Electrochemically induced processes in the formation of phosphorus acid derivatives. 1. Synthesis of trialkyl phosphates from white phosphorus

An electrochemical method, based on the joint action of nucleophilic and electrophilic reagents on P₄, is proposed in order to utilize white phosphorus in the formation of the esters of phosphorus acids. The action of alkoxide ions on white phosphorus in an alcohol medium in the presence of iodine generated at the anode leads to the formation of phosphate esters. A scheme in which the intermediate products are dialkyl and trialkyl phosphites and the side product is dialkyl alkylphosphonate is proposed for the process.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420028 Kazan'. V. I. Ul'yanov-Lenin Kazan State University, 420028 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1322–1328, June, 1992.     

Electrochemically induced processes of formation of phosphoric acid derivatives. 3. Electrosynthesis from white phosphorus in alcohol-water solutions

It has been established that the process of splitting of the P-P bonds of the white phosphorus molecules is initiated by cathode-generated nucleophiles (HO^–, RO^–), while functionalization of the P-H bond formed in phosphoric oligomers occurs under the action only of alcohol. The primary product after splitting of all the P-P bonds in phosphoric oligomers is dialkylphosphite (in alcohol-water media), or trialkylphosphite (in absolute alcohol), in the course of electrolysis being transformed into trialkylphosphate. Formation of esters of pyrophosphoric acid with reduced protogenic character of the medium was examined. It is proposed that under these conditions nucleophilic reagents of the type (P)_c-O^– form and participate in splitting of the P-P bonds.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of the Russian Academy of Sciences, 420083 Kazan. V. I. Ul'yanov-Lenin State University, 420008 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2033–2038, September, 1992.     

Electrochemically induced processes in the formation of phosphorus acid derivatives. 2. The role of polymerization processes in the electrosynthesis of the esters of phosphorus acids from white phosphorus

The mechanism of the electrosynthesis of phosphate esters from white phosphorus was investigated. It was shown that the reaction takes place by two paths, i.e., monomeric (with the participation of dissolved phosphorus) and polymeric (with the participation of phosphorus on the surface of an emulsion drop). It was established that in an alcohol solution of tetraethylammonium iodide the main part of the final product is formed through an intermediate polymeric compound. It was noticed that by studying the dynamics of the accumulation of the dissolved product during electrolysis it is possible to trace the mechanism of reaction of the phosphorus at the individual stages of the process.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420028 Kazan'. V. I. Ul'yanov-Lenin Kazan' State University, 420028 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1328–1333, June, 1992.     

Electrochemical synthesis of phosphorus esters from white phosphorus in the presence of copper complexes and ethanol

In the presence of white phosphorus the redox potentials of the copper ions change and the potential of the reduction wave of Cu^I/Cu⁰ shifts noticeably toward more positive values. The Cu^I—P₄ complex is characterized by a lower value of the electrochemical gap, that is, higher polarizability and reactivity compared to those of the free Cu^I cation. Phosphorus esters can be synthesized from P₄ and ethanol. The latter is in the composition of the copper(ii) complexes, which act as a catalyst-charge mediator.     

Design of ecologically safe and science intensive electrochemical processes

This review discusses the results of and prospects for studies aimed at design of new science intensive, environmentally safe technologies for the synthesis of organophosphorus compounds by halogenation of α-olefins, including modification of rapeseed oil; it also considers methods for the production of some other intermediates for chemical industry. New synthetic applications have been developed, using combined methods of classical organic chemistry and electrochemistry, for processes based on electrochemical generation of catalysts (mediators)—complexes of metals in low oxidation states, halogen complexes, etc. Selective electrochemical procedures are suggested for the synthesis of triphenylphosphine, trialkylphosphates, and nanosized transition metal phosphides from white phosphorus.     

Activation of white phosphorus in the coordination sphere of nickel complexes with σ-donor ligands

Routes of white phosphorus activation in the coordination sphere of the nickel complexes with different ligands are shown. The first route is based on the coordination of a P₄ molecule with the metal, resulting in the deformation of the P₄ tetrahedron without destruction. This case is characteristic of the NiX₂L complexes, which are reduced at higher cathodic potentials (|E_red| > 0.9 V) (X = BF₄, Br, and Cl; L is bpy in DMF, MeCN, and acetone; 2,9-dimethyl-1,10-phenanthroline (phen) and PPh₃ in DMF and acetone). To cleave the P—P bonds in the P₄ molecule, this complex should be reduced on the electrode. The second route is the oxidation of white phosphorus in the coordination sphere of the Ni^II complex. It occurs when the complex has a sufficiently high oxidizing ability and is reduced rather easily (|E_red| < 0.9 V) (X = BF₄, L is 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) in acetone; 1,1′,5,5′-bis[methylenedi(p-phenylene)]di(3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane) (n²p²) in DMF; phen and PPh₃ in MeCN). The P₄ molecule opening is observed to form a new Ni^I complex containing the (P₃) fragment, for example, [(triphos)Ni(P₃)Ni(triphos)](BF₄)₂. Dedicated to the Academician V. I. Minkin on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 919–924, April, 2005.     

Synthesis of alkyl-H-phosphinic acid alkyl esters from red phosphorus and alkyl bromides

Alkyl-H-phosphinic acid alkyl esters are synthesized in 65–71% yield via chemoselective reaction of alkyl bromides with available alkyl-H-phosphinic acids (60–65 °C, Et3N). The latter are prepared, in turn, by direct phosphorylation of alkyl bromides with red phosphorus under phase-transfer conditions.     

Facile synthesis of simple mono-alkyl phosphates from phosphoric acid and alcohols

Simple aliphatic alcohols can be selectively converted into mono-alkyl phosphate esters at the laboratory scale using the acetic anhydride-mediated activation of inorganic phosphate.     

Synthesis of azo derivatives of 4-aminosalicylic acid

For searching a better 4-aminosalicylic acid derivative with higher activity and less side effects against the inflammatory bowel disease, 4-aminosalicylic acid (4-ASA) was protected by benzyloxycarbonyl and acetyl, respectively. The resultant was hydrogenized to remove protective group of amino group, then the product was reacted with NaNO2 to give diazonium salt, which was conjugated with salicylic acid, hydroxybenzene, TV-salicyloyl glycine acid to get azo derivatives of 4-ASA. The azo derivatives were hydrolyzed under the alkaline condition to get the target products. All compounds were characterized by FT-IR, 1H NMR, 13C NMR spectra in details. New derivatives of 4-ASA were characterized. The synthetic route was reasonable and feasible.     

The influence of the sacrificial anode nature on the mechanism of electrochemical arylation and alkylation of white phosphorus

The material of the sacrificial anode has a substantial effect on the nature and yield of the target products of electrochemical phosphorylation of organic halides by white phosphorus in the presence of the nickel complexes with 2,2"-bipyridine. The use of the zinc anode results in the products with tricoordinated phosphorus, viz., triorganylphosphines, the reaction on the aluminum anode affords triorganylphosphine oxides, and the presence of Mg²⁺ ions in the reaction mixture provides the transformation of white phosphorus into cyclic phosphines (PhP)₅.     

Electrochemically promoted C-N bond formation from amines and CO2 in ionic liquid BMIm-BF4: Synthesis of carbamates

A new electrochemical procedure for the synthesis of organic carbamates from amines and carbon dioxide has been developed using selective cathodic reduction of carbon dioxide in CO2-saturated room-temperature ionic liquid BMIm-BF4 solutions containing amines 1a-j, followed by addition of EtI as an alkylating agent. The synthesis was carried out under mild (PCO2 = 1.0 atm, t = 55 degrees C) and safe conditions, and the use of volatile and toxic solvents and catalysts (according to the growing demand for ecofriendly synthetic methodologies), as well as of any supporting electrolyte (for a very easy workup of the reaction mixture), was avoided. Carbamates 2a-j were isolated in good to high yields.     

Intermediate carbene formation in the reaction of thioamides with phosphorus (III) derivatives: Quantum chemical investigation

The reactions of perfluoroalkyl thioamides with trimethyl phosphine, trimethyl phosphite, and tris(dimethylamino)phosphine have been analyzed by means of quantum chemical (DFT and MP2) calculations. The reaction seems to proceed via the nucleophilic attack of the electrophilic carbon atom by the phosphorus lone pair with the formation of cyclic or acyclic adducts. The latter releases the thiophosphate molecule forming perfluoroalkylaminocarbene as the short‐lived intermediate. The reaction of the carbene with the second molecule of trialkyl phosphite yields phosphorus ylide. The ylide undergoes a migration of fluorine from carbon to phosphorus. The reactions of perfluoroalkyl thioamides with phosphines and tris(dimethylamino)phosphine probably proceeds differently. Using alkyl thioamides or amides instead of perfluoroalkyl thioamides also makes the reaction less favorable. The only combination of perfluoroalkyl thioamides with trialkyl phosphite fulfills both the kinetic requirements (moderate activation energies and relative energies for intermediates) and the thermodynamic aspects (higher stabilities of the reaction products compared with the starting materials). © 2013 Wiley Periodicals, Inc.     

Synthesis of derivatives of 4-amino-2-trifluoromethylnicotinic acid

The method for the synthesis of ethyl 4-R-amino-2-trifluoromethylnicotinates from a diphenylboron complex of ethyl 2-acetyl-3-amino-4,4,4-trifluorobut-2-enoate was developed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2221–2223, October, 2004.     

Synthesis of phenol-class azo derivatives of 4-aminosalicylic acid

To explore the better prodrug of 4-aminosalicylic acid（4-ASA）with higher activity and less side effects against the inflammatory bowel disease.4-ASA,after a succession of synthesis process,was conjugated with various carder molecules to get seven azo derivatives of 4-ASA.All compounds were characterized by FT-IR,^1H NMR,^13C NMR spectras in detail.New derivatives of 4-ASA were definituded.