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1.
Chirally Substituted Sulfur Fluorides The compounds CF3? CFCl? SF3, (CF3? CFCl)2SF2, and CF3? CFCl? SOF were prepared and their 19F-nmr spectra fully analysed. In CF3? CFCl? SF3 the chiral carbon atom leads to a splitting of the two axial fluorine atoms on sulfur. (CF3? CFCl)2SF2 exists in a dl-form with equivalent (sulfur)-F atoms and a meso form with non-equivalent (sulfur)-F atoms. CF3? CFCl? SOF exists in two diastereomeric forms.  相似文献   

2.
A 4-Chloro-5-trifluoromethyl-2,2,4-trifluoro-1,3-dioxolane (1) was synthesised by reaction of CF2(OF)2 with CF3CHCFCl; the elimination of HCl from (1) in basic conditions led to the formation of dioxole perfluoro-4-methyl-1,3-dioxole (2). Both these synthetic steps gave the corresponding product in high yield.A new synthetic route for the preparation of CF3CHCFCl, starting from CF2ClBr and CH2CF2, together with some examples of polymerisation products obtained by reaction of dioxole (2) with fluoroolefins are also reported.  相似文献   

3.
A mass spectrometric analysis of the positive ions and neutral products in a silane glow discharge has been performed. The active species, created by dissociation, disproportionation, and ion-molecule reactions are mainly SiH2, SiH3, and H. A calculation of the distribution of the SiH n + ions shows that the silane concentration monitors the abundance of SiH 3 + . The diffusional transport of radicals toward the discharge-tube walls can explain the observed deposition rates. The study of SiH4-SiD4 and SiH4-D2 plasmas emphasizes several reactions which modify the free-radical populations depending on the discharge conditions: disproportionation, termination, recombination, and abstraction. Heterogeneous reactions have also been observed: etching of the film by H atoms and direct incorporation of hydrogen in the growing film. A general scheme for the plasma deposition mechanism is proposed.  相似文献   

4.
The ultraviolet absorption spectrum of CF3CFClO2 and the kinetics of the self reactions of CF3CFCl and CF3CFClO2 radicals and the reactions of CF3CFClO2 with NO and NO2 have been studied in the gas phase at 295 K by pulse radiolysis/transient UV absorption spectroscopy. The UV absorption cross section of CF3CFCl radicals was measured to be (1.78 ± 0.22) × 10?18 cm2 molecule?1 at 220 nm. The UV spectrum of CF3CFClO2 radicals was quantified from 220 nm to 290 nm. The absorption cross section at 250 nm was determined to be (1.67 ± 0.21) × 10?18 cm2 molecule?1. The rate constants for the self reactions of CF3CFCl and CF3CFClO2 radicals were (2.6 ± 0.4) × 10?12 cm3 molecule?1 s?1 and (2.6 ± 0.5) × 10?12 cm3 molecule?1 s?1, respectively. The reactivity of CF3CFClO2 radicals towards NO and NO2 was determined to (1.5 ± 0.6) × 10?11 cm3 molecule?1 s?1 and (5.9 ± 0.5) × 10?12 cm3 molecule?1 s?1, respectively. Finally, the rate constant for the reaction of F atoms with CF3CFClH was determined to (8 ± 2) × 10?13 cm3 molecule?1 s?1. Results are discussed in the context of the atmospheric chemistry of HCFC-124, CF3CFClH. © 1994 John Wiley & Sons, Inc.  相似文献   

5.
Several fluorinated allylic ethers, thioethers and diethers have been prepared in excellent yields by phase transfer catalysis (CTP). The used halogenated compounds are allyl chloride and bromide, p-chloromethylstyrene. The used fluorinated alcohols are aromatic pentafluorophenol and various aliphatics: CF3CH2OH, CF2HCF2CH2OH ClCF2CF2CH2OH,C6F13C2H4OH, HOCH2CF2CFClCF2CH2OH and HOC6H4C(CF3)2C6H4OH. All these new compounds have been characterized by 1H and 13C NMR. We conclude that CTP is the best method to obtain allylic and diallylic compounds.  相似文献   

6.
The mechanism of chloride substitution in CF2CFCl with [Re(CO)5] and [CpFe(CO)2] anions is investigated experimentally and theoretically. The substitution reaction begins with the nucleophile addition to CF2CFCl producing the carbenoid anion [MCF2CFCl] (A) (M = Re(CO)5, CpFe(CO)2). This is shown by trapping the intermediate A with electrophiles - proton donor (t-BuOH) to give MCF2CFClH or with CF2CFRe(CO)5 to give acylmetallate III, and by the formation of the substitution products CF2CFM from the anion A, generated by the deprotonation of MCF2CFClH with t-BuOK. 1,2-Shift of metal carbonyl group concerted with the α-elimination of chloride anion is proposed as the transformation pathway of carbenoid A into CF2CFM. A competing process of carbene insertion into Fe-CO bond is proposed to explain the formation of (XI). The feasibility of these two pathways is confirmed by DFT (B3LYP/SDD and 6-31G) calculations of the carbenes [MCF2CF:] and carbenoid anions [MCF2CFCl]. Transition states (TS) for 1,2-shift (+3.2 kcal/mol) and for nucleophilic addition at CO ligand (+5.4 kcal/mol) are located for [(CO)5ReCF2CFCl], but only one TS corresponding to carbene insertion into Fe-CO bond (+2.1 kcal/mol) is located for [(CO)2CpFeCF2CFCl]. The formation of other newly observed products, F(CO)CHFRe(CO)5 (V) and Cp(CO)2FeCCFeCp(CO)2 (VIII) is also discussed.  相似文献   

7.
Routes to perflouroallyl chloride, CF2:CF.CF2Cl, and to cis-and trans-1-chloro-hexafluoro-2-trifluoromethyl(but-2-ene), (CF2Cl)(CF3)C:CF.CF3 are reported, and their susceptibility to attack by nucleophiles discussed; the allylic chlorine atoms in these olefins are the controlling factor in determining the products obtained.The conversion of 3-chloropentafluoropropene into a series of perfluoroallyl derivatives of general formula R.CF2.CF:CF2 [R = (CF3)3C-, CF3O-, C6F5-, l-, MeO-, etc.] is described, and the further chemistry of 3-chloropentafluoropropene and its derivatives outlined.Water reacts rapidly with (CF2Cl)(CF3)C:CF.CF3 to give CF2:C(CF3).CFCl.CF3 or CF3.CO.CH2.CF3. Methanol affords CF2:C(CF3).CFOMe.CF3 and (MeOCF2)(CF3)C:CF.CF3 as initial products, with subsequent secondary products such as CF3.CFOMe.CH(CF3).CF2OMe, (CF3)(MeO)C:C(CF3).CF3OMe, MeO.CF:C(CF3).CFOMe.CF3, (CF3)(MeO)CF.CH(CF3).CO2Me, and (CF3)(MeO)C:C(CF3).CO2Me. The influence of allylic chlorine and of reaction time on the formation of these products, and mechanistic pathways for their formation are considered.  相似文献   

8.
The technique of laser flash photolysis/laser absorption has been used to obtain an absolute removal rate constant of (3.85 ± 0.18) × 10?10 cm3 molecule?1 s?1 for singlet methylene, 1CH21A1), with germane (GeH4) at ambient temperature. The removal rate constant is compared with the values for methane (CH4) and silane (SiH4) which have been determined previously. © 1995 John Wiley & Sons, Inc.  相似文献   

9.
The technique of laser flash photolysis has been used to set limits on the rate constants for the bimolecular reactions of SiH2 with methane (CH4) and tetramethylsilane (SiMe4) at both ambient and elevated temperatures (ca 600 K). These limits show that the energy barriers to insertion reactions of SiH2 in the C H bonds of CH4 are at least 45(±6) kJ mol−1 and in the C H and/or Si C bonds of SiMe4 are at least 23(±6) kJ mol−1. The best thermochemical estimate of the activation energy for SiH2+CH4 is 59(±12) kJ mol−1. Reasons for the greatly diminished reactivity of SiH2 with C H as compared with Si H bonds are discussed. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 393–395, 1999  相似文献   

10.
Fluorination of chlorofluorinated telomers of general formula Cl(CFClCF2)nCCl3 (n ? 7) was studied using potassium fluoride in dimethylsulfoxide as fluorinating agent. The reaction leads to a mixture of perfluorinated linear olefins having 15 to 30 carbon atoms : CF3(CF2)pCFCF(CF2)mCF3 (p + m = 2n?3).We perfected a method to determine molecular weights of the telomers by gel permeation chromatography (G.P.C.). The olefins obtained by fluorination are analyzed both by vapor phase chromatography (V.P.C.) and by 19F nuclear magnetic resonance (N.M.R.).  相似文献   

11.
The zinc coupling reaction of 1,2-dichloroiodotrifluoroethane (I) in acetic anhydride-methylene chloride has been reinvestigated in more detail than its original disclosure. The expected coupling product C4F6Cl4 was shown to be an isomeric mixture of three components, CF2ClCFClCFClCF2Cl (II, 80%), CFCl2CF2CF2CFCl2 (IIa, 15%) and CF2ClCFClCF2CFCl2 (IIb, 5%). In addition, other products e.g. CF2CFCl, C6F9Cl5 and C8F12Cl6 were formed in minor quantities. A probable mode of formation of the various byproducts via initial formation of CF2CFCl and subsequent telomerization is presented.  相似文献   

12.
《Chemical physics》1987,116(1):151-157
Relative photoexcitation spectra of ionic fragments SiH+3, SiH+2, SiH+ and Si+ originating from photofragmentation of molecular silane (SiH4) have been measured in the 12–19 eV region using a time-of-flight mass-analytic method combined with synchrotron radiation as a light source. No SiH+4 could be detected in a measurement time of a few microseconds. The excitation spectra show a maximum photoionization efficiency around 13.3 eV for SiH+2 and around 14.8 eV for SiH+3. Correlations between photoionization and dissociation are discussed. The assignment of the autoionization structure between 15 and 18 eV by Börlin et al. has been positively examined and extended to include two vibrational progressions composed of the ν1 mode with a frequency of 1690 ± 60 cm−1 and the ν2 mode with 730 ± 80 cm−1.  相似文献   

13.
Isotope-selective IR multiphoton dissociation of CF2C12 molecules in a mixture with HI was experimentally investigated. It was shown that irradiation of the CF2C12-HI mixture leads to the successive buildup of the intermediates CF2HC1 and CF2HI, which also isotopically selectively dissociate simultaneously with the substrate to yield the final product CF2H2 enriched in13C up to 97% at an initial13C concentration of 1.1% in CF2C12. When CF2C12 preliminarily enriched in13C up to 12.3% was used, the attained13C concentration in CF2H2 was as high as ≥99%. Isotopic selectivity and dissociation yields of13C- and12C-containing components of the substrate CF2C12 and both intermediate dissociation products, CF2HC1 and CF2HI, were measured, depending on experimental conditions. The13C distribution over the intermediate and final dissociation products was studied. The side products C2F4C12 and CF2IC1 were detected.  相似文献   

14.
The time-resolved laser magnetic resonance (LMR) method has been applied to kinetic measurements for the first time. An intracavity spectrometer based on a CO2 laser with resonant modulation of the magnetic field and with phase-sensitive detection of the signal has been used. Kinetic curves of generation and disappearance of CI atoms and SiH3 radicals were obtained in the pulse photolysis of a mixture of S2Cl2 + SiH4 under the fourth harmonic of a Nd laser (265 nm, 0.5 mJ, 12.5 Hz) at a total pressure of 520–980 Pa (he as diluent) and a temperature of 326 K. The reagent concentrations were: [S2Cl2 = (2.0?10.2)×1014 cm?3, [SiH4 = (2.4?17.4)×1013 cm?3. To remove the transition saturation, 5.3×1015 cm?3 CCl4 was introduced into the reactor. The fraction of dissociated S2Cl2 was 1‰ Rate constants of the reactions (I) Cl+S2Cl2 → products, (II) Cl+SiH4 → HCl+SiH3 and a preliminary rate constant of the reaction (III) SiH3 + S2Cl2 → products were obtained: k1 ≤ (4.3±1.2)×10?12 cm3/s, k2 = (2.3±0.5)×10?10 cm3/s, k3 = (2.4±0.5)×10?11 cm3/s. At a signal-to-noise ratio of 1:1, 1000 pulses and a 12 cm long detection zone the sensitivity to Cl atoms and to SiH3 radicals was 4×1010 cm?3 and = 1011 cm?3, respectively. The time resolution of the method was 4 μs. The method is shown to be promising for kinetic investigations and experiments on fast processes.  相似文献   

15.
《Chemical physics letters》1987,141(5):423-427
Tunable diode laser transient detection of CF2 C2F4, and HCl following infrared multiphoton dissociation (IRMPD) of CF2HCl has been achieved. Quantification of the HCl and C2F4 leads to the calculation of an infrared absorption linestrength and the ν1 bandstrength for CF2 (X̃1A1). In addition, the rate coefficient for recombination of CF2 was found to be (1.4± 0.4) × 1010 cm3 mol−1 s−1.  相似文献   

16.
CF3SiH3 (I) has been obtained in ~90 % yield from the reaction of CF3SiF3 or CF3SiF2I with LiAlH4 in dibutyl ether at ?78°. (I) has been characterized by its 1H, 19F, 13C and 29Si NMR-, mass-, IR- and Raman spectra. It is thermally stable up to 180° and not attacked by O2, H2O and H3PO4, but cleaved by aqueous alkali. From a rovibrational analysis, Bo = 0.09769(2) cm?1 is deduced, and a long SiC bond, 1.95(1)Å, is predicted.  相似文献   

17.
Kinetic data and product studies are reported for the silane pyrolysis in the presence of olefins and acetylene. The kinetics of silane loss in the presence of acetylene was found to be identical to the initial gas phase silane decomposition step (SiH4 + M → SiH2 + H2 + M) when corrected for pressure fall-off effects. This result and the absence of methane or ethane from the pyrolysis of SiH4 in the presence of 1-butene or 1-pentene demonstrate that silyl radicals and H atoms are not involved in silane-olefin or silane-acetylene reactions. Qualitative aspects and kinetic data from the SiH4 pyrolysis in the presence of propylene are in accord with propylsilane formation via propylsilylene formed by silylene addition to propylene.  相似文献   

18.
Molecular core binding energies of the polymers formed by copolymerization of CF3NO with CF2?CF2, CF2?CFCl, and CF2?CFH, respectively, have been studied by means of ESCA. The results are interpreted in terms of CNDO/2 SCF MO calculations on some model systems. Some evidence for structural irregularity is found for the copolymers with CF2?CFCl and with CF2?CFH. The reaction mechanism for the polymerization is also discussed in terms of the experimental results and INDO SCF MO calculations.  相似文献   

19.
The gas-solid addition reaction between gaseous bromine and solid (E) and (Z)-4-HO2CC6H4CHCFCl has been examined. Reaction under ionic conditions leads to predominant anti-addition of bromine (80% anti for the E isomer; 90% for Z). Addition under radical conditions is slightly stereoselective with a small excess (54:46 for E; 56:44 for Z) of the S,R diastereomer of 4-HO2CC6H4CHBrCFClBr being formed. It is concluded that this olefin system has greater freedom of molecular motion in the solid than 4-HO2CC6H4CFCFX (X = Cl, CF3).  相似文献   

20.
《Chemical physics letters》1985,122(4):361-364
Reaction rate constants of SiH2(X̄1A1) have been directly measured for the first time using the laser photolysis—laser-induced fluorescence method. The preparation of SiH2 radical in the laser photolysis (193 nm) of phenylsilane and the concentration of the radical is demonstrated by a dye laser at 580.1 nm (X̄1A11B1). The reaction rate constants of SiH2(X̄1A1) with H2, CH4, C2H4, SiH4 and Si2H6, are 0.001, 0.01, 0.97, 1.1 and 5.7×10−10 cm3 molecule−1 s−1, respectively. For SiH21B1(0.2,0)), the collision-free lifetime is 0.6 μs and the quenching rate constant for He is 3.8×10−10 cm3 molecule−1 s−1.  相似文献   

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