Synthesis of phosphate-type fluorocarbon-hydrocarbon hybrid surfactants and their adsorption onto calcium hydroxyapatite

Five novel phosphate-type hybrid surfactants, C_mF_2m+1C₆H₄CH[OPO₂(OC₆H₅)Na]C_nH_2n+1 (FmPHnPPhNa: m = 4, 6, 8; n = 3, 5; C₆H₄ = p-phenylene, C₆H₅ = phenyl), have been synthesized. When compared with sulfate-type hybrid surfactants, C_mF_2m+1C₆H₄CH(OSO₃Na)C_nH_2n+1 (C₆H₄ = p-phenylene), the new hybrid surfactants are found to have comparable abilities to lower surface tension of water. The critical micelle concentrations of FmPHnPPhNa follow Klevens rule and their occupied areas per molecule increase with increasing m and n. Calcium hydroxyapatite (CaHAp) pellets modified with FmPH3PPhNa gives high hydrophobic and lipophobic surfaces. The hybrid surfactants are expected as new dental reagents for oral hygiene.     

Synthesis of phosphate-type fluorocarbon-hydrocarbon hybrid surfactants and their adsorption onto calcium hydroxyapatite

Five novel phosphate-type hybrid surfactants, C_mF_2m+1C₆H₄CH[OPO₂(OC₆H₅)Na]C_nH_2n+1 (FmPHnPPhNa: m = 4, 6, 8; n = 3, 5), have been synthesized. When compared with sulfate-type hybrid surfactants, C_mF_2m+1C₆H₄CH(OSO₃Na)C_nH_2n+1 (C₆H₄ = p-phenylene), the new hybrid surfactants were found to have comparable abilities to lower the surface tension of water. The critical micelle concentrations of FmPHnPPhNa followed Klevens’ rule and their occupied areas per molecule increased with increasing m and n. Calcium hydroxyapatite (CaHAp) pellets modified with FmPH3PPhNa gave high hydro and lipophobic surfaces. The hybrid surfactants are expected to be useful as new dental reagents for oral hygiene.     

Synthesis and surface activities of organic solvent-soluble fluorinated surfactants

A variety of fluorinated surfactants soluble in organic solvent were prepared, including C₈F₁₇SO₂NHC_nH_2n+1 (n = 2, 4, 6, 8, 10), C₈F₁₇SO₂NHR (R = C₆H₁₁, C₆H₅), C₈F₁₇SO₂N(C_nH_2n+1)₂ (n = 1, 2, 3, 4) and C₈F₁₇SO₂NH(CH₂)_nNHO₂SC₈F₁₇ (n = 6, 10). Their surface activities in various organic solvents were determined by surface tension measurement. The results showed that these fluorinated surfactants can reduce the surface tension of both polar and non-polar organic solvents. In general, organic solvents with strong polarity or long alkyl chain are beneficial to increase the surface activity of these polar fluorinated surfactants. By comparing fluorinated surfactants with the same fluorocarbon segment and connecting group, C₈F₁₇SO₂N(C_nH_2n+1)₂ (n = 1, 2, 3, 4) showed lower surface activity in organic solvents than C₈F₁₇SO₂NHC_nH_2n+1 (n = 2, 4, 6, 8) with an equal carbon number of the solvophilic group. Through surface tension vs. concentration curves given for N-octyl perfluorooctanesulfonamide in various organic solvents, a break point like the critical micelle concentration of ordinary surfactants in aqueous solutions was observed, and the effect of the different types of organic solvents on adsorption and aggregation behavior was also studied.     

Synthesis and properties of gemini-type hydrocarbon-fluorocarbon hybrid surfactants

Gemini-type hybrid surfactants with two fluorocarbon chains connected through a hydrocarbon spacer, F(CF₂)_m(CH₂)₂CH(OSO₃Na)(CH₂)_nCH(OSO₃Na)(CH₂)₂(CF₂)_mF [Fm(Hn)FmOS, m = 4, 6; n = 5, 6, 7, 8)], were synthesized and their surface chemical properties were examined with the aim to have highly functional and highly water-soluble fluorinated surfactants when compared with the conventional fluorinated surfactants. Comparisons of the surface chemical properties of the synthesized gemini-type hybrid surfactants with those of monounit-type hybrid surfactants, F(CF₂)_m(CH₂)₂CH(OSO₃Na)(CH₂)_nH [FmEHnOS, m = 4, 6; n = 3, 5)], revealed that gemination causes a remarkable lowering (about 1/100) in cmc value while it produces little changes in Krafft point (below 0 °C) and surface tension at cmc (γ_cmc).     

Etude RMN du 13C de composes fluoroaliphatiques et de tensioactifs non ioniques perfluoroalkyles

Carbon-13 chemical shifts, spin-lattice relaxation times and nuclear Overhauser enhancement factors at 28°C are reported for a series of polyfluoroaliphatic compounds :

, and perfluoroalkyl nonionic surfactants C_mF_2m+1CH₂(OC₂H₄)_nOH with m = 6, 7 and n = 3, 4, 5, 6 and C₆F₁₃CH₂CH₂CONH(C₂H₄O)_nH with n = 3, 4. The influence of the perfluoroalkyl group on the ¹³C chemtcal shifts of the neighbouring hydrogenated carbons is discussed in terms of hyperconjugative type interactions between lone electron pairs on fluorine and the neighbouring CC or CO bond. Relaxation data show similar flexibilities of the fluorinated chains in the different molecules investigated. Nonionic surfactants exhibit segmental motions in both the hydrophobic perfluoroalkyl and the hydrophilic polyoxyethylene chains ; these motions appear to be similar to those of the analogous hydrogenated surfactants.     

Synthesis of triphilic, Y-shaped molecular surfactants

Novel multiphilic molecules comprising three chains with antagonistic affinities have been synthesized. These ‘triphilic’ surfactants (FnHmEOy) contain a perfluorinated arm (Fn=C_nF_2n+1), a hydrocarbon arm (Hm=C_mH_2m+1), and a methyl-caped, poly(ethylene glycol) arm (EOy=CH₃(OC₂H₄)_yO). These moieties have variable lengths (n=5 or 7, m=8, 10, or 14, and y=2-7) and are interconnected in a Y shape; hence, each unit is directly connected to the other two. The key intermediates in the synthetic route are 3-F-alkyl-3-alkyloxypropanoic acids, on which the polar EOy chain is subsequently grafted. Monodisperse methyl-caped diethylene glycol (EO2) and triethylene glycol (EO3) led to the corresponding monodisperse triaffine surfactants. In parallel, a library of five F5H10EOy triaffines (y=3-7) has been obtained simultaneously when starting from the polydisperse methyl-caped poly(ethylene glycol) MPEG 350. Separation of pure individual compounds was achieved through column chromatography on silica gel. The relative concentration of the Z and E isomers has been quantified in the reaction mixtures of the intermediates and final products by ¹H NMR (Z largely predominant). Several products have been obtained in their isomerically pure form. Chemical characterization (¹H, ¹³C, and ¹⁹F NMR, elemental analysis) was consistent with the expected structures.     

Synthesis and coordination chemistry of fluorinated phosphonic acids

Phosphonic acids [(HO)₂P(O)C₂H₄C_nF_2n+1] (n = 4, 6) and [(HO)₂P(O)C₆H₄-4-C_nF_2n+1] (n = 0, 1, 6) have been prepared in good yields. Deprotonation and reaction with cis-[PtCl₂(PPh₃)₂] affords fluorinated platinum complexes which have been characterised by elemental analysis, mass spectrometry, IR and NMR spectroscopies. The structures of [Pt{O₂P(O)C₆H₄-4-F}(PPh₃)₂], [Pt{O₂P(O)C₆H₄-4-CF₃}(PPh₃)₂] and [Pt{O₂P(O)C₂H₄C₆F₁₃}(PPh₃)₂] have been determined by single crystal X-ray diffraction.     

Synthesis and coordination chemistry of perfluoroalkylated dithiophosphate ligands

Dithiophosphoric acids [HS₂P(OC₂H₄C_nF_2n+1)₂] (n = 4, 6) have been prepared in high yields. Deprotonation and reaction with transition metal substrates affords fluorous metal complexes which have been characterised by elemental analysis, mass spectrometry, IR and NMR spectroscopies. The structures of [Cu{S₂P(OC₂H₄C_nF_2n+1)₂}(PPh₃)₂] (n = 4, 6) and [Cu{-S₂P(OC₂H₄C₄F₉)₂}(PPh₃)]₂ have been determined by single crystal X-ray diffraction.     

Synthesis of molecular chains: phenylene thioether and sulfoxide oligomers

The application of a general synthetic approach to prepare molecular chains is reported. It is based on a step-by-step method each consisting first in a Pd-catalyzed reaction between ArI and HXAr′Br (Ar=aryl, Ar′=arylene) to give ArXAr′Br followed by a Cu-catalyzed replacement of Br by I to give ArXAr′I that can be reacted with HXAr′Br in the following step. The application of this method is here illustrated to prepare phenylene sulfide oligomers (X=S). Starting from RC₆H₄I-4 (R=H, MeO, NO₂, NH₂) and HSC₆H₄Br-x (x=2, 4) it is possible to grow chains in one direction to give X(C₆H₄S-m)_nC₆H₄R-4 (n=1, X=Br, m=4, R=H, MeO, NO₂, NH₂, SMe and m=2, R=H, MeO, NO₂; n=1, X=I, m=2 or 4, R=H, MeO, NO₂; n=2, X=Br, m=2 or 4, R=H, MeO, NO₂; n=2, X=I, m=4, R=MeO, NO₂; n=3, X=Br, m=4, R=MeO, NO₂; n=3, X=I, m=4, R=NO₂ and n=4, X=Br or I, m=4, R=NO₂). From HSC₆H₄Br-x and IC₆H₄I-4 the chains can grow in two directions to give X(C₆H₄S-4)_nC₆H₄X-4 (n=2 or 4, X=Br or I), 2-XC₆H₄(SC₆H₄-4)_nSC₆H₄X-2 (n=3 or 5, X=Br). Using diiodomesitylene the dithioethers C₆HMe₃-2,4,6-(SC₆H₄X-4)₂-1,3 (X=Br, I) have been prepared. The series of sulfoxides X(C₆H₄S(O)-4)_nC₆H₄R-4 (X=Br, n=1, R=MeO, n=3, R=NO₂, n=4, R=Br; X=R=I, n=2) has been obtained from the corresponding thioethers and PhICl₂.     

ESR Studies on the Micellization Behaviors of a Series of Novel Asymmetric Gemini Surfactants

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New types of asymmetrical bromonium salts [RF(RF′)Br]Y where RF and/or RF′ represent perfluorinated aryl, alkenyl, and alkynyl groups

A series of previously unknown asymmetrical fluorinated bis(aryl)bromonium, alkenyl(aryl)bromonium, and alkynyl(aryl)bromonium salts was prepared by reactions of C₆F₅BrF₂ or 4-CF₃C₆H₄BrF₂ with aryl group transfer reagents Ar′SiF₃ (Ar′ = C₆F₅, 4-FC₆H₄, C₆H₅) or perfluoroorganyl group transfer reagents R_F′BF₂ (R_F = C₆F₅, trans-CF₃CFCF, C₃F₇C≡C) preferentially in weakly coordinating solvents (CCl₃F, CCl₂FCClF₂, CH₂Cl₂, CF₃CH₂CHF₂ (PFP), CF₃CH₂CF₂CH₃ (PFB)). The presence of the base MeCN and the influence of the adducts R_F′BF₂·NCMe (R_F = C₆F₅, CF₃C≡C) on reactions aside to bromonium salt formation are discussed. Reactions of C₆F₅BrF₂ with Alk_F′BF₂ in PFP gave mainly C₆F₅Br and Alk_F′F (Alk_F′ = C₆F₁₃, C₆F₁₃CH₂CH₂), presumably, deriving from the unstable salts [C₆F₅(Alk_F′)Br]Y (Y = [Alk_F′BF₃]⁻). Prototypical reactivities of selected bromonium salts were investigated with the nucleophile I^-and the electrophile H⁺. [4-CF₃C₆H₄(C₆F₅)Br][BF₄] showed the conversion into 4-CF₃C₆H₄Br and C₆F₅I when reacted with [Bu₄N]I in MeCN. Perfluoroalkynylbromonium salts [C_nF_2n+1C≡C(R_F)Br][BF₄] slowly added HF when dissolved in aHF and formed [Z-C_nF_2n+1CFCH(R_F)Br][BF₄].     

Synthesis of a novel type of hybrid fluorocarbon ionic surfactants containing polyoxyethlene chain

A novel type of hybrid ionic surfactants containing oxyethylene chain and fluorocarbon chain in one molecule, n-C₈F₁₇SO₃⁻N⁺(C₂H₅)₃(CH₂CH₂O)_nH (n = 4.0, ∼4.1, 8.7, 13.2, 17.8, 22.3), were prepared. The compounds were achieved from the reaction of polyethylene glycol and perfluorooctanesulfonyl fluoride in the presence of Et₃N. The evaluation of their behavior at the air-water interface has been studied from measurements of surface tension versus variation of concentration, and the properties of the hybrid surfactants are not consistent with the empirical rule observed from the fluorinated nonionic surfactant.     

Formation of perfluorinated polyphenylenes by multiple pentafluorophenylation using C6F5Si(CH3)3

Pentafluorophenylation of perfluoroarenes with C₆F₅Si(CH₃)₃ was investigated by using NMR and MALDI-TOF-MS techniques. Successive multiple pentafluorophenylation easily occurred not only on the para-position but also on the ortho-positions to provide perfluorinated p-phenylene and m-phenylene compounds. The perfluoroarenes having electron-withdrawing substituents provided oligo- to poly-(phenylene)s depending on the added amounts of C₆F₅Si(CH₃)₃, while the perfluoroarenes having electron-donor substituents gave H(C₆F₄)_nF polymers produced from C₆F₅H, which was the decomposed product of C₆F₅Si(CH₃)₃.     

Molecular ionization-dissociation of fluoranthene at 266 nm: Energetic and dissociative pathways

Experimental studies have been carried out for nanosecond 266-nm laser-induced photoionization and dissociation of fluoranthene, C₁₆H₁₀ with pulse energies from 0.5 to 20 mJ using a time of flight mass spectrometer. The fragmentation patterns have been characterized and discussed with respect to the number of absorbed photons. They fall into three regimes. The first regime involves low energy processes, where the molecular parent ion promptly dissociates, resulting in the formation of Cm⁺Hn(m=11−15) by a process where up to two photons are absorbed. The second regime involves intermediate energy, where dissociative processes are activated by up to three-photon absorption and produce a second group of daughter ions: C10⁺Hn, C₉⁺Hn, and C₈⁺Hn. Finally, there is a third dissociative process, characterized by the absorption of up to four photons, producing C₇⁺Hn, C₆⁺Hn, C₅⁺Hn, C₄⁺Hn, and C₃⁺Hn. Most of the detected ions are of the form Cm⁺Hn with m < n. Total deprotonation has also been observed. The mechanism proposed involves the dissociation of the parent ion, which then dissociates by different competitive channels. Helium, neon and argon were used as carrier gases (CG). A detailed discussion is presented regarding the use of He as the CG. The laser pulse intensity allows the absorption of up to nine photons, observed through the formation of multiply charged ions of some of the CG atoms.     

Striking differences between alkyl sulfate and alkyl sulfonate when mixed with cationic surfactants

The properties of alkyl sulfate and alkyl sulfonate are similar except for their Krafft points. However, alkyl sulfate and alkyl sulfonate behave quite differently when they are mixed with cationic surfactants and show some totally unexpected results. In this work sodium alkyl sulfate (C_nH_2n+1SO₄Na,C_nSO₄)–alkyl quaternary ammonium bromide [C_nH_2n+1N(C_mH_2m+1)₃Br, C_nN, m=1–4] mixtures and sodium alkyl sulfonate (C_nH_2n+1SO₃Na, C_nSO₃)–C_nN mixtures were studied. It was found that, in contrast to the single surfactants, C_nSO₃–C_nN mixtures were much more soluble than C_nSO₄–C_nN mixtures. Besides, the two kinds of catanionic surfactant mixtures were quite different in their phase behavior and aggregate properties. The results were interpreted in terms of the interactions between surfactant molecules, which were very different in the two kinds of mixed systems owing to the distinction between alkyl sulfate and alkyl sulfonate in the molecular charge distribution.     

Synthesis and properties of triethylalkylammonium perfluorooctanesulfonates (APFOS)

Six ionic surfactants containing a perfluorooctanesulfonic anion and a positively charged ammonium in a molecule, R_FSO₃⁻N⁺Et₃C_nH_2n+1 (n=2, 4, 6, 8, 10 and 12), were prepared from perfluorooctanesulfonyl fluoride, triethylamine and linear alkanol. Solution properties of triethylalkylammonium perfluorooctanesulfonates (APFOS) have been measured in terms of surface tension. The values of critical micelle concentration (cmc) decrease with an increase of N-alkyl chain length, and the logarithm of the cmc decreases linearly with increasing N-alkyl chain length (n≥6), while the negative values of standard free energy for the adsorption become larger as the N-alkyl chain length increases.     

Addition thermique des iodo-1-perfluoroalcanes sur les perfluoroalkylethylenes

We have undertaken a study of the thermal addition of 1-iodo-perfluoroalkanes (C_nF_{2n + 1}I where n = 4, 6, 8) to perfluoroalkylethylenes (C_nF_{2n + 1} CHCH₂ where n = 4, 6, 8). Structures of the reaction products were established through spectroscopic or chemical identification and the optimal conditions for obtaining 1,2-bis(perfluoroalkyl)iodoethanes determined. The good yields thus obtained demonstrate the utility of this method of perfluoroalkylation.     

Synthesis and fluxional behaviour of new “heavy fluorous” cyclopentadienes

The new “heavy fluorous” cyclopentadienes C₅H_6−n[M(C₂H₄C₆F₁₃)₃]_n (M = Si, n = 1 (3); n = 2 (4) and M = Sn, n = 1 (10)) were synthesized by reaction of cyclopentadienyl lithium with BrSi(C₂H₄C₆F₁₃)₃ (2) or commercial BrSn(C₂H₄C₆F₁₃)₃. Fluorous cyclopentadienes prepared in this manner contain three or six C₆F₁₃ groups, which significantly increase their solubility in perfluorinated solvents. They also provide intermediates for titanium complexes suitable for fluorous biphase catalysis. All three isomers of silylcyclopentadienes 3 and 4 were identified and fully characterized by two dimensional NMR spectroscopy, which was performed at low temperature. The allylic isomers 3a and 4a undergo degenerate metallotropic rearrangement. This fluxional behaviour was compared with the behaviour of previously prepared cyclopentadienes 6 and 7 (C₅H_6−n[SiMe₂(C₂H₄C₈F₁₇)]_n where n = 1, 2, respectively). The presence of allylic isomers 6a and 7a was further confirmed by Diels-Alder cycloaddition of the strong dienophile tetracyanoethylene (TCNE), providing compounds 8 and 9.     

Synthesis of novel lipophilic and/or fluorophilic ethers of perfluoro-tert-butyl alcohol, perfluoropinacol and hexafluoroacetone hydrate via a Mitsunobu reaction: Typical cases of ideal product separation

Fluorophilic ethers having the structure RC(CF₃)₂O(CH₂)₃C_nF_2n + 1 are obtained in high yields, when F-tert-butyl alcohol (R = CF₃), F-acetone hydrate (R = O(CH₂)₃C_nF_2n + 1), F-pinacol (R = C(CF₃)₂O(CH₂)₃C_nF_2n + 1) are reacted with 3-perfluoroalkyl-1-propanols (C_nF_2n + 1(CH₂)₃OH, n = 4, 6, 8, 10) in a Mitsunobu reaction (Ph₃P/DIAD [i-PrO₂CN = NCO₂Pr-i]/ether). The parent lipophilic ethers with the structure of (CF₃)₃CO(CH₂)₃C_nH_2n + 1 were prepared analogously using the corresponding fatty alcohols and F-tert-butyl alcohol. To achieve ideal separations, products were transferred to orthogonal phases relative to the other reaction components using fluorous extraction, fluorous solid-organic liquid filtration, or steam-distillation. Selected physical properties including melting and boiling point, together with fluorous partition coefficients of these ethers were determined and the figures obtained were qualitatively analyzed using relevant thermodynamic theories. Some of these ethers are liquids with rather low freezing points and are miscible with fluorocarbon solvents.     

Synthesis and coordination chemistry of fluorinated xanthate ligands

Alkali metal, copper, nickel and rhodium complexes of alkylated [S₂COC₈H₁₇] and fluoroalkylated xanthate ligands [S₂COC_mH_2mC_nF_2n+1] (m = 2, n = 4, 6; m = 3, n = 1, 8) have been prepared in high yields and characterised by elemental analysis, mass spectrometry, IR and NMR spectroscopies. The structures of [Cu(S₂COC₈H₁₇)(PPh₃)₂], [Cu(S₂COC₃H₆CF₃)(PPh₃)₂], [Ni(S₂COC₃H₆CF₃)₂], [Cp^*RhCl(S₂COC₈H₁₇)] and [Cp^*RhCl(S₂COC₃H₆CF₃)] have been determined by single crystal X-ray diffraction.