A green and efficient access to aryl nitriles via an electrochemical anodic oxidation

The nitrile functionality is a key building block in synthetic chemistry, and has wide applications in pharmaceuticals. However, traditional methodologies for the synthesis of nitriles are limited to harsh reaction conditions. Herein, we report a new and efficient access to aryl nitriles by an electrochemical synthesis. Compared with the conventional synthetic methods, this electrochemical synthesis is more environmentally friendly and easier to handle.     

Synthesis of a spiroacetal moiety of antitumor antibiotic ossamycin by anodic oxidation

Synthesis of the spiroacetal moiety (C20-C33) of the antitumor antibiotic ossamycin, is reported. Anodic oxidation of the dithioacetal effected simultaneous removal of the protecting group and acetalization to afford the corresponding 6,6-spiroacetal structure in excellent yield.     

A green and efficient access to awl nitriles via an electrochemicalanodic oxidation

The nitrile functionality is a key building block in synthetic chemistry, and has wide applications in pharmaceuticals. However, traditional methodologies for the synthesis of nitriles are limited to harsh reaction conditions. Herein, we report a new and efficient access to aryl nitriles by an electrochemical synthesis. Compared with the conventional synthetic methods, this electrochemical synthesis is more environmentally friendly and easier to handle.     

Determination of pesticide transformation products: A review of extraction and detection methods

Pesticides are widely applied and they can produce a variety of transformation products (TPs), through different pathways and mechanisms. Nowadays there is a growing interest related to the determination of pesticide TPs in several matrices (environmental, food and biological samples), due to these compounds can be more toxic and persistent than parent compounds, and some of them can be used as markers of exposure to different pesticides. Although solid-phase extraction (SPE) is mainly used for the extraction of TPs, alternative techniques such as solid-phase microextraction (SPME) and liquid-phase extraction (LPE) can be used. These TPs are mainly determined by liquid chromatography (LC) due to the recent developments in this technique, especially when it is coupled to mass spectrometry (MS) detectors, allowing the determination of known and/or unknown TPs. Furthermore, MS is a very valuable tool for the structural elucidation of unknown TPs. This review discusses all phases of analytical procedure, including sample treatment and analysis, indicating the main problems related to the extraction of TPs from several matrices due to their high polarity, as well as the different alternatives found for the simultaneous determination of parent compounds and TPs, using chromatographic techniques coupled to MS detection.     

Synthesis of immobilized TiO2 nanowires by anodic oxidation and their gas phase photocatalytic properties

In this paper, anodic oxidation method was successfully employed to the direct growth of immobilized TiO₂ nanowires on titanium foil in ethylene glycol electrolyte solution contained HF and water. The morphologies of the TiO₂ nanowires could be tuned by changing the content of HF and water. The structures, morphologies and optical properties of TiO₂ nanowires were characterized by SEM, XRD, UV–vis and PL. It was found that the nanowires originally grew from the splitting of TiO₂ nanotubes. The gas phase photocatalytic activities were investigated by photodegradation of gaseous toluene under UV irradiation, and irregular TiO₂ nanowires showed the best photocatalytic ability.     

Anodic oxidation of chiral sulfinylamines: a new route to highly diastereoselective α-alkylation of piperidine

The anodic oxidation of some chiral non-racemic N-arylsulfinyl piperidines was investigated and for the first time α methoxylated sulfinyl piperidines were obtained. The so-formed compounds are equivalent of chiral N-sulfinyliminiums and used as new intermediates for the preparation of chiral α-substituted piperidine derivatives in good yield and diastereoselectivity.     

Oligomeric oxidation products of the flavonoid quercetin

Some of the main oxidation products of quercetin were shown to be compounds formed by oligomerization of the starting flavonoid. Conditions for the preparative synthesis of these compounds were developed. Their structures were established using HPLC-MS and NMR methods. Quercetin oligomers in the natural sample, outer leaves of modified runners of Allium cepa L., were found using chromatographic procedures. The use of quercetin oligomers as indicators of its oxidation was proposed. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 344–347, July–August, 2008.     

Gamma-, photo-, and thermally-initiated oxidation of linear low density polyethylene: A quantitative comparison of oxidation products

The detailed oxidation products from the initiated oxidation of linear low density polyethylene have been compared by the use of infrared spectroscopy combined with chemical derivatization. Oxidized films were treated with NO or SF₄ to allow the resolution of the various alcohol and hydroperoxides and of the carbonyl species, respectively. All types of initiation gave very similar products but in varying quantities. In photooxidation, hydroperoxide was clearly shown to approach a photostationary concentration either from below for fresh film or from above for samples that had been pre-oxidized by γ-irradiation, prior to UV exposure. Carboxylic acid groups, the main backbone scission product, dominated in photooxidations, possibly as the result of the further oxidation of sec-hydroperoxide sites.     

Decarboxylative bromination of α,β-unsaturated carboxylic acids via an anodic oxidation

A novel bromination of α,β-unsaturated carboxylic acids was developed via a decarboxylation by virtue of a direct anodic electro-oxidation.In this method,ammonium bromide was employed as a bromine source and the reaction features transition-metal-free,short time,and no additional supporting electrolyte.     

Capillary electrophoretic determination of lignin degradation products obtained by permanganate oxidation

A new capillary electrophoretic (CE) technique was developed for the separation of lignin degradation products after permanganate oxidation, yielding information about quality and quantity of various linkages in the lignin molecule. This CE method is a promising alternative to existing gas chromatographic (GC) methods. An advantage in comparison with GC is the short separation time and the fact that the oxidation products (aromatic acids) can be analyzed without derivatization. The selectivity and sensitivity of CE combined with UV detection is adequate and makes it suited for fast routine characterization of lignins. If necessary, the CE method can be coupled with electrospray ionization mass spectrometry in order to make a clear assignment of the peaks.     

Removal of pesticide chlorobenzene by anodic degradation: Variable effects and mechanism

The oxidation of chlorobenzene (CB) was studied by electrochemical electrolysis using boron-doped diamond (BDD), PbO₂ or platine (Pt) as anode and graphite bar as cathode. The effect of applied current density, supporting electrolyte and initial pH value were also studied. The results demonstrated that BDD anode had the best effectiveness and accomplishment of electrochemical degradation of CB compared to PbO₂ and Pt anodes. For a current density of 20 mA/cm² and at pH = 3, the elimination of COD and TOC were about 97% and 98%, respectively, after 360 min of electrolysis with the BDD anode. Pseudo-first order kinetics appears to be the most appropriate to describe the degradation of chlorobenzene. The electrochemical mechanism of chlorobenzene on BDD was proposed based on the identified intermediates.     

Determination of anionic surfactants by bis(ethylenediamine)copper(II) extraction and anodic stripping voltammetry

A stripping voltammetric finish for the measurement of total anionic surfactant has been developed. A limit of detection of 5.0 μg 1^?1 anionic surfactant was observed with a linear calibration from 5.0 to 500 μg 1^?1 in the original sample.     

Advances in the determination of degradation intermediates of personal care products in environmental matrixes: a review

In this review, recent methods developed for the determination of degradation intermediates of personal care products in environmental matrixes focusing on the extraction and determination steps are discussed. The five classes of personal care products evaluated are stimulants, fragrances, sunscreens, antimicrobials, and insect repellents. Methods are critically reviewed in terms of the analytical steps involved in the analysis, sample pretreatment, separation, and detection as well as the different confirmation strategies employed. Preconcentration from aqueous matrixes was performed by solid-phase extraction, liquid–liquid extraction, or solid-phase microextraction, allowing the simultaneous extraction of parent compounds and their degradation intermediates. Following the extraction and cleanup steps, the identification and quantification of degradation intermediates of personal care products at environmental levels (i.e., parts per trillion to parts per billion range) is usually performed by using mass spectrometry techniques such as single quadrupole mass spectrometry and more recently by time-of-flight mass spectrometry or tandem mass spectrometry. The main scope of this review is to critically evaluate the current state of the art of the analytical techniques used and to identify the research needs in the determination of degradation intermediates of personal care products in environmental matrixes.     

Use of an accurate-mass database for the systematic identification of transformation products of organic contaminants in wastewater effluents

In this article, a systematic approach is proposed to assist and simplify the identification of transformation products (TPs) of organic contaminants. This approach is based on the use of characteristic fragmentation undergone by organic contaminants during MS/MS fragmentation events, and the relationship and consistency with the transformations experimented by these chemicals in the environment or during water treatment processes. With this in mind, a database containing accurate-mass information of 147 compounds and their main fragments generated by CID MS/MS fragmentation experiments was created using an LC-QTOF-MS/MS system. The developed database was applied to the identification of tentative TPs and related unexpected compounds in eight wastewater effluent samples. The approach comprises basically three stages: (a) automatic screening, (b) identification of possible TPs and (c) confirmation by MS/MS analysis. Parameters related to the search of compounds in the database have been optimized and their dependence with the exhaustiveness of the study evaluated. Eight degradation products, from the pharmaceuticals acetaminophen, amoxicillin, carbamazepine, erythromycin and azithromycin and from the pesticide diazinon, were identified with a high grade of accuracy. Three of them were confirmed by analysis of the corresponding analytical standards.     

Synthesis of three-dimensional hydrogels based on poly(glycidyl methacrylate-alt-maleic anhydride): Characterization and study of furosemide drug release

In the present work, three-dimensional drug carriers were synthesized via chemical modification of poly (glycidyl methacrylate-alt-maleic anhydride) P(GMA-alt-MA) by isopropylamine (IPA) and ethylenediamine (EDA) with different molar ratios. Then furosemide drug (FR) was loaded on the hydrogels and studied for its slow release in phosphate-buffered saline (PBS) solution (pH = 7.41) at 37 °C. According to the obtained results, the sample with the lowest amount of crosslinking agent (Sample A) showed the highest swelling ratio in comparison to the others. By increasing the rigidity of carrier in the result of increasing the crosslinker density, the amount of the released drug was decreased. However, the release rate for all of samples (slope of the profiles) were rather similar. All the synthesized carriers have shown pH dependent properties and the maximum release rate was shown in basic pH. Also, the drug release experiments in different temperatures showed almost thermal sensitivity properties for synthesized carriers and release rate become faster by increasing the medium temperature. The FT-IR, TGA, and FE-SEM analyses were carried out for characterization of prepared samples and the swelling behavior of prepared hydrogels were measured too. Investigation of the release data with different mathematical models showed the highest adaption with the Higuchi model for all samples.     

Anodic oxidation of a tetrasubstituted cyclooctatetraene. Multiple carbon-carbon bond cleavage and aromatization

Anodic oxidation of 1,2-,5,6-bis[trimethylene]cyclooctaetraene in methanol affords as the major product a substance formed by a complex sequence of carbon-carbon bond cleavages and concomitant aromatization.     

Bis(pyridine)iodonium tetrafluoroborate (IPy2BF4): a versatile oxidizing reagent

The use of bis(pyridine)iodonium tetrafluoroborate (IPy(2)BF(4)) as an oxidizing agent towards different types of alcohols is reported. The observed reactivity involves different reaction pathways, as a function both of the structures of the starting materials and of the experimental conditions. Interestingly, the title iodine-containing compound is capable of a tuneable reaction with simple cycloalkanols, providing straight and selective access either to omega-iodocarbonyl compounds or to ketones, a previously unreported and chemoselective range of oxidation potential. Furthermore, appropriate conditions for the preparation of aldehydes and esters from primary alcohols by easily performed experimental procedures were also established. The beta-scission reactions of cycloalkanols and the alpha-oxidation processes of primary, secondary and benzylic alcohols are discussed.     

Anodic oxidation of 9,9′-bifluorenylidene: electrochemical behaviour and physicochemical properties of relevant polymers

The physicochemical properties and electrochemical behaviour of polymers obtained by the anodic oxidation of the 9,9′-bifluorenylidene are presented together with the polymerization conditions.     

A single step solid-phase extraction method for complete separation of sterol oxidation products in food lipids

One of the crucial steps in determination of sterol oxidation products (SOPs) in foods is their enrichment and purifications by various preparative methods for further analysis by GC and GC–MS. Among the preparative methods, SPE of various adsorbents and solvent systems, are being used most widely. At present, no single step SPE method is suitable to completely separate the SOPs. In this study, a SPE (1 g silica) method, suitable for both transesterified and cold saponified oil samples, was developed to separate completely SOPs from other lipid components. This method resulted in high recovery from rapeseed oil of added 5β,6β-epoxycholestan-3β-ol (94-96%), cholest-5-en-3β-ol-7-one(94%), cholestane-3β,5α,6β-triol (88–91%), cholest-5-en-3β,7α-diol and 5α,6α-epoxycholestan-3β-ol (88–90%). The method has a high sample capacity of up to 1 g transesterified or cold-saponified oil sample. The method was tested and applied to different vegetable oils and to monitor the effects of refining processes on POPs in hazelnut oil.