E-x)曲线为S形外, 其余二元系的V~E值均为负值。在所研究的两个系列中, |V_(min)~E|的大小顺序均为: NMP>γ-BL>DMF≈DMA>DMSO     

Si-C coupling reaction of polychloromethanes with HSiCl3 in the presence of Bu4PCl: Convenient synthetic method for bis(chlorosilyl)methanes

Coupling reaction of polychloromethanes CH_4−nCl_n (n = 2-4) with HSiCl₃ in the presence of tetrabutylphosphonium chloride (Bu₄PCl) as a catalyst occurred at temperatures ranging from 30 °C to 150 °C. The reactivity of polychloromethanes increases as the number of chlorine-substituents on the carbon increases. In the reactions of CCl₄ with HSiCl₃, a variety of coupling products such as bis(chlorosilyl)methanes CH₂(SiCl₃)(SiXCl₂) [X = Cl (1a), H (1b)], (chlorosilyl)trichloromthanes Cl₃CSiXCl₂ [X = Cl (2a), H (2b)], and (chlorosilyl)dichloromthanes Cl₂HCSiXCl₂ [X = Cl (3a), H (3b)] were obtained along with reductive dechlorination products such as CHCl₃ and CH₂Cl₂ depending on the reaction temperature. In the reaction of CCl₄, 2a is formed at the initial stage of the coupling reaction and converted to give CHCl₃ at low temperature of 30 °C, to give 1a, 3a, and CHCl₃ at 60 °C, and to afford 1a as major product and CH₂Cl₂ in competition above 100 °C. Si-H bond containing silylmethanes can be formed by the H-Cl exchange reaction with HSiCl₃. Reaction of CHCl₃ with HSiCl₃ took placed at 80 °C to give three compounds 1a, 3a, and CH₂Cl₂, and finally 3a was converted to give 1a and CH₂Cl₂ at longer reaction time. While the condition for the reaction of CH₂Cl₂ with HSiCl₃ required a much higher temperature of 150 °C. Under the optimized conditions for synthesizing bis(chlorosilyl)methanes 1a,b, a mixture of 1a and 1b were obtained as major products in 65% (1a:1b = 64:1) and 47% (42:5) yields from the reaction of CCl₄ and CHCl₃ at 100 °C for 8 h, respectively, and in 41% (34:7) yield from that of CH₂Cl₂ at 170 °C for 12 h. In the Si-C coupling reaction of polychloromethanes with HSiCl₃, it seems likely that a trichlorosilyl anion generated from the reaction of HSiCl₃ with Bu₄PCl is an important key intermediate.     

Tertiary Phosphane/Tetrachloromethane,a Versatile Reagent for Chlorination,Dehydration, and P?N Linkage

In this review the processes occurring on the treatment of triphenylphosphane with tetrachloromethane are first reported; a key role is played here by (trichloromethyl)phosphonium chloride which reacts with a further amount of the phosphane to give the stable salt [chloro(triphenylphos-phoranediyl)methyl]triphenylphosphonium chloride by way of dichlorophosphorane and (dichloromethylene)phosphorane that is detectable only as an intermediate. The preparative application of the two-component system as a chlorinating, dehydrating, and P—N-linking reagent is ascribable to “phosphorylation”

1 Here and below, “phosphorylation” is used lo mean in general the formation of a phosphorus derivative. In the narrower sense this term denotes the introduction of phosphoryl groups P(O).

of the substrate in question through several reactive species. In these applications the reactions with the substrate compete with reactions of the two-component system with itself, so that the overall course of the reaction is in nearly all cases much more complex than was previously assumed. Nevertheless. very good results can be achieved by the use of this reagent, high yields and mild reaction conditions being characteristic.     

The oxidation of ethane in the presence and absence of tetrachloromethane on calcium hydroxyapatites with incorporated lead

The oxidative dehydrogenation of ethane has been investigated on various lead-added calcium hydroxyapatites and the effect of the addition of tetrachloromethane (TCM) into the feedstream has been examined. The catalysts are stable up to 873 K but are converted to the corresponding phosphates at approximately 973 K. The conversions of ethane and the selectivities to C₁ and C₂ compounds were found to be dependent on the lead contents of the catalysts, both the pretreatment and reaction temperatures, the presence of TCM and the times-on-stream as well as the structural forms of the catalysts. In the absence of TCM the conversion of ethane and the various selectivities show a dependence on the lead content of the catalysts which is similar at 773 and 873 K, but dissimilar at 973 K due, at least in part to the formation of the phosphates at the latter temperature. With TCM in the process feedstream the influence of the chlorapatites which are formed overrides that of the added lead.     

Compound-specific stable isotope analysis of organic contaminants in natural environments: a critical review of the state of the art,prospects, and future challenges

Compound-specific stable isotope analysis (CSIA) using gas chromatography-isotope ratio mass spectrometry (GC/IRMS) has developed into a mature analytical method in many application areas over the last decade. This is in particular true for carbon isotope analysis, whereas measurements of the other elements amenable to CSIA (hydrogen, nitrogen, oxygen) are much less routine. In environmental sciences, successful applications to date include (i) the allocation of contaminant sources on a local, regional, and global scale, (ii) the identification and quantification of (bio)transformation reactions on scales ranging from batch experiments to contaminated field sites, and (iii) the characterization of elementary reaction mechanisms that govern product formation. These three application areas are discussed in detail. The investigated spectrum of compounds comprises mainly n-alkanes, monoaromatics such as benzene and toluene, methyl tert-butyl ether (MTBE), polycyclic aromatic hydrocarbons (PAHs), and chlorinated hydrocarbons such as tetrachloromethane, trichloroethylene, and polychlorinated biphenyls (PCBs). Future research directions are primarily set by the state of the art in analytical instrumentation and method development. Approaches to utilize HPLC separation in CSIA, the enhancement of sensitivity of CSIA to allow field investigations in the µg L^–1 range, and the development of methods for CSIA of other elements are reviewed. Furthermore, an alternative scheme to evaluate isotope data is outlined that would enable estimates of position-specific kinetic isotope effects and, thus, allow one to extract mechanistic chemical and biochemical information.Abbreviations BTEX benzene, toluene, ethylbenzene, xylenes - MTBE methyl tert-butyl ether - PAHs polycyclic aromatic hydrocarbons - VOCs volatile compounds - PCBs polychlorinated biphenyls - CSIA compound-specific (stable) isotope (ratio) analysis - GC-IRMS, GC/IRMS or GCIRMS gas chromatography-isotope ratio mass spectrometry - GC-C-IRMS, GC/C/IRMS or GCC-IRMS gas chromatography-combustion-isotope ratio mass spectrometry - irmGC/MS isotope ratio monitoring gas chromatograph-mass spectrometry - GC/P/IRMS gas chromatography-pyrolysis-isotope ratio mass spectrometry (used for D/H) - KIE kinetic isotope effect - PSIA position-specific isotope analysis (for intramolecular isotope distribution) - SNIF-NMR site-specific natural isotopic fractionation by nuclear magnetic resonance spectroscopy     

氮氧化物与几种氯代烷烃化学反应的激光磁共振研究

以激光磁共振方法研究氮氧化物与二氯甲烷，三氯甲烷，四氯甲烷，１，２－二氯乙烷在紫外光照射和火花放电条件下的化学反应。实验结果表明氯代烷烃与ＮＯ／ＮＯ２在火花放电，紫外光照射条件下发生快速化学反应。所获得的信息对了解大气化学反应及光化学烟雾有着重要的意义。