Kinetics and Mechanistic Study of Acetaminophen‐Captopril Interaction by Electrochemical Methods

In this work kinetics parameters and electrochemical mechanism for electrooxidation of acetaminophen in the absence and presence of captopril in a condition close to acetaminophen natural oxidation pathway was investigated. The electrooxidation of acetaminophen in the presence of captopril was investigated by voltammetry and coulometry methods. The results of this work show that acetaminophen is oxidized to its respective p‐quinoneimine. The quinoneimine attacked by captopril, forms thioether. The proposed electrochemical mechanism is ECEC. The estimated value for homogeneous rate constant k_obs is 3.1×10⁴±155 M^?1s^?1 and k_f/k_b is 1.6×10⁸±8.0×10⁵.     

N,N,N^{\prime },N^{\prime }-Tetrabromobenzene-1,3-disulfonamide and poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) as new and efficient catalysts for the synthesis of highly substituted 1,6-dihydropyrazine-2,3-dicarbonitrile derivatives

Various mono and bis-1,6-dihydropyrazine-2,3-dicarbonitrile derivatives were efficiently synthesized by reacting 2,3-diaminomaleonitrile (DAMN), isocyanides and ketones in the presence of a catalytic amount of $N,N{,}N^{\prime }{,}N^{\prime }$ -tetrabromobenzene-1,3-disulfonamide [TBBDA] and poly( $N$ -bromo- $N$ -ethylbenzene-1,3-disulfonamide) [PBBS] in EtOH/H $_{2}$ O at ambient temperature. Graphic abstract $N,N,N^{\prime },N^{\prime }$ -Tetrabromobenzene-1,3-disulfonamide and poly( $N$ -bromo- $N$ -ethylbenzene-1,3-disulfonamide) as new and efficient catalysts for the synthesis of highly substituted 1,6-dihydropyrazine-2,3-dicarbonitrile derivatives.      

Synthesis and characterization of three novel manganese(II) octaaza macrocyclic Schiff base complexes containing a phenanthroline and two pyridyl units as pendant arms. X-ray crystal structure determination of one manganese(II) complex

Three new branched hexadentate amines (N₆), 3,6-bis(2-pyridylmethyl)-3,6-diazaoctane-1,8-diamine (1), 3,7-bis(2-pyridylmethyl)-3,7-diazanonane-1,9-diamine (2) and 3,8-bis(2-pyridylmethyl)-3,8-diazadecane-1,10-diamine (3) have been synthesized. Subsequently, three novel Schiff base macrocyclic complexes containing a phenanthroline and two 2-pyridylmethylpendant arms have been prepared by template [1+1] cyclocondensation of 2,9-dicarboxaldehyde-1,10-phenanthroline and the branched hexadentate amines (1–3), in the presence of Mn(II) in methanol. These complexes have ligands with 18-, 19- and 20-membered hexaaza macrocycles and two 2-pyridylmethyl pendant arms (L¹, L² and L³, respectively). All the complexes have been characterized by elemental analysis and IR spectroscopy. The crystal structure of [MnL¹](ClO₄)₂ · 3CH₃CN was determined and indicates that in the solid state the complex adopts a slightly distorted hexagonal bipyramidal geometry with the Mn(II) ion located within a hexaaza macrocycle with the two 2-pyridylmethyl pendant arms coordinating in axial positions.     

Metal-enhanced fluorescence of graphene oxide by palladium nanoparticles in the blue-green part of the spectrum

Graphene oxide(GO) has a wide fluorescence bandwidth,which makes it a prospective candidate for numerous applications.For many of these applications,the fluorescence yield of GO should be further increased.The sp~2-hybridized carbons in GO confine the π-electrons.Radiative recombination of electron-hole pairs in such sp~2 clusters is the source of fluorescence in this material.Palladium nanoparticles are good catalysts for sp~2 bond formations.We report on the preparation of GO,palladium nanoparticles and their nanocomposites in two different solvents.It is shown that palladium nanoparticles can considerably enhance the intrinsic fluorescence of GO in the blue-green part of the visible light spectrum.Fluorescence enhancement has been attributed to the catalytic role of palladium nanoparticles in increasing the number of sp2 bonds of GO with the molecules of the surrounding media.It is shown that palladium nanoparticles could be the nanoparticle of choice for fluorescence enhancement of GO because of their catalytic role in sp2 bond formation.     

The effective length of a flat plate heat pipe covered partially by a strip heater on the evaporator section

An approximate method is presented for calculating the effective length of a flat heat pipe when a strip heater is partially covering the evaporator section. For a specific width of the strip heater, the optimal position to achieve a minimum effective length is found when the heater is placed symmetrically at the centre of the evaporator section. In this position, a higher value of the capillary heat transport limit can be achieved as compared to the case where the heater is placed on one side of the evaporator section.     

Highly efficient synthesis of chromeno[2,3-b]pyridine using Graphene-Oxide/N1,N3-bis (pyridin-2-ylmethyl)propane-1,3-diamine-Copper nanocomposites as a novel catalyst

Recent studies about innovations in GO/N-Ligand-Cu Nano-Composites have been done. Graphene-Oxide is improved with N¹,N³-bis (pyridin-2-ylmethyl)propane-1,3-diamine and after that is matched with copper (Cu). The chemical composition and the structure of the catalyst were analyzed by TGA/DTG, EDX, XRD, FT-IR, TEM, and SEM. The results demonstrated that GO/N-Ligand-Cu was able to catalyze the chromeno[2,3-b]pyridine compounds to obtain high yields in short reaction time. The results of the present work are hoped to assist the growth of a new class of heterogeneous catalysts as the high-function candidate for industrial applications.     

Efficient synthesis of novel quinazoline-4(1H)-one derivatives by N-halosulfonamides

Research on Chemical Intermediates - In this research, a facile, effective and one-pot synthesis of new quinazoline-4(1H)-one derivatives is reported. Isatoic anhydride, acid hydrazides or ammonium...     

Synthesis and characterization of some new Cd(II) and Zn(II) macrocyclic Schiff base complexes derived from cyclocondensation of three new linear aromatic (N4) amines and 2,6-diacetylpyridine. Crystal structure and biological activity studies

Six new Cd(II) and Zn(II) macrocyclic Schiff base complexes from cyclocondensation of 2,6-diacetylpyridine and three different liner aromatic amines have been investigated. The resulting ligands, L¹ and L² are 17- and L³ 18-membered pentaaza macrocycles. The complexes have been characterized by a variety of methods such as IR, elemental analysis, EI-Mass and conductivity measurements and in the case of cadmium complex by ¹H and ¹³C NMR spectroscopy. The crystal structure of [CdL¹(CH₃OH)](ClO₄)₂ has been determined. In this complex, the Cd(II) ion is coordinated to five nitrogen donor atoms of the ligand and one oxygen atom from methanol in a N₅O environment. The geometry around the cadmium can be better described as in a slightly distorted pentagonal-pyramidal. The synthesized compounds have antibacterial activity against the three gram-positive bacteria: S. aureus, B. cereus and C. xerosis, and also against the three gram-negative bacteria: E. coli, K. pneumoniae and P. vulgaris. The results show that the antibacterial activity of cadmium complexes is greater than that of zinc complexes.     

Copper(II) complex with (4Z,4Z’)-1,1’-[disulfanediylbis(ethane-2,1-diyl)]-bis[2-methylthio-4-(pyridin-2-ylmethylidene)-1H-imidazol-5(4H)-one] onto a gold electrode surface – a catalyst of electrochemical reduction of nitrite in water solution

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