Catalytic Para‐Xylene Maximization. V. Toluene Methylation with Methanol and Disproportionation of Toluene Using Pt/ZSM‐5 and Pt/Mordenite Catalysts

Toluene was methylated with methanol and disproportionated using catalysts containing different Pt contents (0.2, 0.4 and 0.6%) supported on H‐ZSM‐5 or H‐mordenite (H‐M) zeolites in a fixed‐bed flow‐reactor operated atmospherically at temperatures of 300–500 °C in a flow of hydrogen. Platinum dispersion in the zeolite supports and acid sites strength distribution were evaluated using hydrogen chemisorption (1:1 stoichiometry) and ammonia temperature programmed desorption (TPD) in a differential scanning calorimeter (DSC). Toluene methylation was much faster on all catalysts than toluene disproportionation (DISP). Both reactions were more accelerated using H‐ZSM‐5 containing catalysts than H‐M containing catalysts. The yield of xylenes, and in particular para‐xylene, was significantly influenced by the yield of trimethylbenzenes (TMBs) in product. The selectivities for para‐, ortho‐ and meta‐xylenes production were found largely dependent on the Pt content in the catalysts, particularly when supported on H‐ZSM5‐zeolite. However, using Pt/H‐M catalysts, these selectivities were not strictly controlled by Pt content in the catalysts.     

Automated and enhanced extraction of a small molecule-drug conjugate using an enzyme-inhibitor interaction based SPME tool followed by direct analysis by ESI-MS

We report a novel, fast, and automatic SPME-based method capable of extracting a small molecule-drug conjugate (SMDC) from biological matrices. Our method relies on the extraction of the drug conjugate followed by direct elution into an electrospray mass spectrometer (ESI-MS) source for qualitative and quantitative analysis. We designed a tool for extracting the targeting head of a recently synthesized SMDC, which includes acetazolamide (AAZ) as high-affinity ligand specific to carbonic anhydrase IX. Specificity of the extraction was achieved through systematic optimization. The design of the extraction tool is based on noncovalent and reversible interaction between AAZ and CAII that is immobilized on the SPME extraction phase. Using this approach, we showed a 330% rise in extracted AAZ signal intensity compared to a control, which was performed in the absence of CAII. A linear dynamic range from 1.2 to 25 μg/ml was found. The limits of detection (LOD) of extracted AAZ from phosphate-buffered saline (PBS) and human plasma were 0.4 and 1.2 μg/ml, respectively. This with a relative standard deviation of less than 14% (n = 40) covers the therapeutic range.

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Beiträge zur Chemie der Silicium-Stickstoff-Verbindungen. CV. Ringschlußreaktionen mit 1,5-Bis(alkylamino)trisildioxanen

1.5-Bis(methylamino)hexamethyltrisildioxane reacts in the presence of triethylamine easily with germanium tetrachloride (equ. 1) and ethyldichlorophosphine (equ.2) to give the formerly unknown inorganic eightmembered ring systems Si₃GeN₂O₂ and Si₃PN₂O₂. Respectively. By analogous reacting of silicon tetrachloride only open chained Cl₃Si? Nme? Sime₂? O? Sime₂? O? Sime? NHme (IV; equ. 3) is formed. With metallated 1.5-bis(alkylamino)trisildioxanes, dischlorodiorganylsilanes do not give the expected asymmetric-, but the symmetric cyclotetrasildioxdiazanes V–VII. Dichlorophenylborane, in an analogous reaction, leads to the novel eightmembered ring system BSi₃N₂O₂, but the exact position of the N and O atoms in the ring could not be fixed beyond any doubt. The novel sixmembered ring system BSi₂Ni₂O was realized in compound IX via equ. (6).     

Effect of gemini surfactant additives on pour point depressant of crude oil

Efficiencies of cationic gemini surfactant additives in improving the pour point depressant of crude oil were investigated. The length of alkyl chain is a major factor affecting the improvement of the pour point depression. The adsorption behavior of these gemini surfactants at air/solution and oil/solution interfaces were investigated by measuring the surface tension and interfacial tension as functions of concentration. It is found that there is a good relation between surface properties especially interfacial tension of the gemini surfactants and their efficiency in depressing the pour point. Also, the surface parameters and free energies of micellization and adsorption confirm the decreasing and improving of pour point depression. Crystallization study in crude oil revealed the relationship between the structure and activity of gemini surfactant additives. It is found that the x-ray diffraction patterns of waxes with additives are remarkably different from those without additives. The mechanism of the depressants action has been suggested according the adsorption of each additive. Adsorption of the additive on the surface of the wax particles inhibits their growth and alters the crystal habits through micelle core. Pretreatment of the crude oil with pour point depressants has received the greatest acceptance due to its simplicity and economy.     

Montmorillonite K10 Clay: An Efficient Catalyst for Hantzsch Synthesis of 1,4‐Dihydropyridine Derivatives

An efficient, solid‐catalyst‐mediated Hantzsch synthesis of 1,4‐dihydropyridines is described. This procedure has such advantages as short reaction time, high yields, and simple workup. The catalyst could be reused several times and keeps its initial activity in the subsequent reactions.     

Efficient,Rapid, and Regioselective Bromination of Phenols and Anilines with N-Bromosaccharin Using Tungstophosphoric Acid as a Heterogeneous Recyclable Catalyst

A simple, efficient, and rapid method for high-yielding regioselective mono bromination of phenols and anilines has been achieved by treatment with N-bromasaccharin in the presence of a catalytic amount of tungstophosphoric acid.     

An efficient four-component synthesis of dithiocarbamate derivatives

An environmentally benign, one-pot, four-component synthesis of chemically and pharmaceutically interesting dithiocarbamate derivatives is reported. The one-pot reaction of various aromatic aldehydes, ketones, aliphatic amines, and carbon disulfide, in the presence of potassium hydroxide in urea-choline chloride deep eutectic solvent or ethanol, leads to the corresponding dithiocarbamates in good to excellent yields. This method provides a convenient and time-saving strategy, with a simple work-up procedure.     

Determination of the Monoclonal Antibody Tocilizumab by a Validated Micellar Electrokinetic Chromatography Method

Chromatographia - Tocilizumab is a monoclonal antibody used in the treatment of several inflammatory and autoimmune diseases as well as cancers. Tocilizumab improves clinical outcomes and reduce...     

An approach to the synthesis and characterization of HMS/Pr-Rh-Zr as efficient catalyst for synthesis of tetrahydrobenzo[b]pyran and 1,4-dihydropyrano[2,3-c]pyrazole derivatives

Research on Chemical Intermediates - The aim of present investigation is the synthesis of mesoporous catalyst based on hexagonal mesoporous silica. HMS support has exceptional properties such as...