Application of microcrystalline cellulose as an efficient and cheap sorbent for the extraction of metoprolol from plasma and wastewater before HPLC–MS/MS determination

A dispersive solid-phase extraction method based on a new sorbent has been performed on plasma and wastewater samples to determine metoprolol by high-performance liquid chromatography–tandem mass spectrometry. In this study, the analyte was adsorbed from the samples onto microcrystalline cellulose as a green and efficient sorbent and then eluted for use in the determination step. In the mass spectrometer, the analyte was detected in the positive mode and selectivity of the analysis was increased by sequential mass analysis through multiple reaction monitoring. All of the effective parameters in the extraction of metoprolol from plasma and wastewater were optimized. Under optimal conditions the method was linear in the ranges of 1–1,000 and 0.1–1,000 ng/ml in plasma and wastewater samples, respectively. The detection limits of the method were 0.30 and 0.03 ng/ml in plasma and wastewater samples, respectively. The data showed that the method provides low detection limit, wide linear range, good precision and high extraction recovery. Finally several plasma and wastewater samples were successfully analyzed using the method. The use of a small amount of a green and inexpensive sorbent and a low volume of plasma without the need for further pretreatment steps are the main advantages of the method.     

Synthesis,spectral, DFT calculations and antibacterial studies of Fe(III) complexes of new fluorescent Schiff bases derived from imidazo[4',5':3,4]benzo[1,2‐c]isoxazole

New fluorescent heterocyclic ligands were synthesized by the reaction of 8‐(4‐chlorophenyl)‐3‐alkyl‐3H‐imidazo[4',5':3,4]benzo [1,2‐c]isoxazol‐5‐amine with p‐hydroxybenzaldehyde and p‐chlorobenzaldehyde in good yields. The coordination ability of the ligands with Fe³⁺ ion was examined in an aqueous metanolic solution. Schiff base ligands and their metal complexes were characterized by elemental analyses, IR, UV–vis, mass, and NMR spectra. The optical properties of the compounds were investigated and the results showed that the fluorescence of all compounds is intense and their obtained emission quantum yields are around 0.15 – 0.53. Optimized geometries and assignment of the IR bands and NMR chemical shifts of the new complexes were also computed by using density functional theory (DFT) methods. The DFT‐calculated vibrational wavenumbers and NMR chemical shifts are in good agreement with the experimental values, confirming suitability of the optimized geometries for Fe(III) complexes. Also, the 3D‐distribution map for HOMO and LUMO of the compounds were obtained. The new compounds showed potent antibacterial activity and their antibacterial activity (MIC) against Gram‐positive and Gram‐negative bacterial species were also determined. Results of antibacterial test revealed that coordination of ligands to Fe(III) leads to improvement in the antibacterial activity.     

Solubility of Acetaminophen and Ibuprofen in Polyethylene Glycol 600, N-Methyl Pyrrolidone and Water Mixtures

The solubility of acetaminophen and ibuprofen in binary and ternary mixtures of N-methyl pyrrolidone, polyethylene glycol 600 and water at 25 °C were determined and the solubilities are mathematically represented by the Jouyban–Acree model. The density of the solute-free solvent mixtures was measured and employed to train the Jouyban–Acree model and then the densities of the saturated solutions were predicted. The overall mean relative deviations (OMRDs) for fitting the solubility data of acetaminophen and ibuprofen in binary mixtures are 3.2% and 6.0%, respectively. The OMRDs for fitting the solubilities in ternary solvent mixtures for acetaminophen and ibuprofen are 15.0% and 28.6%, respectively, and the OMRD values for predicting all solubilities of acetaminophen and ibuprofen by a trained version of the Jouyban–Acree model are 9.4% and 17.8%, respectively. The prediction OMRD for the density of saturated solutions is 1.9%.     

Silica Gel‐Supported Polyphosphoric Acid (PPA/SiO2): An Efficient and Reusable Heterogeneous Catalyst for Facile Synthesis of 14‐Aryl‐14H‐dibenzo[a,j]xanthenes under Solvent‐free Conditions

A simple, efficient and green method for the synthesis of 14‐aryl‐14H‐dibenzo[a,j]xanthenes by a one‐pot condensation reaction of β‐naphthol and aryl aldehydes using silica gel‐supported polyphosphoric acid (PPA/SiO₂), an effective and reusable catalyst, under solvent‐free conditions is described. The present methodology offers several advantages, such as a simple procedure with an easy work‐up, short reaction times, high yields, and the absence of any volatile and hazardous organic solvents.     

Carbon-Based Solid Acid as An Efficient and Reusable Catalyst for One-Pot Synthesis of Tetrasubstituted Imidazoles under Solvent-Free Conditions

Carbon‐based solid acid catalyst was found to be highly efficient, eco‐friendly and recyclable heterogeneous catalyst for the multicomponent reaction of benzil, aromatic aldehyde, primary amine and ammonium acetate, giving rise to 1,2,4,5‐tetrasubstituted imidazoles in good to excellent yields. The present methodology offers several advantages, such as high yields, short reaction time, mild reaction condition and a recyclable catalyst with a very easy work up.     

A Carbon Material as a Strong Protonic Acid for Efficient Synthesis of 4(3H)‐Quinazolinones

Carbon‐based solid acid catalyst has been applied to catalyzing the synthesis of 4(3H)‐quinazolinones from the cyclization reaction of 2‐aminobenzamide with aroyl chlorides. The results showed that the catalyst was very efficient with the average yield over 85%. This carbon material with strong protonic acid sites as heterogeneous catalyst has some advantages such as high activity, strikingly simple work‐up procedure, non‐pollution, and reusability, which will contribute to the green process greatly.     

PPA-SiO_2 catalyzed efficient synthesis of polyhydroquinoline derivatives through Hantzsch multicomponent condensation under solvent-free conditions

Silica gel-supported polyphosphoric acid（PPA-SiO₂） was found to be an efficient catalyst for the one-pot four-component Hantzsch condensation reaction of aryl aldehydes,dimedone,ethyl acetoacetate and ammonium acetate to afford the corresponding polyhydroquinoline derivatives in high yields.The main advantages of the present approach are short reaction times,clean reaction profiles,simple experimental and workup procedures.