Hydroxymethylation of 2-Hydroxypropiophenones in Aqueous Medium: Synthesis of 3-Hydroxymethyl-3-methyl-4-chromanones and Their Conversion to 3-Methyl-4-chromanone-3-acetic Acids

Synthesis ◽  
1985 ◽  
Vol 1985 (09) ◽  
pp. 876-878 ◽  
Author(s):  
Daniela Barlocco ◽  
Giorgio Cignarella ◽  
Maria Michela Curzu
Keyword(s):  
Aqueous Medium ◽  
Acetic Acids

scholarly journals Iron-Loaded Catalytic Silicate Adsorbents: Synthesis, Characterization, Electroregeneration and Application for Continuous Removal of 1-Butylpyridinium Chloride

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 950
Author(s):  
Imen Ouiriemmi ◽  
Aida M. Díez ◽  
Marta Pazos ◽  
María Ángeles Sanromán
Keyword(s):  
Aqueous Medium ◽  
Adsorption Capacity ◽  
Carboxylic Acids ◽  
Breakthrough Curve ◽  
Silicate Material ◽  
Continuous Mode ◽  
Operational Conditions ◽  
Adsorbent Regeneration ◽  
Noticeable Reduction ◽  
Acetic Acids

This research proposes the application of iron-loaded sepiolite (S-Fe) as a catalytic adsorbent for the unreported 1-butylpyridinium chloride ([bpy] Cl) treatment in an aqueous medium. Initially, sepiolite was selected as an inexpensive and efficacious adsorbent for [bpy] Cl elimination. After that, sepiolite was loaded with iron for the subsequent electro-Fenton (EF) regeneration treatment. Once kinetic and isotherm studies were performed, providing respectively almost instantaneous adsorption (20 min) and an uptake of 22.85 mg/g, [bpy] Cl adsorption onto S-Fe was studied in continuous mode. The obtained breakthrough curve was analyzed using three standard breakthrough models, being Yoon–Nelson and Thomas the most suitable adjustments. Afterwards, S-Fe regeneration by the EF process was conducted using this iron-loaded silicate material as a heterogeneous catalyst. Under optimized operational conditions (current intensity 300 mA and Na2SO4 0.3 M), complete adsorbent regeneration was achieved in 10 h. The total mineralization of [bpy] Cl was reached within 24 h and among seven carboxylic acids detected, oxalic and acetic acids seem to be the primary carboxylic acids produced by [bpy] Cl degradation. Finally, S-Fe was efficiently used in four consecutive adsorption–regeneration cycles without a noticeable reduction in its adsorption capacity, opening a path for future uses.

Junction of the Epithelium and Lamina Propria of the Bovine Rumen Mucosa

1967 ◽  
Vol 25 ◽  
pp. 68-69
Author(s):  
Al W. Stinson
Keyword(s):  
Osmium Tetroxide ◽  
Squamous Epithelium ◽  
Short Chain Fatty Acids ◽  
Chloride Ions ◽  
Fermentation Products ◽  
Ruminant Species ◽  
Protective Shield ◽  
Stratified Squamous Epithelium ◽  
Lead Hydroxide ◽  
Acetic Acids

The stratified squamous epithelium which lines the ruminal compartment of the bovine stomach performs at least three important functions. (1) The upper keratinized layer forms a protective shield against the rough, fibrous, constantly moving ingesta. (2) It is an organ of absorption since a number of substances are absorbed directly through the epithelium. These include short chain fatty acids, potassium, sodium and chloride ions, water, and many others. (3) The cells of the deeper layers metabolize butyric acid and to a lesser extent propionic and acetic acids which are the fermentation products of rumen digestion. Because of the functional characteristics, this epithelium is important in the digestive process of ruminant species which convert large quantities of rough, fibrous feed into energy.Tissue used in this study was obtained by biopsy through a rumen fistula from clinically healthy, yearling holstein steers. The animals had been fed a typical diet of hay and grain and the ruminal papillae were fully developed. The tissue was immediately immersed in 1% osmium tetroxide buffered to a pH of 7.4 and fixed for 2 hrs. The tissue blocks were embedded in Vestapol-W, sectioned with a Porter-Blum microtome with glass knives and stained with lead hydroxide. The sections were studied with an RCA EMU 3F electron microscope.

Rheological behaviour of the condensed suspension of fluorinated montmorillonite “rassoul” particles in aqueous medium

2005 ◽  
Vol 123 ◽  
pp. 341-344
Author(s):  
A. Khaldoun ◽  
F. González-Caballero ◽  
J. G. López-Durán ◽  
N. Mahrach ◽  
M. L. Kerkeb
Keyword(s):  
Aqueous Medium ◽  
Rheological Behaviour

Changes of Magnetic Characteristics of iron Oxides and Hydroxides in Aqueous Medium

2017 ◽  
Vol 39 (1) ◽  
pp. 46-52
Author(s):  
T. SAVCHENKO ◽  
◽  
A. GRECHANOVSKY ◽  
A. BRIK ◽  
N. DUDCHENKO
Keyword(s):  
Aqueous Medium ◽  
Iron Oxides ◽  
Magnetic Characteristics

Catalytic Enantioselective Benzylation Directly from Aryl Acetic Acids

2018 ◽  
Author(s):  
Patrick Moon ◽  
Zhongyu Wie ◽  
Rylan Lundgren
Keyword(s):  
Functional Group ◽  
Terminal Event ◽  
Radical Intermediates ◽  
Carbon Carbon Bond ◽  
Or Groups ◽  
Reaction Proceeds ◽  
Wide Availability ◽  
Metal Catalyzed ◽  
The Stability ◽  
Acetic Acids

The stability and wide availability of carboxylic acids make them valuable reagents in chemical synthesis. Most transition metal catalyzed processes using carboxylic acid substrates are initiated by a decarboxylation event that generates reactive carbanion or radical intermediates. Developing enantioselective methodologies relying on these principles can be challenging, as highly reactive species tend to react indiscriminately without selectivity. Furthermore, anionic or radical intermediates generated from decarboxylation can be incompatible with protic and electrophilic functionality, or groups that undergo trapping with radicals. We demonstrate that metal-catalyzed enantioselective benzylation reactions of allylic electrophiles can occur directly from aryl acetic acids. The reaction proceeds via a pathway in which decarboxylation is the terminal event, occurring after stereoselective carbon–carbon bond formation. The mechanistic features of the process enable enantioselective benzylation without the generation of a highly basic nucleophile. Thus, the process has broad functional group compatibility that would not be possible employing established protocols.<br>

Surface interaction of sweet potato peels (Ipomoea batata) with Cd(II) and Pb(II) ions in aqueous medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Aqueous Medium ◽  
Sweet Potato ◽  
Adsorption Process ◽  
Low Cost ◽  
Correlation Coefficients ◽  
Order Kinetic ◽  
Thermodynamic Evaluation ◽  
Dissociative Mechanism ◽  
Pseudo Second Order ◽  
Potato Peels

The removal of Cd(II) and Pb(II) ions from aqueous medium was studied using potato peels biomass. The adsorption process was evaluated using Atomic Absorption Spectrophotometer (AAS). The Vibrational band of the potato peels was studied using Fourier Transform Infrared Spectroscopy (FTIR). The adsorption process was carried out with respect to concentration, time, pH, particle size and the thermodynamic evaluation of the process was carried at temperatures of 30, 40, 50 and 60(0C), respectively. The FTIR studies revealed that the potato peels was composed of –OH, -NH, –C=N, –C=C and –C-O-C functional groups. The optimum removal was obtained at pH 8 and contact time of 20 min. The adsorption process followed Freundlich adsorption and pseudo second-order kinetic models with correlation coefficients (R2) greater than 0.900. The equilibrium adsorption capacity showed that Pb(II) ion was more adsorbed on the surface of the potato peels biomass versus Cd (II) ion (200.91 mg/g &gt; 125.00 mg/g). The thermodynamic studies indicated endothermic, dissociative mechanism and spontaneous adsorption process. This study shows that sweet potato peels is useful as a low-cost adsorbent for the removal of Cd(II) and Pb(II) ions from aqueous medium.

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