scholarly journals REACTIVITY OF NUCLEOPHILES AND α-EFFECT IN SUBSTITUTION PROCESSES AT ELECTRON - DEFICIENCY CENTERS (Part 2)

2020 ◽  
Vol 86 (8) ◽  
pp. 77-100
Author(s):  
Anatolii Popov ◽  
Illia Kapitanov ◽  
Anna Serdyuk ◽  
Aleksandr Sumeiko
Keyword(s):  
Organic Phosphorus ◽  
Organophosphorus Pesticides ◽  
Reaction Rates ◽  
Hydroxamic Acids ◽  
Phosphorus Compounds ◽  
Reaction Products ◽  
Electron Pairs ◽  
Alkyl Derivatives ◽  
Solvent Type ◽  
Electron Deficiency

The review analyzes issues related to the reactivity of nucleophiles and the manifestation of the α-effect in substitution processes at electron-deficient centers. The fundamental aspects of this phenomenon, as well as the possibilities and prospects of using α-nucleophiles in systems for the highly efficient degradation of substrates - ecotoxicants of various natures, are discussed. In the first part of the review such aspects were observed: inorganic α-nucleophiles as the most effective class of reagents for the decomposition of organic phosphorus compounds, hydroxylamine, its N-alkyl derivatives, oximes, and hydroxamic acids, reactivity of the НОО– anion in the processes of acyl group transfer, reactivity of oximate ions, inorganic α-nucleophiles as the basis of formulations for the degradation of neurotoxins, vesicants, and organophosphorus pesticides, design of inhibited acetylcholinesterase reactivators based on hydroxylamine derivatives, ways of structural modification of α-nucleophiles and systems based on them. The data on the reactivity of typical inorganic α-nucleophiles in the cleavage of acyl-containing substrates, including phosphorus acid esters, which provide abnormally high reaction rates in comparison with other supernucleophiles, are analyzed. Various types of such α-nucleophiles, features of their structure and reactivity are considered. It was shown that an important feature of hydroxylamine, oximes, and hydroxamic acids is the presence of a fragment with adjacent O and N (–N – O – H) atoms containing one or more lone electron pairs, which determines their belonging to the class of α-nucleophiles. It has been shown that a many of factors can be responsible for the manifestation of the α-effect and its magnitude, the main of which is the destabilization of the ground state of the nucleophile due to repulsion of lone electron pairs, stabilization of the transition state, the unusual thermodynamic stability of reaction products, solvation effects of the solvent, type of hybridization of the electrophilic center, etc.

scholarly journals REACTIVITY OF NUCLEOPHILES AND α-EFFECT IN SUBSTITUTION PROCESSES AT ELECTRON - DEFICIENCY CENTERS

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Anatolii Popov ◽  
Illia Kapitanov ◽  
Anna Serdyuk ◽  
Aleksandr Sumeiko
Keyword(s):  
Organic Phosphorus ◽  
Organophosphorus Pesticides ◽  
Reaction Rates ◽  
Hydroxamic Acids ◽  
Phosphorus Compounds ◽  
Reaction Products ◽  
Electron Pairs ◽  
Alkyl Derivatives ◽  
Solvent Type ◽  
Electron Deficiency

The review analyzes issues related to the reactivity of nucleophiles and the manifestation of the α-effect in substitution processes at electron-deficient centers. The fundamental aspects of this phenomenon, as well as the possibilities and prospects of using α-nucleophiles in systems for the highly efficient degradation of substrates - ecotoxicants of various natures, are discussed. In the first part of the review such aspects were observed: inorganic α-nucleophiles as the most effective class of reagents for the decomposition of organic phosphorus compounds, hydroxylamine, its N-alkyl derivatives, oximes, and hydroxamic acids, reactivity of the НОО– anion in the processes of acyl group transfer, reactivity of oximate ions, inorganic α-nucleophiles as the basis of formulations for the degradation of neurotoxins, vesicants, and organophosphorus pesticides, design of inhibited acetylcholinesterase reactivators based on hydroxylamine derivatives, ways of structural modification of α-nucleophiles and systems based on them. The data on the reactivity of typical inorganic α-nucleophiles in the cleavage of acyl-containing substrates, including phosphorus acid esters, which provide abnormally high reaction rates in comparison with other supernucleophiles, are analyzed. Various types of such α-nucleophiles, features of their structure and reactivity are considered. It was shown that an important feature of hydroxylamine, oximes, and hydroxamic acids is the presence of a fragment with adjacent O and N (–N – O – H) atoms containing one or more lone electron pairs, which determines their belonging to the class of α-nucleophiles. It has been shown that a many of factors can be responsible for the manifestation of the α-effect and its magnitude, the main of which is the destabilization of the ground state of the nucleophile due to repulsion of lone electron pairs, stabilization of the transition state, the unusual thermodynamic stability of reaction products, solvation effects of the solvent, type of hybridization of the electrophilic center, etc.

CHARACTERIZATION OF MODEL AND SOIL ORGANIC MATTER METAL-PHOSPHATE COMPLEXES

1969 ◽  
Vol 49 (3) ◽  
pp. 365-373 ◽  
Author(s):  
M. Lévesque
Keyword(s):  
Organic Matter ◽  
Fulvic Acid ◽  
Organic Phosphorus ◽  
Inorganic Phosphorus ◽  
Chelating Resin ◽  
Alkaline Media ◽  
Phosphorus Compounds ◽  
Metal Phosphate ◽  
Reaction Products ◽  
Soil Extracts

Fulvic acid–metal–phosphate complexes prepared in the laboratory and corresponding complexes extracted (0.1 N NaOH and chelating resin) from a soil were characterized by means of electrophoresis, Sephadex gel filtration, and methods for differentiation of organic and inorganic phosphorus. The findings can be summarized as follows:(1) The prepared material in aqueous solution (after purification by dialysis) comprised three different entities: a fulvic acid–metal–phosphate complex, a fulvic acid–metal complex, and unbonded inorganic phosphate. These entities were reaction products obtained during the formation of fulvic acid–metal–phosphate complexes.(2) Upon hydrolysis in mild alkaline media, the metal–phosphate bonds of the fulvic acid–metal–phosphate complexes were broken; the fulvic acid–metal complexes, freed from the phosphate, remained intact.(3) While metal ions were necessary for bridging phosphorus and fulvic acid, phosphorus in turn may have bridged the fulvic acid–metal units.(4) Significant amounts of complexed inorganic phosphorus were found intermixed with organic phosphorus compounds in soil extracts; this suggested the existence of organic matter metal–phosphate complexes in soil.

γ-strahlenchemische Reaktionen des weißen Phosphors in Cyclohexan- und Cyclohexan-Tetrachlorkohlenstoff-Lösung

1964 ◽  
Vol 19 (7) ◽  
pp. 549-557 ◽  
Author(s):  
K.-D. Asmus ◽  
A. Henglein ◽  
G. Meissner ◽  
D. Perner
Keyword(s):  
Organic Phosphorus ◽  
Phosphinic Acid ◽  
Reaction Scheme ◽  
White Phosphorus ◽  
Phosphorus Compounds ◽  
Reaction Products ◽  
Red Phosphorus ◽  
Γ Irradiation ◽  
Polymeric Form ◽  
Chain Reactions

Red phosphorus, soluble phosphorus organic compounds and small amounts of phosphine are formed when white phosphorus in cyclohexane solution is exposed to γ-rays. The red phosphorus contains one C6H11-group per 4 — 5 P-atoms. It reacts with chlorine to give cyclohexylphosphorusdichloride. Its reactivity towards oxygen can be decreased by high temperatures during irradiation or by high γ-doses. It is concluded from quantitative studies of this “annealing” process that phosphorus atoms carrying C6H11-endgroups are especially reactive in the polymeric form of phosphorus. The low molecular weight products of the reaction between white phosphorus and cyclohexane undergo typical reactions of tertiary phosphines. They can readily be oxidized and chlorinated to yield cyclohexyl-phosphinic-acid or cyclohexyl-phosphorus-dichloride, respectively. White phosphorus acts as a scavenger for free H-atoms and C6H11-radicals from the radiolysis of cyclohexane. This reaction, however, does generally not lead to the complete cracking of all PP-bonds of the P4-molecule.The following products are formed in the γ-irradiation of white phosphorus in cyclohexane in the presence of carbon tetrachloride: Red phosphorus containing C6H11- and CCl3-endgroups, cyclohexylphosphorus-dichloride, trichloromethyl-phosphorus-dichloride, chloroform, cyclohexyl-chloride, hexachloroethane and trichloromethyl-cyclohexane. The yields of these products at various doses, dose rates, temperatures and compositions of the solutions are described. Several products such as C6H11PCl2 are produced with high G-values at temperatures above 100°C. The results are explained by a reaction scheme in which three chain reactions simultaneously occur. They are linked together since they have a common intermediate in the form of the CCl3-radical. At high doses, the reaction products of phosphorus mentioned above (including the red phosphorus) are transformed into soluble organic phosphorus compounds of high boiling points the structure of which has not yet been recognized.

The Reaction and Microscopic Electron Properties from Dynamic Evolutions of Condensed-Phase RDX Under Shock Loading

2020 ◽  
Vol 75 (4) ◽  
pp. 285-291
Author(s):  
Jiao-Nan Yuan ◽  
Hai-Chao Ren ◽  
Yong-Kai Wei ◽  
Wei-Sen Xu ◽  
Guang-Fu Ji ◽  
...  
Keyword(s):  
Shock Wave ◽  
Ground State ◽  
Shock Loading ◽  
Reaction Rates ◽  
Reaction Products ◽  
Decomposition Rates ◽  
Multi Scale ◽  
Wave Velocities ◽  
Wide Gap ◽  
Reaction Initiation

AbstractMicroscopic electron properties of α-hexahydro-1,3,5-trinitro-1,3,5-triazine (α-RDX) with different shock wave velocities have been investigated based on molecular dynamics together with multi-scale shock technique. The studied shock wave velocities are 8, 9 and 10 km ⋅ s−1. It has been said that the shock sensitivity and reaction initiation of explosives are closely relevant with their microscopic electron properties. The reactions, including the reaction products, which are counted from the trajectory during the simulations are analysed first. The results showed that the number of the products strictly rely on shock wave velocities. The reaction rates and decomposition rates are also studied, which showed the differences between the different shock velocities. The results of electron properties show that α-RDX is a wide-gap insulator in the ground state and the metallisation conditions of shocked RDX are determined, which are lower than under-static high pressure.

Medicinal correction of cerebrovascular reactivity — a necessary component of the treatment of cerebral blood circulation disorders

1999 ◽  
Vol 80 (2) ◽  
pp. 94-96
Author(s):  
V. I. Danilov
Keyword(s):  
Blood Circulation ◽  
Organic Phosphorus ◽  
Experimental Studies ◽  
Cerebrovascular Reactivity ◽  
Cerebral Vessels ◽  
Regulatory Mechanisms ◽  
Phosphorus Compounds ◽  
Low Toxic ◽  
The Brain ◽  
Cerebral Blood Circulation

The results of experimental studies made it possible to draw a conclusion on the reality of cerebral vessels reactivity recovery using drugs with primary neurometabolic activity, in particular, dimephosphone, sermion and pyracetam. The advantages of low-toxic nonauticholinesterasic organic phosphorus compounds among the correctors of regulatory mechanisms of circular provision of the brain are shown.

Failure of Phosphorus-32 to Exchange with Organic Phosphorus Compounds

Nature ◽  
1952 ◽  
Vol 169 (4292) ◽  
pp. 192-193 ◽  
Author(s):  
D. R. H. GOURLEY
Keyword(s):  
Organic Phosphorus ◽  
Phosphorus Compounds
Sign in / Sign up

Export Citation Format

Share Document