Thermolyse des anhydrides perfluoroalcanesulfoniques. Mecanisme et application a la synthese des esters RFSO3RF.

Perfluoroalkanesulfonic anhydrides [(R_FSO₂)₂O; R_F=CF₃,C₂F₅,C₄F₉], mixed with the parent acid, decompose thermally to give the corresponding perfluoroalkyl perfluoroalkanesulfonates (R_FSO₃R_F) with liberation of SO₂. If the perfluoroalkyl moieties in the anhydride and the acid are different, a mixture of symmetric and unsymmetric esters is obtained. An ionic bimolecular mechanism is deduced from the results, and a new easy synthesis of the symmetric perfluorinated sulfonic esters is proposed.     

Synthese et reactivite d'organomagnesiens perfluores. V.[1] Synthese et identification de nouveaux composes perfluoroalkyles du mercure a chaine longue.

The reaction of mercuric salts HgY₂ or organic mercuric compounds R_HHgX with long chain perfluorinated Grignard reagents R_FMgBr leads to a series of new perfluoroalkyl mercury derivatives with the general formula R_FHgZ (R_F=C₄F₉, C₆F₁₃, C₈F₁₇ ; Z=R_F,R_H,Y with Y = I,Br,Cl, NO₃,OCOCH₃,OCOCF₃).The synthesis of these organomercuric compounds is described, and their spectroscopic properties are reported.     

The reactions of perfluoro- and α,α-dichloropolyfluoroalkanesulfinates

Sodium perfluoroalkanesulfinate, R_FSO₂Na [R_F?Cl(CF₂)₄, 1a; CF₃(CF₂)₅, 1b; Cl(CF₃)₆, 1c] reacted with bromine in aqueous solution to give the corresponding sulfonyl bromide R_FSO₂Br (2a-2c) and in acetonitrile or acetic acid, to form perfluoroalkyl bromide R_FBr (3a-3c). Heating in acetonitrile at 80°C, 2a-2c were converted smoothly into 3a-3c. However, reaction of sodium α,α-dichloropolyfluoroalkanesulfinate RCCl₂SO₂Na (R?CF₃, Cl(CF₂)n, n=2, 4, 6, 5a-5d) with bromine in aqueous solution gave directly the corresponding bromoalkanes 1-bromo-1,1-dichloropolyfluoroalkane RCCl₂Br (6a-6d). In aqueous potassium iodide solution, 1a-1c, 5a and 5b also reacted with iodine to form the corresponding iodo-polyfluoroalkane 4a-4c, 7a and 7b directly. 6a and 7a underwent free radical addition to alkene readily in the presence of free radical initiator and reacted with Na₂S₂O₄ in the usual way to form α,α-dichloropolyfluoroethane sulfinate (5a). 5a was stable in strong acid, but reacted with strong base to yield 10. 5a was oxidised by hydrogen peroxide to the sulfonate 11 and reduced by zinc in dilute acid to from the α-chloro sulfinate 12.     

Fluorination of perfluoroalkylsulfenyl chlorides,perfluorodialkyl disulfides and perfluorodialkyl sulfides with chlorine monofluoride

In reactions with perfluoroalkylsulfenyl chlorides (R_fSCl; R_f = F₃, C₂F₅, n-C₃F₇, n-C₄F₉) and perfluoroalkyl disulfides (R_fSSR_f′; R_f = R_f′ = CF₃, R_f = CF₃, R_f′ = C₂F₅) at 25°, chlorine monofluoride acts primarily as a chlorinating and fluorinating reagent to give the corresponding perfluoroalkylsulfur chloride tetrafluorides, R_fSF₄Cl, in good yields. However, small amounts of perfluoroalkylsulfur pentafluorides, R_fSF₅, are also obtained. A mixture of the cis and trans isomers of bis(trifluoromethyl)sulfur tetrafluoride and of trifluoromethyl pentafluoroethylsulfur tetrafluoride has been formed by the reaction of the corresponding bis(perfluoroalkyl) sulfides and chlorine monofluoride. The new perfluoroalkylsulfur chloride tetrafluorides are colorless, unpleasant smelling liquids. The infrared, mass and ¹⁹F NMR spectral data, as well as thermodynamic and elementary analysis data, are given for the new compounds.     

Synthese et application de nouveaux sulfures a chaine perfluoree

Metallation of thiols R_FC₂H₄SH followed by alkylation with iodides R′_FC₂H₄I leads either to symmetrical or to unsymmetrical sulphides R_FC₂H₄SC₂H₄R′_F (with R_F=R′_F or R_F ≠ R′_F). All compounds obtained are good solvents of gases (particularly O₂, CO, CO₂, N₂).This property allows their application as biological carriers of dissolved gases.     

Azidoperfluoroalkanes: Synthesis and Application in Copper(I)‐Catalyzed Azide–Alkyne Cycloaddition

We report an efficient and scalable synthesis of azidotrifluoromethane (CF₃N₃) and longer perfluorocarbon‐chain analogues (R_FN₃; R_F=C₂F₅, ⁿ C₃F₇, ⁿ C₈F₁₇), which enables the direct insertion of CF₃ and perfluoroalkyl groups into triazole ring systems. The azidoperfluoroalkanes show good reactivity with terminal alkynes in copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC), giving access to rare and stable N ‐perfluoroalkyl triazoles. Azidoperfluoroalkanes are thermally stable and the efficiency of their preparation should be attractive for discovery programs.     

Electron structure and reactivity of organofluorine compounds. 3. Mndo and ami calculations of the ground state of perfluoroalkyl chlorides,bromides, and iodides

The semiempirical quantum chemical MNDO and AMI methods were used to determine the equilibrium geometries and electron properties of molecules of perfluoroalkyl halides (R_FX): CF₃X, CF₃CF₂X, (CF₃)₂CFX, (CF₃)₃CX for X=Cl, Br, and I. It was determined that the effective charge on the Cl atom in R_FCl is negative, positive on the I atom in R_FI, and depends on R_F for the Br atom in R_FBr. The CF₃ group can act as either an electron acceptor or donor in various perfluoroalkyl halides. The strongest C–I bond in the perfluoroalkyl halides occurs with a tertiary RF group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1059–1063, May, 1990.     

Perfluoro and polyfluoroalkanesulfonic acid: XVII. Difluoromethyl perfluoroalkanesulfonates and their reactions

In contrast to R_FSO₃CH₂R(1)(R=hydrogen, alkyl and perfluoroalkyl) and R_FSO₃CF₂R_F′ (2), the reactions of difluoromethyl perfluoroalkanesulfonates RFSO₃CF₂H (3) With nucleophiles are more complicated. Halide inos, X^? (X = F, Cl, I) and ethanol only attack the alkoxyl carbon atom, cleaving the C? O bond to give HCF₂X (4) and HCF₂OEt (5) respectively. Other reagents such as RCO₂^? (R=CH₃, CF₃), C₆H₅S^? etc. can either attack the carbon or sulfur atom of 3 to give the corresponding products of C? O and S? O bond cleavages. More basic nucleophiles RO^? (R = C₆H₅, Et) mainly abstract the proton of the HCF₂ moiety to produce difluorocarbene. Ether and benzene, which can be alkylated by methyl perfluoroalkanesulfonate, do not react with 3 under similar conditions. The reaction rate of 3 with KF is much slower than that of 1 (R = H). All these data seem to indicate that the shielding effect caused by the two fluorine atoms on the methyl carbon in 3 prevents to some extent the nucleophilic attack on this carbon, but not so completely as in 2 due to the presence of a hydrogen atom.     

The effects of fluorine substitution on the 35Cl NQR spectra of fluoroaromatic compounds containing element-chlorine bonds

The ³⁵Cl NQR spectra of pentafluorosubstituted derivatives of benzene C₆F₅X (X = NPCl₃, CONPCl₃, SO₂NPCl₃, NCCl₂, SCl, COCl, SO₂NCl₂, CONCl₂, PCl₂, SO₂Cl) and phosphazocompounds (dimers, [RNPCl₃]₂; R = C₆F₅, C₆H₅, 2,3,5,6-tetrafluoropyridyl) have been recorded and interpreted. On passing from phenyl to pentafluorophenyl derivatives, the ³⁵Cl NQR frequencies increased. The influence of the relative numbers and positions of the fluorine atoms in the benzene ring on the ³⁵Cl NQR frequencies of fluoro-containing benzoyl chlorides has been discussed. The results are explained in terms of charge alteration on chlorine under the influence of the aromatic fluorine atoms. A linear correlation has been found between ³⁵Cl NQR frequencies of pentafluorophenyl derivatives and those of their hydrocarbon analogues. A relationship between elecronegativity of the element and the ionic character of the element-chlorine bond has been revealed. The reactivities of pentafluorophenyl and phenyl derivatives containing element-chlorine bonds have been predicted using the ν_Cl values.     

Studies on fluoroalkylation and fluoroalkoxylation: 2. Perfluoroalkylation of aromatics with perfluoroalkyl iodides in the presence of copper

Perfluoroalkyl iodide R_fI [R_f = (CF₂)_nO(CF₂)₂SO₂F, n = 2, (a); n = 4, (b); (CF₂)₄Cl, (c)] reacted with substituted benzene C₆H₅Y (Y = alkyl, OCH₃, CF₃, F, Cl, Br, I) in the presence of copper in acetic anhydride to give the corresponding mixture of isomeric disubstituted benzene (R_fC₆H₄Y). The conversion and yield depend on both the amount of copper used and nature of substituent. The likely explanation is that the reaction may involve a free radical process. The perfluoroalkyl radical can be trapped by cyclohexene, isopropylbenzene and styrene. Using DMSO in place of acetic anhydride as a solvent the reaction takes a different course, it is believed that the reaction in DMSO proceeds through a perfluoroalkylcopper intermediate.     

Thermolyse von Phosphor(V)-Schwefel(VI)-nitridhalogeniden

Thermolysis of Phosphorus(V) Sulfur(VI) Nitride Halides Thermolysis of compounds of the type R₂PCl = N–SO₂X (R = Cl, CH₃, C₆H₅; X = F, Cl) results in the formation of the compounds R₂P(O)Cl and [NS(O)X]_n. Pyrolysis of the title compounds with longer chains yields, among others, the cyclic compounds III and IX. IX is also one of the decomposition products of a sulfamide derivative (XXI). Finally the thermal behaviour of carbon containing phosphorus(V) sulfur(VI) nitride chlorides has been investigated.     

Bis- and tris-(trimethylsilyl)methyl derivatives of antimony

Reaction of RMgCl [R = (Me₃Si)₂CH) with SbCl₃ affords RSbCl₂. Also R₂SbCl reacts with RLi to yield R₃Sb, while R′SbCl₂ [R′ = (Me₃Si)₃C] is synthesized from R′Li and SbCl₃. Mass spectra of RSbCl₂ and R′SbCl₂ show that fragmentations proceed with elimination of Me₃SiCl. The chlorides RSbCl₂, R₂SbCl and R′SbCl₂ are thermally very stable.     

Photoinitiated Reactions of Haloperfluorocarbons with Gold(I) Organometallic Complexes: Perfluoroalkyl Gold(I) and Gold(III) Complexes

The study of perfluoroalkyl metal complexes is key to understand and improve metal-promoted perfluoroalkylation reactions. Herein, we report the synthesis of the first gold complexes with primary or secondary perfluoroalkyl ligands by photoinitiated reactions between Au^I organometallic complexes and iodoperfluoroalkanes. Complexes of the types LAuR_F (L=PPh₃ or N,N-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; R_F=n-C₄F₉, n-C₆F₁₃, i-C₃F₇, c-C₆F₁₁) and [Au(R_F)(Ar)I(PPh₃)] (Ar=2,4,6-trimethylphenyl) have been isolated and characterized. Alkynes R_FC≡CR were formed by reaction of Ph₃PAuC≡CR (R=Ph, nHex) with IR_F (R_F=n-C₄F₉, i-C₃F₇). According to the evidences obtained, this transformation undergoes through a photoinitiated radical mechanism. Au^III complexes [Au(n-C₄F₉)(X)(Y)L] (X=Y=Cl, Br, I, Me; X=Me, Y=I) have been prepared or in situ generated, and their thermal or photochemical decomposition reactions have been studied.     

Electron structure and reactivity of organofluorine compounds. 4. AMI calculations of anion radicals of primary,secondary, and tertiary perfluoroalkyl chlorides,bromides, and iodides

Calculations were carried out using the semiempirical quantum chemical AMI method for anion radicals (AR) of the perfluoroalkyl halides (R_FX): CF₃X, CF₃CF₂X, (CF₃)₂-CFX, and (CF₃)₃CX for X=Cl, Br, and I. All the AR's studied are thermally stable. The electron affinity of the perfluoroalkyl halides, and consequently, the thermal stability of their AR's increases in the series from F-methyl to F-tertbutyl halides and from the chlorides to bromides and iodides. During formation of an AR the spin density is preferentially localized on the * orbital of the C–X bond which leads to an increase in the distance between these atoms. Dissociation of the AR of tert-perfluorobutyl iodide to a perfluorocarbanion and an I atom is thermodynamically more favorable than dissociation with formation of a perfluoroalkyl radical and I^–.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1064–1068, May, 1990.     

19F nmr spectra of mesomeric carbanions generated from polyfluorodiarylacetonitriles. The electronic effect of perfluoroalkyl groups

¹⁹F NMR spectra of 1,2- dimethoxyethane solutions of Na- and Li- salts of polyfluorinated carbanions [p - RC₆F₄$\text{C}$(CN)C₆F₄R′-p] Na⁺ (Li⁺) and of their neutral precursors p-RC₆F₄CH(CN)C₆F₄R′-p / R  F or CF₃ and R′= CF₃, CF₂CF₃, CF(CF₃)₂ and C(CF₃)₃/ have been studied. The values of changes in the chemical shifts of fluorine atoms in the ring and the side chain are practically the same when going from the precursor to carbanion with the perfluoroalkyl group being varied. This gave grounds to conclude that the electronic effect of the perfluoroalkyl groups is rather similar. The ¹⁹F NMR method has revealed no differences in the predominant mechanism of the negative charge distribution by these groups.     

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.     

New nitrosyl(perfluorocarboxylato) complexes of the platinum metals

Perfluorocarboxylic acids (R_FCOOH) (R_F = CF₃,C₂F₅ and (for Rh) C₆F₅) react with the species [M(NO)₂(PPh₃)₂] (M = Ru, Os) and [M′(NO)(PPh₃)₃] (M′ = Rh, Ir) to yield new nitrosyl complexes [Ru(OCOR_F)₃(NO)(PPh₃)₂], [OsH(OCOR_F)₂(NO)(PPh₃)₂], [Os(OCOR_F)(NO)₂(PPh₃)₂][OCOR_F], [Ir(OCOR_F)(NO)(PPh₃)₂][OCOR_F] and [Rh(OCOR_F)₂(NO)(PPh₃)₂].     

Reactivite comparee des perfluoroiodoalcanes (RFI) et des perfluoroalcoyl-2 iodo-1 ethanes (RFC2H4I) en presence de couple metallique zinc-cuivre dans les solvants phosphates d'alcoyles

Reactivity of perfluoroalkyl iodides R_FI and 1-perfluoroalkyl-2-iodoethanes R_FC₂H₄I, in presence of a zinc-copper couple in alkyl phosphates solvents, is described. R_FI and R_FC₂H₄I react via an organometalllc route to give per- and poly-fluoroorganozinc (R_FZnI and R_FC₂H₄ZnI) compounds. Then, in particular conditions, they react with alkyl to give phosphoro-fluorinated molecules (phosphinates, phosphine oxides, phosphines). The compounds's stabilities are studied.     

Synthesis of 2-(perfluoroalkyl)ethyl potassium sulfates based on perfluorinated Grignard reagents

The first example of nucleophilic substitution with perfluoroalkyl Grignard reagents on the sp³ carbon centre is described. Thus, a series of organometals R_F-MgBr, prepared from perfluorinated alkyl iodides R_F-I with R_F = C₄F₉, C₆F₁₃, C₈F₁₇, C₁₀F₂₁ and C₁₂F₂₅, reacted with 1,3,2-dioxathiolane-2,2-dioxide to afford the corresponding 2-(perfluoroalkyl)ethyl magnesium sulfates, which were isolated after metathesis to the corresponding potassium salts. In the model reaction, perfluorohexylmagnesium iodide was reacted with methyl triflate yielding polyfluorinated alkane. The attempts to extend the reaction to 1,3,2-dioxathiane-2,2-dioxide were unsuccessful due to its inferior reactivity and only reduced polyfluoroalkane and the product of coupling were detected in the reaction mixture. Polyfluorinated sulfates are easily hydrolyzed with hydrochloric or triflic acid to the corresponding alcohols, which is an alternative to standard transformation of perfluoroalkyl iodides to 2-(perfluoroalkyl)ethanols. Quantum-chemical calculations of the PES of the reaction with both sulfur-containing heterocycles found that the failure of the reaction with 1,3,2-dioxathiane-2,2-dioxide is caused by higher activation energy of the process.     

Efficient Cu‐catalyzed Atom Transfer Radical Addition Reactions of Fluoroalkylsulfonyl Chlorides with Electron‐deficient Alkenes Induced by Visible Light

Fluoroalkylsulfonyl chlorides, R_fSO₂Cl, in which R_f=CF₃, C₄F₉, CF₂H, CH₂F, and CH₂CF₃, are used as a source of fluorinated radicals to add fluoroalkyl groups to electron‐deficient, unsaturated carbonyl compounds. Photochemical conditions, using Cu mediation, are used to produce the respective α‐chloro‐β‐fluoroalkylcarbonyl products in excellent yields through an atom transfer radical addition (ATRA) process. Facile nucleophilic replacement of the α‐chloro substituent is shown to lead to further diverse functionalization of the products.