Facile synthesis of optically pure 1,2-diaryl (and 1-Alkyl-2-aryl) ethyl and propylamines

A concise high-yielding route to synthetically useful 1,2-diaryl (and 1-alkyl-2-aryl) ethyl and propylamines in high enantiomeric purity is described. The key step of this route is the completely stereoselective addition of lithium (R)-ortho-(p-toluenesulfinyl)benzylic carbanions to (S)-N-p-toluenesulfinylimines, which takes place in very high or quantitative yields. N-Desulfinylation and C-desulfinylation of the resulting adducts can be achieved with no loss of optical purity employing conventional methods (TFA and Raney-Ni, respectively).     

Microdetermination ofp-aminophenol

Summary A colorimetric method for the miorodetermination ofp-aminophenol based on indophenol dye formation is described. The conditions for its determination in the presence of theo- andm-isomers are given.

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Zusammenfassung Eine kolorimetrische Methode für die Mikrobestimmung von p-Aminophenol, die auf der Bildung eines Indophenolfarbstoffs beruht, wurde beschrieben. Die Bedingungen für die Bestimmung in Anwesenheit der Ortho- und Meta-Isomeren wurden angegeben.

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Résumé On décrit une méthode colorimétrique pour le microdosage dep-amino-phénole, basée sur la formation d'un colorant indophénolique. On donne les conditions du dosage en présence des isomères ortho et méta.

     

Micellar enhancement of benzodiazepine fluorescence

The interactions that exist between benzodiazepines and surfactants provide micellar enhancement factors for their fluorimetric determination in the range 1.2-6.5, depending on the nature of both the benzodiazepine and the surfactant. A series of benzodiazepines and anionic surfactants were treated topologically to determine the influence of each benzodiazepine substituent on the basic benzodiazepine structure and the influence of both the hydrophobic moiety of the surfactant and its counter ion on the sensitisation process. Sensitisation parameters were used to quantify the effect of the chemical structures of both surfactants and drugs on their interaction.     

Luminescence and compositional studies for the identification of “fire-setting” features at prehistoric mine La Turquesa (Catalonia,Spain)

Journal of Radioanalytical and Nuclear Chemistry - Modern mining activities often leads to destruction of archaeological records, making difficult to date the contexts and tools. In this work, a...     

Computational analysis of the binding ability of heterocyclic and conformationally constrained epibatidine analogs in the neuronal nicotinic acetylcholine receptor

One of the most critical issues on the study of ligand–receptor interactions in drug design is the knowledge of the bioactive conformation of the ligand. In this study, we describe a computational approach aimed at estimating the binding ability of epibatidine analogs to interact with the neuronal nicotinic acetylcholine receptor (nAChR) and get insights into the bioactive conformation. The protocol followed consists of a docking analysis and evaluation of pharmacophore parameters of the docked structures. On the basis of the biological data, the results have revealed that the docking analysis is able to predict active ligands, whereas further efforts are needed to develop a suitable and solid pharmacophore model.     

Catalytic Hydrogenation of L-Ascorbic Acid (Vitamin C): A Stereoselective Process for the Production of L-Gulono-1, 4-Lactone

Reduction of functional groups with hydrogen gas is one of the most important reactions in organic chemistry, dating to the first hydrogenation of ethene to ethane reported by Von Wilde in 1874¹. Indeed, alkenes are generally rapidly hydrogenated, in the presence of a catalyst, usually, platinum, Raney nickel, palladium, or rhodium on carbon, to the corresponding alkane via heterogeneous reaction. Most undergraduate, introductory texts introduce this reaction as occurring via a stermspecific syn addition, although this is an oversimplification, due to possible rearrangements on the catalyst surface². While the chemistry of Vitamin C (L-ascorbic acid), in regards to oxidative degradation, is well studied, its behavior under reductive conditions has been relatively overlooked. The catalytic reduction of ascorbic acid has been reported earlier (24 hours, palladium catalyst, water, 50°) by workers at Pfizer³.     

Exact controllability for Bresse system with variable coefficients

This paper is concerned with the internal exact controllability of a generalized Bresse system with variable coefficients, which the controls functions acts in an arbitrarily small subinterval (l₁,l₂) of (0,L). Our computation suggests a minimal time control and a region where the controls are more effective. The variable coefficients can be viewed as a generalization of Laplacian operator. The main result is obtained by applying Hilbert Uniqueness Method proposed by Lions, without using the Holmgren's uniqueness theorem or the hypothesis of equal‐speed waves of propagation. Copyright © 2015 John Wiley & Sons, Ltd.     

Solubility of carbon dioxide in the solvent system (2-amino-2-methyl-1-propanol + sulfolane + water)

New sets of data for the solubility of CO₂ in the amine solvent system of 2-amino-2-methyl-1-propanol (1) + sulfolane (2) + water (3) were presented in this work. The measurements were done at temperatures of 313.2, 333.2, 353.2, and 373.2 K and CO₂ partial pressures up to 193 kPa. The investigated compositions were as follows: (i) w₁=16.5%$w_1=16.5\%$, w₂=32.2%$w_2=32.2\%$; (ii) w₁=8.2%$w_1=8.2\%$, w₂=41.2%$w_2=41.2\%$; (iii) w₁=22.3%$w_1=22.3\%$, w₂=27.7%$w_2=27.7\%$; and (iv) w₁=30.6%$w_1=30.6\%$, w₂=19.4%$w_2=19.4\%$, where w$w$ is the mass percent of the component. The present solubility data was correlated by a modified Kent–Eisenberg model. The model reasonably represents the present solubility data, not only over the considered conditions, but also for a wider range of temperatures, partial pressures, and compositions.