Unsaturated Carboxylic Acids Research Articles

Review of the fate and transformation of per- and polyfluoroalkyl substances (PFASs) in landfills.

A critical review of existing publications is presented i) to summarize the occurrence of various classes of per- and polyfluoroalkyl substances (PFASs) and their sources in landfills, ii) to identify temporal and geographical trends of PFASs in landfills; iii) to delineate the factors affecting PFASs in landfills; and iv) to identify research gaps and future research directions. Studies have shown that perfluoroalkyl acids (PFAAs) are routinely detected in landfill leachate, with short chain (C4-C7) PFAAs being most abundant, possibly indicating their greater mobility, and reflecting the industrial shift towards shorter-chain compounds. Despite its restricted use, perfluorooctanoic acid (PFOA) remains one of the most abundant PFAAs in landfill leachates. Recent studies have also documented the presence of PFAA-precursors (e.g., saturated and unsaturated fluorotelomer carboxylic acids) in landfill leachates at concentrations comparable to, or higher than, the most frequently detected PFAAs. Landfill ambient air also contains elevated concentrations of PFASs, primarily semi-volatile precursors (e.g., fluorotelomer alcohols) compared to upwind control sites, suggesting that landfills are potential sources of atmospheric PFASs. The fate of PFASs inside landfills is controlled by a combination of biological and abiotic processes, with biodegradation releasing most of the PFASs from landfilled waste to leachate. Biodegradation in simulated anaerobic reactors has been found to be closely related to the methanogenic phase. The methane-yielding stage also results in higher pH (>7) of leachates, correlated with higher mobility of PFAAs. Little information exists regarding PFAA-precursors in landfills. To avoid significant underestimation of the total PFAS released from landfills, PFAA-precursors and their degradation products should be determined in future studies. Owing to the semi-volatile nature of some precursor compounds and their degradation products, future studies also need to include landfill gas to clarify degradation pathways and the overall fate of PFASs.

Impact of the Biodegradation of 6:2 Fluorotelomer Alcohol on the Bacterial Community Structure of Surface Sediment

Fluorotelomer alcohol (6:2 FTOH) is a polyfluoalkyl substance that has been widely used in industry and consumer products in recent years, causing potential harm to the environment. However, currently the impact of 6:2 FTOH and its degradation products on microbial communities in sediment is unclear. The purpose of this study is to explore the impact of the biodegradation of 6:2 FTOH on bacterial community structures in surface sediment based on gene analysis. Surface sediment and river water were collected from Hai river, Tianjin, and a microcosm experiment was performed in the laboratory. The concentration of 6:2 FTOH and its degradation products were analyzed by liquid chromatograph-mass spectrometry/mass spectrometry (LC-MS/MS). The bacterial community structure was analyzed by denaturing gradient gel electrophoresis and high-throughput sequencing. The results showed that 6:2 FTOH could be degraded by microorganisms (half-life was less than 3 d), producing transient products such as 6:2 fluorotelomer carboxylic acid (FTCA) and 6:2 fluorotelomer unsaturated carboxylic acid (FTUCA) and stable products such as 5:2 fluorotelomer (FT) ketone, 5:2 fluorotelomer alcohol (sFTOH), perfluorohexanoic acid(PFHxA), perfluoro-n-pentanoic acid (PFPeA), perfluorobutanoic acid (PFBA) and 5:3 polyfluorinated acid. At different stages of 6:2 FTOH degradation, a change of bacteria and the predominant population became somewhat different. Based on the experimental results for 100 d, at the Phylum level, the biodegradation of 6:2 FTOH greatly increases the abundance of Chloroflexi (+24.8%) and decreases the abundance of Proteobacteria (-17.8%) and Firmicutes (-15.9%). At the Class level, due to the biodegradation of 6:2 FTOH, bacteria with notable increases included Anaerolineae (+19.6%) and δ-Proteobacteria (+4.3%), while bacteria with notable decreases included ε-Proteobacteria (-20.0%), Clostridia (-10.1%), Bacilli (-5.8%) and γ-Proteobacteria (- 4.2%). At the Genus level, due to the biodegradation of 6:2 FTOH, bacteria with notable increases included Anaerolineaceae_(uncultured) (+19.1%) and Thioalkalispira (+13.3%), while bacteria with notable decreases included Vibrio (-14.1%), Sulfurimonas (-13.2%), Bacillus (-5.1%), Sulfurovum (-4.2%) and Fusibacter (-4.1%). These results are helpful for predicting the response of bacteria to the contamination of polyfluoalkyl substances and isolating the bacteria capable of the biodegradation of polyfluoalkyl substances.

Access to Alkyl-Substituted Lactone via Photoredox-Catalyzed Alkylation/Lactonization of Unsaturated Carboxylic Acids.

An efficient photoredox-catalyzed alkylation/lactonization reaction of unsaturated carboxylic acids by using alkyl N-hydroxyphthalimide esters as alkylation reagents has been developed. Varieties of redox-active esters derived from aliphatic carboxylic acids were proved viable in this method, affording alkyl substituted lactones in moderate to good yields. This redox-neutral procedure features mild conditions and operational simplicity, which provides a new strategy for the synthesis of alkyl substituted lactones.

Diversity of compounds in femoral secretions of Galápagos iguanas (genera: Amblyrhynchus and Conolophus), and their potential role in sexual communication in lek-mating marine iguanas (Amblyrhynchus cristatus).

BackgroundChemical signals are widely used in the animal kingdom, enabling communication in various social contexts, including mate selection and the establishment of dominance. Femoral glands, which produce and release waxy secretions into the environment, are organs of central importance in lizard chemical communication. The Galápagos marine iguana (Amblyrhynchus cristatus) is a squamate reptile with a lek-mating system. Although the lekking behaviour of marine iguanas has been well-studied, their potential for sexual communication via chemical cues has not yet been investigated. Here we describe the diversity of the lipophilic fraction of males’ femoral gland secretions among 11 island populations of marine iguanas, and compare it with the composition of its sister species, the Galápagos land iguana (Conolophus subcristatus). We also conducted behavioural observations in marine iguana territorial males in order to explore the possible function of these substances in the context of male dominance in leks.MethodsFemoral secretions were analysed by gas chromatography coupled to mass spectrometry (GC–MS), and chromatography with a flame ionisation detector (GC-FID) in order to characterise the lipophilic composition. To understand the potential role of femoral secretions in marine iguana intraspecific communication, territorial males were sampled for their femoral glands and monitored to record their head bob rate—a territorial display behaviour in males—as well as the number of females present in their leks.ResultsWe found that the gland secretions were composed of ten saturated and unsaturated carboxylic acids ranging in chain length between C16 and C24, as well as three sterols. Cholesterol was the main compound found. Intriguingly, land iguanas have a higher diversity of lipophilic compounds, with structural group of lipids (i.e. aldehydes) entirely absent in marine iguanas; overall the chemical signals of both species were strongly differentiated. Lipid profiles also differed among populations of marine iguanas from different islands, with some islands demonstrating a high diversity of lipophilic compounds (i.e. full spectra of compounds), and others lacking one or more compounds. Among the compounds most frequently found missing were 11- and 13-eicosenoic acids. Gland secretions of males with a better body condition and with a higher dominance status (i.e. those accompanied by females and with higher head bob display) were proportionately richer in C20-unsaturated fatty acids (11-eicosenoic acid).DiscussionLand and marine iguanas strongly diverged in their chemical composition of the femoral glands likely due to ecological differences between both species. Despite that marine iguana populations varied in their femoral gland composition that was not related to their genetic structure. Our results indicated that 11-eicosenoic acid may play an important role in intraspecific chemical communication in marine iguanas.

Oxidation products of biodiesel in diesel fuel generated by artificial alteration and identified by mass spectrometry

The aim of the present study is the storage stability evaluation of diesel fuel and various blends of diesel with fatty acid methyl esters (FAME, biodiesel), derived from rapeseed and soybean oil, by means of artificial fuel alteration. In this case, this is a lab-based procedure to effect accelerated changing of fuel properties under defined and reproducible conditions via oxidative stress. All oxidation products – volatile, liquid or solid – were captured thus enabling in-depth characterisation of the oxidised fuels obtained by conventional analytical methods as well as gas chromatography coupled with mass spectrometry (GC–MS). Special focus was laid on the identification of oxidation products in the oxidised fuels at various stages of the experiments. It could be demonstrated that especially neutralisation number and water content behaved proportionally to the oxygen consumption. They showed only marginal changes during the induction period, while increasing dramatically with the rapid onset of oxygen consumption as soon as the induction period was passed. The investigated fuels were ranked according to their storage stability in the order of neat diesel fuel>B7 blends>B20 blends>neat FAME. FAME content decreased rapidly in the stage characterised by rapid oxygen pressure break down, corresponding to 60% FAME loss in B20RME. As main oxidation products in B20 RME, azelaic acid mono-ME, 9-oxo-nonanoic acid ME and hexanoic acid were identified. Moreover, carboxylic acids with chain lengths from C1 up to C9 as well as hydroxycarboxylic acids, dicarboxylic acids, and carboxylic acids with an epoxy group were formed. In B20 SME, main oxidation products were the same as detected for B20 RME. However, a distinctly broader variety of oxidation products was determined, e.g., carboxylic acid methyl esters from C8 to C18, unsaturated carboxylic acids up to C8, alcohols, and aldehydes. The main oxidation products detected in all samples are identical with those evolving during alteration of model mixtures containing linoleic acid methyl ester and linolenic acid methyl ester, respectively.

Phenolic compound explorer: A mid-infrared spectroscopy database

Analyses of phenolic compounds can be time-consuming and not always very reliable. Mid-infrared (MIR) spectroscopy could be used as a non-destructive tool for food quality analysis and control. The MIR spectra of 36 standard phenolic compounds (13 phenolic acids [hydroxybenzoic and hydroxycinnamic acids], 23 flavonoids [flavonols, flavones, isoflavones, flavanols, and flavanones]) were collected using an Attenuated Total Reflectance (ATR) accessory. Data were collected to build a spectral database in order to identify spectral features of each family of phenolic compounds studied. The phenolic compound spectra showed common spectral bands associated with aromatic six-membered rings and phenol moieties. The bands were numerous between 1640 and 700cm−1, leading to an overlap with other signals specific to different families. The methoxy group present in some phenolic compounds showed bands between 1470 and 950cm−1. The phenolic acids were characterized mainly by bands of unsaturated carboxylic acids, esters and alkenes, whereas flavonoids were characterized mainly by bands associated with benzopyrylium, Benzo-γ-pyrone and 2-phenyl-3,4-dihydro-2H-chromen-3-ol vibrations. A comparison of flavonoids with phenolic acids showed that the latter could be distinguished by bands of carboxylic acids between 1755 and 1630cm−1. Flavonoids were characterized by numerous peaks in the 1650–1400cm−1 region and at spectral frequencies inferior to 1200cm−1. Principal Component Analysis (PCA) was performed on the MIR spectra, resulting in good discrimination of the families of the studied flavonoids and phenolic acids. The spectral regions 1755–1400cm−1 and 1000–870cm−1 were of great importance in distinguishing the studied families of phenolic compounds. The study allows starting to build a MIR spectral database for phenolic compounds as bioactive components of food.

Enantioselective CuH-Catalyzed Hydroacylation Employing Unsaturated Carboxylic Acids as Aldehyde Surrogates.

The direct asymmetric copper hydride (CuH)-catalyzed coupling of α,β-unsaturated carboxylic acids to aryl alkenes to access chiral α-aryl dialkyl ketones is reported. A variety of substrate substitution patterns, sensitive functional groups, and heterocycles are tolerated in this reaction, which significantly expands the range of accessible products compared with existing hydroacylation methodology. Although mechanistic studies are ongoing, we propose that CuH-catalyzed silylation of unsaturated acids occurs to access a uniquely effective acyl electrophilic coupling partner.

PB09 不飽和カルボン酸誘導体を用いる光反応性液晶の構造と物性(化学・材料,ポスター発表,2012年日本液晶学会討論会)

PB09 不飽和カルボン酸誘導体を用いる光反応性液晶の構造と物性(化学・材料,ポスター発表,2012年日本液晶学会討論会)

Correlations between Structure and Near-Infrared Spectra of Saturated and Unsaturated Carboxylic Acids. Insight from Anharmonic Density Functional Theory Calculations.

By near-infrared (NIR) spectroscopy and anharmonic density functional theory (DFT) calculations, we investigate five kinds of saturated and unsaturated carboxylic acids belonging to the group of short-chain fatty acids: propionic acid, butyric acid, acrylic acid, crotonic acid, and vinylacetic acid. The experimental NIR spectra of these five kinds of carboxylic acids are reproduced by quantum chemical calculations in a broad spectral region of 7500-4000 cm-1 and for a wide range of concentrations. By employing anharmonic GVPT2 calculations on DFT level, a detailed interpretation of experimental spectra is achieved, elucidating structure-spectra correlations of these molecules in the NIR region. We emphasize the spectral features due to saturated and unsaturated alkyl chains, the location of a C═C bond within the alkyl chain, and the dimerization of carboxylic acids. In particular, the existence of a terminal C═C bond leads to the appearance of highly specific NIR bands. These pronounced bands are located at wavenumbers where no overlapping with other structure-specific bands occurs, thus making them good structural markers. Most of the spectral differences between these two groups of molecules remain subtle, and would be difficult to reliably ascribe without quantum chemically calculated NIR spectra. Moreover, anharmonic DFT calculations provide insights on the manifestation of hydrogen bonding through distinctive spectral features corresponding to cyclic dimers. The resulting spectral baseline elevation is common for all five investigated carboxylic acids, and remains consistent with previous results on acetic acid.

Iridium-Catalyzed Asymmetric Hydrogenation of Unsaturated Carboxylic Acids.

Chiral carboxylic acid moieties are widely found in pharmaceuticals, agrochemicals, flavors, fragrances, and health supplements. Although they can be synthesized straightforwardly by transition-metal-catalyzed enantioselective hydrogenation of unsaturated carboxylic acids, because the existing chiral catalysts have various disadvantages, the development of new chiral catalysts with high activity and enantioselectivity is an important, long-standing challenge. Ruthenium complexes with chiral diphosphine ligands and rhodium complexes with chiral monodentate or bidentate phosphorus ligands have been the predominant catalysts for asymmetric hydrogenation of unsaturated acids. However, the efficiency of these catalysts is highly substrate-dependent, and most of the reported catalysts require a high loading, high hydrogen pressure, or long reaction time for satisfactory results. Our recent studies have revealed that chiral iridium complexes with chiral spiro-phosphine-oxazoline ligands and chiral spiro-phosphine-benzylamine ligands exhibit excellent activity and enantioselectivity in the hydrogenation of α,β-unsaturated carboxylic acids, including α,β-disubstituted acrylic acids, trisubstituted acrylic acids, α-substituted acrylic acids, and heterocyclic α,β-unsaturated acids. On the basis of an understanding of the role of the carboxy group in iridium-catalyzed asymmetric hydrogenation reactions, we developed a carboxy-group-directed strategy for asymmetric hydrogenation of olefins. Using this strategy, we hydrogenated several challenging olefin substrates, such as β,γ-unsaturated carboxylic acids, 1,1-diarylethenes, 1,1-dialkylethenes, and 1-alkyl styrenes in high yield and with excellent enantioselectivity. All these iridium-catalyzed asymmetric hydrogenation reactions feature high turnover numbers (up to 10000) and turnover frequencies (up to 6000 h-1), excellent enantioselectivities (greater than 95% ee with few exceptions), low hydrogen pressure (<12 atm), and operational simplicity. These features make chiral iridium catalysts superior or comparable to well-established chiral ruthenium and rhodium catalysts for asymmetric hydrogenation of unsaturated carboxylic acids. A number of chiral natural products and pharmaceuticals have been prepared by concise routes involving an iridium-catalyzed asymmetric hydrogenation of an unsaturated carboxylic acid as a key step. As part of a mechanistic study of iridium-catalyzed asymmetric hydrogenation of unsaturated acids, we isolated, for the first time, the migratory insertion intermediate in the iridium-catalyzed asymmetric hydrogenation of olefins, and this result strongly supports the involvement of an Ir(III)/Ir(V) catalytic cycle. The rigid, bulky scaffold of the chiral spiro-P,N-ligands of the catalysts not only prevents them from undergoing deactivating aggregation under the hydrogenation conditions but also is responsible for the efficient chiral induction. The carboxy group of the substrate acts as an anchor to ensure coordination of the substrate to the iridium center of the catalyst during the reaction and makes the hydrogenation proceed smoothly.

DMAP‐Catalyzed [4 + 2] Cycloaddition of α,β‐Unsaturated Carboxylic Acids with Ketones for Synthesis of α,β‐Unsaturated δ‐Lactones

The DMAP‐catalyzed [4 + 2] cycloaddition of α,β‐unsaturated carboxylic acids with ketones furnishing α,β‐unsaturated δ‐lactones in good yields (up to 80%) is described, which is the first example of remote γ‐C(sp3)‐H activation of α,β‐unsaturated carboxylic acids facilitated by DMAP, a pyridine‐based catalyst. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Copper(II) Acetate‐Catalyzed Hydroxysulfenylation‐Initiated Lactonization of Unsaturated Carboxylic Acids with Oxygen as Oxidant and Oxygenation Reagent

AbstractA copper(II) acetate‐catalyzed aerobic thiolation of C=C double bonds, oxygenation, and intramolecular cyclization reactions of unsaturated carboxylic acids with thiols has been explored. The reaction proceeds through a new hydroxysulfenylation‐initiated lactonization pathway with carboxyl as electrophilic group, which provides an efficient access to assembly highly valuable thio‐substituted lactone derivatives with good yields under mild conditions. Several control experiments, as well as an isotope labelling experiment disclose that oxygen acts as both oxidant and reactant being transferred into the final product. The mechanistic studies support the discovery of a new strategy through difunctionalization of alkenes based on unsaturated carboxylic acids to construct the diversely substituted lactones.magnified image

Aerobic biodegradation of 2 fluorotelomer sulfonamide-based aqueous film-forming foam components produces perfluoroalkyl carboxylates.

The biodegradation of 2 common fluorotelomer surfactants used in aqueous film forming foams (AFFFs), 6:2 fluorotelomer sulfonamide alkylamine (FTAA) and 6:2 fluorotelomer sulfonamide alkylbetaine (FTAB), was investigated over 109 d with aerobic wastewater-treatment plant (WWTP) sludge. Results show that biodegradation of 6:2 FTAA and 6:2 FTAB produces 6:2 fluorotelomer alcohol (FTOH), 6:2 fluorotelomer carboxylic acid (FTCA), 6:2 fluorotelomer unsaturated carboxylic acid (FTUCA), 5:3 FTCA, and short-chain perfluoroalkyl carboxylates (PFCAs). Additional degradation products included 6:2 fluorotelomer sulfonamide (FTSAm), which was a major degradation product in the presence of either active or sterilized sludge, whereas 6:2 fluorotelomer sulfonate (FTSA) production was measured with sterilized sludge only. Six additional degradation products were tentatively identified by quadrupole time-of-flight mass spectrometry (qTOF-MS) and attributed to N-dealkylation and oxidation of 6:2 FTAA. Environ Toxicol Chem 2017;36:2012-2021. © 2017 SETAC.

Combination of polymerization and polycondensation in the synthesis, chemical modification, and cure of rolivsan thermosetting resins

Rolivsan thermosetting resins (ROLs) attract constant attention due to their epoxy-like high processability; at the same time, their high-temperature performance is much better than that of epoxy resins and bismaleimides. Development of these materials involves a nontrivial approach to synthesis of thermostable resins; this approach is based on introducing a new structure-forming tool, that is, 1-arylethanol group. The present article demonstrates the important role of polycondensation in rolivsan chemistry. ROLs consist of (di)vinylaromatic ethers and thermosensitive monomeric and oligomeric (di)methacrylates, which are formed after a series of acid-catalyzed reactions between di-secondary aliphatic-aromatic diols, such as bis-[4-( α-hydroxyethyl)phenyl] ether, and unsaturated carboxylic acids, such as methacrylic acid. The process of ROL cure is a combination of polymerization and polycondensation. In the course of this process, in the temperature range from 140°С to 170°С, the initial densely cross-linked ROL-copolymer is formed as a result of three-dimensional radical copolymerization of highly unsaturated components. Post-cure of ROLs in the 200–300°С temperature interval leads to structural rearrangement (polycondensation). Cured ROLs demonstrate morphology typical of thermosets; they consist of highly cross-linked spherical microdomains that are weakly bound by less densely cross-linked polymer interlayers. Thermocatalytic transformations of rolivsans modified by small amounts of additives (epoxies and aromatic diamines) were used in the development of a new approach to synthesis of heat-resistant thermosetting resins via high-temperature polycondensation in interdomain layers (which are used as a peculiar kind of microreactors).

Copper(I)‐Catalyzed α‐Acryloyloxylation of Ketones with α,β‐Unsaturated Carboxylic Acids To Form α‐Acryloyloxy Ketones

An efficient method for the α‐C–H acryloyloxylation of ketones with α,β‐unsaturated carboxylic acids was developed, using copper(I) as a catalyst. The most concise approach to form α‐acryloyloxy ketones is through direct oxidative coupling at the α‐C(sp3)–H position of ketones. This method gives the products in high yields, and has a wide substrate scope in terms of both ketones and unsaturated carboxylic acids. A copper(I)‐catalyzed reaction mechanism is proposed based on the results of control experiments.

Neutral iridium catalysts with chiral phosphine-carboxy ligands for asymmetric hydrogenation of unsaturated carboxylic acids.

We developed neutral iridium catalysts with chiral spiro phosphine-carboxy ligands (SpiroCAP) for asymmetric hydrogenation of unsaturated carboxylic acids. Different from the cationic Crabtree-type catalysts, the iridium catalysts with chiral spiro phosphine-carboxy ligands are neutral and do not require the use of a tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF-) counterion, which is necessary for stabilizing cationic Crabtree-type catalysts. Another advantage of the neutral iridium catalysts is that they have high stability and have a long lifetime in air. The new iridium catalysts with chiral spiro phosphine-carboxy ligands exhibit unprecedented high enantioselectivity (up to 99.4% ee) in the asymmetric hydrogenations of various unsaturated carboxylic acids, particularly for 3-alkyl-3-methylenepropionic acids, which are challenging substrates for other chiral catalysts.

Mechanism Studies of Ir-Catalyzed Asymmetric Hydrogenation of Unsaturated Carboxylic Acids.

The Ir-catalyzed asymmetric hydrogenation of olefins is widely used for production of value-added bulk and fine chemicals. The iridium catalysts with chiral spiro phosphine-oxazoline ligands developed in our group show high activity and high enantioselectivity in the hydrogenation of olefins bearing a coordinative carboxyl group, such as α,β-unsaturated carboxylic acids, β,γ-unsaturated carboxylic acids, and γ,δ-unsaturated carboxylic acids. Here we conducted detailed mechanistic studies on these Ir-catalyzed asymmetric hydrogenation reactions by using (E)-2-methyl-3-phenylacrylic acid as a model substrate. We isolated and characterized several key intermediates having Ir-H bonds under the real hydrogenation conditions. Particularly, an Ir(III) migratory insertion intermediate was first isolated in an asymmetric hydrogenation reaction promoted by chiral Ir catalysts. That this intermediate cannot undergo reductive elimination in the absence of hydrogen strongly supports the involvement of an Ir(III)/Ir(V) cycle in the hydrogenation. On the basis of the structure of the Ir(III) intermediate, variable-temperature NMR spectroscopy, and density functional theory calculations, we elucidated the mechanistic details of the Ir-catalyzed hydrogenation of unsaturated carboxylic acids and explained the enantioselectivity of the reactions. These findings experimentally and computationally elucidate the mechanism of Ir-catalyzed asymmetric hydrogenation of olefins with a strong coordinative carboxyl group and will likely inspire further catalyst design.

HPLC-MS/MS methods for the determination of 52 perfluoroalkyl and polyfluoroalkyl substances in aqueous samples.

Two quantitative methods using high-performance liquid chromatography (HPLC) combined with triple quadrupole tandem mass spectrometry (MS/MS) were developed to determine perfluoroalkyl and polyfluoroalkyl substances (PFASs) in aqueous samples. The first HPLC-MS/MS method was applied to 47 PFASs of 12 different substance classes with acidic characteristics such as perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs), as well as precursor substances and biotransformation intermediates (e.g., unsaturated fluorotelomer carboxylic acids). In addition, 25 13C-, 18O-, and 2H-labeled PFASs were used as internal standards in this method. The second HPLC-MS/MS method was applied to fluorotelomer alcohols (FTOHs) and perfluorooctane sulfonamidoethanols as these compounds have physicochemical properties different from those of the previous ones. Accuracy between 82% and 110% and a standard deviation in the range from 2% to 22% depending on the substances were determined during the evaluation of repeatability and precision. The method quantification limit after solid-phase extraction ranged from 0.3 to 199ng/L depending on the analyte and matrix. The HPLC-MS/MS methods developed were suitable for the determination of PFASs in aqueous samples (e.g., wastewater treatment plant effluents or influents after solid-phase extraction). These methods will be helpful in monitoring campaigns to evaluate the relevance of precursor substances as indirect sources of perfluorinated substances in the environment. In one exemplary application in an industrial wastewater treatment plant, FTOHs were found to be the major substance class in the influent; in particular, 6:2-FTOH was the predominant compound in the industrial samples and accounted for 74% of the total PFAS concentration. The increase in the concentration of the transformation products of FTOHs in the corresponding effluent, such as fluorotelomer carboxylic acids, unsaturated fluorotelomer carboxylic acids, n:3 polyfluorinated saturated carboxylic acids (n indicates the number of nonfluorinated carbon atoms), and PFCAs, indicated biotransformation of FTOHs or their derivatives during wastewater treatment. However, only 33mol% of the total amount of PFASs present in the influent was quantified in the corresponding effluent. Graphical abstract Method development of an HPLC-MS/MS multi-method for the determination of PFASs in aqueos samples.

ChemInform Abstract: Copper‐Catalyzed Amino Lactonization and Amino Oxygenation of Alkenes Using O‐Benzoylhydroxylamines.

A copper-catalyzed amino lactonization of unsaturated carboxylic acids has been achieved as well as the analogous intermolecular three-component amino oxygenation of olefins. The transformation features mild conditions and a remarkably broad substrate scope, offering a novel and efficient approach to construct a wide range of amino lactones as well as 1,2-amino alcohol derivatives. Mechanistic studies suggest that the reaction proceeds via a distinctive O-benzoylhydroxylamine-promoted electrophilic amination of alkenes.

Fabrication of a Novel Water Swellable Styrene-butadiene Rubber through the In-situ Polymerization of Lithium Acrylate

A novel water-swellable rubber (WSR) was prepared by blending styrene butadiene rubber (SBR) with dicumyl peroxide (DCP) and unsaturated carboxylic acid salt lithium acrylate (LiAA). The mechanical properties and water absorption behavior of WSR were studied. The results showed that LiAA was developed into polylithiumacrylate (PliAA) during the process of SBR vulcanization through in-situ polymerization, leading to the improvement of the mechanical properties and water absorption performance. The optimum usages of DCP and triallyl isocyanurate (TAIC) to attain the highest water swelling ratio for WSR were 3 and 1 phr, respectively. In addition, the tensile strength and the hardness of WSR were also enhanced by incorporating DCP or TAIC.