An Efficient One-pot Three-component Process for Synthesis of Perfluoroalkylated Quinolizines

A facile multi-component process for the synthesis of perfluoroalkylated quinolizine derivatives was achieved using various arylidenemalononitriles, pyridine, and methyl perfluoroalk-2-ynoates as starting materials. Moderate yields were obtained under mild condition. The structures of perfluoroalkylated quinolizine derivatives were char- acterized by means of IH NMR, 13C NMR, 19F NMR, IR, LRMS and HRMS. Furthermore, the reaction mechanism was proposed.

Reaction of Grignard Reagents with Diethyl Perfluoroacyl (1-Cyanoethyl)phosphonates. Synthesis of Perfluoroalkylated α,β-Unsaturated Nitriles with Predominant Z-Selectivity

Diethyl (1-cyanoethyl) phosphorate 1 was reacted with n-butyl-lithium in tetrahydrofuran (THF) at - 78 °C and the resulting carbanion 2 reacted with perfluoroalkanoic add anhydride to afford perfluoroacylated phosphorate 3. Without isolation 3 was attacked by Grignard reagents giving perfluoroalkylated α, β-unsaturated nitriles in 46%-88% yields with high Z-stereoselectivity (Z: E = 89–62:11–38).

Studies on the reactions of silyl enol ether with perfluoroorganic compounds——Ⅲ.Synthesis of perfluoroalkylated α,β-unsaturated aldehydes and their derivatives

Per-and poly-fluoroalkylated α,β-unsaturated alkenals were synthesized by the reaction of silyl enol ether of alkanals with per-and poly-fluoroalkyl iodide initiated by Na_2S_2_O4 conveniently in high yield.Their corresponding alkenol and 2,4-dinitrophenylhydrazone were also synthesized.

SYNTHESIS AND CHARACTERIZATION OF A NOVEL FLUORINE-CONTAINING HYDROPHOBICALLY ASSOCIATING POLYMER

In this article, the synthesis and characterization of a novel fluoromonomer and its copolymer with acrylamide is reported. 2-perfluoroamyl-4-hydroxylquinoline 2 was synthesized from ethyl 2, 2-dihydroperfluoroheptanoate in high yields. The monomer 4 was then synthesized from 2 in two steps readily in high yields. Synthesis and characterization of copolymers of acrylamide (AM) and the fluoromonomer were investigated. The composition and intrinsic viscosity of these copolymers were studied. It was found that the rheological properties of aqueous solutions of polyacrylamide were modified significantly when a small proportion of the fluoromonomer 4 was incorporated on investigating the viscosity-concentration profiles, pseudoplasticity of these solutions and the effect of the presence of surfactant. These results could be explained by the hydrophobic association of the fluorocarbon segments in the aqueous solutions of these copolymers.

A NEW CONVENIENT METHOD FOR THE SYNTHESIS OF PERFLUOROALKYL 2H-PYRROLE

The reaction between 2,5-Dimethylpyrrole (1) and R_FI (2)(R_F: a, Cl(CF_2)_4; b, Cl(CF_2)_6; c, Cl(CF_2)_8; d, n-C_6F_(13); e, n-C_8F_(17)) in the presence of Na_2S_2O_4-NaHCO_3 in acetonitrile resulted in the formation of 2-perfluoroalkyl-2,5-dimethyl-2H-pyrrole (3) as a major product in good yield.

NEW METHOD FOR GENERATION OF t-BUTYL PERFLUOROALKYL NITROXIDES

Electron transfer reactions between O-benzoyl t-butylhydroxyl- amine,t-BuNHOCOPh(1)and perfluorodiacyl peroxides(RfCO_2)_2(2)may serve as a novel method for generating useful t-hutyl perfluoroalkyl nitroxldes at room temperature in CFCl2-CF2Cl.

Surface Perfluoroalkyl Chains Segregation: A Tool for Reducing Calcium Deposits in Medical Grade Poly(Methyl Methacrylate)

Intraocular lenses can be manufactured from a wide variety of polymers, but due to the lost cost associated with the use of Poly (methyl methacrylate) (PMMA), it is still the preferred material used in the developing countries. However, a major drawback to its use is the build-up of calcium containing deposits that are formed on the intraocular lens over a period of time. In an attempt to hinder this deposition, surface modification of medical grade PMMA has been carried out using perfluoroalkyl chain (1,2,4-trifluoro-3-(C10F21CH2O)-7-(N,N)-dimethylaminoacridine) segregation. The segregation was explored using a 1% 1,2,4-trifluoro-3-(C10F21CH2O)-7-(N,N)-dimethyla-minoacridine in two methods: film casting and spin-coating, a thin film onto preformed PMMA discs. Both methods were compared against control PMMA to determine which method provided the best hindrance against calcium containing deposits when immersed in a simulated aqueous humour solution. Characterisation of the surface using scanning electron microscopy coupled with energy;dispersive x-ray analysis indicated that the surface segregation of perfluoroalkyl chains had hindered calcification in both methods. This pleminary research shows promising results of employing perfluoroalkyl chains in the surface segregation of biomaterials that can be employed in intraocular lenses.

SYNTHESIS OF ACYCLIC ANALOGS OF BENZOTRIAZOLE AND INDOLE NUCLEOSIDE CONTAINING PERFLUOROALKYL GROUP

1-[(2-hydroxyethoxy)methyl]benzotriazole and -indole containing perfluoroalkyl group have been synthesized.

Meta-Analysis on the associations between Prenatal Perfluoroalkyl Substances Exposure and Adverse Birth Outcomes

The epidemiological associations between the prenatal perfluoroalkyl substances(PFASs)exposure and the reproductive outcomes remain controversial.A continuous evaluation is needed to combine the inconsistent results.In this study,we explored the associations between PFASs exposure and the low birth weight(LBW),preterm birth and small for gestational age(SGA).The quality of selected literature,quantitative estimates,publication bias and subgroup analysis were performed on the basis of 17 retrieved articles published before December 2020.The results showed a significant positive association between the perfluorooctane sulfonate(PFOS)exposure and the risk of LBW[Odds ratio(OR)=1.17;95%confidence interval(CI):1.01,1.36;heterogeneity:P=0.30,I2=17%].The positive association was also observed between the PFOS and the risk of preterm birth(OR=1.19;95%CI:1.01,1.39,P=0.007;I2=62%).There was a paucity of evidence regarding the negative effects of perfluorooctanoic acid(PFOA),perfluorohexanesulfonic acid(PFHxS)and perfluorononanoic acid(PFNA)on the pregnancy outcomes.The findings from the subgroup analysis(the sampling period,the birth gender and biologic specimens)did not substantially altered the results of the overall pooled estimate ORs.The increased prevalence of negative birth outcomes with gestational PFASs exposure warrants further explorations from biological process perspective.

ORGANOPHOSPHINE INITIATED REACTION OF PERFLUOROALKYL IODIDES WITH ALKENES

perfluoroalkyl iodides reacted with alkenes in acetonitrile solu- tion containing catalytic amount of organophosphine under mild condition to give the corresponding adducts in moderate to good yields.Reaction was shown to involve a free radical mechanism.

Reaction of 4-Ethoxyl-1,1,1-trifluoromethyl-3-butenone with perfluorophenyl hydrazine and perfluoroalkyl hydrazides

The presence of fluorine in biologically active compounds can impart a profound influence on their biological active. This influence has lead to the development of several potent agricultural and therapeutic agents[1]. During the study on the reactions of 4 - ethoxyl - 1, 1, 1 -trifluoromathyl-3-butenone 1, we found which is a very useful building-block in synthesis of fluoro-containing heterocyclic compounds[2]. Compound 1 can react with perfluorophenyl hydrazine and afford 1- perfluorophenyl-5-trifluoromethyl- 5 -hydroxy-4, 5 -2H- pyrazole 2 in excellent yield. It’s structure is further supported by X-ray diffraction.

Analysis of PFAS Levels and Associations with Adolescent Anthropometric Outcomes in NHANES

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are found in some consumer products due to their heat resistance and durability. However, there is potential for these substances to bioaccumulate in humans. It is relevant to investigate biological effects of these chemicals, as studies have suggested early life exposure may impact human developmental outcomes such as infant birth weight and youth adiposity. The objective of the current study was to determine if a relationship exists between increasing levels of certain PFAS and anthropometrics in adolescents ages 12 - 18. The three PFAS examined were: perfluorodecanoic acid (PFDeA), 2-(N-methyl-perfluoroctane sulfonamido) acetic acid (Me-PFOSA-AcOH), and perfluoroundecanoic acid (PFUA). The data was obtained from the National Health and Nutrition Examination Survey (NHANES) from the years 2011-2012 (N = 287) and 2013-2014 (N = 344). An additional analysis combined data from 3 NHANES survey cycles using sampling weights for the years 2011-2016 (N = 875) to generate a larger sample size of detectable PFAS. PFAS concentrations were classified as above or below the lower limit of detection (LLOD) to evaluate differences in weight, waist circumference, BMI (body mass index), and height using Student’s t-tests. These same anthropometric outcomes were examined as continuous variables in linear regression models and were stratified by sex. In the 2013-2014 dataset, there were significant inverse associations between female concentrations of PFUA and PFDeA with waist circumference (PFUA β = −0.056;95% CI, −0.106, −0.005;PFDeA β = −0.06;95% CI, −0.10, −0.02), weight-for-age z-score (PFUA β = −0.40;95% CI, −0.74, −0.05;PFDeA β = −0.38;95% CI, −0.64, −0.12), and BMI-for-age z-score (PFUA β = −0.48;95% CI, −0.86, −0.10;PFDeA β = −0.45;95% CI, −0.73, −0.16). In the 2011-2012 dataset, males displayed a significant inverse relationship between PFDeA and waist circumference (β = −0.08;95% CI, −0.14, −0.02), weight-for-age z-score (β = −0.49;95% CI, −0.88, −0.11), and BMI-for-age z-score (β = −0.44;95% CI, −0.84, −0.05). In the combined analysis of NHANES years 2011-2016, there were significant inverse associations with PFUA and PFDeA and weight-for-age z-score, waist circumference, and BMI-for-age z-score. In the given sample years, there was no compelling evidence for a relationship between any of the perfluoroalkyl chemicals and height, nor between Me-PFOSA-AcOH and any of the body measures after adjusting for age, sex, and race/ethnicity. This suggests that PFUA and PFDeA exposure in adolescents may be related to smaller waist circumference, weight, and BMI, but longitudinal studies are recommended to confirm these findings.

Synthesis and Characterization of Superhydrophobic-Superoleophobic and Anti-Corrosion Coatings via Sol-Gel Process

Superoleophobic nanocomposite coatings with improved hydrophobic properties were obtained by incorporation of a perfluoroalkyl polymer in hybrid sol-gel matrix containing silica and titania nanoparticles. SiO2 and TiO2 nanoparticles were synthesized based on sol-gel precursors utilizing tetraethyl orthosilicate, 3-glycidoxypropyl trimethoxysilane, and tetra (n-butyl orthotitanate). SEM and EDX images of the coating demonstrated that a Silica nanosphere had been aggregated in superporous structure. The analysis results show that nano-sized inorganic particles (10 - 20 nm) have a uniform distribution and dispersion. By increasing the PFOTES, the oleophobicity of coatings increased due to lowering of surface energy in the presence of fluoropolymer. Results of EIS measurement show that PFOTES and TiO2 nanoparticles increased anti-corrosion property of hybrid coatings. This method introduces a simple way to produce water- and oil-repellent self-cleaning coatings on large areas of different substrates like glass, ceramic, metal and composites.

Migration mechanism and risk assessment of perand polyfluoroalkyl substances in the Ya'Er Lake oxidation pond area,China

The migration mechanisms,sources,and environmental risks of 29 legacy and emerging perfluorinated and polyfluoroalkyl species present in an oxidation pond(Ya'Er Lake)were investigated for treating sewage based on the analysis of their occurrence and distribution.The concentration of per-and polyfluoroalkyl substances(PFAS)in pond area was between0.30 and 63.2 ng/g dw(dry weight),with the overall average concentration of 8.00 ng/g dw.Notably,the PFAS concentrations in the surface sediments near the sewage outlet in Pond-1(50.2 ng/g dw)and Pond-5(average 15.1 ng/g dw)were 1–2 orders of magnitude higher than those in other areas.In general,the legacy PFAS,i.e.,perfluorooctane sulfonic acid was considered to be the major pollutant in the polluted area,on average,accounting for 73.0%of the total concentration of PFAS pollutants.By evaluating the regional distribution of different PFAS homologs,the short-chain PFAS pollutants with lower K_(ow)were found to migrate farther in both horizontal and vertical directions.The sewage outlets in Pond-1 and Pond-5are the main pollution sources in polluted area and the emerging PFAS pollutants in Pond-5have replaced the legacy PFAS pollutants as the main pollutants.Based on positive matrix factorization analysis,three main industrial sources of PFAS pollutants in the study area were identified:protective coating,fire-fighting,and food packaging sources.Moreover,the environmental risk assessment results showed that most study areas exhibited medium environmental risk(0.01≤Risk quotient(RQ)<1),indicating that the ecological environment risks in this area need further attention.

Enhanced electrochemical oxidation of perfluorooctanoic acid on Ti/SnO_(2)-Sb electrode by surface morphology regulation

Electrochemical oxidation is an effective method to degrade persistent organic pollutants.However,due to the limited catalytic activity of traditional thin film electrodes,the anodic oxidation process is slow and usually requires high energy consumption.Herein,Ti/SnO_(2)-Sb electrode with regulated surface structure was reported to enhance the performance for electrochemical oxidation of persistent organic pollutants.The electrode deposited with SnO_(2)-Sb nanoneedles(Ti/N-SnO_(2)-Sb)showed higher oxidation activity.Its kinetic constant for perfluorooctanoic acid(PFOA)oxidation was 2.0 h^(-1)and the total organic carbon removal rate was 81.7%(4 h)at a relatively low current density of 6 mA/cm^2.Compared with Ti/SnO_(2)-Sb thin film and nanoparticles,Ti/N-SnO_(2)-Sb significantly improved the electrochemical active area and·OH yield,and simultaneously reduced the electron transfer resistance,which enabled it to oxidize PFOA more rapidly even at a lower potential.This work provides a new strategy for promoting the electrochemical oxidation performance.

Emergency of per-and polyfluoroalkyl substances in drinking water:Status,regulation,and mitigation strategies in developing countries

The detection of per-and polyfluoroalkyl substances(PFAS)in water presents a significant challenge for developing countries,requiring urgent attention.This review focuses on understanding the emergence of PFAS in drinking water,health concerns,and removal strategies for PFAS in water systems in developing countries.This review indicates the need for more studies to be conducted in many developing nations due to limited information on the environmental status and fate of PFAS.The health consequences of PFAS in water are enormous and cannot be overemphasized.Efforts are ongoing to legislate a national standard for PFAS in drinking water.Currently,there are few known mitigation efforts from African countries,in contrast to several developing nations in Asia.Therefore,there is an urgent need to develop economically viable techniques that could be integrated into largescale operations to remove PFAS from water systems in the region.However,despite the success achieved with removing long-chain PFAS from water,more studies are required on strategies for eliminating short-chain moieties in water.

Perfluoroalkyl acids(PFAAs) in urban surface water of Shijiazhuang, China: Occurrence, distribution,sources and ecological risks

It is extremely important to analyze the contaminative behaviors of Perfluoroalkyl acids(PFAAs) due to their serious threats to urban environments which are closely related to humans. Current study aimed to explore the distribution, source apportionment and ecological risk assessment of PFAAs in surface water from Shijiazhuang, China. The concentrations of ΣPFAAs ranged from 19.5 to 125.9 ng/L in the investigation area. Perfluorobutanesulfonic acid(PFBS) and perfluoropentanoic acid(PFPeA) were the predominant contaminants(mean value: 14.3 ng/L and 16.6 ng/L, respectively). The distribution of PFAAs according to geospatial analysis and hierarchical clustering analysis(HCA) showed that higher levels of ΣPFAAs were detected in the southern surface water of Shijiazhuang and there was a stepwise decrease from the wet season to the dry season. Furthermore, based on source apportionment,the dominant potential sources were found to be wastewater treatment plant(WWTP) effluents and industrial discharge. The risk quotients(RQs) revealed low ecological risks of all PFAAs for aquatic organisms in Shijiazhuang surface water. Collectively, this study provided basic data for regulatory strategies for controlling PFAA pollutions in urban surface water.

Occurrence and Health Risk of Perfluoroalkyl Acids in Popular Shellfish from a Typical Coastal Area of the East China

As crucial homologous members of per-and polyfluoroalkyl substances(PFASs),perfluoroalkyl acids(PFAAs)have aroused wide public concern because of their unique properties(persistence,bioaccumulation,long-distance migration and toxicity).Studies have shown their potential hazard to wildlife and humans,with food consumption as one of the primary routes of PFAA exposure for general population,especially seafood intake.In this study,17 PFAAs were quantified in 9 shellfish species from Yuhuan City,a typical coastal area of the East China.The total mean concentrations of PFAAs were in the range of 5.03–381 ng/g dry weight(dw),with the highest concentration found in Neverita didyma and the lowest in Babylonia lutosa.Concentrations and composition profiles of PFAAs varied significantly among different species,indicating differences in the bioaccumulation potential of PFAAs among species.Perfluorooctanoic acid(PFOA)was presented as the most abundant PFAA in this study,followed by perfluorobutanoic acid(PFBA).Significant positive correlations were observed among some individual PFAAs(p<0.05),indicating that they may share similar pollution sources or undergo similar compound behaviors.Health risk assessment indicated a relatively high threat for local residents exposed to PFAAs through shellfish consumption.

Association between serum levels of TSH and free T4 and per- and polyfluoroalkyl compounds concentrations in pregnant women

Many per-and polyfluoralkyl substances(PFASs)may disrupt maternal thyroid hormone homeostasis in pregnancy.Concerns should be raised regarding the PFASs exposure in pregnant women because thyroid hormones are involved in the early development of the fetus.In this study,we measured the concentrations of 13 PFASs,including five novel shortchain PFASs,in serum from 123 pregnant women in Beijing,China.Linear regression models were used to investigate the association between thyroid-stimulating hormone(TSH)or free thyroxine(FT4)levels and PFASs concentrations under consideration of the impacts of pregnancy-induced physiological factors.We found that perfluorobutanoic acid(PFBA)(β=0.189,95%CI=-0.039,0.417,p=0.10)and perfluorodecanoic acid(PFDA)(β=-0.554,95%CI=-1.16,0.049,p=0.071)were suggestive of significant association with TSH in thyroid peroxidase antibody(TPOAb)negative women.No association was observed between all PFASs and FT4 levels after controlling for these confounding factors,such as BMI,gestational weight gain and maternal age.These findings suggest that it should pay more attention to the association between thyroid hormone levels and short-chain PFASs concentrations.Future studies could consider a greater sample and the inclusion of other clinical indicators of thyroid function,such as free T3 and total T3.

Insights into the enzymatic degradation of DNA expedited by typical perfluoroalkyl acids

Perfluoroalkyl acids(PFAAs)are considered forever chemicals,gaining increasing attention for their hazardous impacts.However,the ecological effects of PFAAs remain unclear.Environmental DNA(eDNA),as the environmental gene pool,is often collected for evaluating the ecotoxicological effects of pollutants.In this study,we found that all PFAAs investigated,including perfluorohexanoic acid,perfluorooctanoic acid,perfluorononanoic acid,and perfluorooctane sulfonate,even at low concentrations(0.02 and 0.05 mg/L),expedited the enzymatic degradation of DNA in a nonlinear dose–effect relationship,with DNA degradation fragment sizes being lower than 1,000 bp and 200 bp after 15 and 30 min of degradation,respectively.This phenomenon was attributed to the binding interaction between PFAAs and AT bases in DNA via groove binding.van der Waals force(especially dispersion force)and hydrogen bonding are the main binding forces.DNA binding with PFAAs led to decreased base stacking and right-handed helicity,resulting in loose DNA structure exposing more digestion sites for degrading enzymes,and accelerating the enzymatic degradation of DNA.The global ecological risk evaluation results indicated that PFAA contamination could cause medium and high molecular ecological risk in 497 samples from 11 contamination-hot countries(such as the USA,Canada,and China).The findings of this study show new insights into the influence of PFAAs on the environmental fates of biomacromolecules and reveal the hidden molecular ecological effects of PFAAs in the environment.