Zur Bildung und Stabilität von Difluormethylenphosphoranen,R3P⊕-C̄–F2

Inhaltsübersicht. Die Reaktion von Difluorhalogenmethanen, CF₂X₂, mit Phosphanen, R₃P, in Gegenwart von Metallen und Carbonylverbindungen, R″R′CO, führt zur Bildung geminaler Difluorolefine, R″R′C=CF₂. Die sorgfältige Untersuchung der Einzelschritte dieser komplexen Reaktion zeigt, daß intermediär Difluorhalogenmethylphosphoniumhalogenide, [R₃P–CF₂X]X, und Difluormethylenphosphorane, R₃P^⊕ – c?^?-F₂, gebildet werden. Die Phosphoniumsalze sind stabil und können als kristalline Substanzen isoliert werden. Durch Metalle oder Phosphene werden sie zu den instabilen Difluormethylenphosphoranen reduziert. Diese zersetzen sich beim Fehlen geeigneter Reaktionspartner in Phosphan und Difluorcarben, CF₂. Ihre Bildung durch Addition von CF₂ an R₃P ist nicht möglich. Mit Halogenwasserstoffen bilden sie Difluormethylphosphoniumsalze, [R₃P-CHF₂]X. Formation and Stability of Difluoromcthylene Phosphoranes, R₃P^⊕ —c?F₂ In the presence of metals and carbonyl compounds, R″R′CO, the reaction of difluoro-halomethanes, CF₂X₂, with phosphanes, R₃P, leads to the formation of geminal difluoroolefins, R″R′C=CF₂. Our investigations have proved that difluorohalomethylphosphonium halides, [R₃P–CF₂X]X, and difluoromethylene phosphoranes, R₃P^⊕–C??F₂, are formed intermediately. The phosphonium salts are stable. They can be isolated as crystalline substances. They are reduced by metals or phosphanes forming unstable difluoromethylene phosphoranes as intermediates. These decompose into phosphane and difluorocarbene, CF₂, if suitable reactants are absent. Their reaction with hydrogen halides, HX, yields difluoromethylphosphonium salts, [R₃P–CHF₂]X. The formation of difluoromethylene phosphoranes by addition of CF₂ to R₃P is not possible.     

Sereoselective Addition of Benzaldehyde N,N-Dimethyl-Hydrazone to 2-RfO-4-Oxo-5,6-Benzo-1,3,2-Dioxaphosphorinanes. The Spatial Structure of 2-Pentafluorophenoxy-4-Dimethylamino-2,5-Dioxo-3-Phenyl-6,7-Benzo-1,4,2-Oxazaphosphepine

Abstract

[3+2]-Cycloaddition of N,N-dimethylhydrazone benzaldehyde (I) to 2-R_FO-4-oxo-5,6-benzo-l,3,2-dioxaphosphorinanes (II) yields the new heterocycle - 2-R_FO-4-Me₂N-2,5-dioxo-3-phenyl-6,7-benzo- 1,4,2-dioxaphosphepine (III) [R_F = C₆F₅, CH(CF₃)₂) with high stereoselectivity (above 94%). The reaction is likely to involve the initial interaction of nitrogen as a nucleophile with wbonyl carbon as an electrophile. The hydrolysis of (III) leads to phosphonic acid (IV) (OR_F = OH).     

Reactions of mesomeric fluorocarbanions with acid anhydrides. Transformation of trifluoromethyl groups into fluorocarbonyl and perfluoroacyl groups

It was found that the reaction of mesomeric fluorocarbanions of the CF₃$\text{C}\text{θ}$XCOY type with benzoic anhydride leads to the loss of benzoyl fluoride and the formation of mesomeric carbanions of the FCO$\text{C}\text{θ}$XCOY type. In a similar reaction with perfluorocarboxylic acid anhydrides, besides a CF₃→COF transformation, further change of COF into COR_F is observed, leading to the formation of salts containing mesomeric anions of the R_FCO$\text{C}\text{θ}$XCOY type, which, upon acidification, give 1,1- -bis(perfluoroacyl)-2,2,2-trifluoroethanes CF₃CH(COR_F)₂ , tris- (perfluoroacyl)methanes (R_FCO)₃CH and bis(trifluoroacetyl)- acetic ester (CF₃CO)₂CHCOOMe. It has been shown that perfluoroalkyl groups in β-diketones and β,β′-triketones may hinder enolization despite their electron-attracting effect.     

Reactions of diorganoytterbium compounds with ketones and aldehydes

Reactions of the diorganolanthanoids R₂Yb (R = PhCC or C₆F₅) with aldehydes (R′CHO) and ketones (R′₂CO) (R = Me or Ph) followed by hydrolysis generally gives the alcohols RR′CH(OH) or RR′₂COH, but, with benzophenone, reduction giving benzopinacol either competes (R = PhCC) or is predominant (R = C₆F₅).     

The dark reactions F2 + CF3I,C2F5I,and n-C3F7I

The reactions between F₂ and the lowest members of the homologous series of perfluoroalkyl iodides (CF₃I, C₂F₅I, and n-C₃F₇I) have been studied. For these compounds, an exponential decrease in the alkyl iodide concentration over time following an induction period is observed for certain experimental conditions. Other conditions lead to chaotic-like kinetic behavior where the rate of alkyl iodide consumption continually changes. Kinetic rate data with CF₃I show that the disappearance rate depends upon both the type of surface and surface preparation. For all three compounds, Arrhenius plots reveal activation energies on the order of 10 kcal/mol, consistent with effective initiation steps of F₂ + RI → RIF + F, where R represents the CF₃, C₂F₅, or n-C₃F₇ radical respectively. The end products of the F₂ + RI reactions are RF, R₂, and IF₅, suggesting that the R radicals play an important kinetic role. Introducing O₂ into the F₂ + RI reaction systems results in successive oxidation of R by O₂, leading to the formation of CF₂O as an additional end product. IF(B → X) emission is observed from the RI-rich F₂ + RI reactions, confirming the existence of IF as an intermediate. © 1996 John Wiley & Sons, Inc.     

The reaction of perfluoro-2,4-dialkyloxolanes with anhydrous aluminum chloride

Several kinds of perfluoro-2,4-dialkyloxolanes (A), having such alkyl groups as R_fR′_fCF₃ (2a); R_fC₂F₅, R′_fCF₃ (3a); R_fCF₃, R′_fC₂F₅ (4a); R_fR′_fC₂F₅ (5a); R_fCF₃, R′_fnC₃F₇ (6a) on the 2 and 4 positions of the oxolane ring, respectively, were treated with AlCl₃ in a heterogeneous reaction to give the corresponding perfluoro-2,5,5-trichloro-2,4-dialkyloxolanes (B). For purposes of comparison, the respective reactions of perfluoro-2-methyl-oxolane (la), perfluoro-2-n-butyloxolane (7a), and perfluoro-2, 5-dimethyloxolane (8a) with AlCl₃ were also conducted. An increasingly higher reaction temperature was needed for the reaction of A with AlCl₃ to give B as the carbon number of A increased. Cis- and trans-perfluoro-4-chloro-2,4-dimethyl-γ-butyrolactones (2c) were obtained from the hydrolytic reactions of cis- and trans-perfluoro-2,5,5-trichloro-2,4-dimethyloxolanes (2b), respectively, with fuming H₂SO₄. Physical properties and ¹⁹F nmr data are given for these new compounds.     

Action des perfluoroalkylcuivre(I) sur les perfluoroalkylethylenes

A series of new polyfluorinated dienes 3, containing the novel -CFCHCHCF-, pattern has been synthesized (50–70% yields) by reacting perfluoroalkyl iodides with perfluoroalkyl-ethylenes in the presence of copper. The monoalkenes R_fCFCHCH₂CF₂R′_f and the saturated compounds R_fCF₂CH₂CH₂CF₂R′_f were obtained by varying the experimental conditions. The ¹H and ¹⁹F NMR spectra are analysed and the reaction mechanism is discussed.     

Synthese de polysiloxanes fluores. Partie IV. Obtention de disiloxanes fluores

New disiloxanes containing aromatic or aliphatic fluorinated groups are prepared and identified. The general formula of these compounds is: R_F-Q-CH₂-CH₂-Si(CH₃)₂-O-Si(CH₃)₂-CH₂-CH₂-Q′-R′_F · R_F and R′_F are halogenated groups such as C₆F₅-, C_nF_2n+1-, Cl(CFCl-CF₂)_n, CF₃-CFH-CF₂-, CF₃-, or CCl₃-. In most cases, Q or Q′ is an oxygen atom. Symmetrical disiloxanes are obtained by hydrolysis of corresponding fluorinated monochlorodimethylsilanes, and the asymmetrical ones are prepared in two steps by reacting the fluorinated olefins H₂C = CH-Q-R_F and H₂C = CH-Q′-R′_F with dihydrotetramethylsiloxane. The structures of these various compounds are elucidated by ¹H-, ¹³C- NMR and IR spectroscopy     

Transmission of electronic effects in certain ployenes

The effect of substituent variation in compounds of the general type R(CHCH)_nCHO (1) or p-RC₆H₄ (CHCH)_nCHO (2) on the stretching vibrations of the CHO group (ν_co), the dipole moments (μ), the long wave maxima (λ_max), and the halfwave potentials (E_{$\text{1}\text{2}$}) for the polarographic reduction of the CHO group have been studied as well as the influence of variation of substituent R on the rate constants (k) of the alkaline hydrolysis of polyenic esters R(CHCH)_nCOOEt (3). A linear relationship between the σ⁺, σ_c⁰ or σ_c⁺ values and the experimental values of ν_co, μ, gl_max, E_{$\text{1}\text{2}$} and k has been established, which indicates the importance of the mesomeric mechanism of the transmission of electronic effects through the chain of conjugated double bonds in compounds 1, 2 and 3. Transmission coefficients (π′) for one (π′_1F), two (π′_2F), three (π′_2F), and four (π′_4F) double bonds were calculated, and it was found that these values are bound together by the ratio: (π′_1F):(π′_2F):(π′_3F):(π′_4F) = (π′_1F):(π′_1F)²:(π′_1F)³:(π′_1F⁴, i.e. the influence of substituents R is decreased m a geometrical progression when the number of double bonds increases. The distribution of the electronic density in 1 was calculated by the LCAO SCF method in the Pariser-Parr-Pople approximation, and it was found that the π-electronic density values at the O atoms of the CHO group correlates well with σ_c⁰ constants and the calculated values of π′_1F, π′_2F, and π′_3F are bound together by the above ratio.     

Darstellung und charakterisierung von (CF3)2PPH2 und (CF3)2AsPH2

(CF₃)₂EPH₂ (E = P,As) may be prepared in high yield by the cleavage of M-P bonds in compounds of the type R₃MPH₂ (M = Si, Ge, Sn) with (CF₃)₂EX (X = Cl, Br, I). The direction of bond fission depends on X and on the reaction temperature. These new compounds may also be obtained, but in lower yield, by the reaction of LiAl(PH₂)₄ with (CF₃)₂EX. Application of the principle of this reaction to other R′₂EX compounds [(CH₃)₂PCl, (CH₃)₂AsI, F₂PX (X = Br, I)] has been investigated. The IR and NMR spectra of the new compounds are reported.     

Fluoroalcohols as solvents for aliphatic polyamides

Some fluoroalcohols have been prepared by free-radical addition of methanol, ethanol and isopropanol to fluoroolefins as C₃F₆, CFHCFCF₃, (CF₃)₂CFCFCFCF₃, H(CF₂)₄CFCF₂, The general reaction is (1) R_fCFCF₂ + RR′CHOH = R_fCFHCF₂CRR′OH where R_f is a fluoroalkyl group, R and R′ are H or CH₃. NMR data of these alcohols are reported. 2,2,3,4,4,4-hexafluorobutanol (HFB) shows the best solvent ability among the compounds of this class. Its properties and solvent power have been evaluated and compared to the ones of trifluoroethanol (TFE) and hexafluoroisopropanol (HFIP). Some toxicological data related to HFB, TFE and HFIP are also reported.Owing to their strong tendency to form hydrogen bonds, fluoroalcohols are excellent solvents for polymeric materials which possess receptive sites for hydrogen bonding formation. The bonding power of the OH has been investigated by IR and NMR Spectroscopy on amide-group containing substrates. The properties and the correlations observed have pointed out that HFB may be usefully used as solvent for some aliphatic polyamides as Nylon 6.The polymer-solvent system Nylon 6-HFB has been studied and the constants of Mark-Houwink equation determined.     

Perfluormethyl-element-liganden XXVlI [1] Darstellung und spektroskopische untersuchung von W(CO)5L-komplexen (L = R2EER′2, R2EE′R; R,R′ = CH3; CF3; E = P,As; E′ = S,Se, Te)

W(CO)₅L complexes (L = R₂EER′₂, R₂EE′R; R, R′ = CH₃, CF₃; E = P, As; E′ = S, Se, Te) have been prepared by reaction of W(CO)₅·THF with L at room temperature or by redistribution reaction of W(CO)₅E₂Me₄ with E₂(CF₃)₄ or E′₂Me₂ as well as by cleavage of E₂(CF₃)₄ with W(CO)₅EMe₂H. The new compounds were characterized by analytical and spectroscopic (IR, NMR, MS) methods; by comparison with of the data of free and coordinated ligands the effects of complexation are studied.     

Fluorocarbon derivatives of nitrogen. Part 10. Preparation of heptafluoro- and 1-chlorohexafluoro-2-nitrosopropane,and conversion on the latter to chloropentafluoroacetone oxime

Details are given for the preparation of heptafluoro-2-nitrosopropane and 1-chlorohexafluoro-2-nitrosopropane $\text{via}$ the routes CF₃CFCF₂ → [with CsFR_FCO₂Ag (R_F = CF₃, nC₃F₇)] (CF₃)₂CFAg → (with NOCl) (CF₃)₂CFNO and CF₃CFCF₂ → (with CsClNOCl) CF₃(CF₂Cl)CFNO, respectively, and for conversion of the latter nitroso-compound to chloropentafluoroacetone oxime $\text{via}$ reduction with aqueous potassium hydrogen sulphite.     

Relative rate constants for reactions of HFC 152a, 143, 143a, 134a,and HCFC 124 with F or Cl atoms and for CF2CH3, CF2HCH2, and CF3CFH radicals with F2, Cl2, and O2

Relative rate experiments using UV photolysis of F₂ or Cl₂ have been used to determine rate constant ratios for several hydrofluorocarbon (HFC) reactions with Cl or F atoms and for HFC alkyl radicals with molecular halogens. For mixtures with F₂ present, dark reactions are, also, observed which are attributed to thermal dissociation of the F₂ to form F atoms. At 296 K, the rate of reaction (1a) [CF₂HCH₃ + F → CF₂CH₃ + HF] relative to (1b) [CF₂HCH₃ + F → CF₂HCH₂ + HF] is k_1a/k_1b = 0.73 (±0.13) and is independent of T (= 262–348 K). At 296 K, the ratio of reaction (2a) [CF₂HCH₂F + F → products] to that of (k_1a + k_1b) is (k_1a + k_1b)/k_2a = 2.7 (±0.4), and for reaction (2b) [CF₃CH₃ + F → products] (k_1a + k_1b)/k_2b = 22 ± 12. The temperature dependence (263–365 K) of the rate constant of reaction (3) [CF₃CFH₂ + Cl → products] relative to reaction (4) [CF₃CFClH + Cl → products] is k₃/k₄(±10%) = 1.55 exp(?300 K/T). For the alkyl radicals formed from HFC 152a (CF₂HCH₂ and CF₂CH₃) and from HFC 134a (CF₃CFH), rate constants for the reactions with F₂ and Cl₂ were measured relative to their reactions with O₂. The rate constant of reaction (5cl) [CF₂CH₃ + Cl₂ → CF₂ClCH₃ + Cl] relative to (5o) [CF₂CH₃ + O₂ → CF₂(O₂)CH₃] is k_5cl/k_5o(±15%) = 0.3 exp(200 K/T). For reaction (5f) [CF₂CH₃ + F₂ → CF₃CH₃ + F], k_5f/k_5o(±35%) = 0.23. The ratio for reaction (6f) [CF₂HCH₂ + F₂ → CF₂HCH₂F + F] relative to (6o) [CF₂HCH₂ + O₂ → CF₂HCH₂O₂] is k_6f/k_6o(±40%) = 1.23 exp(?730 K/T). The rate constant ratio for reaction (8cl) [CF₃CFH + Cl₂ → CF₃CFClH + Cl] relative to reaction (8o) [CF₃CFH + O₂ → CF₃CFHO₂] is k_8cl/k_8o(±18%) = 0.16 exp(?940 K/T). For reaction (8f) [CF₃CFH + F₂ → CF₃CF₂H + F], k_8f/k_8o(±35%) = 0.6 exp(?860 K/T). © 1993 John Wiley & Sons, Inc.     

The reaction of fluorine atoms with formyl fluoride and the CFO self-reaction at 293 K

A fast-flow apparatus with mass spectrometric detection was used to study the system F + CHFO between 2 and 3.5 mbar total pressure. The rate constant of the primary reaction was evaluated directly to yield at 298 K k₍₁₎ = (8.8 ± 1.4) * 10^?13 cm³ * molecule^?1 * s^?1. Numerical modelling was used to determine the rate constant at 298 K of the subsequent reaction CFO + CFO → CF₂O + CO: k₍₂₎ = (4.9 ± 2.0) * 10^?11 cm³ * molecule^?1 * s^?1. The possible occurrences of secondary reactions, CFO + F + M → CF₂O + M, and CFO + F₂ → CF₂O + F, can be excluded under the present conditions. © 1993 John Wiley & Sons, Inc.     

Synthesis and reactions of fluorinated iminium salts

Different methods for the preparation of fluorinated iminium salts RR¹CNR²R³⁺MF₆^? (R=R¹=F ; R²=R³=CH₃, C₂H₅ M=As, Sb 4a ? c R=H, R¹=F; R²=R³=CH₃ M=As, Sb 5a, b R=R¹=CF₃; R²=H, R³=CH₃ M=Sb 12 R=R¹=CF₃; R²=R³=CH₃ M=As 14) are reported, the spectroscopic properties (IR, NMR) of the cations of these salts are briefly discussed. By F^?-addition to these salts, $\text{e.g.}$ to 16, perfluoroalkyl-bis(alkyl)-amines ($\text{e.g.}$ (CF₃)₂CFN(CH₃)₂ 15) can be prepared; from the methylation of CF₃NCF₂ bis(trifluoromethyl) methylamine (CF₃)₂NCH₃ (11) was obtained.     

Verbindungen des Typs (F3C)2EE′R mit Pseudohalogen-Charakter (E = P,As; E′ = S,Se, Te)

Perfluoromethyl Element Ligands. XLI. [1] Compounds of the Type (F₃C)₂EE′R with Pseudohalide Character (E = P, As; E′ = S, Se, Te) Perfluoromethyl phosphorus and -arsenic compounds of the type (F₃C)₂EE′R (E = P, As; E′ = S, Se, Te; R = organic group) are prepared either by dismutation (metathesis) of E₂(CF₃)₄ with (RE′)₂ or by reaction of the iodine compounds (F₃C)₂EI with mercury(II) organosulfanides Hg(SR)₂ and characterized by spectroscopic (¹H, ¹⁹F, ³¹P-NMR; IR; MS) as well as analytical investigations (C, H).     

Organothallium compounds : XVII. Halogenobis(polyfluorophenyl)thallium(III) complexes

The preparations, stabilities and structures of the complexes R₂TlX and R₂ LTlX (R = C₆F₅, p-HC₆F₄, or o-HC₆F₄; X = Br or Cl; L = Ph₃PO, 2,2′-bipyridyl (bpy) or Ph₃P) have been examined or (R = C₆ F₅) reinvestigated. The derivatives R₂TlX are monomeric in acetone, from which the complex (p-HC₆F₄)₂ Me₂COTIBr has been isolated. In this solvent, the complexes R₂LTlX (L = Ph₃PO, bpy, or Ph₃P) undergo partial dissociation by loss of L. When L = bpy, there is also slight ionization into R₂LTl⁺ and R₂TlX^?₂. The acceptor properties of R₂TlX compounds towards uncharged ligands decrease R = C₆F₅ ? p-HC₆F₄ > o-HC₆F₄ > Ph. Dimeric behaviour is observed for R₂TIX compounds in benzene, whilst R₂LTlX (L = Ph₃PO or bpy) derivatives show slight but significant association. In the solid state, R₂TlX compounds are considered to be polymeric with five coordinate thallium, and R₂LTlX derivatives to be dimeric with five (L = Ph₃PO) or six (L = bpy) coordinate thallium by contrast with four coordinate dimeric and four or five coordinate monomeric structures previously proposed for the respective pentafluorophenyl derivatives. Halogen bridging is unsymmetrical for R = C₆F₅ or p-HC₆F₄, but may be more symmetrical for R = o-HC₆F₄ when L = Ph₃PO or bpy. Reported structural data for the complexes (C₆F₅)LTlX (L = Ph₃AsO, Ph₃P, Ph₃As, or 1,10-phenanthroline; X = Br or Cl) and (C₆F₅)₂TlCl^?₂ are reinterpreted and the proposed structures revised.     

Thermolyse des halogenures de perfluoroalcanesulfonyle

Perfluoroalkanesulfonyl chlorides [R_FSO₂Cl ; R_F  CF₃, C₂F₃, C₄F₉], decompose thermally to give the corresponding perfluoroalkyl chlorides with evolution of SO₂. The latter retards the reaction, but it is catalysed by copper which also inhibits the SO₂ effect. 2-methyl-2-nitrosopropane traps the perfluoroalkyl free radicals. In the presence of a perfluoroalkyl iodide [R′_FI ≠ R′_F≠R_F], other products, R_FI and R_FCl, are obtained. A free radical chain-mechanism is then suggested.On the other hand, perfluorobutanesulfonyl fluoride is very stable thermally.