CAN TRICHLOROMETHANE SULFONYL BROMIDE BE USED AS AN ADDENDUM AS WELL AS A TELOGEN IN ITS ADDITION REACTION T0 VINYLIDENE FLUORIDE?

CCl_3SO_2Br used as a "telogen" reacts with CH_2=CF_2 to give mainly the "mono-adduct" CCl_3CH_2CF_2Br, together with very small amouats of CCl_3CF_2CH_2Br, CCl_2BrCH_2CF_2Br andthe "di-adduct" CCl_3(CH_2CF_2)_2Br. The result indicates that CCl_3SO_2Br can be used as anaddendum in trichloromethyl-bromo-addition reactions to olefins.     

CX_3NO(X=F、Cl)分子结构和稳定性的ab initio研究

本文用STO-3G基组对分子CF_3NO(1)、CF_2ClNO(2)、CFCI_2NO(3)和CCl_3NO(4)的各种可能存在的稳定构型进行了研究.结果表明:(1)卤素与氧在同侧的构型比其它构型稳定;(2)在同一分子中,Cl与O同侧比F与O同侧更为稳定;(3)分子从1至4稳定性下降.本文计算结果与实验符合较好。     

CX3NO(X=F、Cl)分子结构和稳定性的ab initio研究

本文用STO-3G基组对分子CF_3NO(1)、CF_2ClNO(2)、CFCI_2NO(3)和CCl_3NO(4)的各种可能存在的稳定构型进行了研究. 结果表明:(1) 卤素与氧在同侧的构型比其它构型稳定; (2) 在同一分子中, Cl与O同侧比F与O同侧更为稳定; (3) 分子从1至4稳定性下降. 本文计算结果与实验符合较好。     

连续二氧化碳激光敏化氧化CF2HCL,CF2=CF2,CF2=CFCl,CHCl3,CHCl=CCl2和CH2=CH2

本文报道了连续二氧化碳激光敏化氧化CF_2HCl,CF_2==CF_2,CF_2==CFCL,CHCl_3,CHCl==CCl_2和CH_2==CH_2的反应,讨论了某些反应的机制。结果表明,激光敏化方法可以使不能直接吸收激光的反应物分子在气相中发生反应,并有可能产生卡宾。     

CX3NO2(X=F,Cl)分子结构的稳定性

分子CF_3NO_2(1)、CF_2CINO_2(2)、CFCl_2NO_2(3)和CCl_3NO_2(4)在光化学和大气化学中是一类重要的分子。虽然它们的许多性质被广泛研究,但是从理论上尤其是ab initio分子轨道法对它们分子结构和化学键的研究报导极少。本文在ab initio/STO-3G水平上,全构型优化,系统地研究了这类分子的结构和各种构型的稳定性,并与实验以及CX_3NO(X=F,Cl)的结构进行了比较。计算采用Gaussian-82程序。在VAX-8350计算机上完成。结果和讨论分子各种稳定构型的键长、键角、Hartree-Fock能量、电荷密度及偶极矩列于表1至表3。     

在烷氧自由基的β-断裂中形成·CF_3和·CH_3的相对难易度研究

形成全氟烷基与碳氢烷基的相对难易度的直接比较问题,是一个根本性问题,但至今未获解决。我们用改进的方法成功地合成了新的次氯酸醋CF_3C(CH_3)_2OCl和CCl_3C(CH_3)_2OCl;又参照Kinillov方法,合成了新的二烷基过二碳酸酯(CF_3C(CH_3)_2OCO_2?_2,并对上述化合物在CCl_4溶液中的热分解反应进行了详细的研究。通过测定相应的烷氧自由基的β-断裂产物的方法,第一次可靠地给出了在烷氧自由基的β-断裂中,·CH_3与·CF_3,·CCl_3与·CH_3形成的相对难易度。     

The CO_2 laser-induced radical-chain reactions between CH_3CF_2H and chlorine-atom donors CF_2ClCFCl_2, CF_3CCl_3 CFCl_3 or CF_2Cl_2

The CO_2 laser induced room temperature reactions of CH_3CF_2H or another protium-donorCH_3CHClCH_3 with chlorine-atom donors (Z--Cl) CFCl_2CF_2Cl, CF_3CCl_3, CFCl_3 or CF_2Cl_2, havebeen investigated. Some of these reactions can yield two important monomers (CF_2=CH_2 andCF_2=CFCl) for fluoropolymers simultaneously. The yield dependence of these two alkenes on experi-mental conditions has been studied. A laser-initiated chain process is supported by identifica-tion of Z--H intermediates in these reactions.     

多氟烯烃和炔烃的钯催化氢化

本文报道Pd/Al_2O_3(1%)催化剂催化氢化CF_3CCl=CClCF_3,CF_3CCI==CHCF_3和CF_3C=CCF_3等多氟烯烃和炔烃的结果。经1~H和(19)~F核磁共振、质谱、红外等分析,证明了用制备色谱分离后的氢化产物主要成份的结构。前二者的氢化产物中主要是CF_3CH_2CH_2CF_3和CF_3CH_2CHClCF_3的混合物,而CF_3C=CCF_3氢化后只生成CF_3CH_2CH_2CF_3。     

亚硫酸四氟乙二醇酯的环断裂反应

含有亚硫酸四氟乙二醇酯(1)的四氟乙烷磺内酯(2)与H(CF_2)_4CH_2OH和三乙胺反应可获得草酸酯(CO_2CH_2CF_2CF_2—CF_2CF_2H)_2(3)。化合物(3)生成的机理解释为由于1的破环,生成了SOF_2和(COF)_2,后者进一步与H(CF_2)_4CH_2OH反应生成3。 3与二乙胺反应生成Et_2NCOCO_2CH_2(CF_2)_4H(4)。3和4皆为新化合物。     

(CX~3)~2CO,CF~3COX和CXCl~3(X=H或D)对CH(A,B)自由基的猝灭

本文报道室温下用266nm激光光解-荧光猝灭方法测定CH_3COCH_3,CD_3COCD_3,CF_3CO_2H,CF_3CO_2D,CHCl_3和CDCl_3分子猝灭电子激发态CH(A,B)自由基的速率常数,考察了含不同同位素原子的猝灭剂分子对CH(A,B)猝灭的同位素效应.实验发现,含D的分子比相应含H的分子对CH(A,B)的猝灭具有更大的速率常数.     

Theoretical study of the substituent effects on the S-H bond dissociation energy and ionization energy of 3-pyridinethiol: Prediction of novel antioxidant

The S-H bond dissociation enthalpies [BDE(S-H)] of a set of 5-X- and 6-X-3-pyridinethiols (X = F, Cl, CH3, OCH3, NH2, N(CH3)2, CF3, CN, and NO2) have been computed using the density functional theory based (RO)B3LYP procedure with 6-311++G(2df,2p) basis set. The effects of substituents on the BDE(S-H), proton affinity of the pyridinethiol anion [PA(S-)] and ionization energy (IE) are analyzed and their correlations with Hammett's substituent constants are examined. Subsequently, a series of 6-substituted 3-pyridinethiols have been explored to find out their antioxidant potentials. Finally, a number of 3-pyridinethiol based compounds are theoretically proposed as novel antioxidants.     

Atmospheric chemistry of CH3CHF2 (HFC-152a): kinetics, mechanisms, and products of Cl atom- and OH radical-initiated oxidation in the presence and absence of NO(x)

Smog chamber/Fourier transform infrared (FTIR) and laser-induced fluorescence (LIF) spectroscopic techniques were used to study the atmospheric degradation of CH3CHF2. The kinetics and products of the Cl(2P(3/2)) (denoted Cl) atom- and the OH radical-initiated oxidation of CH3CHF2 in 700 Torr of air or N2; diluents at 295 +/- 2 K were studied using smog chamber/FTIR techniques. Relative rate methods were used to measure k(Cl + CH3CHF2) = (2.37 +/- 0.31) x 10(-13) and k(OH + CH3CHF2) = (3.08 +/- 0.62) x 10(-14) cm3 molecule(-1) s(-1). Reaction with Cl atoms gives CH3CF2 radicals in a yield of 99.2 +/- 0.1% and CH2CHF2 radicals in a yield of 0.8 +/- 0.1%. Reaction with OH radicals gives CH3CF2 radicals in a yield >75% and CH2CHF2 radicals in a yield <25%. Absolute rate data for the Cl reaction were measured using quantum-state selective LIF detection of Cl(2P(j)) atoms under pseudo-first-order conditions. The rate constant k(Cl + CH3CHF2) was determined to be (2.54 +/- 0.25) x 10(-13) cm3 molecule(-1) s(-1) by the LIF technique, in good agreement with the relative rate results. The removal rate of spin-orbit excited-state Cl(2P(1/2)) (denoted Cl) in collisions with CH3CHF2 was determined to be k(Cl + CH3CHF2) = (2.21 +/- 0.22) x 10(-10) cm3 molecule(-1) s(-1). The atmospheric photooxidation products were examined in the presence and absence of NO(x). In the absence of NO(x)(), the Cl atom-initiated oxidation of CH3CHF2 in air leads to formation of COF2 in a molar yield of 97 +/- 5%. In the presence of NO(x), the observed oxidation products include COF2 and CH3COF. As [NO] increases, the yield of COF2 decreases while the yield of CH3COF increases, reflecting a competition for CH3CF2O radicals. The simplest explanation for the observed dependence of the CH3COF yield on [NO(x)] is that the atmospheric degradation of CH3CF2H proceeds via OH radical attack to give CH3CF2 radicals which add O2 to give CH3CF2O2 radicals. Reaction of CH3CF2O2 radicals with NO gives a substantial fraction of chemically activated alkoxy radicals, [CH3CF2O]. In 1 atm of air, approximately 30% of the alkoxy radicals produced in the CH3CF2O2 + NO reaction possess sufficient internal excitation to undergo "prompt" (rate >10(10) s(-1)) decomposition to give CH3 radicals and COF2. The remaining approximately 70% become thermalized, CH3CF2O, and undergo decomposition more slowly at a rate of approximately 2 x 10(3) s(-1). At high concentrations (>50 mTorr), NO(x) is an efficient scavenger for CH3CF2O radicals leading to the formation of CH3COF and FNO.     

Sensitivity of silver(I) complexes of a pyrimidine-hydrazone ligand to solvent, counteranion, and metal-to-ligand ratio changes

Metal complexation studies were performed with AgSO(3)CF(3) and AgBF(4) and the ditopic pyrimidine-hydrazone ligand 6-(hydroxymethyl)pyridine-2-carboxaldehyde (2-methylpyrimidine-4,6-diyl)bis(1-methylhydrazone) (1) in both CH(3)CN and CH(3)NO(2) in a variety of metal-to-ligand ratios. The resulting complexes were studied in solution by NMR spectroscopy and in the solid state by X-ray crystallography. Reacting either AgSO(3)CF(3) or AgBF(4) with 1 in either CH(3)CN or CH(3)NO(2) in a 1:1 metal-to-ligand ratio produced a double helicate in solution. This double helicate could be converted into a linear complex by increasing the metal-to-ligand ratio; however, the degree of conversion depended on the solvent and counteranion used. Attempts to crystallize the linear AgSO(3)CF(3) complex resulted in crystals with the dimeric structure [Ag(2)1(CH(3)CN)(2)](2)(SO(3)CF(3))(4) (2), while attempts to crystallize the AgSO(3)CF(3) double helicate from CH(3)CN resulted in crystals of another dimeric complex, [Ag(2)1(SO(3)CF(3))(CH(3)CN)(2)](2)(SO(3)CF(3))(2)·H(2)O (3). The AgSO(3)CF(3) double helicate was successfully crystallized from a mixture of CH(3)CN and CH(3)NO(2) and had the structure [Ag(2)1(2)](SO(3)CF(3))(2)·3CH(3)NO(2) (4). The linear AgBF(4) complex could not be isolated from the double helicate in solution; however, crystals grown from a solution containing both the AgBF(4) double helicate and linear complexes in CH(3)CN had the structure [Ag(2)1(CH(3)CN)(2)](BF(4))(2) (5). The AgBF(4) double helicate could only be crystallized from CH(3)NO(2) and had the structure [Ag(2)1(2)](BF(4))(2)·2CH(3)NO(2) (6).     

Raman spectrum, conformational stability, barriers to internal rotations and DFT calculations of 1,1,1-trifluoro-propane-2-thione with double-internal-symmetric rotor

The Raman spectrum (3500-100 cm-1) of 1,1,1-trifluoro-propane-2-thione (TFPT), CF3C(S)CH3 of the solid phase has been recorded. The internal rotation of CH3 and/or CF3 moieties around CC bonds in TFPT allow five hypothetical conformers (Cs and C1 point groups). Aided by quantum chemical (QC) calculations, the Cc conformer is the only stable form (CF3 and CH3 groups are eclipsing the CS bond) which contains a planar FCC(S)CH backbone and possess intramolecular hydrogen sulfur interactions. However, other conformations (with the orientation of sulfur atom being trans to either hydrogen or fluorine atom) are either transition states or not fully converged geometry with "gauche" orientation. Moreover, the calculation were carried out at the level of Becke three Lee-Yan-Parr (B3LYP) parameters up to 6-311++G(d,p) basis sets. The torsional barriers are adequately described by a three-fold potential, V3 which have been determined utilizing the optimized structural parameters from the B3LYP/6-31G(d) basis set along with potential surface scan. Barriers of 1.28 kcal/mol (448 cm-1) and 1.94 kcal/mol (678 cm-1) were calculated for CH3 and CF3 symmetric rotors, respectively. Complete vibrational assignments have been reported for the stable Cc isomer which is supported by normal coordinate analysis and potential energy distributions (PEDs) for all fundamentals. Moreover, equilibrium geometries, vibrational frequencies are compared to the corresponding experimental values of acetone, 1,1,1-trifluoroacetone (TFA), hexafluoroacetone (HFA) and other molecules having the CF3 moiety whenever appropriate.     

Analysis of the intermolecular interactions between CH3OCH3, CF3OCH3, CF3OCF3, and CH2F2, CHF3

The intermolecular interaction energy curves of CH(3)OCH(3)-CH(2)F(2), CF(3)OCH(3)-CH(2)F(2), CF(3)OCF(3)-CH(2)F(2), CH(3)OCH(3)-CHF(3), CF(3)OCH(3)-CHF(3), and CF(3)OCF(3)-CHF(3) complexes were calculated by the MP2 level ab initio molecular orbital method using the 6-311G** basis set augmented with diffuse polarization functions. We investigate the fluorine substitution effects of both methane and dimethyl ether on intermolecular interactions. In addition, orientation dependence of intermolecular interaction energies is also studied with utilizing eight types of orientations. Our analyses demonstrate that partial fluorinations of methane make electrostatic interaction dominant, and consequently enhance attractive interaction at several specific orientations. On the contrary, fluorine substitutions of dimethyl ether substantially decrease the electrostatic interaction between ether and CH(2)F(2) or CHF(3); thus, there is no such characteristic interaction between the C-H of fluorinated methane and ether oxygen of CF(3)OCF(3) as conventional hydrogen bonding, due to reduced polarity of fluorinated ether. The combination of different pairs of the electrostatic interaction is therefore responsible for the intermolecular interaction differences among the complexes investigated herein and also their orientations.     

Atmospheric chemistry of CF3CH2CH2OH: kinetics, mechanisms and products of Cl atom and OH radical initiated oxidation in the presence and absence of NOX

Relative rate techniques were used to study the kinetics of the reactions of Cl atoms and OH radicals with CF(3)CH(2)C(O)H and CF(3)CH(2)CH(2)OH in 700 Torr of N(2) or air diluent at 296 +/- 2 K. The rate constants determined were k(Cl+CF(3)CH(2)C(O)H) = (1.81 +/- 0.27) x 10(-11), k(OH+CF(3)CH(2)C(O)H) = (2.57 +/- 0.44) x 10(-12), k(Cl+CF(3)CH(2)CH(2)OH) = (1.59 +/- 0.20) x 10(-11), and k(OH+CF(3)CH(2)CH(2)OH) = (6.91 +/- 0.91) x 10(-13) cm(3) molecule(-1) s(-1). Product studies of the chlorine initiated oxidation of CF(3)CH(2)CH(2)OH in the absence of NO show the sole primary product to be CF(3)CH(2)C(O)H. Product studies of the chlorine initiated oxidation of CF(3)CH(2)CH(2)OH in the presence of NO show the primary products to be CF(3)CH(2)C(O)H (81%), HC(O)OH (10%), and CF(3)C(O)H. Product studies of the chlorine initiated oxidation of CF(3)CH(2)C(O)H in the absence of NO show the primary products to be CF(3)C(O)H (76%), CF(3)CH(2)C(O)OH (14%), and CF(3)CH(2)C(O)OOH (< or =10%). As part of this work, an upper limit of k(O(3)+CF(3)CH(2)CH(2)OH) < 2 x 10(-21) cm(3) molecule(-1) s(-1) was established. Results are discussed with respect to the atmospheric chemistry of fluorinated alcohols.     

CF3CH2CF2CH3（HFC-365mfc）与Cl原子反应的微观机理及动力学性质

采用密度泛函理论方法 M06-2X结合6-31+G(d,p)基组研究了CF3CH2CF2CH3与Cl原子反应的反应机理.计算获得了CF3CH2CF2CH3的两种可区分的稳定几何构象RC1和RC2以及与它们相对应的8条氢提取反应通道和2条取代反应通道.运用改进的正则变分过渡态理论(ICVT)并结合小曲率隧道效应校正(SCT),在M06-2X/6-31+G(d,p)水平上计算了各氢提取通道的速率常数,并由Boltzmann配分函数得到总包反应的速率常数kT(cm3.molecule-1.s-1).计算结果表明,体系的总反应速率常数与已有实验值相吻合,进而给出了该反应在200～1000 K温度区间内反应速率常数kT的三参数表达式kT=1.88×10-22T3.76.exp(-1780.69/T),并讨论了两种构象RC1和RC2对总反应的贡献及各构象中氢提取发生在—CH3或—CH2—基团上的位置选择性.此外,由于缺少相关反应物及产物自由基标准生成焓ΔHf,298 K的数据,利用等化学键法估算了在上述物种的标准生成焓.     

Theoretical Investigation of CH3CF2O2+HOO Reaction

The reactions of CH3CF2O2 with HOO are important chemical cyclic processes of photochemical contamination. In this paper, the reaction pathways and reaction mechanism of CH3CF2O2+HOO are investigated extensively with the Gaussian 98 package at the B3LYP/6-311++G** basis sets. The use of vibrational mode analysis and electron population analysis to reveal the reaction mechanism is firstly reported. The study shows that CH3CF2CO2+HOO→IM1→TS1→CH3CF2O2H+O2 channel is the energetically most favorable, CH3CF2CO2H and O2 are the principal products, and the formation of CH3OH and CF2O is also possible.     

Theoretical study of reactant activation in 1,3-dipolar cycloadditions of cyclic nitrones to free and Pt-bound nitriles

[reaction: see text] 1,3-Dipolar cycloaddition of the cyclic nitrones CH2(CH2)2CH=NO (N1), CH2CH2OCH=NO (N2), CH2-OCH2CH=NO (N3), and O(CH2)2CH=NO (N4) to organonitriles, RCN-both free (R = CH(3), CF(3)) and ligated to Pt(II) and Pt(IV) (in the complexes trans-[PtCl(2)(NCCH(3))(2)] (1) and trans-[PtCl(4)(NCCH(3))(2)] (2))-was investigated extensively by theoretical methods at different levels of theory. The effectiveness of two types of dipolarophile activation (by introducing a strong electron-acceptor group R and by coordination to a metal center) was analyzed and compared. The influence of factors such as the nature of the cyclic nitrone and the nature of the solvent on the reactions was also studied. The reactivity of dipoles and dipolarophiles increases along the series N4 < N1 approximately N3 < N2 and CH(3)CN < CF(3)CN < 1 < 2; the latter demonstrates that the coordination of RCN to a Pt center provides an even higher activation effect upon cycloaddition in comparison with the introduction of a strong electron-acceptor group R such as CF(3). A higher reactivity of the cyclic dipole N1 in comparison with acyclic nitrones (e.g., CH(3)CH=N(CH(3))O) is interpreted to be a result of its exclusive existence in a more strained and hence more reactive E- rather than Z-configuration. The activation and reaction energies have been calculated at different basis sets and levels of theory, up to MP4(SDTQ), CCSD(T), and CBS-Q. The activation energies are weakly sensitive to a change of the correlated methods. The consideration of the solvent effects results in the increase of the activation barriers, and such enhancement is less pronounced for the nonpolar or low polar solvents. The cycloadditions to CH(3)CN and CF(3)CN were found to be nearly synchronous, but these reactions involving 1 and 2 are clearly asynchronous. Moreover, the reaction of N2 with 2 proceeds via a very early acyclic transition state, while for all other reactions the transition states have a cyclic nature.     

CF3O2自由基和NO反应机理的理论研究

用密度泛函理论(DFT)的B3LYP方法, 分别在6-31G、6-311G、6-311+G(d)基组水平上研究了CF3O2自由基和NO反应机理. 研究结果表明, CF3O2自由基和NO反应存在三条可行的反应通道, 优化得到了相应的中间体和过渡态. 从活化能看, 通道CH3O2+NO→IM1→TS1→IM2→TS2→CF3O+ONO的活化能最低, 仅为70.86 kJ•mol-1, 是主要反应通道, 主要产物是CF3O和NO2. 而通道CH3O2+NO→IM1→TS3→CF3ONO2和CH3O2+NO→TS4→IM3→TS5→IM4→TS6→CF3O+NOO的活化能较高, 故该反应难以进行.