Benson group additivity values of phosphines and phosphine oxides: Fast and accurate computational thermochemistry of organophosphorus species

Composite quantum chemical methods W1X-1 and CBS-QB3 are used to calculate the gas phase standard enthalpy of formation, entropy, and heat capacity of 38 phosphines and phosphine oxides for which reliable experimental thermochemical information is limited or simply nonexistent. For alkyl phosphines and phosphine oxides, the W1X-1, and CBS-QB3 results are mutually consistent and in excellent agreement with available G3X values and empirical data. In the case of aryl-substituted species, different computational methods show more variation, with G3X enthalpies being furthest from experimental values. The calculated thermochemical data are subsequently used to determine Benson group additivity contributions for 24 Benson groups and group pairs involving phosphorus, thereby allowing fast and accurate estimations of thermochemical data of many organophosphorus compounds of any complexity. Such data are indispensable, for example, in chemical process design or estimating potential hazards of new chemical compounds. © 2018 Wiley Periodicals, Inc.     

Atom-Economic Synthesis of Tris[2-(organylthio)ethyl]phosphine Oxides from Phosphine and Vinyl Sulfides

Abstract

Phosphine, generated from elemental phosphorus in the system KOH-toluene-H₂O, reacts with vinyl sulfides under free radical conditions (AIBN, dioxane, 65–70°C, atmospheric pressure) to form regiospecifically tris[2-(organylthio)ethyl]phosphines, which are readily oxidized in air to corresponding tris[2-(organylthio)ethyl]phosphine oxides.     

Catalytic oxidation of organic substrates with hydrogen peroxide in two-phase systems in the presence of peroxo-polyoxotungstates containing organic ligands

The prospects of using bifunctional homogeneous metal-complex catalysts based on peroxo-polyoxotungstates with organic ligands (tertiary phosphine oxides) were exemplified by oxidation of benzyl alcohol and cyclooctene with hydrogen peroxide in two-phase systems (organic phase — liquid phase).     

PCl3- and organometallic-free synthesis of tris(2-picolyl)phosphine oxide from elemental phosphorus and 2-(chloromethyl)pyridine hydrochloride

In the superbase KOH/H₂O/toluene/phase-transfer catalyst system, 2-picolyl chloride, generated in situ from 2-(chloromethyl)pyridine hydrochloride, reacts with elemental phosphorus at 65–95?°C for 3?h to afford tris(2-picolyl)phosphine oxide in 50% yield. Single crystal X-ray analysis of the latter revealed one polymorph form of this tertiary phosphine oxide.     

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.     

Synthesis of mono-, di-, tri-, and tetraethyl-o-carboranes by electrophilic alkylation ofo-carborane with ethyl bromide in the presence of AICl3 and their transformations

Optimal conditions for the preparation of 9-ethyl-, 9,12-diethyl, 8,9,12-triethyl-, and 8,9,10,12-tetraethyl-o-carboranes under the action of EtBr on o-carborane in the presence of AICl₃ were determined. The behavior of these o-carborane derivatives towards electrophilic and nucleophilic reagents was studied. The presence of four ethyl groups in positions 8, 9, 10, and 12 of the carborane polyhedron increases the electron density on the boron atoms in positions 4, 5, 7, and II to the point where they are able to enter into reactions of electrophilic substitution, and in positions 3 and 6 to the point that they become resistant to the action of nucleophilic reagents. Reactions of 1,2-dilithium-8,9,10,12-tetraethyl-o-carborane with various electrophilic reagents were studied.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp 2755–2763, November, 1996.     

Synthesis of a diverse set of phosphorus ligands on solid support and their screening in the Heck reaction

Representative members from five different families of supported phosphine and phosphinite ligands have been prepared from common templates—polymer-bound aminoalcohols. These include β-aminophosphines, N,β-diphosphinoamines, α,β-diphosphinoamines, β-aminophosphinites and N-phosphino-β-aminophosphinites. Representatives of each family of ligands were complexed with Pd(OAc)₂ and screened in the Heck reaction of iodo- and bromobenzene. While the reaction of iodoarenes is ligand-independent, the reaction of bromoarenes is ligand-sensitive. The rationale for this behavior is suggested. Lead ligands for the reaction of bromoarenes were determined.     

Direct synthesis of α-hydroxyketone phosphates from terminal alkynes and H-phosphine oxides in the presence of PhI(OAc)_2 and H_2O

A simple and highly efficient one-pot method for the construction of α-hydroxyketone phosphates from terminal alkynes and H-phosphine oxides has been developed in the presence of PhI(OAc)_2 and H_2O.The present protocol provides an attractive approach to α-hydroxyketone phosphates in good to high yields,with the advantages of operation simplicity,the use of commercially available materials,broad substrate scope,high atom efficiency and good tolerance to scale-up synthesis.     

Synthesis of Schiff's bases from furylacroleins and aminopyridines in the presence of molecular sieves

We have studied the reactions of (hetero)aromatic aldehydes with 2-aminopyridines. The results obtained suggest that molecular sieves play a role in these processes not only as a dehydrating agent but also as an acid catalyst. We have synthesized a series of novel heterocyclic azomethines.Dedicated to Professor M. A. Yurovskaya on her Jubilee.Latvian Institute of Organic Synthesis, Riga LV-1006 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 324–335, March, 2000.     

35Cl NQR spectra, structure, and mutual influence of substituents in the series of chlorine-containing organic compounds of pentavalent phosphorus

Regularities of transmission of the effect of equatorial and axial substituents were established for a number of chlorine-containing organic compounds of pentatalent phosphorus using³⁵Cl NQR spectra. The field constants of³⁵Cl NQR frequencies of the chlorine atoms participating in the P−Cl bond were estimated for a series of tetrahedral phosphorus ions. The³⁵Cl NQR frequencies of chlorine atoms in tetracoordinated ions of pentavalent phosphorus and in analogous isoelectronic silicon compounds are related by a linear dependence. Deceased Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 915–922, May, 1999.     

A one-pot synthesis of a branched tertiary phosphine oxide from red phosphorus and 1-(tert-butyl)-4-vinylbenzene in KOH-DMSO: an unusually facile addition of P-centered nucleophiles to a weakly electrophilic double bond

Red phosphorus reacts with 1-(tert-butyl)-4-vinylbenzene in a superbase media (KOH-DMSO, 90-100 °C, 3 h) to give tris[4-(tert-butyl)phenethyl]phosphine oxide in 77% yield. Microwave activation of the reaction affords the phosphine oxide in 82% yield in 6 min.     

Synthesis of SAPO-41 from a new reproducible route using H3PO3 as the phosphorus source and its application in hydroisomerization of n-decane

In the new reproducible route, phosphorous acid (H₃PO₃) or the mixture of H₃PO₃ and phosphoric acid (H₃PO₄) are used as the phosphorus source to synthesize microporous silicoaluminophosohates. It is found that gels containing H₃PO₃ favor the formation of SAPO-41 materials. With only H₃PO₃ as the phosphorus source, pure SAPO-41 phase can be prepared with high crystallinity. When the mixture of H₃PO₃ and H₃PO₄ is used as the phosphorus source, the crystallization of SAPO-41 can be accelerated. Raman and XRD results show that SAPO-41 can be formed after crystallizing for 12 h. The dosage of the template di-n-propylamine (DPA) can be reduced in the mixed phosphorus source system. The SAPO-41 has been used to prepare catalysts for the hydroisomerization of n-decane. High selectivity of isomerization (89.5%) has been observed even at high conversion (88%) over the Pt/SAPO-41.     

Synthesis of 1-morpholino-1-(phenylethynyl)cycloalkanes from enamines and phenylacetylene in the presence of Cu(I) halides

1-Morpholino-1-(phenylethynyl)cyclopentane and 1-morpholino-1-(phenylethynyl)cyclohexane were obtained by reactions of enamines, derivatives of cyclic ketones, with phenylacetylene in the presence of CuI. A scheme for catalysis by Cu(I) compounds with the intermediate formation of copper phenylacetylide and iminium salts was suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 169–170, January, 1994.     

One‐Pot Synthesis of Functionalized 3‐Aryl‐1‐phenyl‐1H‐pyrazoles from Hydrazonoyl Chlorides and Acetylenic Esters in the Presence of Ph3P

The zwitterionic 1 : 1 intermediates generated by addition of Ph₃P to acetylenic esters is trapped by 1‐[(aryl)chloromethylene]‐2‐phenylhydrazines (=N‐phenylarenecarbohydrazonoyl chlorides) to yield functionalized 3‐aryl‐1‐phenyl‐1H‐pyrazoles in good yields.     

Pesticides in water and the performance of the liquid-phase microextraction based techniques. A review

The control of pesticides in surface, drinking and groundwater is nowadays a real necessity. In the European Community, their concentration must comply with the established parametric and environmental quality standards (EQSs). Regarding the new legislation, this article updates the information concerning the monitoring of pesticides and the technical specifications for their measurement in water samples where ultra-sensitive analytical methods are required. For some compounds, like pesticides, there is still a need to improve the performance of the existing methods. High sensitive techniques like gas chromatography tandem mass spectrometry (GC–MS/MS) and liquid chromatography coupled with mass spectrometry (LC–MS) have been developed. However, for most of the substances present at trace and ultra-trace levels the extraction and preconcentration steps are so far essential for their detection. Advances at a micro scale have been made and different types of microextractions are being developed. Liquid-phase microextraction (LPME) is an example. The study of this technique has increased in the last years and some innovations have been recently reported for pesticides water analysis. This article reviews the new developed LPME-based techniques and compares its performance with the analytical specifications established for pesticides water monitoring. The results show that LPME-based techniques can be a promising tool to improve the nowadays performance of methods used in pesticides water control.