Recyclable Pd2dba3/XPhos/PEG-2000 System for Efficient Boryl­ation of Aryl Chlorides: Practical Access to Aryl Boronates

Pd2dba3/XPhos in poly(ethylene glycol) (PEG-2000) is shown to be a highly stable and efficient catalyst for the borylation of aryl chlorides with bis(pinacolato)diboron. The borylation reaction proceeds smoothly at 110 °C, delivering a wide variety of aryl boronates in good to excellent yields with high functional group tolerance. The crude products were easily isolated via simple extraction of the reaction mixture with cyclohexane. Moreover, both expensive Pd2dba3 and XPhos in PEG-2000 system could be readily recycled and reused more than six times without loss of catalytic efficiency.

Cirsium vulgare leaves: isolation and identification of phenolic compounds

There are a few new researches on the pharmaceutical and nutraceutical application of Cirsium vulgare, but they do not reflect the full potential use of this plant. For the best of our knowledge, no study has been conducted so far to determine the impact of extraction methods and conditions on the extraction yields of phenolic compounds from Cirsium vulgare. We aimed to investigate a simple and sensitive HPLC-PDA method to determine phenolic compounds in Cirsium vulgare extracts. Three extraction techniques as maceration (ME), ultrasound-assisted extraction (UAE) and heat-reflux extraction (HRE) were applied and compared for sample preparation to obtain a high recovery of the phenolic compounds. The developed HPLC-PDA method can be used for the preparations of extracts with a high content of bioactive compounds for both pharmaceutical and nutraceutical applications. Moreover, it was validated and used for the qualitative and quantitative evaluation of phenolic compounds. A simple extraction procedure for phenolic compounds from Cirsium vulgare leaves was optimized in this work through the use of the heatreflux extraction method with 50% ethanol and extraction time of 1.5 h.

Simple extraction procedure for free amino acids determination in selected gluten-free flour samples

The simple extraction of flours samples followed by free amino acids determination procedures was studied and optimised. The conditions of amino acids derivatisation reaction with ninhydrin for chromatographic determination of free amino acids sum was discussed. The developed method was processed in terms of linearity, precision, accuracy, and limits of detection and quantification. Moreover, capillary isotachophoresis and HPLC methods were applied for individual free amino acids determination. The proposed extraction procedure is simple, fast and convenient for different flours samples. Studied procedures were used for free amino acids determination in twelve gluten-free flour samples (corn, oat, soy, rice, pumpkin, millet, peanut, hemp seed, buckwheat, amaranth, pea and chickpea) and the obtained results were compared with wheat flour.

Exploring Secondary Metabolites in Coffee and Tea Food Wastes

Coffee and tea are popular beverages worldwide, and therefore generate large amounts of waste. Here we describe the caffeine content and phenolic profile in three types of teas and coffees, and how they vary with two successive extractions. Although the first extraction was far more efficient than the second, green tea also showed a high content of flavanols in the second extraction, as did mate tea for phenolic acids. Black tea could also be a good option since caffeine content was highest in both extractions. Water also proved to be the most effective solvent in almost all cases, which represent a major benefit for urban horticulture, as it is a simple extraction method from an easily accessible source. Coffee and tea residues are a rich source of caffeine and phenolic compounds that could potentially be used as alternatives to conventional pesticides.

Easy and effective analytical method of carbendazim, dimethomorph, and fenoxanil from Protaetia brevitarsis seulensis using LC-MS/MS

Traditionally in Korea, Protaetia brevitarsis seulensis (white-spotted flower chafer) has been used as a medicine, and recently has attracted increased attention due to its antithrombotic efficacy. Some of spent mushroom compost or fermented oak sawdust, a feedstock for P. brevitarsis, were contaminated with three fungicides, carbendazim, dimethomorph, and fenoxanil, which could be transferred to the insect. This study was aimed to optimize a simple extraction method combined with liquid chromatography tandem mass spectrometry and apply it to the real samples. After the pulverized samples (5 g) were extracted with acetonitrile (10 mL) and formic acid (100 μL), fat and lipids in the samples were slowly precipitated at -20°C for 24 hours. After eight different clean-up methods were investigated, the mixture of 150 mg MgSO4/25 mg PSA/25 mg C18 was selected due to optimal recovery of the target compounds. Recovery (77.9%‒80.8% for carbendazim, 111.2%‒116.7% for dimethomorph, and 111.9%‒112.5% for fenoxanil) was achieved with reasonable relative standard deviation (<5.5%) The analytical method developed in this study was used to analyze three compounds in the 24 insect samples donated by the insect farm owners but no target compounds were detected. These results can provide important data for establishing the pesticide safety standards for P. brevitarsis before the medical applications.

Study of the Three-Component Reactions of 2-Alkynylbenzaldehydes, Aniline, and Dialkyl Phosphites—The Significance of the Catalyst System

New, practical approaches for the synthesis of α-amino (2-alkynylphenyl)-methylphosphonates and 1,2-dihydroisoquinolin-1-ylphosphonates were developed. By the propylphosphonic anhydride (T3P®)-mediated Kabachnik–Fields reaction of 2-alkynylbenzaldehydes, aniline, and dialkyl phosphites, α-amino (2-alkynylphenyl)-methylphosphonates were obtained selectively in high yields. The method developed is a simple operation and did not require a chromatographic separation since the products could be isolated from the reaction mixture by a simple extraction. At the same time, 2,3-disubstituted-1,2-dihydroisoquinolin-1-ylphosphonates could be prepared effectively from the same kinds of starting materials (2-alkynylbenzaldehydes, aniline, and dialkyl phosphites) at 60 °C in a short reaction time by changing the catalyst for CuCl. Therefore, it was proved that the catalyst system applied played a crucial role with respect to the reaction outcome.

Upper Secondary School and University Level Students’ Perceptions of Extractions in Context: Experiences from a Simple Laboratory Experiment

We discuss the pedagogical challenges associated with the current way of introducing extraction in upper secondary school chemistry education. These challenges were identified based on a survey of upper secondary school textbooks and verified through a questionnaire study. To address the identified challenges, we introduce a simple and effective extraction experiment which focuses on building a deeper conceptual understanding of extraction processes. The operationally simple extraction experiment and the accompanying questionnaire revealed that while students have several chemical misconceptions arising from the use of superficial everyday examples, they have all the necessary knowledge for developing a deeper understanding of chemistry. Providing a suitable experimental platform for developing and re-evaluating their knowledge allows the students to reasonably independently re-conceptualize their thinking toward a more coherent view of the surrounding world and the related scientific models. Furthermore, the work analyses the challenges that can be encountered when using everyday examples in teaching, and demonstrates that student-discovered examples of chemical systems can be a powerful method for generating meaningful and relevant ways to introduce scientific phenomena in STEM education.

Effect of ZnO Nanomaterial and Red and Green Cabbage Dyes on the Performance of Dye-Sensitised Solar Cells

Visible light can be converted into electricity using dye sensitised solar cells (DSSCs), with their performance mainly based on the type of dye used as a sensitiser. Currently, dyes extracted from natural sources are highly preferred by researchers in this field. Natural dyes reduce the high cost of metal complex sensitisers and replace expensive processes of chemical synthesis with simple extraction processes. Natural dyes are environmentally friendly, abundant, easily extractable, and safe. Their application has become a promising development in DSSC technology. In this study, two natural dyes extracted from the plant leaves of green cabbage (GC) and red cabbage (RC) that were used as sensitisers. The performance characteristics of RC and GC extracts were investigated using both cyclic voltammetry and amperometry methods for solar cell detection. At an extraction temperature of 60 °C maintained for 8 h under optimum conditions, the measured values of maximum power (Pm), fill factor (FF), and efficiency (η) were 1.36 mW/cm2, 92.34%, and 0.161% for RC, and 0.349 mW/cm2, 44.19%, and 0.095% for GC, respectively. The RC and GC extracts exhibited excellent electrochemical performance with respect to current density potential and good cycling stability.

A straightforward, purification-free procedure for the synthesis of Ando and Still-Gennari type phosphonates.

Z-Selective Still-Gennari and Ando modifications of the typically E selective Horner-Wadsworth-Emmons reaction are highly valuable synthetic tools in organic chemistry. These procedures are based on application of bis-(2,2,2-trifluoroethyl) phosphonates or diaryl phosphonates, respectively, for the olefination of carbonyl groups. In our research, we present an improved, straightforward, purification-free procedure for the synthesis of these reagents. The key step of our procedure is the reaction of phosphonic dichlorides with the appropriate sodium alkoxides, which results in 52-97% isolated yields of the desired products on a gram scale. The whole 3-step process is performed in one pot. Most importantly the product is obtained in over 95% purity after simple extraction, avoiding column chromatography or distillation. Moreover, we present synthesis of a novel Still-Gennari type reagents, bis (1,1,1,3,3,3 hexafluoroisopropyl) phosphonates, which may exhibit improved Z-selectivity in Still-Gennari olefinations.