- The aliphatic ring-opening and SNAr substitution in the reactions of perfluorobenzocycloalkenones with K2CO3 in water and methanol
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In the reactions with aqueous K2CO3, perfluorinated benzocyclobuten-1-one, 3-R-indan-1-ones and 4-R-tetralin-1-ones (R = F, C2F5) undergo selective cleavage of the СO–С(Ar) bond to yield (2,3,4,5-tetrafluorophen
- Zonov, Yaroslav V.,Wang, Siqi,Karpov, Victor M.,Mezhenkova, Tatyana V.
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- Synthesis and catalytic activity of ruthenium complexes modified with chiral racemic per- and polyfluorooxaalkanoates
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Silver salts of racemic 2H-perfluoro(3-oxahexanoic) (3a), perfluoro(2-methyl-3-oxahexanoic) (3b) and 2,3,3,3-tetrafluoro-2-methoxypropanoic acid (3c) gave with Hoveyda-Grubbs 2nd generation catalyst 4 or its bis(polyfluoroalkylated) analogue 5 the corresponding bis(polyfluoroacylated) ruthenium complexes 1a–1c or 2a, 2b as mixtures of three diastereoisomers. Their catalytic activity in model ring-closing metathesis (RCM) reactions decreased in the order 1b–2b?>?1a–2a?>?1c due to increased steric hindrance around the catalytic centre in complexes 1a, 1c and 2a, as well as due to lower acidity of acid 3c resulting in lower electrophilicity of the complex 1c. Thus, the complexes 1b and 2b displayed high activity in RCM of bis-unsaturated malonates forming disubstituted (RCM2) or trisubstituted (RCM3) double bond and were even significantly active in the formation of tetrasubstituted bond (RCM4), while complexes 1a, 1c were active in RCM2 but inactive in RCM3. Moreover, the yield of RCM2 catalyzed with complex 1c was rather low.
- Lipovská, Pavlína,Rathouská, Lucie,?im?nek, Ond?ej,Ho?ek, Jan,Kola?íková, Viola,Rybá?ková, Markéta,Cva?ka, Josef,Svoboda, Martin,Kví?ala, Jaroslav
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- The effect of oxygen in the photocatalytic oxidation pathways of perfluorooctanoic acid
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The influence of oxygen in the photocatalytic oxidation of perfluorooctanoic acid (PFOA) promoted by a commercial nano-sized titanium dioxide was studied by testing the reaction in different conditions: static air, oxygen flux, nitrogen flux and pre-saturated nitrogen flux. The reaction was monitored by Total Organic Carbon (TOC) analysis and Ionic Chromatography (IC). Shorter chain perfluorocarboxylic acids (PFCAs; Cn, n = 1-7) intermediate degradation products were quantitatively determined by High-Performance Liquid Chromatography combined with Mass Spectrometry (HPLC-MS) analysis. The presence of shorter chain PFCAs in solution was also monitored by 19F NMR. The experimental findings are in agreement with two major oxidative pathways: Cn → Cn-1 photo-redox and β-scissions routes mediated by COF2 elimination. Depending on the experimental conditions, the mutually operating mechanisms could be unbalanced up to the complete predominance of one pathway over the other. In particular, the existence of the β-scissions route with COF2 elimination was corroborated by the isolation and characterization of carbonyl difluoride, a predicted fluorinated decomposition by-product.
- Sansotera, Maurizio,Persico, Federico,Rizzi, Valentina,Panzeri, Walter,Pirola, Carlo,Bianchi, Claudia L.,Mele, Andrea,Navarrini, Walter
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p. 159 - 168
(2015/11/10)
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- Free-radical selective functionalization of 1,4-naphthoquinones by perfluorodiacyl peroxides
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Perfluoroalkyl radicals, generated by thermal decomposition of perfluorodiacyl peroxides, react selectively with quinone rings of 1,4-naphthoquinones. In the presence of a non-conjugated alkene such as 1-hexene, perfluoroalkyl radicals add to the double bonds of the olefin forming a radical adduct, which selectively adds to the naphthoquinone ring. Several perfluorodiacyl peroxides have been synthesized and used for the direct and alkene-mediated functionalization of naphthoquinones. Geometrical parameters and electron density topology of all perfluorodiacyl peroxides have been calculated by the density functional formalism and quantum theory of atoms in molecules to attempt a rationalization of the experimental reactivity.
- Sansotera, Maurizio,Gambarotti, Cristian,Famulari, Antonino,Baggioli, Alberto,Soave, Raffaella,Venturini, Francesco,Meille, Stefano V.,Wlassics, Ivan,Navarrini, Walter
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p. 5298 - 5309
(2014/07/08)
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- Development of technology of perfluoroethyl isopropyl ketone production
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Synthesis of perfluoroethyl isopropyl ketone by an interaction of hexafluoropropene with perfluoropropionic acid fluoride or hexafluoropropene oxide was examined. Interchangeability of perfluoropropionic acid fluoride and hexafluoropropene oxide was demonstrated. The features of perfluoroethyl isopropyl ketone synthesis were studied in polar aprotic solvents on catalysts: alkali metal fluoride. A method for obtaining perfluoroethyl isopropyl ketone by direct catalytic reaction in a tubular reactor without use of solvents was suggested and investigated. The mechanism of interaction was considered. The main impurities resulting in obtaining perfluoroethyl isopropyl ketone were determined. The methods of cleaning perfluoroethyl isopropyl ketone were worked out.
- Fenichev,Babenko,Bispen,Moldavskii
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p. 376 - 386
(2013/07/05)
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- Process for the manufacture of fluorinated alcohols
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Process for the manufacture of fluorinated alcohols having the formula ???????? CnFmH2n+1-mCH2OH?????(1) wherein n is 1 or 2; and m is an integer from 1 to 5, but not larger than 2n+1; by hydrogenating the corresponding fluorinated carboxylic acids and/or their derivates having the formula ???????? CnFmH2n+1-mCOR?????(2) wherein n and m have the above meanings and R represents OH, Cl, Br, F, and OR', wherein R' is a hydrocarbon rest, in the presence of a catalyst and of water but excluding the hydrogenation of trifluoroacetic acid to form trifluoroethanol.
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Page/Page column 4
(2008/06/13)
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- Free radical and isomerisation processes during the electrochemical fluorination of n-butyryl chloride, i-butyryl chloride and pivaloyl chloride in anhydrous hydrogen fluoride
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Electrochemical perfluorination (ECPF) of the title compounds containing primary, secondary and tertiary carbon atoms was carried out in anhydrous hydrofluoric acid (AHF). Detailed analysis of major and minor products suggest that carbon chain isomerisation involving cyclo-propane intermediate is more prevalent during ECPF of i-butyryl chloride when compared to n-butyryl chloride. Simple statistical probability involving free radical intermediates also support this observation. ECPF involving cyclo-propane intermediate is even more prevalent in pivaloyl chloride containing three methyl substituents. In this case, perfluorinated cyclo-propane intermediates were also observed in the product sample. Distribution of minor perfluorinated and partially fluorinated products also suggest the predominant role of normal free radical pathway involving single-electron transfer.
- Velayutham,Jayaraman,Kulangiappar,Ilayaraja,Babu, Y. Ram,Rao, P. Santhan,Reddy, S. Narayana,Babu, K. Victor,Noel
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p. 1111 - 1118
(2008/09/16)
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- Reductive alkylation of perfluorocarboxylic acid esters with CCl 3F or CCl4 and synthesis of higher linear perfluoroketones
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Barbier-type reductive alkylation of perfluorocarboxylic acid esters (I) with CFCl3 and activated Al was successfully performed to give α,α-dichloroperfluoroketones (II). A similar reaction of CF 3COOEt with CCl4 and Al provided a convenient synthesis of CF3COCCl3. Ketones (II) were fluorinated further with SbF5 to form higher linear perfluoroketones (IX). An alternative approach to the synthesis of ketones (IX) was proposed by reductive perfluoroalkylation of esters (I) under the action of RFI and Al.
- Zeifman, Yu.V.,Postovoi
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p. 1815 - 1819
(2007/10/03)
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- Changing mechanisms in the β-cyclodextrin-mediated hydrolysis of phenyl esters of perfluoroalkanoic acids
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The rate of hydrolysis of esters CF3(CF2) nCOOPh (1 (n = 1), 2 (n = 2), and 3 (n = 6)) was measured at pH 6.00 and at pH higher than 9.00 in the presence of β-cyclodextrin (β-CD). For compounds 1 and 2 the reaction rate decreases as the β-CD concentration increases, and they show saturation effects at all pH. It is suggested that the substrate forms an inclusion complex with cyclodextrin. Analysis of the rate data allows calculation of the association equilibrium constant, KCD, the rate constant for the reaction of the included compound, kc, and KTS which is the hypothetical association equilibrium constant for the transition state of the cyclodextrin-mediated reaction. The dependence of log KCD and log KTS with the number of atoms in the chain is different. We suggest that the reactions of 1 and 2 take place with the perfluorinated alkyl chain included in the cavity, whereas the transition state for the reaction of phenyl trifluoroacetate involves a complex with the aryl ring inside the cavity. At low pH the inhibition comes from the protection of the carbonyl group toward nucleophilic attack by water. In basic pH the reaction of HO- as an external nucleophile is also inhibited. The cyclodextrin-mediated reaction involves the ionized OH group at the rim of the cyclodextrin cavity with poor efficiency due to an unfavorable orientation of the substrate in the complex. On the other hand, the reaction of compound 3 is strongly accelerated by cyclodextrin because the association of the substrate with cyclodextrin competes with the monomer-aggregate equilibrium and at high enough cyclodextrin concentration the main species present in solution is the complex between 3 and cyclodextrin.
- Fernandez, Mariana A.,De Rossi, Rita H.
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p. 6887 - 6893
(2007/10/03)
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- Atmospheric chemistry of C2F5CHO: mechanism of the C2F5C(O)O2 + HO2 reaction
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Smog chamber/FTIR techniques were used to study the gas-phase reaction of C2F5C(O)O2 with HO2 radicals in 100-700 Torr of air, or O2, diluted at 296 K. The reaction proceeds by two pathways leading to formation of C2F5C(O)OH and O3 in a yield of 24+/-4 percent and C2F5C(O)O radicals, OH radicals and O2 in a yield of 75+/-4 percent. The gas phase reaction of CnF(2n+1)C(O)O2 with HO2 radicals offers a potential explanation for at least part of the observed environmental burden of fluorinated carboxylic acids, CnF(2n+1)C(O)OH. As part of this work an upper limit for the rate constant of reaction of Cl atoms with C2F5C(O)OH at 296 K was determined; k(Cl + C2F5C(O)OH) -17 cm3 molecule-1 s-1.
- Andersen, M. P. Sulbaek,Hurley, M. D.,Wallington, T. J.,Ball, J. C.,Martin, J. W.,Ellis, D. A.,Mabury, S. A.
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- Perfluoroalkylation of simple inorganic molecules: A one step route to novel perfluoroalkylated compounds
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Reactions of (CH3)3SiRf (Rf = CF3, C2F5) with NOCl, NO/NO2, SO2, CO2, in the presence of caesium fluoride provide a one step synthetic route to perfluoroalkylated compounds in very good yields.
- Singh, Rajendra P.,Shreeve, Jean'ne M.
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p. 1818 - 1819
(2007/10/03)
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- A novel catalytic pathway for perfluoroacyl peroxide synthesis
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matrix presented A new catalytic method for synthesis of bis(perfluoroacyl) peroxides (BPFAP) was elaborated by using hydrogen peroxide and perfluoroacyl anhydrides. The desired BPFAP were formed quantitatively in situ when perfluoroacyl anhydride was mixed with hydrogen peroxide (ratio ≥ 2:1) in the presence of a catalytic amount of the carboxylate RfCOO- M+. The essentially irreversible character of this process was shown experimentally and supported on the basis of DFT calculations. The synthesis of new acetyltrifluoroacetyl peroxides is also described.
- Krasutsky, Pavel A.,Kolomitsyn, Igor V.,Carlson, Robert M.
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p. 2997 - 2999
(2007/10/03)
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- Multiple pathways in cyclodextrin-catalyzed hydrolysis of perfluoroalkylamides
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The hydrolysis of p-nitroanilide of perfluoroalkanoic acids, CF3(CF2)nCO-, with n = 1, 2, 3, 5, 6, and 7, 1a-f, was studied in the presence of β-cyclodextrin (CD). All reactions were catalyzed by CD through the formation of a 1:1 and 1:2 inclusion complexes. The association equilibrium constants for the 1:1 complexes were dependent on the number of carbons of the fluoroalkyl chain, whereas those of the 1:2 complexes were almost independent. These results indicate that, in the former case, the perfluoroalkyl chain is included, while in the latter, the CD unit encloses the aryl ring. For compounds 1a,b both complexes were more reactive than the substrate itself. The ratio of the reaction of complexed to uncomplexed substrate had its highest value for 1a in the case of the 1:1 complex, and for 1b, the 1:2 complex. This is attributed to the geometry of the complexes. Although compounds 1c-e reacted at the same rates in the free or 1:1 complexed form, CD accelerated the reactions because of an increase of the pKa of the substrate, which results in a higher concentration of the neutral reactive substrate at the same pH. Compound 1f formed aggregates even at 10-6 M concentration, and CD-induced deaggregation resulted in catalysis of the reaction.
- Granados, Alejandro,De Rossi, Rita H.
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p. 3690 - 3696
(2007/10/02)
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- FLUOROALIPHATIC ESTERS OF FLUOROSULFONIC ACID. 2. REACTION BIS(FLUOROSULFATO)PERFLUOROALKANES WITH CESIUM FLUORIDE
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2,3-Bis(fluorosulfato)perfluoroalkanes split under the action of CsF in the absence of solvents, giving a mixture of α-fluorosulfatoperfluoro ketones, perfluoroalkene sulfates, and perfluoro α-diketones.The occurence of these reactions in solutions results mainly in the formation of oxides of the corresponding fluoroolefins or products of their conversions.The reactions carried out are the first examples of nucleophilic substitution at a secondary carbon atom in a perfluorinated saturated chain.
- Rogovik, V. M.,Delyagina, N. I.,Mysov, E. I.,Cherstkov, V. F.,Sterlin, S. R.,German, L. S.
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p. 1870 - 1876
(2007/10/02)
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- A NEW METHOD FOR THE PREPARATION OF PERFLUOROCARBOXYLIC ACIDS
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The reaction of both primary perfluoroalkyl iodides and bromides containing 3-12 carbon atoms with a rongalite-NaHCO3 reagent in aqueous dipolar aprotic solvents, such as DMF or DMSO, has been investigated.The reaction gave sodium perfluorocarboxylates in 51-86percent yields, and these were transformed to the respective perfluorocarboxylic acids by treatment with sulfuric acid.This provides a new method for the synthesis of perfluorocarboxylic acids.
- Huang, Bing-Nan,Haas, A.,Lieb, M.
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- Process for the preparation of zomepirac and related compounds
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Zomepirac and its analogs have been prepared from a 5-aroyl-3-hydroxycarbonyl-4-substituted pyrrole-2-acetic acid via acidic decarboxylation.
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- SYNTHESE D'ACIDES PERFLUORES DE HAUTS POIDS MOLECULAIRES
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Perfluorinated olefins of general formula CF3-(CF2)p-CF=CF-(CF2)m-CF3 (3 /= m + p /= 25) are oxidized by potassium permanganate or ruthenium tetroxide.The linear high molecular weight perfluorinated carboxylic acids so obtained are characterized by 19F N.M.R. spectroscopy.
- Battais, A.,Boutevin, B.,Pietrasanta, Y.,Sierra, P.
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- OXYDATION ANODIQUE DE IODOPERFLUOROALCANES DANS LES ACIDES PERFLUOROALCANESULFONIQUES. PREPARATION DE NOUVEAUX ESTERS SULFONIQUES TOTALEMENT FLUORES RFSO3R'F A LONGUES CHAINES
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Perfluorinated sulphonic esters RFSO3R'F and fluorosulphates FSO3R'F, are easily obtained by anodic oxidation of iodoperfluoroalkanes R'FI in perfluoroalkene sulphonic acids RFSO3H (RF=CF3, C2F5, C4F9) and fluorosulphuric acid.With di-iodo compound I(CF2)4I, the mono and the diester can be selectively obtained.The alkaline hydrolysis of these esters produces perfluorinated carboxylic compounds.Polyfluorinated iodide R'FCH2CH2I are also oxidized in similar conditions.The mechanism of the electrolytic reaction is discussed.
- Germain, A.,Commeyras, A.
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p. 487 - 492
(2007/10/02)
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- THERMAL DECOMPOSITION OF PERFLUOROALKANOYL PEROXIDES IN HYDROCARBON SOLVENTS
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The rate constants were obtained for the thermal decomposition of trifluorocateyl, pentafluoropropionyl, and heptafluorobutyryl peroxides in isooctane and heptane.The obtained values were 1.2*1015 exp(-113,000/RT) sec-1, 3.7*1017 exp(-118,800/RT) sec-1, and 6.5*1012 exp(-92,000/RT) sec-1.The proportions of the gaseous products formed in the reactions at 50 deg C were as follows: In isooctane CF3H/CO2 = 0.71 0.01, C2F5H/CO2 = 0.65 0.05; in heptane CF3H/CO2 = 0.95 0.02, C2F5H/CO2 = 0.89 0.03, C3F7H/CO2 = 0.66 0.03.The thermal decomposition of the peroxides in heptane can be used for kinetic measurements by the method of competing reactions.
- Serov, S. I.,Zhuravlev, M. V.,Sass, V. P.,Sokolov, S. V.
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p. 1360 - 1362
(2007/10/02)
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