Functionalization of 2-Amino-3-benzyl-6-(benzylthio)pyrimidin-4(3H)-one: An Efficient Access to the Synthesis of Polycyclic Pyrimidine Scaffolds

Russian Journal of General Chemistry - 2-Aminouracil is used in the synthesis of a new series of tri- and tetracyclic pyrimidine scaffolds as the precursor. Thiazolo[5,4-d]triazolo[4,3-a]pyrimidine...     

Microwave‐Assisted Synthesis of Arylazoaminopyrazoles as Disperse Dyes for Textile Printing

The synthesis of heterocyclic azo‐dyes via conventional heating and microwave (MW) heating was investigated. From a sequence of reactions starting from cyanoacetic acid, 4‐arylazo‐2H‐pyrazol‐3‐ylamines and 4‐arylazo‐2‐phenyl‐2H‐pyrazol‐3‐ylamines were obtained. The structures these compounds were obtained by inspection of spectroscopic and analytical techniques including ¹H and ¹³C NMR spectroscopy, IR spectroscopy, mass spectrometry, and elemental analysis. The fastness properties and UV/Vis absorption spectroscopic data of these disperse dyes in printing polyester fabrics were investigated.     

Optical nanosensor design with uniform pore geometry and large particle morphology

Appropriate design of nanosensors for optically selective, sensitive sensing systems is needed for naked-eye detection of pollutants for environmental cleanup of toxic heavy-metal ions. Mesostructured materials with two- or three-dimensional (2D or 3D) geometries and large particle morphologies show promise as probe carriers, and can therefore be used to reproducibly fabricate uniformly packed nanosensors. This is the first report on the effects of significant key properties of the mesostructured carriers, such as morphology, geometry, and pore shape, on the functionality of optical nanosensor designs. Such mesostructured sensors with superior physical characteristics can be used as components in sensing systems with excellent stability and sensitivity, and with rapid detection response. The nanosensor design can enhance the selectivity even at low concentrations of the pollutant target ions (nanomolar level). Among the nanosensors developed here, the large pore-surface grains of highly ordered 3D monoliths (HOM) exhibited a high adsorption capability of the Pyrogallol Red probe and high accessibility to analyte ion transport, leading to possible naked-eye detection of Sb(III) ions at concentrations as low as 10(-9) mol dm(-3) and at a wide detection range of 0.5 ppb to 3 ppm. A key finding in our study was that our mesostructured nanosensor designs retained highly efficient sensitivity without a significant increase in kinetic hindrance, despite the slight decrease of the specific activity of the electron acceptor/donor strength of the probe functional group after several regeneration/reuse cycles. The results, in general, indicate that large-scale reversibility of optical nanosensors is feasible in such metal-ion sensing systems.     

Effects of 3-amino-1,2,4-triazole on the inhibition of copper corrosion in acidic chloride solutions

Effects of 3-amino-1,2,4-triazole (ATA) on the inhibition of copper corrosion in 0.5 M HCl solutions have been studied using gravimetric, electrochemical, and Raman spectroscopy investigations. Weight-loss measurements after varied immersion periods revealed that the dissolution rate of copper decreased to a minimum, while the inhibition efficiency (zeta%) and consequently the degree of surface coverage (theta) increased with the presence of ATA and the increase of its concentration. Potentiodynamic polarization, chronoamperometric, and electrochemical impedance spectroscopy (EIS) measurements after 0, 24, and 48 h immersion of the copper electrode in the test solutions showed that the presence of ATA molecules significantly decreased cathodic, anodic, and corrosion (jcorr) currents and corrosion rates (Rcorr) and greatly increased polarization resistance (Rp), zeta%, and theta; this effect was increased on increasing the ATA content in the solution. Raman spectroscopy confirmed that ATA molecules strongly adsorbed onto the copper surface, blocking its active sites and preventing it from being corroded easily.     

Thiophenylhydrazonoacetates in heterocyclic synthesis

Benzo[b]thiophen-2-yl-hydrazonoesters 4 were synthesized by coupling of 2-diazo-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide ( 1 ) with either ethyl cyanoacetate or ethyl acetoacetate. The reactivity of 4 toward a variety of nitrogen nucleophiles was investigated to yield pyrazole, isoxazole, pyrimidine, triazine, pyrazolopyridine, and pyrazolopyrimidine derivatives. © 2003 Wiley Periodicals, Inc. 15:15–20, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/.hc10205     

Efficient construction of the hexacyclic ring core of palau'amine: the pKa concept for proceeding with unfavorable equilibrium reactions

Palau''amine has received a great deal of attention as an attractive synthetic target due to its intriguing molecular architecture and significant immunosuppressive activity, and we achieved its total synthesis in 2015. However, the synthesized palau''amine has not been readily applicable to the mechanistic study of immunosuppressive activity, because it requires 45 longest linear steps from a commercially available compound. Here, we report the short-step construction of the ABCDEF hexacyclic ring core of palau''amine. The construction of the CDE tricyclic ring core in a single step is achieved by our pK_a concept for proceeding with unfavorable equilibrium reactions, and a palau''amine analog without the aminomethyl and chloride groups is synthesized in 20 longest linear steps from the same starting material. The palau''amine analog is confirmed to retain the immunosuppressive activity. The present synthetic approach for a palau''amine analog has the potential for use in the development of palau''amine probes for mechanistic elucidation.

A palau''amine analog (2) was synthesized from 2-cyclopentenone in 20 steps. The construction of the CDE tricyclic ring core in a single step is achieved by our pK_a concept for proceeding with the unfavorable equilibrium reactions.     

QuEChERS method combined with GC‒MS for pesticide residues determination in water

A miniaturized, QuEChERS based, liquid–liquid extraction method followed by gas chromatography–mass spectrometry was developed and validated for pesticide residues determination in water. Malathion, chlorpyrifos, profenofos, chlorfenapyr, pyriproxyfen, λ-cyhalothrin, coumaphos and α-cypermethrin were selected for this study. The accuracy, precision, specificity, linearity, limit of detection and limit of quantification were evaluated. The recovery ranged from 85.3 to 107% with RSD ranging from 1.8 to 15.4%. The linearity showed reliable range (0.995–0.999). The limit of detection ranged from 0.3 to 4 μg/L. Matrix effect was evaluated. The obtained results meet the European Commission standard legislations, implying that our method can be considered accurate and reproducible. The validated method was used to analyze river and well water samples. No residues of the investigated pesticides were detected in all collected water samples.     

Encapsulation of proteins into tunable and giant mesocage alumina

Protein bioadsorption has rapidly attracted attention partially because of the promising advances in diagnostic assays, sensors, separations, and gene technology. Tunable and giant mesocage alumina cavities (5 nm to 20 nm) show capability in size-selective encapsulation and diffusivity of large proteins into interior pores.