Cloused cycle of production of ulltrafine polytetrafluoroethylene and new areas of use of fluoropolymer manufacture waste

The features of processes of ultrafine polytetrafluoroethylene manufacture of waste technological polytetrafluoroethylene by hydrothermal method and thermal degradation with an exhaustive fluorination in the presence of cobalt trifluoride were studied. Compositions and properties of gaseous and solid products of pyrolysis and recycling in ultrafine polytetrafluoroethylene manufacture were determined. Methods of use of ultrafine polytetrafluoroethylene, gaseous products, and spent catalyst were developed. On the basis of the experiments a closed scheme of producing ultrafine polytetrafluoroethylene was proposed in view of its application with recycling of accompanying gas fraction, and separating manufacture waste with recycling of cobalt trifluoride catalyst and using the resulting cobalt difluoride for producing composite coatings and lubricants.     

Chemiluminescence from polytetrafluoroethylene

The chemiluminescence emission from commercial samples of polytetrafluoroethylene, PTFE (Halon G-80 and Halon G-10), was studied at temperatures between 25 and 172°C. The emission intensity decreased on extended heating, removal of the surface layer, solvent extraction, or changing from an atmosphere of oxygen to an inert atmosphere. Films of PTFE deposited from the vapor phase showed comparatively little chemiluminescence under these conditions. Ozone-induced chemiluminescence was observed at 37°C from G-10 but not from G-80, or from films deposited from the vapor phase. The chemiluminescence intensity from ozone and G-10 was not reduced by solvent extraction.     

Selective extraction of light lanthanides(III) with 18-crown-6 and perfluorooctanoate

The extraction of La(III), Gd(III), and Lu(III) with 18-crown-6 (18C6) has been studied using pentadecafluorooctanoate (PDFO) as a counter anion. Very high extractability of La(III) was observed in various organic solvents such as benzene, chloroform, 1,2-dichloroethane, and nitrobenzene. The predominant species extracted into benzene was found to be Ln(PDFO)₃ (18C6), and the extraction constants (K _ex,s1 =[Ln(PDFO)₃ (18C6)]_org/[Ln³⁺][PDFO]³[18C6]_org) were 10^13.12 for La(III), 10^9.74 for Gd(III), and 10^9.67 for Lu(III). These values are 10¹⁰ times higher than those in the trichloroacetate-18C6 system reported previously. The present PDFO-18C6 system was superior to the picrate- and hexafluoroacetylacetonate-18C6 system for the separation efficiency of light lanthanides(III).     

In situ extraction/preconcentration of PCBs and PAHs from aqueous samples using polytetrafluoroethylene tubing

In situ extraction/preconcentration of organics from water samples was accomplished using polytetrafluoroethylene (PTFE) tubing. Polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were concentrated inside the tubing by flowing aqueous samples through it. The adsorbed PCBs and PAHs were then recovered by solvent desorption. The eluent was subsequently analyzed using gas chromatography with electron capture detection (GC-ECD) or gas chromatography with flame ionization detection (GC-FID). Multiple samples were simultaneously processed to concentrate organics onto several PTFE tubings. Analyses of seawater and surface microlayers using this technique demonstrated that organics in the surface microlayers were elevated with respect to those in the water column, consistent with previous findings.     

Structure of fluoropolymer products prepared from solutions of tetrafluoroethylene telomers

The molecular and morphological structures of fluoropolymer products obtained by deposition of tetrafluoroethylene telomers from acetone solutions on substrates have been studied by IR and NMR spectroscopy, X-ray powder diffraction, and atomic force microscopy. The molecular structure of the basic element of the sample is similar to that of PTFE, even though this element is composed of shorter chains carrying CH₃-C=O-CH₂ end groups. The supramolecular structure of the sample differs from that of PTFE by the character of disorder and a lower degree of crystallinity. Coatings obtained from solutions of tetrafluoroethylene telomers are of the island pattern with strongly overlapped regions.     

Efficient total synthesis of sapinofuranone B

[structure: see text] An efficient enantioselective synthesis of sapinofuranone B (1) using Sharpless asymmetric dihydroxylation, Sonogashira coupling, and Wittig olefination as the key steps is described.     

Efficient total synthesis of manzacidin B

The highly diastereoselective synthesis of the marine natural product, (?)-manzacidin B, is described. A novel copper-catalyzed aldol reaction of the α-methylserine-derived aldehyde with an isocyanoacetate possessing (1R)-camphorsultam as the chiral auxiliary proceeded in a highly diastereoselective manner to give the (4R,5R,6R)-adduct, which was converted into manzacidin B in a few steps.     

Efficient green extraction of polyphenols from post-harvested agro-industry vegetal sources in Piedmont

A study of the polyphenols content and antioxidant capacity of grapevine waste and hazelnut skins (roasted material) from post-harvest products that originate from Piedmont (Italy) has been carried out and the results herein presented. Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) were used to achieve process intensification in shorter extraction times, with lower environmental impact and higher selectivity compared to classic maceration. Besides classic solvents, the aqueous β-cyclodextrin solution (1.5%) showed to be an excellent extraction medium for grapevine waste. Total phenolic content (TP) from grapevine waste ranged from 18.23 ± 2.4 to 198 ± 3 mg gallic acid equivalents (GAE)/g dry weight, while total antioxidant capacity (TAC) expressed as EC₅₀ ranged from 0.0902 ± 0.08 mg/mL to 0.0041 ± 0.02 mg/mL. For hazelnut skins, TP ranged from 61.68 ± 0.8 to 200.79 ± 3.0 mg GAE/g dry weight, while TAC ranged from 0.0021 ± 0.0004 to 0.0002 ± 0.0001 mg/mL extract. We have shown that, compared to maceration, the use of UAE and MAE methods can enhance polyphenols recovery and antioxidant capacity.     

Solid-phase extraction of several phthalate esters from environmental water samples on a column packed with polytetrafluoroethylene turnings.

A method for the determination of several phthalate esters in water samples using solid-phase extraction coupled to high-performance liquid chromatography was developed. A polytetrafluoroethylene turnings packed column was used as a SPE adsorbent material. The analytes were sorbed on polytetrafluoroethylene turnings, from which they were eluted by a small amount of acetonitrile, followed by a RP-HPLC-UV analysis. Detection limits (3sigma) of 4.7, 3.1, 3.6, 4.3, and 5.8 ng mL(-1) for di-n-butyl-phthalate, di-cyclohexyl-phthalate, di-n-octyl-phthalate, di-n-nonyl-phthalate and di-iso-decyl-phthalate, respectively, were achieved. Acceptable recovery results (92.1-127.5%) were obtained on five phthalate esters spiked samples.     

何首乌中蒽醌类物质的超声波提取工艺优化

采用超声波辅助法提取何首乌中蒽醌类物质.讨论了甲醇体积分数、提取时间、提取温度、料液比和提取功率5个因素对提取效率的影响;通过正交试验确定了何首乌中蒽醌类物质的最佳提取工艺条件,甲醇体积分数为80%,提取时间为1.0h,提取温度为45℃,料液比为1∶15(g∶mL),提取功率为700W.此条件下蒽醌类物质的最大提取率为1.472 9%.     

微波预处理提取蛇足石杉中总生物碱的工艺优化

蛇足石杉为厥类植物,属石松类石杉科(Huperziacease)石杉属(Huperzia),又名千层塔、蛇足草.从蛇足石杉中提取分离得到的石杉碱甲(Hup A),是一种强效的可逆性胆碱酯酶抑制剂,在临床上主要用于治疗重症肌无力、改善老年性记忆功能减退 [1-2].     

Integrated extraction and purification of total bioactive flavonoids from Toona sinensis leaves

An integrated procedure was developed to extract and purify total flavonoids from Toona sinensis leaves for the first time, in which pressurized liquid extraction was performed in tandem with HPD100 macroporous resin column. Consequently, the total flavonoids can be extracted using 10% EtOH, and the recovery and purity of total flavonoids was 71.05% and 66.60%. Moreover, products of high quality were obtained in an environmentally friendly process with lower consumption of time and solvent. The results demonstrated that the integrated extraction-adsorption procedure was an efficient process for the preparation of total bioactive flavonoids from Toona sinensis leaves.     

Efficient and scalable serial extraction of DNA and RNA from frozen tissue samples

Advances in cancer genomics have created a demand for scalable sample processing. We here present a process for serial extraction of nucleic acids from the same frozen tissue sample based on magnetic silica particles. The process is automation friendly with high recoveries of pure DNA and RNA suitable for analysis.     

Efficient removal of ruthenium byproducts from olefin metathesis products by simple aqueous extraction

Simple aqueous extraction removed ruthenium byproducts efficiently from ring-closing metathesis (RCM) reactions catalyzed by a poly(ethylene glycol) (PEG) supported N-heterocyclic carbene-based ruthenium complex.     

Aqueous two-phase extraction system of sodium perfluorooctanoate and dodecyltriethylammonium bromide mixture and its application to porphyrins and dyes

A new aqueous two-phase system is developed consisting of sodium perfluorooctanoate (SPFO) and dodecyltriethylammonium bromide (C₁₂NE) cationic–anionic surfactant mixture. The two phases with a clear interfacial boundary formed when SPFO to C₁₂NE molar ratio is 1.2:1 in the presence of 5% (v/v) nitric acid. The top phase is transparent and the bottom phase is opalescent. Extractions of dyes, porphyrin compounds with the two-phase system were performed. The results show that hydrophobic molecules were extracted into the surfactant-rich bottom phase with high extraction efficiencies. Positively charged porphyrins were extracted into the bottom phase with higher extraction efficiencies than negatively charged porphyrins. Such a new anionic surfactant two-phase system would be complementary to the C₁₂NE–SDS (sodium dodecyl sulfate) cationic two-phase which has been proven to be effective for extractions of porphyrins with substituted groups like carboxyl or sulfonic acid groups.     

Multicompartment micelles from hyperbranched star-block copolymers containing polycations and fluoropolymer segment

In this Article, we have investigated the self-assembly of a series of amphiphilic hyperbranched star-block copolymers to form multicompartment micelles in acidic aqueous solution (pH 3.0) or in a dimethylformamide/water (pH 3.0) mixture. These hyperbranched star-block copolymers were prepared via oxyanion-initiated polymerization process, using hydroxyl-terminated hyperbranched poly[3-ethyl-3-(hydroxymethyl)oxetane] (HP) as a macroinitiator precursor with multi-reactive sites. It was turned into oxyanion end-capped macroinitiator through the reaction with potassium hydride, and followed by a sequential addition of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) and 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate (OFPMA). The resultant HP-star-PDMAEMA-b-POFPMA copolymers were characterized via 1H NMR, 19F NMR, and gel permeation chromatography (GPC). The analyses of transmission electron microscopy (TEM), dynamic light scattering (DLS), and microelectrophoresis confirmed that these copolymers could directly self-organize into supramolecular multicompartment micelles with different diameters, depending on the length of the PDMAEMA segment, which can be protonated in acidic aqueous medium. The measurement of the zeta potential gave further evidence of the aggregating structures for the multicompartment micelles.     

The aggregation of sodium perfluorooctanoate in water

The self-aggregation of sodium perfluorooctanoate (SPFO) has been studied by pH, ion-selective electrodes, changes in Rhodamine 6G colour and fluorescence, conductivity, surface tension and viscosity measurements. It has been determined that the aggregation of SPFO is gradual. It starts to aggregate at 0.01 mol dm^–3 with the formation of pre-micelles of perfluorooctanoate ions, which capture counterions at C=0.02 mol dm^–3 and form micelles at a critical micelle concentration (CMC) of 0.03 mol dm^–3. Micelles at the CMC are highly ionised and strongly hydrated. At C*=0.06 mol dm^–3, a low ionisation degree was found, indicating the formation of a more compact micellar structure. Micelles at the CMC show energetic advantage in comparison with the adsorbed state at the air/solution interface, and this advantage increases at C* originating desorption.     

Efficient total synthesis of (-)-stemoamide

An efficient diastereoselective synthesis of (-)-stemoamide has been accomplished from a pyroglutamic acid derivative in eight steps and with 24% overall yield. The synthesis features an intramolecular samarium diiodide-promoted 7-exo-trig cyclization of a ketyl radical generated from the corresponding aldehyde.     

Efficient total syntheses of louisianins C and D

An efficient synthetic route for the preparation of louisianins C and D was developed starting with the commercially available 4-cyanopyridine. Louisianins C and D were synthesized in seven steps and with overall yields 22% and 20%, respectively, following a novel cyclization-decarboxylation sequence involving 4-bromo-6,7-dihydrocyclopenta[c]pyridin-5-one as the key intermediate.     

Efficient total syntheses of polygodial and drimenin.

A short and stereoselective total synthesis of (±) polygodial and drimenin is presented. The efficiency of the synthesis is due to the easy access to intermediate diol $\text{4}$ and its successful direct oxidation into polygodial.