scholarly journals Lysozyme-mediated p-nitrophenyl penta-n-acetyl-.BETA.-chitopentaoside production in aqueous-dimethylsulfoxide solvent system, as a substrate for a lysozyme assay.

1989 ◽  
Vol 53 (2) ◽  
pp. 383-388 ◽  
Author(s):  
Taichi Usui ◽  
Hidenori MATSUI
Keyword(s):  
Solvent System ◽  
Aqueous Dimethylsulfoxide

The Dissociation of Anilinium Ions in Aqueous Dimethylsulfoxide

1972 ◽  
Vol 50 (4) ◽  
pp. 474-478 ◽  
Author(s):  
Keith Yates ◽  
Graeme Welch
Keyword(s):  
Aqueous Solution ◽  
Solvent System ◽  
Ionization Mechanism ◽  
Normal Order ◽  
Aqueous Dimethylsulfoxide

The pKa values often substituted primary anilines and six substituted tertiary anilines have been determined in 70% DMSO–water. The ΔpKa values relative to those in aqueous solution indicate that DMSO is about 2 log units stronger as a base than H2O. The normal order of basicity (tertiary > primary) is inverted in this solvent system and the Hammett ρ values for the two series provide evidence for a different ionization mechanism than that in water.

The H− acidity function for dimethylformamide–water

1970 ◽  
Vol 48 (21) ◽  
pp. 3354-3357 ◽  
Author(s):  
E. Buncel ◽  
E. A. Symons ◽  
Douglas Dolman ◽  
Ross Stewart
Keyword(s):  
Solvent System ◽  
Tetramethylammonium Hydroxide ◽  
Acidity Function ◽  
Hydroxide Ion ◽  
Indicator Method ◽  
Aqueous Dimethylsulfoxide

The H− acidity function has been determined for N,N-dimethylformamide–water mixtures containing tetramethylammonium hydroxide by the Hammett indicator method. Basicity in the aqueous dimethylformamide system exceeds that in aqueous tetramethylenesulfone but is slightly less than in aqueous dimethylsulfoxide, at equivalent molar compositions of solvent and base. However, the basic aqueous dimethylformamide solvent system is only of limited utility as a result of reaction of hydroxide ion with the dimethylformamide.

STUDIES ON THYROIDAL COLLOID PINOCYTOSIS USING A DOUBLE ISOTOPE TECHNIQUE

1972 ◽  
Vol 70 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Mario A. Pisarev ◽  
Noe Altschuler ◽  
Leslie J. DeGroot
Keyword(s):  
Acid Phosphatase ◽  
Thyroid Hormone ◽  
Trichloroacetic Acid ◽  
Specific Activity ◽  
Acid Precipitation ◽  
Solvent System ◽  
Blood Stream ◽  
Radioactive Materials ◽  
Isotope Technique ◽  
Double Isotope

ABSTRACT The process of secretion of the thyroid hormone involves several steps: pinocytosis of thyroglobulin, fusion of the colloid droplets with the lysosomes, digestion of thyroglobulin by a cathepsin, dehalogenation of tyrosines and release of thyronines into the blood stream. The present paper describes a double isotope technique for studying the first two steps. Thyrotrophin (TSH) administration to rats increased the radioactivity present in all fractions, specially in the 15 000 × g pellet. When the subcellular distribution of acid phosphatase was determined, the highest specific activity was found in this fraction, thus indicating the presence of lysosomes. The content of radioactive materials in the 15 000 × g pellet was analyzed by trichloroacetic acid precipitation and by ascending paper chromatography using n-butanol:ethanol:ammonium hydroxide (5:1:2;v/v) as solvent system. The results obtained showed that 90% of the radioactivity was protein bound and strongly suggest that this material is thyroglobulin.

OPTIMIZATION OF THIN LAYER CHROMATOGRAPHY METHODS FOR SEPARATION AND IDENTIFICATION OF ANTIDEPRESSANTS IN THEIR MIXTURE

2014 ◽  
Vol 21 (1) ◽  
pp. 11-15
Author(s):  
Daiva Kazlauskienė ◽  
Guoda Kiliuvienė ◽  
Palma Nenortienė ◽  
Giedrė Kasparavičienė ◽  
Ieva Matukaitytė
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Solvent System ◽  
Ammonia Solution ◽  
Relative Standard ◽  
Rf Values ◽  
Solvent Systems ◽  
Paroxetine Hydrochloride ◽  
Fluvoxamine Maleate ◽  
Layer Chromatography

By conducting the toxicological analysis it is meaningful to determine the analytical system that could identify simultaneously several medicinal preparations quickly and precisely. The purpose of this work was to create and validate the method of thin-layer chromatography that would be suitable to separate the components of antidepressant mixture (amitriptyline hydrochloride, paroxetine hydrochloride, sertraline hydrochloride, fluvoxamine maleate and buspirone hydrochloride) and to identify them. The system was validated with regard to the sensitivity, repetition of data, resistance and particularity. The solvent systems with potential of high separation of components in their mixture were created: acetonitrile, methanol, ammonia solution 25 percent (85:10:5); acetonitrile, methanol, ammonia solution 25 percent (75:20:5); dichlormethane, 1,4-dioxane, ammonia solution 25 percent (50:45:5); dichlormethane, 1,4-dioxane, ammonia solution 25 percent (42:55:3); trichlormethane, 1,4-dioxane, ammonia solution 25 percent (25:70:5); trichlormethane, 1,4-dioxane, ammonia solution 25 percent (60:36:4). One of the most suitable solvent systems for separation of the analyzed mixture (sertraline, amitriptyline, paroxetine, buspirone, fluvoxamine) was determined – acetonitrile, methanol, ammonia solution 25 percent (85:10:5). When this solvent system was used, the average Rf values of the analyzed compounds differed the most. Validation was conducted – the relative standard deviation (RSD, percent) of the average Rf value of the analyzed compounds varied from 0,6 to 1,8 percent and did not exceed the permissible error of 5 percent. The sensitivity of methodology was determined by assessing the intensity of the mixture’s spots on the chromatographic plate. The detection limit of buspirone was 0,0012 µg; sertraline – 0,0008 µg; amitriptyline – 0,0004 µg; fluvoxamine – 0,0004 µg; paroxetine – 0,0008 µg. The resistance of results to the changed conditions – it was determined that when the amounts of the solvents acetonitrile and methanol were increased or decreased to two milliliters, the average Rf values of the analyzed compounds did not change statistically significantly

Arene Dearomatization via Radical Hydroarylation

2019 ◽  
Author(s):  
Autumn Flynn ◽  
Kelly McDaniel ◽  
Meredith Hughes ◽  
David Vogt ◽  
Nathan Jui
Keyword(s):  
Precious Metal ◽  
Room Temperature ◽  
Aryl Halide ◽  
Solvent System ◽  
Benzene Derivatives ◽  
Green Solvent ◽  
Photocatalytic System

A photocatalytic system for the dearomative hydroarylation of benzene derivatives has been developed. Using a combination of an organic photoredox catalyst and an amine reductant, this process operates through a reductive radical-polar crossover mechanism where aryl halide reduction triggers a regioselective cyclization event, giving rise to a range of complex spirocyclic cyclohexadienes. This light-driven protocol functions at room temperature in a green solvent system (aq. MeCN), without the need for precious metal-based catalysts or reagents, or the generation of stoichiometric metal byproducts.

Optimization of Precipitating Solvent System for Pilot Testing in CLIMIT Demo Project INSPIRE

2019 ◽  
Author(s):  
Inna Kim ◽  
Ugochukwu E. Aronu ◽  
Solrun J. Vevelstad ◽  
Geir Haugen ◽  
Andreas Grimstvedt ◽  
...  
Keyword(s):  
Solvent System ◽  
Pilot Testing

Phytochemical evaluation of leaf extracts of Naringi crenulata (roxb.) Nicolson

2016 ◽  
Vol 5 (11) ◽  
pp. 5110
Author(s):  
Sartaj Ahmad Allayie ◽  
Mushtaq Ahmed Parray* ◽  
Bilal Ahmad Bhat ◽  
S. Hemalatha
Keyword(s):  
Quantitative Analysis ◽  
Solvent System ◽  
Great Promise ◽  
Phytochemical Analysis ◽  
Bioactive Constituents ◽  
Leaf Extracts ◽  
Traditional Medicines ◽  
The People ◽  
Wide Range ◽  
Rf Values

The use of traditional medicines holds a great promise as an easily available source as effective medicinal agents to cure a wide range of ailments among the people particularly in tropical developing countries like India. The present study investigates the qualitative and quantitative analysis of the major bioactive constituents of N. crenulata leaf extracts. The extractive values of aqueous, acetone and chloroform extracts were found to be 11.34, 4.24 and 6.06 respectively. Qualitative phytochemical analysis of these three solvent extracts confirm the presence of Alkaloids, Saponins, Flavonoids and Phenolic compounds in all the three extracts; however, these phytochemicals were more significant in aqueous extract. Quantitative analysis was carried out using TLC method by different solvent system. Amongst various solvent systems, Butanol: acetic acid: water (9: 0.9: 0.1 v/v/v) shows maximum resolution and number of spots produced at long UV (365 nm) and under iodine vapours. The TLC chromatograms constituted different coloured phytochemical compounds with different Rf values. It can be conveniently used to evaluate the quality of different area samples. This indicates that the leaves can be useful for treating different diseases because the therapeutic activity of a plant is due to the presence of particular class of compounds and thus can serve as potential sources of useful drugs in future.

Metal free decarboxylative aminoxylation of carboxylic acids using a biphasic solvent system

2021 ◽  
Vol 19 (1) ◽  
pp. 273-278
Author(s):  
Göran Schulz ◽  
Andreas Kirschning
Keyword(s):  
Carboxylic Acids ◽  
Solvent System ◽  
Radical Scavenger ◽  
Synthetic Approach ◽  
Metal Free ◽  
System P

The oxidative radical decarboxylation of carboxylic acids with TEMPO as radical scavenger in a biphasic solvent system is reported which is successfully used in a new synthetic approach for the antidepressants indatraline.

Sign in / Sign up

Export Citation Format

Share Document