Structural evidence for the arc-shaped topology of hetero[5]polynorbornanes

Two novel polarofacial-[5]-polynorbornanes, O ² N ₂ O ²– and COCOC–, were synthesized by cycloaddition reactions and their molecular and crystal structures were determined. These hetero[5]polynorbornanes posses heteroatoms at the norbornene bridges located at the outer convex surface, whereas functionalities are positioned on the inner concave surface. Molecular structures attest the extent of the curvature of their polycyclic backbone, and established that the COCOC-[5]-polynorbornane possesses more curved topology due to larger steric repulsion of 7-norbornane bridges. These experimental results are in good agreement with computational predictions of geometry. Quantum chemical study has identified lone pair repulsive interactions and steric repulsions of bridges as important factors for determining curvature.     

Energy Properties and Biomass Yield of Miscanthus x Giganteus Fertilized by Municipal Sewage Sludge

The application of municipal sewage sludge as fertilizer in the production of non-food energy crops is an environmentally and economically sustainable approach to sewage sludge management. In addition, the application of municipal sewage sludge to energy crops such as Miscanthus x giganteus is an alternative form of recycling nutrients and organic material from waste. Municipal sewage sludge is a potential source of heavy metals in the soil, some of which can be removed by growing energy crops that are also remediation agents. Therefore, the objective of the research was to investigate the effect of municipal sewage sludge applied at three different rates of 1.66, 3.22 and 6.44 t/ha on the production of Miscanthus. Based on the analyses conducted on the biomass of Miscanthus fertilized with sludge from the wastewater treatment plant in three fertilization treatments, it can be concluded that the biomass of Miscanthus is a good feedstock for the process of direct combustion. Moreover, the application of the largest amount of municipal sewage sludge during cultivation had no negative effect on the properties of Miscanthus biomass. Moreover, the cellulose and hemicellulose content of Miscanthus is ideal for the production of second-generation liquid biofuels. Fertilizer treatments had no effect on the content of cellulose and lignin, while a significant statistical difference was found for hemicellulose.     

Enzyme-catalyzed cascade synthesis of hydroxyiminoacetamides

In order to synthesize N-(3-azido-1-phenylpropyl)-2-hydroxyiminoacetamide, a key compound for the preparation of acetylcholinesterase (AChE) reactivators of the N-substituted 2-hydroxyiminoacetamide type, it was necessary to develop a method for forming an amide bond between an ethyl glyoxylate oxime and an amine. Using Candida antarctica lipase B (CAL-B) in a cascade enzyme-BOP catalyzed reaction, the efficient synthesis of the target hydroxyiminoacetamide was achieved.     

Simple and effective preparation of amino sulfonylureas from amino acids: application to the synthesis of amino sulfonylurea-containing peptidomimetics

Several amino sulfonylureas have been synthesized, starting from amino acids. The synthetic procedure is simple affording high yields of products under mild conditions. Furthermore, it is shown that these compounds can be incorporated into a peptide sequence.     

Ferric chloride/tetraethyl orthosilicate as an efficient system for synthesis of dihydropyrimidinones by Biginelli reaction

An efficient method for the Biginelli reaction of aldehydes, acetoacetate esters and urea employing tetraethyl orthosilicate in the presence of ferric chloride is described. These improved reaction conditions allow the preparation of a wide variety of substituted dihydropyrimidinones (including sterically encumbered ones) in high yields and purity under mild reaction conditions.     

Calcium trifluoromethanesulfonate-catalysed aminolysis of epoxides

Aminolysis of epoxides catalysed by calcium trifluoromethanesulfonate under mild reaction conditions is described. The novel method is very efficient in the synthesis of wide variety of β-amino alcohols with high regio- and stereoselectivity.     

Electroactivated Disposable Pencil Graphite Electrode – New,Cost-effective,and Sensitive Electrochemical Detection of Bioflavonoid Hesperidin

In this paper, for the first time, electroactivated disposable pencil graphite electrode (ePGE) was used for the detection of bioflavonoid hesperidin with cyclic and differential pulse voltammetry. The electroactivation efficiency of the pencil graphite electrode (PGE) was examined employing electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) and the enhancement of electron transfer kinetics of the PGE after the electroactivation was found. Hesperidin is irreversibly oxidized on the ePGE and its oxidation was the most pronounced at pH=5.0. Two electrode processes were detected, on one hand, a mixed diffusion and adsorption control was observed for the first electrode process. On the other hand, only diffusion control was observed in the second electrode process. Linear dependence between the peak current and the hesperidin concentration was obtained in the concentration range from 5×10⁻⁷ mol dm⁻³ to 1×10⁻⁵ mol dm⁻³ and the determined lower limit of detection (LOD) was 2×10⁻⁷ mol dm⁻³. Moreover, hesperidin in pharmaceutical formulation (containing active substance, hesperidin, and excipients) was quantified using ePGE. A good correlation was obtained between experimentally obtained hesperidin concentration by voltammetric analysis and concentration determined by standard HPLC technique (R²=0.9462).