- UTRASOUND-PROMOTED DIRECT CARBOXYLATION OF PERFLUOROALKYL IODIDES
-
Perfluoroalkyl iodides were directly carboxylated with Zn and CO2 under utrasonic irradiation affording the corresponding perfluoroalkanoic acids.
- Ishikawa, Nobuo,Takahashi, Mitsuru,Sato, Takehiko,Kitazume, Tomoya
-
-
Read Online
- SYNTHESE D'ACIDES PERFLUORES DE HAUTS POIDS MOLECULAIRES
-
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.
-
-
Read Online
- An improved synthesis of perfluorocarboxylic acids
-
Perfluoroalkyl iodides C(n)F(2n+1) CF2I (3 2CO2H in 91% yield, by reaction with zinc-copper couple in the presence of solid carbon dioxide in trimethyl phosphate as the solvent.
- Benefice-Malouet,Blancou,Itier,Commeyras
-
-
Read Online
- A novel liquid plasma AOP device integrating microwaves and ultrasounds and its evaluation in defluorinating perfluorooctanoic acid in aqueous media
-
A simplified and energy-saving integrated device consisting of a microwave applicator and an ultrasonic homogenizer has been fabricated to generate liquid plasma in a medium possessing high dielectric factors, for example water. The microwave waveguide and the ultrasonic transducer were interconnected through a tungsten/titanium alloy stick acting both as the microwave antenna and as the horn of the ultrasonic homogenizer. Both microwaves and ultrasonic waves are simultaneously transmitted to the aqueous media through the tungsten tip of the antenna. The microwave discharge liquid plasma was easily generated in solution during ultrasonic cavitation. The simple device was evaluated by carrying out the degradation of the perfluorooctanoic acid (PFOA), a system highly recalcitrant to degradation by conventional advanced oxidation processes (AOPs). PFOA is 59% degraded in an aqueous medium after only 90 s of irradiation by the plasma. Intermediates were identified by electrospray mass spectral techniques in the negative ion mode.
- Horikoshi, Satoshi,Sato, Susumu,Abe, Masahiko,Serpone, Nick
-
-
Read Online
- Photocatalytic decomposition of environmentally persistent perfluorooctanoic acid
-
Perfluorooctanoic acid was photocatalytically decomposed by using TiO 2/Ni-Cu, and a small bias potential (-0.1 V) applied on TiO 2/Ni-Cu electrode greatly enhanced its decomposition. Copyright
- Chen, Jing,Zhang, Pengyi,Zhang, Li
-
-
Read Online
- The effect of oxygen in the photocatalytic oxidation pathways of perfluorooctanoic acid
-
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
-
-
Read Online
- Electrocatalytic degradation of perfluorooctanoic acid by LaNixY1-xO3 (Y = Fe, Cu, Co, Sr) gas dispersion electrode
-
Perfluorooctanoic acid (PFOA), as a refractory organic pollutant, seriously harms the environment and damages human health. Here, the electrocatalytic method was selected to degrade PFOA. In this work, perovskite catalysts doped with different elements, and corresponding gas diffusion electrodes (GDE) were prepared by the gel-sol method and citric acid complexation method. The crystal structure, microscopic morphology, and electrochemical properties of the LaNixY1-xO3 (Y = Fe, Cu, Co, Sr) perovskite catalyst electrode were analyzed by XRD, TEM, and CV. Moreover, the electrocatalytic performances of the as-prepared electrodes were assessed by the degradation of PFOA, and the Sr-doped GDE exhibited the highest degradation rate of PFOA. The optimum degradation conditions, such as the current density, pH, and initial concentration were also investigated. It was observed that when the current density was 20 mA/cm2, pH was 5, and initial concentration was 0.25 mmol/L, the Sr-doped GDE had the best degradation and defluorination efficiency of PFOA reached 90.0 % and 75.1 %, respectively. High performance liquid chromatography-mass spectrometry (HPLC-MS) was used to analyze the intermediate products of PFOA degradation and obtain the degradation pathway. With the combined action of [rad]OH and O2, PFOA was degraded by stepwise removal of CF2 groups, which were ultimately degraded into F? and CO2.
- Chen, Yongyang,Guo, Dan,Dong, Xiaochun,Li, Yahui,Huang, Yixuan,Chen, Hao,Li, Shanping
-
-
Read Online
- Synthesis, structural characterization, and unusual field-effect behavior of organic transistor semiconductor oligomers: Inferiority of oxadiazole compared with other electron-withdrawing subunits
-
A new series of heterocyclic oligomers based on the 1,3,4-oxadiazole ring were synthesized. Other electron-deficient cores (fluorenone and fumaronitrile) were introduced to investigate the oligomers as n-channel materials. The physical properties, thin film morphologies, and field-effecttransistor characteristics of the oligomers were evaluated. Thin films were deposited at different substrate temperatures and on variously coat ed Si/Si02 for device optimization. Contrary to our expectations, the thin film devices of 4 revealed p-channel behavior, and the average hole mobility was 0.14 cm 2 V-1 s-1 (maximum value 0.18 cm2 V-1 s-1). Compound 11 is the first example of an oxadiazole-containing organic semiconductor (OSC) oligomer in an n-channel organic field-effect transistor (OFET) and shows moderate mobilities. Non- oxadiazole-containing oligomers 9 and 12 showed n-channel OFET behavior on hexamethyldisilazane- treated and Cytop spin-coated Si02 in vacuum. These are the first fluorenone- and fumaronitrile-based n-OSCs demonstrated in transistors. However, oxadiazole-core materials 14 and 16 were inactive in transistordevices.
- Lee, Taegweon,Landis, Chad A.,Dhar, Bal Mukund,Jung, Byung Jun,Sun, Jia,et al.
-
experimental part
p. 1692 - 1705
(2009/07/25)
-
- Free radical and isomerisation processes during the electrochemical fluorination of n-butyryl chloride, i-butyryl chloride and pivaloyl chloride in anhydrous hydrogen fluoride
-
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
-
p. 1111 - 1118
(2008/09/16)
-
- Degradation of fluorotelomer alcohols: A likely atmospheric source of perfluorinated carboxylic acids
-
Human and animal tissues collected in urban and remote global locations contain persistent and bioaccumulative perfluorinated carboxylic acids (PFCAs). The source of PFCAs was previously unknown. Here we present smog chamber studies that indicate fluorotelomer alcohols (FTOHs) can degrade in the atmosphere to yield a homologous series of PFCAs. Atmospheric degradation of FTOHs is likely to contribute to the widespread dissemination of PFCAs. After their bioaccumulation potential is accounted for, the pattern of PFCAs yielded from FTOHs could account for the distinct contamination profile of PFCAs observed in arctic animals. Furthermore, polar bear liver was shown to contain predominately linear isomers (>99%) of perfluorononanoic acid (PFNA), while both branched and linear isomers were observed for perfluorooctanoic acid, strongly suggesting a sole input of PFNA from "telomer"-based products. The significance of the gas-phase peroxy radical cross reactions that produce PFCAs has not been recognized previously. Such reactions are expected to occur during the atmospheric degradation of all polyfluorinated materials, necessitating a reexamination of the environmental fate and impact of this important class of industrial chemicals.
- Ellis, David A.,Martin, Jonathan W.,De Silva, Amila O.,Mabury, Scott A.,Hurley, Michael D.,Sulbaek Andersen, Mads P.,Wallington, Timothy J.
-
p. 3316 - 3321
(2007/10/03)
-
- A novel catalytic pathway for perfluoroacyl peroxide synthesis
-
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.
-
p. 2997 - 2999
(2007/10/03)
-
- Multiple pathways in cyclodextrin-catalyzed hydrolysis of perfluoroalkylamides
-
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.
-
p. 3690 - 3696
(2007/10/02)
-
- REACTIVITE DES PERFLUOROIODOALCANES AVEC LES CARBONATES ET PYROCARBONATES D'ALCOYLES EN PRESENCE DE COUPLE METALLIQUE ZINC-CUIVRE
-
Perpluoroalkyl iodides RFI, in dissociating solvents, in the presence of zinc-copper couple give perfluoroorganic compounds RFZnI, which reac with alkyl carbonates and pyrocarbonates to give perfluorocarboxylic acids and perfluorocarboxylis esters of industrial interest.
- Benefice, S.,Blancou, H.,Commeyras, A.
-
p. 1541 - 1544
(2007/10/02)
-
- OXYDATION ANODIQUE DE IODOPERFLUOROALCANES DANS LES ACIDES PERFLUOROALCANESULFONIQUES. PREPARATION DE NOUVEAUX ESTERS SULFONIQUES TOTALEMENT FLUORES RFSO3R'F A LONGUES CHAINES
-
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.
-
p. 487 - 492
(2007/10/02)
-
- Process for functionalizing perfluorohalogenoalkanes
-
The present invention relates to the process of preparing perfluoro functional compounds from a perfluorohalogenoalkane having the general formula: wherein RF is a saturated, unsaturated, straight, or branched chain perfluoroalkyl radical containing 2 to 12 carbon atoms, and X is selected from chlorine, bromine, or iodine, comprising reacting said perfluorohalogenoalkane with a functionalizing reagent in the presence of a metallic couple dispersed in a sulfoxide-type solvent, said metallic couple having the general formula: wherein M1 is metal selected from Group IB, IIA, IIB, or IIIA of the Periodic Table and M2 is a metal having an electrochemical potential such that it can be deposited on metal M1.
- -
-
-