Search results for "Phosphorus"

Studies on the synthesis of heterocyclic compounds. Part VIII. A facile synthesis of new pyrazolo[3,4-b]benzazepine-4,9-diones

1982

2-Carbomethoxybenzoyl chloride reacted with some 5-methylamino-l-phenyl-3-R-pyrazoles to yield N-methyl-l-phenyl-3-R-pyrazol-5-yl)-2-carbomethoxybenzamides. These products were readily transformed into the corresponding acid, which in turn, refluxed in phosphorus oxychloride afforded the tricyclic system, l-phenyl-3-R-pyrazolo[3,4-b]benzazepine-4,9-dione.

Rapid characterization of alkylpolyphosphonates by CZE with indirect photometric and mass spectrometric detection.

2006

Methods for the rapid characterization of industrial alkylpolyphosphonates (APPs) by infusion MS and CZE with indirect photometric (IPD) and MS detection are described. Technical-grade APPs, including alkylaminepolyphosphonates with 3-5 phosphonate groups and different hydrocarbon skeletons, hydroxyethyl-amino-bis(methylenephosphonic acid), hydroxyethylidene-diphosphonic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid, were examined. A 10 mM solution of adenosine triphosphate disodium salt at pH 2.2 was used as BGE. The nominal compounds of the industrial APPs and their impurities were well resolved in less than 15 min. The peaks were identified by using extracted ion electropherograms…

ChemInform Abstract: Applications and Stereoselective Syntheses of P-Chirogenic Phosphorus Compounds

2016

Phosphorus compounds bearing chirality on the P-center are usually qualified as P-chirogenic or P-stereogenic. This chemical class concerns natural products, agrochemistry, molecular materials, biology and pharmacy, although it is certainly in coordination chemistry and in asymmetric catalysis using chiral transition metal complexes that P-chirogenic phosphorus compounds are the most used. The chiral phosphine ligands and their uses in asymmetric metal-catalyzed reactions have been widely reviewed in literature. However, an overview covering the applications as well as the stereoselective syntheses of all classes of phosphorus compounds has not yet been provided. This review reports the bes…

Separation of aromatic aminophosphonic acid enantiomers by capillary electrophoresis with the application of cyclodextrins

2002

The detailed studies concerning capillary electrophoresis separation of aminophosphonic acid enantiomers with various commercially available cyclodextrins are presented. The obtained results show that the separation of these stereoisomers is dependent on pH of background electrolyte, concentration of cyclodextrin as well as on the type of applied chiral selector. The separation mechanism is based on the co-operative effect of hydrogen bond type interactions enhanced by hydrophobic forces and sterical constrains between aminophosphonate and cyclodextrin. With application of elaborated method, enantiomeric baseline or partial separation of 18 alpha-aminophosphonic acids was achieved. This sep…

Use of biological and sedimentation models for designing Peñíscola WWTP.

2004

This paper presents Peñíscola wastewater treatment plant design. Peñíscola is a tourist city in Castellón (Spain), whose population changes significantly between summer and the rest of the year. The design of the biological and settling treatment units has been confirmed by computer model simulations and provided for biological organic matter, nitrogen and phosphorus removal. Two different treatment schemes have been proposed in order to optimize the plant performance during both seasonal operations. During low-load season, the plant will be operated under extended aeration conditions, so further sludge stabilization will not be needed. During high-load season, the plant will be operated un…

Organic Field Effect Transistors: Noncovalent Functionalization and Passivation of Black Phosphorus with Optimized Perylene Diimides for Hybrid Field…

2020

White Phosphorus Is Air-Stable Within a Self-Assembled Tetrahedral Capsule

2009

Molecular Fire Quencher Cage-shaped molecular assemblies can regulate the reactivity of smaller molecules trapped within them. Mal et al. (p. 1697 ) extend this approach to enable the protection of elemental white phosphorus (P 4 ), a substance that rapidly ignites on contact with oxygen. The tetrahedral cages self-assemble in aqueous solution through coordination of six ligands to four iron ions, and efficiently capture phosphorus from a suspension. The water-soluble host-guest constructs were stable in air for at least 4 months, but released intact P 4 rapidly on displacement by added benzene.

Synthesis of new 2,2′-disubstituted 5,5′-dimethyl-4,4′-bitriazoles and 2-(4-Triazolyl)quinoxalines

2000

Thermal rearrangement of 3-acylisoxazole arylhydrazones allowed facile preparation of 2H-1,2,3-triazoles which were firstly reacted with isoamyl nitrite and then with an opportune arylhydrazine to produce the corresponding α-hydroxyiminohydrazones 8a-h. The reaction of compounds 8a-h with phosphorus pentachloride afforded the desired 4,4′-bitriazoles 1a-h. The α-hydroxyiminoketone derivative 7 or the α-diketone 14 reacted easily with 1,2-phenylenediamine to afford 1,2,3-triazoles 2a-c bearing the quinoxaline moiety at position 4. Improved yields of the quinoxalines 2a-c were obtained when 1,2-phenylenediamine was reacted with the dioxime 15.

Synthesis of Carbolines via Microwave-Assisted Cadogan Reactions of Aryl-Nitropyridines

2018

Unexpected Conformational Behaviour of a Diphosphate Derived from a Spherand-Type Calixarene

2005

The spherand-type calixarene 2a, which consists of three diphenol units linked by methylene bridges, was treated with phosphorus pentachloride and then with water. A C1-symmetrical conformation was found for the resulting bisphosphate 7 in the crystalline state by X-ray analysis, with an anti orientation of the phosphoryl groups. MM3 calculations lead to a nearly identical conformation for the most stable isomer (RRS-twist), while a slightly higher energy was found for an RRS-crown isomer with a syn orientation of the phosporyl groups. Surprisingly, all NMR studies (1H, 13C and 31P) of 7 are in agreement with a dynamic C2 symmetry in solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Wein…