scholarly journals Asymmetric Electrophilic Reactions in Phosphorus Chemistry

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 108 ◽  
Author(s):  
Anastasy O. Kolodiazhna ◽  
Oleg I. Kolodiazhnyi
Keyword(s):  
Absolute Configuration ◽  
Electrophilic Substitution ◽  
Organophosphorus Compounds ◽  
Phosphoryl Group ◽  
Substitution Reactions ◽  
Molecular Chemistry ◽  
Electrophilic Reactions ◽  
Wide Range ◽  
Further Development ◽  
Organophosphorus Chemistry

This review is devoted to the theoretic and synthetic aspects of asymmetric electrophilic substitution reactions at the stereogenic phosphorus center. The stereochemistry and mechanisms of electrophilic reactions are discussed—the substitution, addition and addition-elimination of many important reactions. The reactions of bimolecular electrophilic substitution SE2(P) proceed stereospecifically with the retention of absolute configuration at the phosphorus center, in contrast to the reactions of bimolecular nucleophilic substitution SN2(P), proceeding with inversion of absolute configuration. This conclusion was made based on stereochemical analysis of a wide range of trivalent phosphorus reactions with typical electrophiles and investigation of examples of a sizeable number of diverse compounds. The combination of stereospecific electrophilic reactions and stereoselective nucleophilic reactions is useful and promising for the further development of organophosphorus chemistry. The study of phosphoryl group transfer reactions is important for biological and molecular chemistry, as well as in studying mechanisms of chemical processes involving organophosphorus compounds. New versions of asymmetric electrophilic reactions applicable for the synthesis of enantiopure P-chiral secondary and tertiary phosphines are discussed.

ELECTROPHILIC REACTIONS OF STEROIDAL AND OTHER α-PHENYL DIENES

1966 ◽  
Vol 44 (19) ◽  
pp. 2233-2239
Author(s):  
Maurice Douek ◽  
George Just
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Perchloric Acid ◽  
Electrophilic Substitution ◽  
Aluminium Chloride ◽  
Substitution Reactions ◽  
Electrophilic Reactions ◽  
Electrophilic Substitution Reactions

3-Phenylcholesta-3,5-diene (I) is shown to undergo electrophilic substitution reactions exclusively at the 6 position with formaldehyde – perchloric acid, acetic anhydride – aluminium chloride, and the Vilsmeier reagent.In the case of formaldehyde, the final product is "dimmer" II. The reaction is specific for formaldehyde and can be used to detect trace amounts of formaldehyde in, for example, commercial acetic acid and acetic anhydride.

Stereochemistry of electrophilic and nucleophilic substitutions at phosphorus

2019 ◽  
Vol 91 (1) ◽  
pp. 43-57 ◽  
Author(s):  
Oleg I. Kolodiazhnyi
Keyword(s):  
Nucleophilic Substitution ◽  
Absolute Configuration ◽  
Electrophilic Substitution ◽  
Thermodynamic Control ◽  
Nucleophilic Substitutions ◽  
Electrophilic Substitutions ◽  
Organophosphorus Chemistry

Abstract Nucleophilic and electrophilic substitutions are the most often applied reactions in organophosphorus chemistry. They are closely interrelated, because in a reacting pair always one reagent is an electrophile, and another nucleophile. The reactions of electrophilic and nucleophilic substitutions at the phosphorus center proceed via the formation of a pentacoordinated intermediate. The mechanism of nucleophilic substitution involves the exchange of ligands in the pentacoordinate phosphorane intermediate, leading to the more stable stereomer under the thermodynamic control. Electrophilic substitution proceeds with retention of absolute configuration, whereas nucleophilic substitution with inversion of configuration at the phosphorus center.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

The Chemistry of Triazine Isomers: Structures, Reactions, Synthesis and Applications

2020 ◽  
Vol 20 ◽  
Author(s):  
Neelottama Kushwaha ◽  
C S Sharma
Keyword(s):  
Basic Property ◽  
Electrophilic Substitution ◽  
Antimicrobial Agents ◽  
Resonance Energy ◽  
Heterocyclic Ring ◽  
Ring System ◽  
Agricultural Fields ◽  
Substitution Reactions ◽  
Anti Cancer ◽  
Benzene Structure

: Triazine is the six-membered heterocyclic ring containing three nitrogen which replaces carbon-hydrogen unit in the benzene ring. Based on nitrogen position present in the ring system, it is categorized in three isomeric forms i.e.1, 2, 3-triazine (vicinal triazine), 1, 2, 4-triazine (asymmetrical triazine or isotriazine) and 1, 3, 5-triazine (symmetrical or s-triazine or cyanidine). Triazines have weakly basic property. Its isomers have much weaker resonance energy than benzene structure, so nucleophilic substitution reactions are more preferred than electrophilic substitution reactions. Triazine isomers and their derivatives are known to play important roles possessing various activities in medicinal and agricultural fields such as anti-cancer, antiviral, fungicidal, insecticidal, bactericidal, herbicidal, antimalarial and antimicrobial agents.

Organotellurium compounds: an overview of synthetic methodologies

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Muhammad Irfan ◽  
Rabia Rehman ◽  
Mohd. R. Razali ◽  
Muhammad Adnan Iqbal ◽  
◽  
...  
Keyword(s):  
Material Science ◽  
Electrophilic Substitution ◽  
Comprehensive Understanding ◽  
Substitution Reactions ◽  
Current Review ◽  
Synthetic Routes ◽  
Electrophilic Substitution Reactions ◽  
Synthetic Methodologies ◽  
Organotellurium Compounds

AbstractIn wake of emerging applications of organotellurium compounds in biological and material science avenues, the current review describes their key synthetic methodologies while focusing the synthesis of organotellurium compounds through five ligand-to-metal linkages including carbon; carbon-oxygen; carbon-nitrogen; carbon-metal; carbon-sulfur to tellurium. In all of these linkages whether tellurium links with ligands through a complicated or simple pathways, it is often governed through electrophilic substitution reactions. The present study encompasses these major synthetic routes so as to acquire comprehensive understanding of synthetic organotellurium compounds.

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