Trityl-initiated copolymerizations of propylene oxide with tetrahydrofuran. VIII. Influence of reaction parameters

The copolymerization of propylene oxide (PO) with tetrahydrofuran (THF) in dichloroethane (DCE) has been studied at ?10, 0, +10, and +20°C. The reactions were initiated by triphenylmethyl cations associated with the following gegenions: PF₆^?, SbF₆^?, and AsF₆^?. The overall energies of activation (E_α of PO and E_a of THF) obtained with the three gegenions increase as one passes from PF₆^? to AsF₆^? then to SbF₆^?, though the magnitude of the increase in each case is not substantial. On the other hand, the associated frequency factors A show a considerable variation with the gegenion. The bimodal distributions of the molecular weights, obtained by GPC with the copolymer produced from reactions initiated with triphenylmethyl hexafluorophosphate, show that the proportions of the lower molecular weight component (L) decrease as the solvent is changed from DCE to toluene, and this is even more marked when bulk polymerization conditions are adopted. The proportions of the higher molecular weight component (H) however increase, as does its molecular weight. The GPC molecular weight distributions of the copolymers initiated with triphenylmethyl hexafluorophosphate in DCE to which water has been added, show that the molecular weight of component H decreases with increasing concentration of water, while that of component L remains practically unchanged at a value of 308. This corresponds to an average degree of polymerization (DP ) of 4 to 5. The NMR and infrared spectra of copolymers prepared in the presence of still higher initial water concentrations indicate that the PO-based polymer segments are present in excess of those required for a 1:1 copolymer.     

Kinetics and mechanism of the cationic polymerization of tetrahydrofuran in solution. I. THF–CCI4 system

Polymerization of THF in CCl₄ solvent was initiated with 1,3-dioxolan-2-ylium eations with AsF₆^?, PF₆^?, and SbF₆^? anions as well as with esters of fluorosulfonic and trifluoromethanesulfonic acids. With these esters polymerization proceeds with a marked acceleration period, due to slow initiation. The corresponding rate constants of initiation and their dependence on the polarity of the THF/CCl₄ mixture were determined. The rate constant of propagation on the macroion-pairs (k_p^±) of the polytetrahydrofurylium cation with AsF₆^?, PF₆^?, and SbF₆^? and CF₃SO₃^?, anions was found to be independent in CCl₄ solvent on the anion structure and given by the expression: k_p^± = 2.93 × 10^?2 exp {?4.7 × 10³/T} at [THF]₀ = 8.0M. This constant depends on the polarity of the polymerization mixture, and at 25°C for the THF-CCl₄ system, k_p^± = 1.78 × 10^?2 exp {?4.9/D}; thus, in CCl₄ at [THF]₀ = 8.0M, and at 25° k_p^± = 4.0 × 10^?21/mole-sec. In the polymerization with derivatives of CF₃SO₃H (able to form the corresponding macroester) the overall polymerization rate is much lower than that with complex anions because of the reversible conversion of the macroion-pairs into the macroester (internal return). The macroester is much less reactive than the macroionpair (10²–10³ times) in the monomer addition reaction. At [THF]₀ = 8.0M and at 25°C, 96.5% of the growing species exists in the macroester form. Polymerization of THF initiated with derivatives of CF₃SO₃H is a subject of a strong special salt-effect. At a sufficiently high ratio of [AgSbF₆] to [I]₀, where the initiator I is C₂H₅OSO₂CF₃, the overall polymerization rate is equal to that observed for the polymerization of THF on the macroion-pairs, since the internal return within the triflate ion-pair (the macroester formation) is eliminated and polymerization proceeds on the macroion-pairs with SbF₆- anions exclusively.     

Darstellung von μ-Schwefeldisulfoniumsalzen [(CH3)2S?Sx?S(CH3)2]2+2A− (x = 1–3, A− = AsF6−, SbF6−, SbCl6−). Über die Analogie im Reaktionsverhalten zwischen Sulfanen und Sulfoniumsalzen

Preparation of μ-Sulfurdisulfonium Salts [(CH₃)₂S? S_x? S(CH₃)₂]²⁺2A^? (x = 1–3, A^? = AsF₆^?, SbF₆^?, SbCl₆^?). On the Analogy of the Reactivity of Sulfanes and Sulfonium Salts The preparation of the μ-sulfurdisulfonium salts [(CH₃)₂S? S_x? S(CH₃)₂]²⁺(A^?)₂ with x = 1–3 and A^? = AsF₆^?, SbF₆^?, SbCl₆^? is reported. The salts are formed by reaction of (CH₃)₂SH⁺A^? and (CH₃)₂SSH⁺A^? with SCl₂ and S₂Cl₂, resp. They are characterized by vibrational spectroscopic measurements. [(CH₃)₂S? S₂? S(CH₃)₂]²⁺(SbF₆^?)₂ crystallizes in the space group C2/c with a = 1 884.5(7) pm, b = 1 302.8(5) pm, c = 1 477.2(5) pm, β = 98.62(3)° und Z = 8.     

Über die Kristallstrukturen von CH3PF2H+AsF6− und CH3PF2H+SbF6− und eine einfache Darstellung von CH3PF2

On the Crystal Structures of CH₃PF₂H⁺AsF₆^? and CH₃PF₂H⁺SbF₆^? and a simple Method for Preparation of CH₃PF₂ A simple method for preparation of CH₃PF₂ from CH₃PCl₂ is reported. The phosphonium salts CH₃PF₂H⁺MF₆^? are obtained by the reaction of CH₃PCl₂ with superacidic systems HF/MF₅ (M = As, Sb). CH₃PF₂H⁺SbF₆^? crystallizes in the space group P1 with a = 548.4(4) pm, b = 695.5(8) pm, c = 960.2(9) pm, α = 94.68(5)°, β = 97.19(6)°, γ = 94.41(6)° and Z = 2. CH₃PF₂H⁺SbF₆^? crystallizes in P1 with a = 554.3(3), b = 724.2(4), c = 970.4(5), α = 94.73(4)°, β = 96.14(5)°, γ = 95.30(4)°.     

Reaction of PF5·CH3CN with sulfide

Nitriles react with PF₅ and also with AsF₅, SbF₅ forming 1:1-adducts. Using C₂Cl₃F₃ as a solvent is of advantage for this reaction. PF₅·CH₃CN and [N(C₂H₅)₄]SH give [N(C₂H₅)₄][P₂S₂F₈] with a sulfur double bridge and hexafluorophosphate in acetonitrile [1]. In case of AsF₅·CH₃CN a salt with the anion [AsF₅NHCSCH₃]^? has been isolated [2]. Following products have been confirmed in a reaction mixture of PF₅·CH₃CN and SH^? in acetonitrile by NMR (³¹P and ¹⁹F): [PF₆]^?, [F₅PSPF₅]^2?,

, F₄PSH, F₃PS, HPS₂F₂, [PS₂F₂]^?, [F₅PNC(SH)CH₃]^?, [F₅PNHCSCH₃]^?, [F₅PSH]^?. With a ratio PF₅·CH₃CN: SH^? = 2:1 the S-bridge-complexes are prefered whereas in case of a ratio 1:1 the non-bridged P-complexes are the main products.     

Effect of the Counterion on the Cationic Polymerization Rate of Ethylene Oxide by Trityl Salts

The cationic polymerization of ethylene oxide by trityl salts (BF₄ ^?, SbCl₆ ^?, AsF₆ ^?, and PF₆ ^? as counterions) in nitrobenzene at different temperatures has been studied. The kinetic analysis was carried out by use of an automatic manometer, and it showed that the polymerization rate constant depends neither on the counterion type nor on the initial initiator concentration. These facts allowed us to conclude that macrocations and macroion pairs have the same reactivity.     

Redox cationic polymerization: The diaryliodonium salt/ascorbate redox couple

Strong Brønsted acids are produced on reduction of diaryliodonium salts containing anions of the type BF₄^?, AsF₆^?, PF₆^?, SbF₆^? by ascorbic acid and its derivatives in the presence of catalytic amounts of copper salts. The cationic polymerizations of cyclohexene oxide, tetrahydrofuran, and s-trioxane were studied using the diaryliodonium salt/ascorbate redox couple.     

Photoinitiated cationic polymerization by dialkyl-4-hydroxyphenylsulfonium salts

On irradiation with ultraviolet light, dialkyl-4-hydroxyphenylsulfonium salts undergo reversible photodissociation and in the process generate ylids and Brønsted acids. When the anions are nonnucleophilic in character, as, for example, BF₄^?, AsF₆^?, PF₆^?, and SbF₆^?, the strong acid which is produced is capable of initiating cationic polymerization. The polymerization of several monomers was carried out to demonstrate the general applicability of these new photoinitiators.     

Metallkomplexe mit anionischen Liganden von Elementen der 4. Hauptgruppe. XI. Substitutionsreaktionen der Trichlorgermid- und Trichlorstannid-Ionen an Metalltrifluorphosphin-Komplexen

Metal Complexes with Anionic Ligands of Main Group IV Elements. XI. Substitution Reactions of Trichlorogermide and Trichlorostannide Ions with Metaltrifluorophosphine Complexes The photochemical reactions of [SnCl₃]^? in THF with the metal(0)-trifluorophosphine complexes of Ni, Fe, and Mo result in [Ni(PF₃)₃SnCl₃]^?, [Fe(PF₃)₃(SnCl₂]^?, and [Mo(PF₃)₅SnCl₃]^?. [GeCl₃]^?, in substitution reactions not as reactive as [SnCl₃]^?, does react under similar conditions with Fe(NO)₂(PF₃)₂ only, to yield [Fe(NO)₂(PF₃)GeCl₃]^?. With CpMn(PF₃)₃ (Cp = h⁵-C₅H₅) by the intermediatly formed CpMn(PF₃)₂THF both substitution derivatives [CpMn(PF₃)₂ECl₃]^? (E = Ge, Sn) are found. The metallate(0) complexes are isolated as [As(C₆H₅))₄]⁺- and [N(C₂H₅)₄]⁺ -salts; the i.r.- and ¹⁹F-n.m.r.-spectra are reported.     

Beiträge zur Chemie der Schwefelhalogenide. 16. Dimethyliodsulfonium(IV)-Salze

Contributions to the Chemistry of Sulfur Halides. 16. Dimethyliodosulfonium(IV) Salts Some preparative methods of iodosulfonium(IV) salts, (CH₃)₂SI⁺AsF₆^? and (CH₃)₂SI⁺SbCl₆^?, are reported. These salts are stable up to ?20°C and they are characterized by Raman and n.m.r. spectroscopy.     

Cationic polymerization of N-vinyl carbazole by trityl salts—I.: Reactivity of propagating species

The cationic polymerization of N-vinyl carbazole, initiated by Ph₃C⁺ AsF₆^? and Ph₃C⁺ PF₆^? in methylene dichloride at 20 and 0°, has been studied in some detail. Reactions were very fast and rates of monomer consumption were measured using an adiabatic calorimetric technique. Initiation was relatively “slow” but complete, and termination was deduced to be insignificant during kinetic lifetimes. Values for k_p were found to vary with the initial initiator concentration; this dependence is discussed in terms of current theories regarding equilibria between ion pairs and free ions in non-aqueous solvents. k_p⁺ values estimated from two methods of extrapolation are 9.5 · 10⁵ M^?1 sec^?1 at 20° and 4.8 · 10⁵ M^?1 sec^?1 at 0°. Finally, it has been found that ion pairs are much less reactive than free ions in this system.     

π-Arene complexes of the main group elements. II. Complexes of cadmium(II) and zinc(II)

π-Arene complexes of cadmium(II) and zinc(II) have been prepared from the first time. The 1:1 complexes Cd(AsF₆)₂. Arene(Arene=hexaethylor hexamethylbenzene, pentamethylbenzene, durene, $\text{p}$-xylene or benzene), Cd(SbF₆)₂. Arene(Arene = hexamethylbenzene, toluene or benzene) and Zn(SbF₆)₂. Arene(Arene = hexamethylbenzene or pentamethylbenzene) are synthesized from the strong acid salt and arene in liquid sulfur dioxide. ¹H and ¹³C NMR spectra are consistent with localized bonding of the arene to the metal cation. Exchange-averaged vn]¹³C chemical shifts for the systems Cd(AsF₆)₂-arene-SO₂ confirm the 1:1 stoichiometry in solution and suggest that the stabilities of the complexes are in the approximate range 0.48 – 2.1 M^?1 for the series benzene-hexamethylbenzene. For the system Cd(AsF₆)₂-C₆Me₆-SO₂, a detailed ¹¹³Cd NMR study is consistent with the solution stoichiometry and stability determined from ¹³C NMR. In general, complexation to an arene produces deshielding of the ¹¹³Cd resonance of Cd(AsF₆)₂.     

Über die Darstellung der Pnikogenoniumsalze AsH4+SbF6−, AsH4+AsF6−, SbH4+SbF6−

On the Preparation of Pnikogenonium Salts AsH₄⁺SbF₆^?, AsH₄⁺AsF₆^?, SbH₄⁺SbF₆^? The preparation of the pnikogenonium salts AsH₄⁺SbF₆^?, AsH₄⁺AsF₆^? and SbH₄⁺SbF₆^? by protonation from the hydrides AsH₃, SbH₃ in superacidic systems HF/SbF₅ and HF/AsF₅, resp. is reported. The salts are characterized by vibrational and mass spectra. A general valence force field is calculated. The following onium ions are know as hexafluoroantimonate:      

Über die Darstellung der Trimercaptosulfoniumsalze [S(SH)3]+AsF6− und [S(SH)3]+SbCl6−

Preparation of Trimercaptosulfonium Salts [S(SH)₃]⁺AsF₆^? and [S(SH)₃]⁺SbCl₆^? The preparation of the trimercaptosulfonium salts [S(SH)₃]⁺AsF₆^? and [S(SH)₃]⁺SbCl₆^? from SCl₃⁺ salts with excessive H₂S at 193 K is reported. The [S(SH)₃]⁺SbCl₆^? is transferred into [S(SCl)₃]⁺SbCl₆^? by reaction with Cl₂ at low temperatures. The new [S(SH)₃]⁺ cation is isoelectronic to P(PH₂)₃. In addition, its existence is supported by an ab-initio calculation. The results show a potential well for C_3v configuration with SH bonds bended towards the top of the pyramid for the isolated ion. Also the results of a force-field calculation are reported.     

Bromsulfenyl(trihalogen)phosphonium-Salze Cl3−nBrnPSBr+AsF6− (n = 0 – 3) und Cl3PSBr+SbF6− — Oxidative Bromierung von Thiophosphorylhalogeniden

Bromosulfenyl(trihalogeno)phosphonium Salts Cl_3?nBr_nPSBr⁺AsF₆^? (n = 0 – 3) and Cl₃PSBr⁺SbF₆^? — Oxidative Bromination of Thiophosphorylhalides The bromosulfenyl(trihalogeno)phosphonium salts Cl_3?nBr_nPSBr⁺AsF₆^? (n = 0 – 3) and Cl₃PSBr⁺SbF₆^? are prepared by oxidative bromination of the corresponding thiophosphorylhalides with Br₂/MF₅ (M = As, Sb) and characterized by vibrational and NMR spectroscopy.     

Beiträge zur Chemie der Schwefel-Halogenide. 20. Di(methylthio)methyl- und Di(phenylthio)methylsulfonium-hexafluoroarsenat und -hexachloroantimonat

Contributions to the Chemistry of Sulfur Halides. 20. Di(methylthio)methyl- and Di(phenylthio)methylsulfonium Hexafluoroarsenate and Hexachloroantimonate Preparation and spectroscopic characterization of di(methylthio)methyl- and di(phenylthio)methylsulfonium salts CH₃S(SCH₃)₂⁺A^? and CH₃S(SC₆H₅)₂⁺A^? (A^? = AsF₆^?, SbCl₆^?) is reported. Complementary the crystal structure of di(methylthio)methylsulfonium hexafluoroarsenate has been determined.     

Antimonypentafluoroorthotellurates: Sb(OTeF5)3, Sb(OTeF5)5 and salts of Sb(OTeF5)6−

Antimony(III)pentafluoroorthotellurate has been synthesized from SbF₃ and B(OTeF₅)₃. Contrary to a previous report it is a low melting, sublimable solid (mp = 28°, bp (0.1 torr) = 68°, ¹⁹F - NMR: AB₄ spinsystem δ (A) = ?42.7, δ (B) = ?38.1, J (AB) = 186 Hz). It reacts with F₂, Cl₂ and Br₂ to give SbF₂(OTeF₅)₃, SbCl₄⁺Sb(OTeF₅)₆^? and SbBr₄⁺ Sb(OTeF₅)₆^? respectively. Interaction of Xe(OTeF₅)₂ and Sb(OTeF₅)₃ yields Sb(OTeF₅)₅, which is unstable at room temperature. Salts containing the new anion Sb(OTeF₅)₆^? have been synthesized either from Sb(OTeF₅)₅ and a corresponding pentafluoroorthotellurate e.g. Sb(OTeF₅)₅ + NMe₄⁺ OTeF₅^? = NMe₄⁺ Sb(OTeF₅)₆^?, or from SbCl₄ Sb(OTeF₅)₆^? and an appropriate chloride SbCl₄⁺ Sb(OTeF₅)₆^? + NOCl = SbCl₅ + NO⁺ Sb(OTeF₅)₆^?, or oxidatively, using a mixture of Xe(OTeF₅)₂ and Sb(OTeF₅)₅, e.g. C₆F₆ + $\text{1}\text{2}$ Xe(OTeF₅)₂ + Sb(OTeF₅)₅ = C₆F₆⁺ Sb(OTeF₅)₆^? + $\text{1}\text{2}$ Xe.     

X-ray Crystal Structure of (CNSSS)2(M)2 (M = AsF6 −, SbF6 −, Sb2F11 −)

The crystal structures of (CNSSS)₂(AsF₆)₂, (CNSSS)₂(SbF6)₂, and two phases of (CNSSS)₂(Sb₂F₁₁)₂ have been determined. The AsF₆ ^?, SbF₆ ^?, and α-Sb₂F₁₁ ^? salts crystallize as reddish-brown plates whereas the β-Sb₂F₁₁ ^? salt crystallizes as green rods. The dication ^ß+SSSNCCNSSS^+ß (1²⁺) is the same in all four structures and consists of two 7π rings linked by a sp²-sp² C-C bond (1.462 Å in 1 (AsF₆)₂). The packing in the four structures is similar with stacks of dications along the a-axis and alternating sheets of dications and anions lying in the bc-plane. The differences in the dication-dication contacts is reflected in the variable temperature magnetic data.     

pH determination in anhydrous hydrogen fluoride and superacid media by means of the chloranil electro-chemical indicator system

The electro chemical systems of chloranil (quinone/semiquinone and semiquinone/hydroquinone) are shown to be usable as pH indicators in anhydrous hydrogen fluoride and in the superacid mixtures HF + MF_n (where MF_n = PF₅, BF₃, TaF₅, NbF₅, AsF₅ and SbF₅). The combined use of both hydrogen and chloranil electrodes has allowed the establishment of a complete potential-pH diagram of chloranil in the whole acidity range of HF. The quinone/semiquinone system can be used at very high acidity levels (solutions of AsF₅ or SbF₅) where the hydrogen electrode does not function correctly. A new value of the autoprotolysis constant of HF is reported (K_i = [H⁺. [F^-] = 10^-13.7 mol² l^-2) and compared with earlier values. The equilibrium constants of acid-base systems of the quinone (Q/QH⁺) and hydroquinone (QH₂/QH₃⁺ and QH²⁺₄) forms of chloranil, and the disproportionation constant of the semiquinone (QH₂⁺ form are also reported. The indicator system allows the acidity levels reached in HF to be placed on an R(H) scale (where R(H) = 0 corresponds to pH = 0 in aqueous solution). These levels were found to lie between R(H) = -14.2 for 1 M KF solution and R(H) = -27.9 for 1 M SbF₅ (i.e. 18% by weight).