Kinetics study of the gas-phase reactions of C2F5OC(O)H and n-C3F7OC(O)H with OH radicals at 253–328 K

The rate constants, k₁ and k₂ for the reactions of C₂F₅OC(O)H and n-C₃F₇OC(O)H with OH radicals were measured using an FT-IR technique at 253–328 K. k₁ and k₂ were determined as (9.24 ± 1.33) × 10⁻¹³ exp[−(1230 ± 40)/T] and (1.41 ± 0.26) × 10⁻¹² exp[−(1260 ± 50)/T] cm³ molecule⁻¹ s⁻¹. The random errors reported are ±2 σ, and potential systematic errors of 10% could add to the k₁ and k₂. The atmospheric lifetimes of C₂F₅OC(O)H and n-C₃F₇OC(O)H with respect to reaction with OH radicals were estimated at 3.6 and 2.6 years, respectively.     

新型双四面体过渡金属簇合物的合成与表征

利用Co₂(CO)₈与[Cl₃CC(O)OCH₂]₂的反应合成了以C(O)OCH₂CH₂OC(O)桥联两个Co₃C四面体骨架为特征的新型双四面体簇合物[(CO)₉Co₃(μ₃-C)C(O)OCH₂]₂(1);1与不同物质的量比的Na[M(CO)₃C₅H₄R](M=Mo,W;R=H,C(O)Me)反应,得到一步交换的产物(CO)₉Co₃(μ₃-C)C(O)OCH₂CH₂OC(O)(μ₃-C)Co₂M(CO)₈(C₅H₄R)[M=Mo,R=H(2);M=Mo,R=C(O)Me(3);M=W,R=H(4);M=W,R=C(O)Me(5)]或两步交换的产物[(C₅H₄R)(CO)₈Co₂M(μ₃-C)C(O)OCH₂]₂[M=Mo,R=H(6);M=Mo,R=C(O)Me(7);M=W,R=H(8);M=W,R=C(O)Me(9)].5或9分别与Na[Mo(CO)₃C₅H₅]以12的物质的量比反应得到含一个手性四面体骨架(CoMoWC)的(C₅H₅)(CO)₈Co₂Mo(μ₃-C)C(O)OCH₂CH₂O·C(O)(μ₃-C)CoMoW(CO)₇(C₅H₄C(O)Me)(C₅H₅)(10)或含两个手性四面体骨架(CoMoWC)的[(C₅H₅)(C₅H₄C(O)Me)(CO)₇CoMoW(μ₃-C)C(O)OCH₂]₂(11);对化合物1_11进行了CH元素分析、IR和¹HNMR等表征.结果表明,在金属交换反应中处于不同簇环境下的Co(CO)₃基团反应活性不同.对化合物1进行了晶体X射线衍射分析.化合物1的晶体属单斜晶系,P2₁/n(#14)空间群,晶胞参数a=0.933 0(2)nm,b=1.519 7(4)nm,c=1.178 3(4)nm,=91.16(2)°,Z=2,F(000)=972.分子结构呈中心对称.     

Reactions of the sterically hindered organosilicon diol (Me3Si)2C(SiMe2OH)2 and some of its derivatives

The diol R₂C(SiMe₂OH)₂ (R = Me₃Si) has been shown to react with: SO₂Cl₂ to give R₂ Me₂; SOCl₂ to give R₂C(SiMe₂Cl)₂; Me₃SiI or Me₃SiCl to give R₂C(SiMe₂OSiMe₃)₂; R′COCl; (R′ = Me or CF₃) to give R₂C(SiMe₂O₂CR′)-(SiMe₂Cl); (R′CO)₂O (R′ = Me or CF₃ to give R₂C(SiMe₂O₂CR′)₂; with MeOH containing acid to give R₂C(SiMe₂OMe)₂; with neutral MeOH to give R₂C-(SiMe₂OMe)₂ and probably R₂ Me₂; MeLi to give R₂C(SiMe₂OLi)₂ (and the latter to react with PhMeSiF₂ to give R₂ Me₂). The diacetate R₂C(SiMe₂O₂CMe)₂ reacts with CsF in MeCN to give R₂C(SiMe₂F)₂; it does not react with NaN₃ or KSCN in MeCN, but the bis(trifluoroacetate) reacts with these salts with KOCN to give R₂C(SiMe₂X)₂ (X = N₃, NCS, NCO).     

Solid state photodecomposition studies of K4Ti(O2)4·2H2O, K3Ta(O2)2F4 and K2V2O3(O2)2F2

The compounds K₄Ti(O₂)₄·2H₂O, K₃Ta(O₂)₂F₄ and K₂V₂O₃(O₂)₂F₂ undergo photolysis in the solid state. The photolysis kinetics obey the parabolic rate equation p = kt^1/2 and indicate a monoexcitation process for the photolysis. These features are similar to those reported previously for peroxo complexes. The mechanism of evolution of oxygen reported earlier appears to be the same in all these solids.     

Fluorination of C6F5MX3 compounds (M=Si, Ge; X=F, Cl, Br, Alk) with xenon difluoride and XeF Y salts

Compounds of the formula C₆F₅MX₃ (M=Si, Ge; X=Cl, Br) react with XeF₂, exchangingchlorine (bromine) atoms for fluorine. Interaction of C₆F₅MX₃ (X=F, Alk) with XeF₂ inthe presence of BF₃·OEt₂ or with XeF⁺ NbF₆^- proceeds by the addition of two fluorineatoms to the pentafluorophenyl ring.     

可见光诱导烯烃去芳香化成环合成含氟氮杂螺环已二烯酮

发展了一种可见光诱导的N-苄基丙烯酰胺去芳香化成环合成多氟烷基化氮杂螺环已二烯酮的反应。 此反应以多氟烷基碘或溴为自由基源,以fac-Ir(ppy)₃(fac:面式;ppy:2-苯基吡啶)作为光催化剂,在发光二极管(LED)蓝光灯照射条件下,使N-丙烯酰基-N-苄基苯甲酰胺串联自由基加成/去芳香化环合,合成了一系列含氟氮杂螺环已二烯酮类化合物,产率为61%~85%。 值得提出的是,此反应能快速在氮杂螺环已二烯酮骨架上引入多种多氟烷基基团如CF₃I、C₃F₇I、C₄F₉I、C₆F₁₃、C₈F₁₇I、CH₂CF₂I和BrCF₂CO₂Et(Et:乙基)等,且底物适用范围广、反应条件温和(室温)、催化体系绿色,为具有潜在药用价值和生理活性的多氟烷基化氮杂螺环已二烯酮的合成提供了一条高效、快捷的新途径。     

Theoretical Exploration of Stereochemical Nonrigidity for RfCo（PF3）x（CO）4-x（Rf=CF3, C2F5, C3F7, x=0-4）

The stereochemical nonrigidity of RfCo（PF3）x（CO）4-x（Rf=CF3,C2F5,C3F7,x=0-4） was studied at the theoretical level of B3LYP/6-31 1＋G^＊ via Gaussian 09.The intramolecular rearrangements in these penta-coordinated compounds are mainly caused by the vibrations of perfluoroalkyl groups.All the barriers along the reaction coordinate are less than 66.9 kJ/mol,which indicates that the rearrangements are kinetically favorable and hard to elucidate by experiment.Besides,ligand PF3 is a ligand similar to CO,the energy difference between the reactant and product is small.     

Reactions of fluorinated acid anhydrides, (CF3CO)2O, (CF3SO2)2O and (FSO2)2O, with organometallic substrates of group 15 (As, Sb and Bi)

(C₆H₅)₃MX₂ (M = As, Sb; X = OCOCF₃ and M = Sb, Bi; X = SO₃F, SO₃CF₃) compounds prepared by the interaction of triphenylmetal(V) substrates with (CF₃CO)₂O, (CF₃SO₂)₂O and (FSO₂)₂O have been characterized by molecular weight determination, elemental and spectroscopic (IR, ¹H and ¹⁹F NMR, mass) analyses.     

Preparation and reactions of some sterically hindered silanols, including [tris(trimethylsilyl)methyl]silanetriol

The silanol TsiSiMe₂OH (Tsi = (Me₃Si)₃C) has been made by hydrolysis of the iodide TsiSiMe₂I in H₂O/dioxane or H₂O/Me₂SO. It has been shown to react with some acid chlorides RCOCl (R=Me, Et, CICH₂ Ph, 4-O₂NC₆H₄, and 3,5- (O₂N)₂C₆H₃) and anhydrides (RCO)₂O (R = Me, CF₃, or Ph) to give the carboxylates TsiSiMe₂OCOR, and with SO₂Cl₂ to give TsiSiMe₂OSO₂Cl. The triol TsiSi(OH)₃ has been made by treatment of TsiSiH(OH)I with H₂O/Me₂SO at 150°C or with a mixture of aqueous AgClO₄ and an organic solvent. The triol has been shown to react with RCOCl (R = Me, Et, or Ph) or (RCO)₂O (R = Ph) to give the corresponding TsiSi(OCOR)₃, with (CF₃CO)₂O to give TsiSi(OH)₂(OCOCF₃), and with a mixture of Me₃SiCl and AgClO₄ in benzene or one of Me₃Sil and (Me₃Si)NH to give TsiSi(OSiMe₃)₃. The triol is unusually stable, but decomposes at its m.p. of 285–290°C.     

FTIR studies on the gas phase laser-induced decomposition of CF3CH2ONO

The unimolecular decomposition of CF₃CH₂O (2,2,2-trifluoroethoxy) radical generated from 355 nm pulsed nanosecond laser photolysis of CF₃CH₂ONO (2,2,2-trifluoroethylnitrite) in the gas phase has been studied using Fourier transform infrared absorption spectroscopy. The radical preferentially dissociates via its C–H bond cleavage to yield CF₃CHO (trifluoroacetaldehyde) as the major product. The infrared spectrum of formaldehyde, one of the products of C–C bond dissociation of CF₃CH₂O was not observed under a range of nitrite and argon buffer gas pressures. Similar results were obtained when thermal heating and broadband xenon lamp irradiation of the nitrite were carried out. The addition of high pressures of NO further decreased the production of CF₃CHO since recombination of NO with the trifluoroethoxy radical competes with the unimolecular dissociation process. Surprisingly, CF₃CDO was also the only product observed when the deuterated species CF₃CD₂ONO was photolysed by the 355 nm laser. These observations contradicted MP2/aug-cc-pVTZ calculations which were found to favour the C–C bond dissociation channel. However, 355 nm photolysis of CF₃CH₂ONO in the presence of O₂ yielded trifluoroethylnitrate, CF₃CH₂ONO₂ as the main product while CF₃CHO and CF₂O were also observable at much lower yields.     

The cleavage of a cluster carbonyl C---O bond by trifluoromethanesulphonic anhydride

The reaction of the octahedral dianion [Ru₆(CO)₁₈]²⁻ with trifluoromethanesulphonic (triflic) anhydride [(CF₃SO₂)₂O] quantitatively yields the neutral carbido-cluster [Ru₆C(CO)₁₇] as a result of the cleavage of a coordinated carbonyl ligand.     

A rationalization of orientation and reactivity in the nucleophilic replacement reactions of aromatic polyhalo-compounds

C₆F₅X compounds react with nucleophiles at the position para to X in some cases (X = H, CH₃, NMe₂, SMe, CF₃), meta in others (X = NH₂, O⁻) and occasionally at both meta and para in comparable amounts (X = OMe, NHME); significant amounts of ortho-replacement also occur (X = Cl, OMe). These orientations, and those in polychloro-aromatics and polyfluoro-polynuclear aromatics, can be rationalized by considering the relative stabilities of the Wheland-type intermediates involved (I, II, III), provided the halogens are taken as electron-repelling in π-systems. Reactivities can be rationalized if ground state stabilities are considered as well. A number of predictions have been made on the basis of these arguments.     

Homo- and hetero-bridged mixed-valence dinuclear complexes which contain the fragment ‘Rh(C6F5)3’

The reaction of the anionic mononuclear rhodium complex [Rh(C₆F₅)₃Cl(Hpz)]^t- (Hpz = pyrazole, C₃H₄N₂) with methoxo or acetylacetonate complexes of Rh or Ir led to the heterodinuclear anionic compounds [(C₆F₅)₃Rh(μ-Cl)(μ-pz)M(L₂)] [M = Rh, L₂ = cyclo-octa-1,5-diene, COD (1), tetrafluorobenzobarrelene, TFB (2) or (CO)₂ (4); M = Ir, L₂ = COD (3)]. The complex [Rh(C₆F₅)₃(Hbim)]⁻ (5) has been prepared by treating [Rh(C₆F₅)₃(acac)]⁻ with H₂bim (acac = acetylacetonate; H₂bim = 2,2′-biimidazole). Complex 5 also reacts with Rh or Ir methoxo, or with Pd acetylacetonate, complexes affording the heterodinuclear complexes [(C₆F₅)₃Rh(μ-bim)M(L₂)]⁻ [M = Rh, L₂ = COD (6) or TFB (7); M = Ir, L₂ = COD (8); M = Pd, L₂ = η³-C₃H₅ (9)]. With [Rh(acac)(CO)₂], complex 5 yields the tetranuclear complex [{(C₆F₅)₃Rh(μ-bim)Rh(CO)₂}₂]₂₋. Homodinuclear Rh^III derivatives [{Rh(C₆F₅)₃}₂(μ-L)₂]^·- [L₂ = OH, pz (11); OH, S^tBu (12); OH, SPh (13); bim (14)] have been obtained by substitution of one or both hydroxo groups of the dianion [{Rh(C₆F₅)₃(μ-OH)}₂]²⁻ by the corresponding ligands. The reaction of [Rh(C₆F₅)₃(Et₂O)_x] with [PdX₂(COD)] produces neutral heterodinuclear compounds [(C₆F₅)₃Rh(μ-X)₂Pd(COD)] [X = Cl (15); Br (16)]. The anionic complexes 1–14 have been isolated as the benzyltriphenylphosphonium (PBzPh₃⁺) salts.     

Measurement of C2F4Cl2, CCl4, CHF3 and O2 by wavelength modulation laser atomic absorption spectroscopy of excited Cl, F and O in a dc discharge applying semiconductor diode lasers

The concentrations of C₂F₄Cl₂ and CCl₄, CHF₃ and C₂F₄Cl₂, and O₂ have been measured in a dc gas discharge by wavelength modulation laser absorption spectroscopy of excited chlorine, fluorine and oxygen, respectively, applying semiconductor diode lasers. Argon and helium at reduced pressure were used as plasma gases. Preliminary 3σ detection limits of 0.6–1.5 ppb for chlorine compounds by absorption of the Cl 837.60 nm line, about 70 ppb of fluorine compounds by the F 739.87 nm line, and about 20 ppb oxygen molecules by the O 777.18 nm line were found.     

Ergebnisse aus versuchen zur darstellung von bis(trifluormethylsulphanyl)thioketen (CF3S)2C=C=S

The attempted preparation of bis(trifluoromethylsulphanyl)thioketene is described. Mono-and di-(trifluoromethylsulphanyl)-substituted orthothioesters may be prepared fromCH₃C(SC₂H₅)₃ and CF₃SCl in the presence of anhydrous ZnCl₂. The unstable compoundshave been isolated and characterized. The corresponding CF₃Se and CF₃SO₂ derivativesare only formed as intermediates which decompose to ketene diethylmercaptal. Suchmono- and di-substituted products are obtained in good yield from H₂C=C(SC₂H₅)₂ andCF₃ECl (E=S, Se). The reaction of H₂C=C(SC₂H₅)₂ with CF₃SO₂F gave only poor yieldsof (CF₃SO₂)_nCH_2−n=C(SC₂H₅)₂ (n=1, 2) which were only capable of characterizationin etheral solution by spectral means. Attempts to prepare (CF₃S)₂C=C=S by refluxing(CF₃S)₂CHC(O)Cl, (CF₃S)₂CHC(O)OH or (CF₃S)₂C=C=O with P₄S₁₀ in toluene yieldedonly the cyclic dimer and the corresponding 1,3,4-trithiolan.     

Reactions of pentafluorophenylxenon(II) hexafluoroarsenate [C6F5Ze] [AsF6] with halide anions in acetonitrile

Reactions of [C₆F₅Xe]⁺ [AsF₆]⁻ in acetonitrile with halide anions X⁻ show different results depending on X. If X = I, Br or Cl, then C₆F₅X is obtained. If X = F, then C₆F₅H and C₆F₅---C₆F₅ are produced, and if X = HF₂, then C₆F₆, C₆F₅H and C₆F₅---C₆F₅ are formed.     

Fourier transform IR product study of the reaction of CFO radicals with O2 at 298 K

Experimental results are presented of a Fourier transform IR product study at 298 K of the reaction system CFO+O₂ at oxygen pressures between 3 and 250 mbar. Pulsed photolysis of oxalyl fluoride (CFO)₂ or formyl fluoride (CHFO) at 193 nm was used to produce CFO. As stable products we detected bis-fluoroformyl peroxide, carbonyl fluoride and carbon dioxide. The yields of the peroxide and of CF₂O were measured as a function of [O₂]/[precursor] and are discussed qualitatively.     

NO reduction and CO oxidation over Cu/Ce/Mg/Al mixed oxide catalyst in FCC operation

Simultaneous NO reduction and CO oxidation in the presence of O₂, H₂O and SO₂ over Cu/Mg/Al/O (Cu-cat), Ce/Mg/Al/O (Ce-cat) and Cu/Ce/Mg/Al/O (CuCe-cat) were studied. At low temperatures (<340 °C), the presence of O₂ or H₂O enhanced the activity of CuCe-cat for NO and CO conversions, but significantly suppressed the activity of Cu-cat and Ce-cat. At high temperature (720 °C), the presence of O₂ or H₂O had no adverse effect on the NO and CO conversions over these catalysts. The addition of SO₂ to NO+CO+O₂+H₂O system had no effect on the reaction of CO+O₂ over Cu-cat, but deactivated this catalyst for NO+CO and CO+H₂O reactions; over Ce-cat, all of these reactions of NO+CO,CO+O₂ and CO+H₂O were suppressed significantly; over CuCe-cat, NO+CO and CO+O₂ reactions were not affected while the reaction of CO+H₂O was slightly inhibited.     

Fluorescence of CF2(B1, 040,K'' = 9) excited by the 253.7 nm Hg resonance line

Resonance fluorescence spectra of CF₂(¹B₁, 040, K' = 9) excited at 253 7 nm have been observed in the photolysis of C₂F₄ using a low-pressure mercury lamp. At low C₂F₄ pressures, the spectra with a series of doublet hands from 254 to 400 nm were consistent with the transitions from ¹B₁, 040, K'=9 to ¹A₁, 0v'₂0, K' = 8, 10, and also to ¹A₁, 1v'₂0, K' = 8, 10 The appearance of doublet bands (Δ K = ±1) provides clear evidence that the transition is of the perpendicular type.     

直线型l-CnH(n=5,6)自由基与氧气反应机理的理论研究

为了探索更长的碳链自由基l-C_nH与O₂反应的机理, 在CCSD(T)/CC-PVTZ+ZPVE//B3LYP/6-311++G(d,p)的计算水平下, 讨论了当n=5,6时, l-C_nH+O₂的各个异构化反应通道. 当n=5时, 主要反应通道为碳迁移过程, 生成主要产物为P2(CO₂+C₄H); 当n=6时, 碳-氧交换[产物为P1(CO+HC₅O)]和氧迁移过程[产物为P3(³O+HC₆O)]均为主要通道, 并具有很高的竞争性. 将所得结构与l-C_nH(n≤4)+O₂的反应机理进行了对比.