Spectrophotometric determination of dopamine in pharmaceutical formulations

A new spectrophotometric method was developed for the estimation of dopamine. The method is based on the bromination of the dopamine with a solution of excess brominating mixture. After bromination, the excess brominating mixture is treated with potassium iodide to produce a yellow solution. The absorbance of yellow solution was measured at 350 nm on a Spectronic 1001 spectrophotometer against distilled water as a blank.From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 3, 2005, pp. 2842285.Original English Text Copyright © 2005 by Rami Reddy, Sreedevi, Prabhavathi, Chakravarthy.This article was submitted by the authors in English.     

High-Performance Thin-Layer Chromatographic Determination of Itopride Hydrochloride in its Pharmaceutical Preparation and in the Bulk Drug

JPC – Journal of Planar Chromatography – Modern TLC - A normal-phase high-performance thin-layer chromatographic (HPTLC) method has been established for quantitative estimation of...     

Urea and thiourea derivatives of 3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1, 2, 4]triazolo[4,3-a]pyrazine: Synthesis,characterization, antimicrobial activity and docking studies

Abstract

An efficient and robust synthetic procedure was developed primarily for the synthesis of a precursor compound; 3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1, 2, 4]triazolo[4,3-a]pyrazine (11), from 2-chloropyrazine (7) through the chemical transformations such as hydrazine substitution, trifluoroacetyl group induction, cyclization and pyrazine ring reduction. A new series of urea derivatives 13a-e and thiourea derivatives 13f-j of compound 11 have been synthesized and the structures of all the compounds were confirmed using spectroscopic analyses such as IR, ¹H NMR, ¹³C NMR, LC-MS and HRMS. The newly synthesized compounds were screened for their in vitro antimicrobial activity against five bacteria and two fungi, in which compounds 13d, 13i and 13j displayed potential activity against bacterial strains and 13a, 13d, 13g and 13j against fungal strains with the MIC values in the range of 6.25–25.0 µg/mL. An overall comparison of the activity results revealed that thiourea derivatives contain better activity than that of urea compounds. Molecular docking studies on poly (ADP-ribose) polymerase 15 (ARTD7, BAL3) demonstrated that all the synthesized compounds possess significant binding energies (-8.1 to -9.8?kcal/mol) with no adverse effect in the active site of protein.     

Impact of homogeneous–heterogeneous reactions on heat and mass transfer flow of Au–Eg and Ag–Eg Maxwell nanofluid past a horizontal stretched cylinder

The object of this study is to analyze the impact of heterogeneous and homogeneous reactions on the flow, heat and mass transfer analysis of Maxwell nanofluid of Tiwari–Das kind over a stretched cylinder by considering convective boundary condition and velocity slip. Ethylene glycol (Eg) is used as base fluid; while gold (Au) and silver (Ag) are taken as nanoparticles. The governing equations represent nanofluid momentum, and energy and mass are reduced to system of nonlinear ordinary differential equations by utilizing similarity transformation procedure and are numerically evaluated by using finite element method. The sway of several pertinent parameters on the sketches of velocity, temperature and concentration is plotted through graphs. In addition to that the values of rate of heat transfer and skin-friction coefficient are calculated and presented through tables. The values of skin-friction coefficient are intensified as the values of homogeneous–heterogeneous reaction parameters rises. The velocity and concentration scatterings are both declines as the strength of Maxwell parameter raises.

     

Simple methods to synthesize 2-pyridones: reactions of 2-aroyl-3,3-bis(alkylsulfanyl)acrylaldehydes and cyanoacetamide

5-Aroyl-6-(methylsulfanyl)-2-oxo-1,2-dihydro-3-pyridinecarbonitriles and 5-aroyl-4-(methylsulfanyl)-2-oxo-1,2-dihydro-3-pyridinecarbonitriles are synthesized effectively by the reaction of 2-aroyl-3,3-bis(alkylsulfanyl)acrylaldehydes and cyanoacetamide under two different conditions.     

The reaction of 2‐aroyl‐3,3‐bis(alkylsulfanyl)acrylaldehydes and hydroxylamine hydrochloride: Facile synthesis of differently substituted isoxazoles

2‐Aroyl‐3,3‐bis(alkylsulfanyl)acrylaldehyde was utilized for the synthesis of three different isoxazoles by reacting with hydroxylaminehydrochloride. We synthesized differently substituted isoxazoles like (aryl)[5‐(methylsulfanyl)‐4‐isoxazolyl]methanones, 3‐(methylsulfanyl)‐5‐phenyl‐4‐isoxazolecarbonitriles and 5‐aryl‐3‐(methylsulfanyl)‐4‐isoxazolecarbaldehyde oximes in good yields by varying the substratereagent stoichiometry and temperature of the reaction medium.     

4,4,9,9-Tetraphenyl pyrroloindolizine: a structural analogue of calix[2]pyrrole

Synthesis, spectral and structural characterization of a pyrroloindolizine derivative having structural similarity with calix[2]pyrrole is described. Here, two pyrrole rings are connected with two meso-carbon atoms having an N,α-linkage and an α,β-linkage to afford the smallest analogue in the calixpyrrole family. Detailed NMR spectroscopic studies along with single crystal X-ray analysis confirm the assigned structure of the molecule.     

A Generalized Measure of Cumulative Residual Entropy

In this work, we introduce a generalized measure of cumulative residual entropy and study its properties. We show that several existing measures of entropy, such as cumulative residual entropy, weighted cumulative residual entropy and cumulative residual Tsallis entropy, are all special cases of this generalized cumulative residual entropy. We also propose a measure of generalized cumulative entropy, which includes cumulative entropy, weighted cumulative entropy and cumulative Tsallis entropy as special cases. We discuss a generating function approach, using which we derive different entropy measures. We provide residual and cumulative versions of Sharma–Taneja–Mittal entropy and obtain them as special cases this generalized measure of entropy. Finally, using the newly introduced entropy measures, we establish some relationships between entropy and extropy measures.     

Catalytic Conversion of Glucose into Levulinic Acid Using 2-Phenyl-2-Imidazoline Based Ionic Liquid Catalyst

Levulinic acid (LA) is an industrially important product that can be catalytically valorized into important value-added chemicals. In this study, hydrothermal conversion of glucose into levulinic acid was attempted using Brønsted acidic ionic liquid catalyst synthesized using 2-phenyl-2-imidazoline, and 2-phenyl-2-imidazoline-based ionic liquid catalyst used in this study was synthesized in the laboratory using different anions (NO₃, H₂PO₄, and Cl) and characterized using ¹H NMR, TGA, and FT-IR spectroscopic techniques. The activity trend of the Brønsted acidic ionic liquid catalysts synthesized in the laboratory was found in the following order: [C₄SO₃HPhim][Cl] > [C₄SO₃HPhim][NO₃] > [C₄SO₃HPhim][H₂PO₄]. A maximum 63% yield of the levulinic acid was obtained with 98% glucose conversion at 180 °C and 3 h reaction time using [C₄SO₃HPhim][Cl] ionic liquid catalyst. The effect of different reaction conditions such as reaction time, temperature, ionic liquid catalyst structures, catalyst amount, and solvents on the LA yield were investigated. Reusability of [C₄SO₃HPhim][Cl] catalyst up to four cycles was observed. This study demonstrates the potential of the 2-phenyl-2-imidazoline-based ionic liquid for the conversion of glucose into the important platform chemical levulinic acid.