scholarly journals Effect of chemical structure on the sonochemical degradation of perfluoroalkyl and polyfluoroalkyl substances (PFASs)

2016 ◽  
Vol 2 (6) ◽  
pp. 975-983 ◽  
Author(s):  
Nerea Abad Fernandez ◽  
Lucia Rodriguez-Freire ◽  
Manish Keswani ◽  
Reyes Sierra-Alvarez
Keyword(s):  
Chain Length ◽  
Chemical Structure ◽  
Functional Group ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Polyfluoroalkyl Substances ◽  
Perfluoroalkyl And Polyfluoroalkyl Substances

The study provides insights into the effect of carbon chain length, functional group substitutions and chemical structure on sonochemical degradation of perfluoroalkyl and polyfluoroalkyl substances.

scholarly journals Alkyl halides as both hydride and alkyl sources in catalytic regioselective reductive olefin hydroalkylation

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xianxiao Chen ◽  
Weidong Rao ◽  
Tao Yang ◽  
Ming Joo Koh
Keyword(s):  
Chain Length ◽  
Functional Group ◽  
Carbon Chain ◽  
Reducing Agent ◽  
Alkyl Halides ◽  
Bioactive Molecules ◽  
Catalytic Process ◽  
Carbon Chain Length ◽  
Simple Protocol

AbstractAmong the plethora of catalytic methods developed for hydrocarbofunctionalization of olefins to date, reactions that regioselectively install a functionalized alkyl unit at the 2-position of a terminal unactivated C=C bond to afford branched products are scarce. Here, we show that a Ni-based catalyst in conjunction with a stoichiometric reducing agent promote Markovnikov-selective hydroalkylation of unactivated alkenes tethered to a recyclable 8-aminoquinaldine directing auxiliary. These mild reductive processes employ readily available primary and secondary haloalkanes as both the hydride and alkyl donor. Reactions of alkenyl amides with ≥ five-carbon chain length regioselectively afforded β-alkylated products through remote hydroalkylation, underscoring the fidelity of the catalytic process and the directing group’s capability in stabilizing five-membered nickelacycle intermediates. The operationally simple protocol exhibits exceptional functional group tolerance and is amenable to the synthesis of bioactive molecules as well as regioconvergent transformations.

Electrochemical degradation of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in groundwater

2015 ◽  
Vol 71 (10) ◽  
pp. 1569-1575 ◽  
Author(s):  
A. M. Trautmann ◽  
H. Schell ◽  
K. R. Schmidt ◽  
K.-M. Mangold ◽  
A. Tiehm
Keyword(s):  
Carbon Chain ◽  
Contaminated Groundwater ◽  
Carbon Chain Length ◽  
Order Kinetic ◽  
Electrochemical Degradation ◽  
Boron Doped Diamond ◽  
Polyfluoroalkyl Substances ◽  
Hazardous Pollutants ◽  
Chain Lengths ◽  
Perfluoroalkyl And Polyfluoroalkyl Substances

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) represent hazardous pollutants and are frequently detected in the environment, e.g. in contaminated groundwater. PFASs are persistent to biodegradation and conventional oxidation processes such as ozonation. In this study electrochemical degradation of PFASs on boron-doped diamond (BDD) electrodes is demonstrated. Experiments were performed with model solutions and contaminated groundwater with a dissolved organic carbon (DOC) content of 13 mg/L. The perfluorinated carboxylic acids (PFCAs) perfluorobutanoate, perfluoropentanoate, perfluorohexanoate, perfluoroheptanoate and perfluorooctanoate, and the perfluorinated sulfonic acids (PFSAs) perfluorobutane sulfonate, perfluorohexane sulfonate, perfluorooctane sulfonate and 6:2 fluorotelomer sulfonate were detected in the groundwater samples. At PFAS concentrations ranging from 0.26 to 34 mg/L (0.7 to 79 μM), the degradation of PFASs was achieved despite of the high DOC background. Pseudo first-order kinetic constants of PFSA degradation increased with the increase of carbon chain length. Fluoride formation as well as the generation of PFCAs with shortened chain lengths was observed. Inorganic byproducts such as perchlorate were also formed and have to be considered in further process optimization.

Molecular Features of Odorants Systematically Influence Slow Temporal Responses Across Clusters of Coordinated Antennal Lobe Units in the Moth Manduca sexta

2004 ◽  
Vol 92 (1) ◽  
pp. 236-254 ◽  
Author(s):  
Kevin C. Daly ◽  
Geraldine A. Wright ◽  
Brian H. Smith
Keyword(s):  
Chain Length ◽  
Manduca Sexta ◽  
Antennal Lobe ◽  
Functional Group ◽  
Carbon Chain ◽  
Stimulus Generalization ◽  
Carbon Chain Length ◽  
Molecular Features ◽  
Behavioral Studies ◽  
Cross Correlation Analysis

Behavioral studies of olfactory discrimination and stimulus generalization in many species indicate that the molecular features of monomolecular odorants are important for odor discrimination. Here we evaluate how features, such as carbon chain length and functional group, are represented in the first level of synaptic processing. We recorded antennal lobe ensemble responses in the moth Manduca sexta to repeated 100-ms pulses of monomolecular alcohols and ketones. Most units exhibited a significant change in spike rate in response to most odorants that outlasted the duration of the stimulus. Peristimulus data were then sampled over 780 ms for each pulse of all odorants. Factor analysis was used to assess whether there were groups of units with common response patterns. We found that factors identified and represented activity for clusters of units with common temporal response characteristics. These temporally patterned responses typically spanned 780 ms and were often dependent on carbon chain length and functional group. Furthermore, cross-correlation analysis frequently indicated significant coincident spiking even during spontaneous activity. However, this synchrony occurred mainly between units recorded on the same tetrode. In a final analysis, the Euclidean distance between odor responses was calculated for each pair of odorants using factors as dimensions. The distance between responses for any two odorants was maximized by ∼240 ms. This time course corresponded to the brief sequence of coordinated bursts across the recorded population. The distance during this period was also a function of systematic differences in molecular features. Results of this Euclidian analysis thus directly correlate to previous behavioral studies of stimulus generalization in M. sexta.

scholarly journals Alkyl Halides as Both Hydride and Alkyl Sources in Catalytic Regioselective Reductive Olefin Hydroalkylation

2020 ◽  
Author(s):  
Xianxiao Chen ◽  
Weidong Rao ◽  
Tao Yang ◽  
Ming Joo Koh
Keyword(s):  
Chain Length ◽  
Functional Group ◽  
Carbon Chain ◽  
Reducing Agent ◽  
Alkyl Halides ◽  
Bioactive Molecules ◽  
Catalytic Process ◽  
Carbon Chain Length ◽  
Simple Protocol

Among the plethora of catalytic methods developed for hydrocarbofunctionalization of olefins to date, reactions that regioselectively install a functionalized alkyl unit at the 2-position of a terminal unactivated C=C bond to afford branched products are scarce. Here, we show that a Ni-based catalyst in conjunction with a stoichiometric reducing agent promote Markovnikov-selective hydroalkylation of unactivated alkenes tethered to a recyclable 8-aminoquinaldine directing auxiliary. These mild reductive processes employ readily available primary and secondary haloalkanes as both the hydride and alkyl donor, obviating the need for additional hydrosilane, acidic or basic additives. Reactions of alkenyl amides with ≥five-carbon chain length regioselectively afforded β-alkylated products through remote hydroalkylation, underscoring the fidelity of the catalytic process and the directing group's capability in stabilizing five-membered nickelacycle intermediates. The operationally simple protocol exhibits exceptional functional group tolerance and is amenable to the synthesis of bioactive molecules as well as regioconvergent transformations.

scholarly journals Alkyl Halides as Both Hydride and Alkyl Sources in Catalytic Regioselective Reductive Olefin Hydroalkylation

2020 ◽  
Author(s):  
Xianxiao Chen ◽  
Weidong Rao ◽  
Tao Yang ◽  
Ming Joo Koh
Keyword(s):  
Chain Length ◽  
Functional Group ◽  
Carbon Chain ◽  
Reducing Agent ◽  
Alkyl Halides ◽  
Bioactive Molecules ◽  
Catalytic Process ◽  
Carbon Chain Length ◽  
Simple Protocol

Among the plethora of catalytic methods developed for hydrocarbofunctionalization of olefins to date, reactions that regioselectively install a functionalized alkyl unit at the 2-position of a terminal unactivated C=C bond to afford branched products are scarce. Here, we show that a Ni-based catalyst in conjunction with a stoichiometric reducing agent promote Markovnikov-selective hydroalkylation of unactivated alkenes tethered to a recyclable 8-aminoquinaldine directing auxiliary. These mild reductive processes employ readily available primary and secondary haloalkanes as both the hydride and alkyl donor, obviating the need for additional hydrosilane, acidic or basic additives. Reactions of alkenyl amides with ≥five-carbon chain length regioselectively afforded β-alkylated products through remote hydroalkylation, underscoring the fidelity of the catalytic process and the directing group's capability in stabilizing five-membered nickelacycle intermediates. The operationally simple protocol exhibits exceptional functional group tolerance and is amenable to the synthesis of bioactive molecules as well as regioconvergent transformations.

scholarly journals Alkyl Halides as Both Hydride and Alkyl Sources in Catalytic Regioselective Reductive Olefin Hydroalkylation

2020 ◽  
Author(s):  
Xianxiao Chen ◽  
Weidong Rao ◽  
Tao Yang ◽  
Ming Joo Koh
Keyword(s):  
Chain Length ◽  
Functional Group ◽  
Carbon Chain ◽  
Reducing Agent ◽  
Alkyl Halides ◽  
Bioactive Molecules ◽  
Catalytic Process ◽  
Carbon Chain Length ◽  
Simple Protocol

Among the plethora of catalytic methods developed for hydrocarbofunctionalization of olefins to date, reactions that regioselectively install a functionalized alkyl unit at the 2-position of a terminal unactivated C=C bond to afford branched products are scarce. Here, we show that a Ni-based catalyst in conjunction with a stoichiometric reducing agent promote Markovnikov-selective hydroalkylation of unactivated alkenes tethered to a recyclable 8-aminoquinaldine directing auxiliary. These mild reductive processes employ readily available primary and secondary haloalkanes as both the hydride and alkyl donor, obviating the need for additional hydrosilane, acidic or basic additives. Reactions of alkenyl amides with ≥five-carbon chain length regioselectively afforded β-alkylated products through remote hydroalkylation, underscoring the fidelity of the catalytic process and the directing group's capability in stabilizing five-membered nickelacycle intermediates. The operationally simple protocol exhibits exceptional functional group tolerance and is amenable to the synthesis of bioactive molecules as well as regioconvergent transformations.

scholarly journals The Accumulated Effect of the Number of Ethylene Oxide Units and/or Carbon Chain Length in Surfactants Structure on the Nano-Micellar Extraction of Flavonoids

2020 ◽  
Vol 11 (3) ◽  
pp. 57
Author(s):  
Karolina Śliwa ◽  
Paweł Śliwa
Keyword(s):  
Chain Length ◽  
Chemical Structure ◽  
Structural Changes ◽  
High Efficiency ◽  
Extraction Process ◽  
Extraction Methods ◽  
Carbon Chain ◽  
Ionic Surfactants ◽  
Carbon Chain Length ◽  
Hydrophilic Lipophilic Balance

Classical extraction methods used for isolation of active substances from plant material are expensive, complicated and often environmentally unfriendly. The ultrasonic assistance micelle-mediated extraction method (UAMME), based on green chemistry principles, seems to be an interesting alternative. This work aimed to find a connection between the chemical structure of non-ionic surfactants and the efficiency of the extraction process. The effect of hydrophobic chain length and number of ethoxy groups on the quality of Bidens tripartite extracts was investigated. Several ethoxylated fatty alcohols were used: Ceteareth-20, Steareth-20, Oleth-20, Oleth-10, Oleth-5, C12-C13 Pareth-12, C12-C15 Pareth-12 and Ceteareth-12. The bioflavonoid compositions with the HPLC method was determined. The hydrophilic lipophilic balance (HLB) of studied surfactants, as well as the surface tension of surfactant solutions, were compared, to determine the explanation for the obtained differences in bioflavonoids concentration. The structural changes influenced by polyphenol extraction were monitored using Dynamic Light Scattering (DLS) measurements. In this work, probably for the first time, the connection between the chemical structure of non-ionic surfactants and the efficiency of the extraction process was found. The experimental and theoretical approach rationalized the choice of an appropriate eluent. We propose some structurally dependent factors, whose optimal value gave a high efficiency to the UAMME.

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