Studies on sulfinatodehalogenation: IV. The sulfinatodebromination of primary perfluoroalkyl bromides and perfluoroalkylene α, ω-dibromides

Using PTC or cosolvent, both perfluoroalkyl bromides such as Br (CF₂)₂O(CF₂)₂SO₂Na ( 1 ), Br(CF₂)₂OCF₂CO₂H ( 2 ), Cl(CF₂)₄Br ( 3 ), Cl(CF₂Br ( 4 ), n-C₆F₁₃Br ( 5 ), n-C₈F₁₇Br ( 6 ), H(CF₂)₈Br ( 7 ), α, ω-dibromides O(CF₂CF₂Br)₂ ( 8 ), Br(CF₂)₆Br ( 9 ) and Br(CF₂)₈Br ( 10 ) reacted readily with Na₂S₂O₄ in the presence of NaHCO₃ in aqueous solution to form the corresponding perfluoroalkane sulfinates NaO₂S(CF₂)₂O(CF₂)₂SO₂Na ( 11 ), NaO₂S(CF₂)₂OCF₂CO₂Na ( 12 ), Cl(CF₂)₄SO₂Na ( 13 ), Cl(CF₂)₂SO₂Na ( 14 ), n-C₃F₁₃SO₂Na ( 15 ), n-C₈F₁₇SO₂Na ( 16 ), H(CF₂)₈SO₂Na ( 17 ), α, ω-disulfinates O(CF₂CF₂SO₂Na)₂ ( 18 ), NaO₂S(CF₂)₄SO₂Na ( 19 ) and NaO₂S(CF₂)₈SO₂Na ( 20 ) in 66—97% yields. To this new and general reaction of perfluoroalkyl bromides, the name sulfinatodebromination is proposed.     

Studies on sulfinatodehalogenation: III. The sulfinatodeiodination of primary perfluoroalkyl iodides and α,ω-perfluoroalkylene diiodides by sodium dithionite

Using P. T. C. or cosolvents, both perfluoroalkyl iodides such as Cl(CF₂),_nI (n=2, 4, 6, 1a-1c), H(CF₂)₈I (1d), CF₃(CF₂)_nI (n=3, 5, 7, 1e-1g), and α. ω-perfluoroalkylene diiodides such as (ICF₂CF₂)₂O (4a), I (CF₂)_nI (n=6, 8, 10, 4b-4d) reacted smoothly with sodium dithionite in aqueous solution under mild conditions to give the corresponding perfluoroalkanesulfinates Cl(CF₂)_nSO₂Na (n=2, 4, 6, 2a-2c), H(CF₂)₈SO₂Na (2d), CF₃(CF₂)nSO₂Na (n=3, 5, 7, 2e-2g), α, ω-perfluoroalky-lenedisulfinates O (CF₂CF₂SO₂K)₂ (5a), and KO₂S(CF₂)_nSO₃K (n=6, 8, 10, 6b-6d) in moderate to high yields. These sulfinates were converted to the corresponding sulfonyl chlorides by reacting with chlorine in the usual way. Thus the discovery of the new reagent renders sulfinatodeiodination a practical method for the synthesis of perfluorosulfinic and perfluorosulfonic acids and their derivatives from the corresponding perfluoroalkyl iodides.     

Studies on sulfinatodehalogenation: IX. Synthesis and reaction of secondary perfluoroalkyl iodides

Several derivatives of secondary perfluoroalkyl iodides such as CF₃CFI(CF₂)₂O(CF₂)₃SO₂F (3), CF₃CFI(CF₂),O(CF₂)₂SO₃Na (4), CF₃CFI(CF₃)_n Cl (n=2, 7a; n=4, 7b) and CF₃(CF2)₂-OCFICF₃ (8) were synthesized using known methods, their reaction with sodium dithionite was studied and various olefins were added into the reaction system as radical traps to yield the 1:1 radical adducts.     

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.     

The reaction of perfluoroalkanesulfinates: IV. Perfluoroalkyl radical addition to olefins initiated by single electron oxidation of perfluoroalkanesulfinate

Sodium perfluoroalkanesulfinates [Cl (CF₂)_n SO₂ Na (1), a , n = 4; b , n = 6; c , n = 8] with the reduction potentials about 0.95—1.00V could be oxidized readily with various oxidizing agents such as Mn (OAc)₃ 2H₂O, Ce (SO₄)₂, HgSO₄ and Co₂O₃ to generate perfluoroalkyl radicals which added to the olefins RCH ? CHR' to give two kinds of adducts, namely RCH (R_f) CHXR' (3, X ? H; 4, X ? OAc), with good yields depending upon the solvent system used. Different oxidizing agents showed slight variation on the yields of the adducts. The reaction time could be greatly shortened at higher temperature. Thus, this reaction provides a new way for introducing a perfluoroalkyl group into olefinic compounds.     

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.     

Perfluoroalkylation of aromatic compounds with perfluoroalkyl radical generated from the oxidation of sodium perfluoroalkanesulfinate

Sodium perfluoroalkanesulfinates [R_fSO₂Na(1), R_f = Cl (CF₂)_n; a, n = 4; b, n = 6; c, n = 8] on oxidation with various single electron oxidizing agents, such as Mn (OAc)₃ · 2H₂O and Ce (SO₄)₂, yielded perfluoroalkyl radicals capable of perfluoroalkylating aromatic compounds to give a mixture of o-and p-monoperfluoroalkylated products. Thus, this reaction provides a new method for the synthesis of o-and p-monoperfluoroalkyl substituted aromatic compounds.     

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.     

Studies on sulfinatodehalogenation XIII. Synthesis of 2-perfluoroalkyl-2-deoxy-D-glucose,mono- and poly-O-polyfluoroalkylated-D-glucoses

Sodium dithionite-initiated addition of R_FI (1) [R_F=1a, Cl(CF₂)₄; 1b, Cl(CF₂)₆; 1c, Cl(CF₂)₆; 1d, n-C₆F₁₃; 1e, n-C₃F₁₇] to the properly protected glucose derivatives 2, 9, 12 and 15 gave polyfluoroalkylated glucose derivatives 7, 11, 14 and 17 respectively in good yields after reduction and deprotection. These compounds are strongly surface active.     

Polyfluorinated radical cations

The synthesis of the first trifluoromethanesulfonate esters of the type CF₃SO₃(CH₂)_nO₃SCF₃ (n=1,2,3) are reported. The new compounds are prepared from Cl(CH₂)_nCl by substitutive electrophilic dehalogenation reactions with CF₃SO₂OX (x=Cl,Br). The extension of this reaction to HCCl₃ results in HC(O₃SCF₃)₃ but the compound is unstable at 22°.     

Polar addition of perfluoro-tert-hexyl iodide to alkenes and alkynes

The effective charges on the atoms in molecules of perfluoroalkyl halides of general formula (CF₃)_nCF_3–nX (X=Cl, Br, I) have been calculated by the AM1 semiempirical method. In polar solvents perfluoro-tert-hexyl iodide is reduced under the action of alkenes and aromatic hydrocarbons to form 2-hydroperfluoro-2-methyl-pentane and perfluoro-2-methyl-2-pentene. In ethyl acetate the regio- and stereo-specific addition of perfluoro-tert-hexyl iodide to alkenes, butadiene, and alkynes takes place, which is associated with the realization of a polar ion-radical mechanism for the reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2057–2061, September, 1989.     

Gas chromatographic properties of tetrafluoroethylene telomers

The paper describes an investigation of the gas chromatographic properties of tetrafluoroethylene telomers of general formula F(CF₂)_nI, Br(CF₂)_nBr, Br(CF₂)_nI, I(CF₂)_nI and (CF₃)₂CF(CF₂)_nI. The telomers are well resolved on columns with squalene, silicone oil or tritolyl phosphate stationary phases, and relative retention volumes are given for these three columns. The temperature dependence of the relative retention volumes of F(CF₂)_nI and Br(CF₂)_nBr telomers has been investigated. The relative retention volumes are correlated with the telomer boiling points, and with structural features of the telomers.     

Chemical transformation of bis((perfluoroalkyl)sulfonyl)methanes and 1,1,3,3‐tetraoxopolyfluoro‐1,3‐dithiaycloalkanes

Halogenation of the potassium or silver salts of bis((trifluoromethyl)sulfonyl)methane(CF₃SO₂)₂CH₂ and its cyclo analogues (CF₂)_nSO₂‐CH₂SO₂CF₂ with N‐fluoro‐bis((trifluoromethyl)sul‐fonyl)imine (CF₃SO₂)₂NF, chlorine or bromine gave good yields of the corresponding α‐halo disulfones (CF₃SO₂)₂CHX and (CF₂)_nSO₂CHXSO₂CF₂ (X: F, Cl, Br; n = 1,2). Some chemical transformations of these fluorinated α‐halo‐disulfones are described. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 147–151, 1999     

Synthesis and Crystal Structure of Hexakis(N—allylthiourea)tetracopper(I) Tetratrifluoromethanesulfonate, [Cu4{CH2=CHCH2NHC(S)NH2}6](SO3CF3)4

Hexakis(N—allylthiourea)tetracopper(I) Tetratrifluoromethanesulfonate, [Cu₄{CH₂=CHCH₂NHC(S)NH₂}₆](CF₃SO₃)₄ (sp.gr.P2₁/n, a = 13.5463(8), b = 24.129(2), c = 19.128(1)Å, β = 108.053(6)°, Z = 4, R = 0.0440 for 13548 unique reflections) was obtained by reduction of Cu(CF₃SO₃)₂ with excess of N—allylthiocarbamide in benzene medium. Four crystallographical independent Cu atoms possess trigonal environment of three S atoms of CH₂=CHCH₂NHC(S)NH₂ moiety and form Cu₄S₆⁴⁺ adamantane—like fragments. The latteres are connected with CF₃SO₃^— anions via (C)—H···F hydrogen bonds.     

Bi-functional fluoroalkylation reagents: an introduction to halo-substituted 3-oxa-perfluoroalkanesulfonyl fluorides

X(CF₂CF₂)_nOCF₂CF₂SO₂F (X=I, Br, Cl; n=1, 2, 3, 4) are widely used fluoroalkylation reagents, which can incorporate ‘heavy’ fluorous tags into organic compounds. X(CF₂CF₂)_nOCF₂CF₂SO₂F have both sulfonyl and halo groups. They behave as bi-functional fluoroalkylation reagents. The cleavage of the C–I bonds of I(CF₂CF₂)_nOCF₂CF₂SO₂F by reductants (such as Na₂S₂O₄, Zn), single electron transfer reagents and radical initiator systems (like Bz₂O₂, AIBN, and (t-BuO)₂, or under UV and heat) gives, respectively, the sulfinatodehalogenated products, the hydrodehalogenated products, the homo-coupling products and the perfluoroalkylated products (if alkenes, alkynes or arenes were added). The functionalization of the sulfonyl groups (SO₂F) of X(CF₂CF₂)_nOCF₂CF₂SO₂F by esterification, amidation, and fluorination affords the corresponding perfluoroalkanesulfonates, fluoroalkanesulfonamide, and perfluoroalkanes. In many cases, both the halo and sulfonyl groups of X(CF₂CF₂)_nOCF₂CF₂SO₂F are transformed. These transformations finally lead to hundreds of useful highly fluorinated materials, such as supper acids, catalysts, surfactants, ion-exchange resins, electrolytes, polymers, and dense ionic liquids. Furthermore, X(CF₂CF₂)_nOCF₂CF₂SO₂F have commendable advantages, such as the easy preparation, the wide range of substrate tolerance, the mild reaction condition, and the high yields of desired products, which make them very promising. This review briefly summarizes the synthesis, reactivity, and applications of these intriguing reagents.     

Force field studies of some trifluoromethyl- and trichloromethyl-mercury-II) compounds

Force constants of [Hg(CF₃)₂], [Hg(CCl₃)₂], [Hg(CF₃)X] (X = Cl, Br, or I) and [Hg(CCl₃)X] (X = Cl or Br) have been calculated using a valence force field and wavenumber data from solutions. The potential energy distributions show substantial mixing between the symmetrical stretching and umbrella deformation coordinates of the trihalomethyl groups. The high degree of mixing of HgC and HgX stretching coordinates in [Hg(CF₃)Br] and [Hg(CF₃)I] accounts for the discontinuous frequency and intensity trends in the [Hg(CF₃)X] series.The results are discussed in comparison with methylmercury and other trifluoromethyl systems.     

Studies on sulfinatodehalogenation. XX. Sodium dithionite-initiated addition of per- and polyfluoroalkyl iodides to cyclic enol ethers and chemical conversions of the products

Per- and polyfluoroalkyl iodides [R_FI, R_F=Cl(CF₂)₄, 1a ; Cl(CF₂)₆, 1b ; Cl(CF₂)₈, 1c ; n-C₆F₁₃, 1d ; n-C₈F₁₇, 1e ] reacted with cyclic enol ethers such as 2,3-dihydrofuran (2) and 3,4-dihydro-2H-pyran (3) in aqueous acetonitrile in the presence of sodium dithionite and sodium bicarbonate at room temperature (10–15°C) to give the corresponding 2-(F-alkyl) hemiacetals in high yields. The adducts were oxidized with Ce(NH₄)₂(NO₃)₆ in acetonitrile or reduced with LiAlH₄ in ether to form the corresponding 2-(F-alkyl)lactones or diols respectively in good yields. In the presence of p-toluenesulfonic acid, the adducts were refluxed in benzene and CH₃CN to produce the corresponding 2,3-dihydro-4-(F-alkyl) furan and 3,4-dihydro-5-(F-alkyl)-2H-pyran. This is a new and effective method for preparing these useful organofluorine compounds.     

Studies on sulfinatodehalogenation XIII. A new sulfinatodehalogenation reagent system: NaHSO3/K3[Fe(CN)6]

The reaction of perfluoroalkyl iodide or perfluoroalkyl bromide with sulfite radical anion (SO₂) generated from sodium bisulfite / potassium ferricyanide in water/ DMF at 70—75°C gave the corresponding perfluoroalkanesulfinate in good yield. Furthermore, it was shown that the reagent system can also initiate the addition of perfluoroalkyl iodide to olefins or alkynes at 50—65°C.     

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.     

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.