The Experts below are selected from a list of 1140 Experts worldwide ranked by ideXlab platform

Akira Sekiya - One of the best experts on this subject based on the ideXlab platform.

  • Electrochemical Fluorination of several esters derived from oxolane-2-yl-carboxylic acid, oxolane-2-yl-methanol and oxane-2-yl-methanol
    Journal of Fluorine Chemistry, 2005
    Co-Authors: Abe Takashi, Masanori Tamura, Akira Sekiya
    Abstract:

    Abstract Electrochemical Fluorination (ECF) of the ester derivatives of oxolane-2-yl-carboxylic acid (1), oxolane-2-yl-methanol (2) and oxane-2-yl-methanol (3) were investigated. Perfluoro(oxolane-2-yl-carbonylfluoride) (4) was obtained from derivatives of 1 and 2, and perfluoro(oxane-2-yl-carbonylfluoride) (5) was obtained from derivatives of 3 as the desired compounds, respectively. From the ECF of acetates of 2 and 3, perfluorospiroethers having a dioxolane ring were also obtained as the cyclization product in low yield together with the desired perfluoroacid fluoride (4 and 5). The structure of these perfluorospiroethers was confirmed by analyzing the chlorinated products, which were obtained by the reaction with AlCl3.

Toshio Fuchigami - One of the best experts on this subject based on the ideXlab platform.

  • alkali metal fluorides in fluorinated alcohols fundamental properties and applications to Electrochemical Fluorination
    Journal of Organic Chemistry, 2021
    Co-Authors: Naoki Shida, Hiroaki Takenaka, Akihiro Gotou, Tomohiro Isogai, Akiyoshi Yamauchi, Yosuke Kishikawa, Yuuya Nagata, Ikuyoshi Tomita, Toshio Fuchigami
    Abstract:

    Fundamental properties of alkali metal fluorides (MF, M = Cs, K) dissolved in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) or in 3,3,3-trifluoroethanol (TFE) are investigated, including solubility, conductivity, and viscosity. Solid-state structures of single crystals obtained from CsF/HFIP and CsF/TFE are described for the first time, giving insights into the multiple interactions between fluorinated alcohols and CsF. Applications in Electrochemical Fluorination reactions are successfully demonstrated.

  • Bipolar Electrochemical Fluorination of Triphenylmethane and Bis(phenylthio)diphenylmethane Derivatives in a U-shaped Cell
    'The Electrochemical Society of Japan', 2021
    Co-Authors: Naoki Shida, Toshio Fuchigami, Akihiro Gotou, Tomohiro Isogai, Akiyoshi Yamauchi, Ikuyoshi Tomita, Elena Villani, Mokurai Sanuki, Kazuhiro Miyamoto, Shinsuke Inagi
    Abstract:

    Electrochemical Fluorination of triphenylmethane derivatives and bis(phenylthio)diphenylmethane derivatives by using a split bipolar electrode is described. The reaction conditions for the Fluorination of triphenylmethane were further optimized from the previous report to obtain the desired product in quantitative yields. Fluorination reaction cleanly proceeded under a wide range of voltage applied between the driving electrodes, from 25 to 100 V. Use of lower voltage is preferable in terms of energy efficiency, whereas higher voltage shortened the reaction time. The optimized conditions were applicable to the Fluorination of other triphenylmethane derivatives and bis(phenylthio)diphenylmethane derivatives to give the corresponding fluorinated products

  • Anodic Fluorination and Cathodic Michael Addition of Schiff Bases Bearing Trifluoromethyl and Ester Groups
    'The Electrochemical Society of Japan', 2021
    Co-Authors: Nanae Imai, Shinsuke Inagi, Toshio Fuchigami
    Abstract:

    Anodic Fluorination of N-(diphenylmethyleneamino)-2,2,2-trifluoroethane and N-[bis(methylthio)methyleneamino]-2,2,2-triphenylethane in acetonitrile containing poly(HF) salt ionic liquids afforded monofluorinated products in moderate to good yields. On the other hand, anodic Fluorination of N-[bis(methylthio)methylene]glycine methyl ester provided mono- and difluoroproducts depending on the amount of electricity passed. This is the first successful Electrochemical Fluorination of open-chain α-amino acid derivatives. Cathodic Michael addition of N-(diphenylmethyleneamino)-2,2,2-trifluoroethane to activated olefins such as acrylate and acrylonitrile was also successfully carried out using a titanium cathode

  • The selective Electrochemical Fluorination of S-alkyl benzothioate and its derivatives
    'Beilstein Institut', 2018
    Co-Authors: Shunsuke Kuribayashi, Shinsuke Inagi, Tomoyuki Kurioka, Biing-jiun Uang, Toshio Fuchigami
    Abstract:

    We herein report that the regioselective anodic Fluorination of S-alkyl benzothioate and its derivatives in various aprotic solvents using Et3N·nHF (n = 3–5) and Et4NF·nHF (n = 3–5) as supporting electrolyte and a fluorine source successfully provided the corresponding α-fluorinated products in moderate yields. Dichloromethane containing Et4NF·4HF was found to be the most suitable combination as electrolytic solvent and supporting salt as well as fluorine source for the anodic Fluorination. The Electrochemical Fluorination of cyclic benzothioates such as benzothiophenone was also achieved

  • synthesis of fluorinated triazole and isoxazole derivatives by Electrochemical Fluorination
    Tetrahedron, 2016
    Co-Authors: Shunsuke Kuribayashi, Naoki Shida, Shinsuke Inagi, Toshio Fuchigami
    Abstract:

    Abstract Partially fluorinated triazole derivatives were synthesized through anodic Fluorination of alkynes having arylthio group and following Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) with benzyl azide. The other route toward the fluorinated triazoles, namely the anodic Fluorination of triazole derivatives once prepared by advanced CuAAC of the alkyne and azide above was also investigated. It was shown that these two routes are mutually complementary methodology for the synthesis of new mono- and difluoromethyltriazole derivatives. Furthermore, Cu(I)-catalyzed isoxazole synthesis from fluorinated alkynes and imidoyl chloride was demonstrated.

Robert J Letcher - One of the best experts on this subject based on the ideXlab platform.

  • linear and branched perfluorooctane sulfonate pfos isomer patterns differ among several tissues and blood of polar bears
    Chemosphere, 2013
    Co-Authors: Alana K Greaves, Robert J Letcher
    Abstract:

    Perfluorooctane sulfonate (PFOS) is a globally distributed persistent organic pollutant that has been found to bioaccumulate and biomagnify in aquatic food webs. Although principally in its linear isomeric configuration, 21-35% of the PFOS manufactured via Electrochemical Fluorination is produced as a branched structural isomer. PFOS isomer patterns were investigated in multiple tissues of polar bears (Ursus maritimus) from East Greenland. The liver (n = 9), blood (n = 19), brain (n = 16), muscle (n = 5), and adipose (n = 5) were analyzed for linear PFOS (n-PFOS), as well as multiple mono- and di-trifluoromethyl-substituted branched isomers. n-PFOS accounted for 93.0 ± 0.5% of Σ-PFOS isomer concentrations in the liver, whereas the proportion was significantly lower (p<0.05) in the blood (85.4 ± 0.5%). Branched isomers were quantifiable in the liver and blood, but not in the brain, muscle, or adipose. In both the liver and blood, 6-perfluoromethylheptane sulfonate (P6MHpS) was the dominant branched isomer (2.61 ± 0.10%, and 3.26 ± 0.13% of Σ-PFOS concentrations, respectively). No di-trifluoromethyl-substituted isomers were detectable in any of the tissues analyzed. These tissue-specific isomer patterns suggest isomer-specific pharmacokinetics, perhaps due to differences in protein affinities, and thus differences in protein interactions, as well transport, absorption, and/or metabolism in the body.

  • isomer specific accumulation of perfluorooctane sulfonate in the liver of chicken embryos exposed in ovo to a technical mixture
    Environmental Toxicology and Chemistry, 2011
    Co-Authors: Sean W Kennedy, Jason M Obrien, Shaogang Chu, Robert J Letcher
    Abstract:

    Prior to its recent phaseout, perfluorooctane sulfonate (PFOS) was produced by Electrochemical Fluorination processes, which yielded technical mixtures composed of linear isomer (∼65–79%) and several branched isomers (∼21–35%). Because PFOS can biomagnify in wildlife, birds that occupy higher trophic levels are at increased risk of exposure. We hypothesized that the pharmacokinetic properties of PFOS are isomer-specific in developing chicken (Gallus gallus domesticus) embryos exposed to technical grade PFOS (T-PFOS). In the present study, T-PFOS was composed of 62.7% linear isomer (L-PFOS), and 37.3% branched isomer, including six mono(trifluoromethyl)-branched isomers and four bis(trifluoromethyl)-branched isomers. Concentrations of 0.1, 5, or 100 µg/g of T-PFOS were injected into the air cell of chicken eggs prior to incubation. After pipping, compared with T-PFOS, the PFOS isomer profile in embryonic liver tissue for the 0.1 µg/g dose group showed 21% enrichment in the proportion of L-PFOS with a corresponding decrease in the proportion of branched isomers. Not all branched isomers were discriminated against at equal rates. The proportion of two mono(trifluoromethyl)-branched isomers and three bis(trifluoromethyl)-branched isomers decreased to a greater degree than other branched isomers. In contrast, the mono-branched isomer, P6MHpS, was overrepresented in the low-dose group. In the higher dose groups, L-PFOS was still enriched but only by approximately 10%, which indicated a dose-dependent change in isomer composition relative to T-PFOS. These results show that accumulation of PFOS in chicken embryo livers is dependent on the presence and position of branches on the alkyl backbone. This supports the hypothesis that the pharmacokinetics of PFOS are isomer-specific in biota, and may help explain why wildlife PFOS burdens are dominated by L-PFOS relative to T-PFOS mixtures. Environ. Toxicol. Chem. 2011;30:226–231. © 2010 SETAC

Abe Takashi - One of the best experts on this subject based on the ideXlab platform.

  • Electrochemical Fluorination of several esters derived from oxolane-2-yl-carboxylic acid, oxolane-2-yl-methanol and oxane-2-yl-methanol
    Journal of Fluorine Chemistry, 2005
    Co-Authors: Abe Takashi, Masanori Tamura, Akira Sekiya
    Abstract:

    Abstract Electrochemical Fluorination (ECF) of the ester derivatives of oxolane-2-yl-carboxylic acid (1), oxolane-2-yl-methanol (2) and oxane-2-yl-methanol (3) were investigated. Perfluoro(oxolane-2-yl-carbonylfluoride) (4) was obtained from derivatives of 1 and 2, and perfluoro(oxane-2-yl-carbonylfluoride) (5) was obtained from derivatives of 3 as the desired compounds, respectively. From the ECF of acetates of 2 and 3, perfluorospiroethers having a dioxolane ring were also obtained as the cyclization product in low yield together with the desired perfluoroacid fluoride (4 and 5). The structure of these perfluorospiroethers was confirmed by analyzing the chlorinated products, which were obtained by the reaction with AlCl3.

Lingyan Zhu - One of the best experts on this subject based on the ideXlab platform.

  • Perfluoroalkyl Acids Including Isomers in Tree Barks from a Chinese Fluorochemical Manufacturing Park: Implication for Airborne Transportation
    2018
    Co-Authors: Hangbiao Jin, Lingyan Zhu, Guoqiang Shan, Hongwen Sun, Yi Luo
    Abstract:

    Measurement of airborne perfluoroalkyl acids (PFAAs) is challenging, but important for understanding their atmospheric transport. Tree bark is good media for monitoring semivolatile compounds in the atmosphere. Whether it could work as an indicator of airborne PFAAs was first examined in this study. Bark and leaf samples collected around a Chinese fluorochemical manufacturing park (FMP) were analyzed for PFAAs and their branched isomers. Total PFAA concentrations (∑PFAAs) in the bark (mean, 279 ng/g dw) and leaf (250 ng/g dw) samples were comparable. ∑PFAAs in the barks collected within the boundaries of the FMP were significantly (p < 0.05) higher than those outside the FMP, and displayed a decreasing spatial trend as the distance from the FMP increased. However, such spatial difference and trend were not observed for the leaves. PFAA compositional profiles in most of the tree barks were consistent with each other, but different from those in tree leaves. These results indicated that tree barks mainly accumulated airborne PFAAs, while uptake from soil and translocation could make partial contribution to those in leaves. Perfluorooctanoate and perfluorooctanesulfonate in barks had strictly consistent isomeric compositions with their Electrochemical Fluorination products. Overall, these results indicated that the bark could be a good indicator of airborne PFAAs with respect to their occurrence, isomeric signature, and atmospheric transport

  • isomeric specific partitioning behaviors of perfluoroalkyl substances in water dissolved phase suspended particulate matters and sediments in liao river basin and taihu lake china
    Water Research, 2015
    Co-Authors: Xinwei Chen, Yifeng Zhang, Lingyan Zhu, Shuhong Fang, Xiaoyu Pan, Liping Yang
    Abstract:

    Abstract The occurrence and distribution of eleven perfluoroalkyl substances (PFASs) and the isomers of perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS) and perfluorooctane sulfonamide (PFOSA) were investigated in water dissolved phase, sediment and suspended particulate matter (SPM) in two typical watersheds in China: Liao River Basin and Taihu Lake. The total concentrations of the PFASs in the dissolved phase were 44.4–781 ng/L in Liao River with high contribution of perfluorobutane sulfonate (PFBS) (75.7%) and PFOA (9.86%). The ∑PFASs in the dissolved phase in Taihu Lake was 17.2–94.4 ng/L with PFOA (39.8%), perfluorohexanoate (PFHxA) (30.1%) and PFOS (16.8%) as the dominant PFASs. The log K oc values of the PFASs in both SPM and sediment increased with increasing the perfluorinated carbon chain length. In Liao River Basin, the long chain perfluorocarboxylates (C10-12) bound with SPM contributed >30% to the total amount in water, suggesting that SPM could not be ignored when the environmental load of long chain PFASs in water was assessed. For the isomers of PFOA, PFOS and PFOSA, the linear isomers always displayed higher partition coefficients on particulate phases than the branched ones. An established isomer-profiling technique was applied to assess the relative contributions of various industrial origins for PFOA. In Liao River, when SPM was included in the water samples, there were contributions of PFOA from Electrochemical Fluorination (ECF) (∼55%), linear telomer (∼41%) and isopropyl telomer (∼4%) sources. While, the results based on the dissolved phase alone indicated more contribution of ECF (∼70%) source and lower contribution from linear telomer (∼26%) source. The discrepancy suggests that omitting SPM from water samples might lead to misunderstanding on the industrial origins of PFOA. In Taihu Lake, the isomer profile of PFOA was influenced mainly by ECF (∼88%) and partially by linear-telomer (∼12%) sources.

  • serum levels of perfluoroalkyl acids pfaas with isomer analysis and their associations with medical parameters in chinese pregnant women
    Environment International, 2014
    Co-Authors: Weiwei Jiang, Yifeng Zhang, Lingyan Zhu, Jimin Deng
    Abstract:

    Perfluoroalkyl acids (PFAAs) are a group of chemicals used for many applications and widely present in the environment and humans. In this study, serum levels of PFAAs and isomers of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) were analyzed in 141 Chinese pregnant women. Among all the samples, total PFOS (∑PFOS, mean concentration 7.32ng/mL) was predominant, followed by ∑PFOA (mean 4.78ng/mL) and perfluorodecanoate (PFDA, mean 1.45ng/mL). On average, the proportion of linear PFOS (n-PFOS) was 66.7% of ∑PFOS, which was higher than the general population, implying that maternal women could excrete branched PFOS isomers to the fetus by transplacental transfer. Moreover, the proportion of n-PFOS decreased significantly with the increasing concentration of ∑PFOS in the serum samples (r=-0.342, p<0.001). The mean proportion of n-PFOA in the serum samples was 99.0%, which was much higher than the technical ECF (Electrochemical Fluorination) products (ca. 70%). The small proportion of branched isomers of PFOA suggests that there is still a source of ECF PFOA in China. Significant correlations (p<0.005) were observed between the concentrations of some PFAAs with certain medical parameters in the pregnant women. For example, the levels of most perfluorinated carboxylic acids (PFCAs) were found to correlate with albumin significantly, which might be a sign of immunotoxicity of these chemicals. The adverse effects of PFAA exposure to pregnant women may increase the health risk of the fetus. Interestingly, not only the PFAA concentrations but also the percentages of PFOS and PFOA isomers were correlated with certain medical parameters. This implies that the compositions of PFOS or PFOA should be considered in human health risk assessment in the future.

  • trophic magnification and isomer fractionation of perfluoroalkyl substances in the food web of taihu lake china
    Environmental Science & Technology, 2014
    Co-Authors: Shuhong Fang, Weiwei Jiang, Yifeng Zhang, Xinwei Chen, Shuyan Zhao, Liping Yang, Lingyan Zhu
    Abstract:

    Biomagnification of perfluoroalkyl substances (PFASs) are well studied in marine food webs, but related information in fresh water ecosystem and knowledge on fractionation of their isomers along the food web are limited. The distribution, bioaccumulation, magnification, and isomer fractionation of PFASs were investigated in a food web of Taihu Lake, China. Perfluorooctanesulfonate (PFOS) and perfluorocarboxylates (PFCAs) with longer carbon chain lengths, such as perfluorodecanoate (PFDA) and perfluoroundecanoate (PFUnA), were predominant in organisms, while perfluorohexanoate (PFHxA) and perfluorooctanoate (∑PFOA) contributed more in the water phase. The consistent profile signature of PFOA isomers in water phase with 3M Electrochemical Fluorination (ECF) products suggests that ECF production of PFOA still exists in China. Linear proportions of PFOA, PFOS and perfluorooctane sulfonamide (PFOSA) in the biota were in the range of 91.9–100%, 78.6–95.5%, and 72.2–95.5%, respectively, indicating preferential b...