scholarly journals Catalytic Synthesis of the Esters of Phosphorus Acids from White Phosphorus and Aliphatic or Aromatic Alcohols

2017 ◽  
Vol 4 (1) ◽  
pp. 11 ◽  
Author(s):  
R.R. Abdreimova ◽  
F.Kh. Faizova ◽  
D.N. Akbayeva ◽  
G.S. Polimbetova ◽  
S.M. Aibasova ◽  
...  
Keyword(s):  
Metal Ion ◽  
Catalytic Efficiency ◽  
Side Reaction ◽  
White Phosphorus ◽  
Reduced Form ◽  
Radical Chain ◽  
Catalytic Systems ◽  
Variable Nature ◽  
Aromatic Alcohols ◽  
A Minor

<p>The various esters of the phosphoric and phosphorous acids have been obtained directly from white phosphorus and aliphatic (or aromatic) alcohols under aerobic atmosphere in the presence of the CuX<sub>2</sub> or FeX<sub>3</sub> (X = Cl, NO<sub>3</sub>, C<sub>3</sub>H<sub>7</sub>CO<sub>2</sub>) salts. Irrespective of the variable nature of the used alcohols and catalysts, trialkyl(aryl) phosphates and dialkyl phosphites are a major products, whereas trialkyl(aryl) phosphites and dialkyl phosphates are a minor products of the phosphorylation process. Thanks to the presence of catalysts, the possible side reaction route of the radical chain oxidation of white phosphorus by oxygen to phosphorus oxides has been precluded. A comparison between the catalytic properties of CuX<sub>2</sub> and FeX<sub>3</sub> has been done. Although both of them have been found an efficient catalysts for the syntheses, the Cu(II) salts are active at 50-65 °C, whereas the Fe(III) based catalytic systems become competitive in terms of catalytic efficiency when reaction is carried out at 70-90 °C. Aromatic alcohols are characterised by less reactivity in this catalytic reaction as compared with an aliphatic ones. The same coordinative redox mechanism of the oxidative P-O coupling of P<sub>4 </sub>to ROH in the presence of both Cu(II) and Fe(III) catalysts has been proposed. Relevant steps of the catalytic cycle including the complexation of both white phosphorus and alcohol molecules to metal ion, the reduction of catalyst by white phosphorus, and the oxidation of reduced form of catalyst by oxygen have been also considered.</p>

scholarly journals Copper (II) Catalyzed Oxidative Alkoxylation of White Phosphorus. Communication 2.

2010 ◽  
Vol 12 (3,4) ◽  
pp. 267
Author(s):  
R.R. Abdreimova ◽  
F.Kh. Faizova ◽  
A.A. Karimova
Keyword(s):  
Metal Ion ◽  
Phosphorous Acid ◽  
White Phosphorus ◽  
Reduced Form ◽  
Molar Ratio ◽  
Main Reaction ◽  
Reaction Products ◽  
Dimethyl Phosphite ◽  
Trialkyl Phosphates ◽  
Oxidative Alkoxylation

White phosphorus has been catalytically oxidized by oxygen in alcoholic solutions of copper (II) acetylacetonate, halides or carboxylates to yield dialkyl phosphites and trialkyl phosphates under mild reaction conditions. Trialkyl phosphite has been observed as unstable organophosphorus intermediate, which is being converted into the main reaction products. In the case of methanolic solutions, the derivatives of two step acidolysis of dimethyl phosphite, monomethyl phosphite and phosphorous acid, have been additionally detected among the reaction products. The influence of the copper (II) catalysts on the kinetics of accumulation and transmutation of organophosphorus products has been explored. It has been found that the Cu(II) compounds take a role of catalysts-electron-carriers from white phosphorus to oxygen. The indispensable molar ratio between catalyst and white phosphorus and the order of catalytic activity for the copper (II) compounds have been established. The major steps of the catalytic reaction including (i) the coordination of white phosphorus and alcohol to metal ion, (ii) the redox decomposition of this intermediate complex accompanied by reducing elimination of elementary copper and formation of organophosphorus product and (iii) the oxidation of the reduced form of catalyst by oxygen have been<br />also suggested.

Protonation effects on dynamic flux properties of aqueous metal complexes

2009 ◽  
Vol 74 (10) ◽  
pp. 1543-1557 ◽  
Author(s):  
Herman P. Van Leeuwen ◽  
Raewyn M. Town
Keyword(s):  
Complex Formation ◽  
Metal Ion ◽  
Good Description ◽  
Minor Component ◽  
Outer Sphere ◽  
Metal Species ◽  
Central Metal ◽  
Inner Sphere ◽  
A Minor ◽  
Protonated Ligand

The degree of (de)protonation of aqueous metal species has significant consequences for the kinetics of complex formation/dissociation. All protonated forms of both the ligand and the hydrated central metal ion contribute to the rate of complex formation to an extent weighted by the pertaining outer-sphere stabilities. Likewise, the lifetime of the uncomplexed metal is determined by all the various protonated ligand species. Therefore, the interfacial reaction layer thickness, μ, and the ensuing kinetic flux, Jkin, are more involved than in the conventional case. All inner-sphere complexes contribute to the overall rate of dissociation, as weighted by their respective rate constants for dissociation, kd. The presence of inner-sphere deprotonated H2O, or of outer-sphere protonated ligand, generally has a great impact on kd of the inner-sphere complex. Consequently, the overall flux can be dominated by a species that is a minor component of the bulk speciation. The concepts are shown to provide a good description of experimental stripping chronopotentiometric data for several protonated metal–ligand systems.

scholarly journals Metal Ion-Binding Properties of the Diphosphate Ester Analogue, Methylphosphonylphosphate, in Aqueous Solution

1999 ◽  
Vol 6 (6) ◽  
pp. 321-328 ◽  
Author(s):  
Bin Song ◽  
Jing Zhao ◽  
Fridrich Gregáň ◽  
Nadja Prónayová ◽  
S. Ali A. Sajadi ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Minor Role ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Ph Titration ◽  
Role Based ◽  
The Stability ◽  
A Minor ◽  
Complex Stabilities

The stability constants of the 1:1 complexes formed between methylphosphonylphosphate (MePP3-), CH3P(O)2--O-PO32- , and Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+,​ or Cd2+ (M2+) were determined by potentiometric pH titration in aqueous solution (25 C° ; l = 0.1 M, NaNO3 ). Monoprotonated M(H;MePP) complexes play only a minor role. Based on previously established correlations for M2+ -diphosphate monoester complex-stabilities and diphosphate monoester β-group. basicities, it is shown that the M(Mepp)- complexes for Mg2+ and the ions of the second half of the 3d series, including Zn2+ and Cd2+, are on average by about 0.15 log unit more stable than is expected based on the basicity of the terminal phosphate group in MePP3-. In contrast, Ba(Mepp)- and Sr(Mepp)- are slightly less stable, whereas the stability for Ca(Mepp)- is as expected, based on the mentioned correlation. The indicated increased stabilities are explained by an increased basicity of the phosphonyl group compared to that of a phosphoryl one. For the complexes of the alkaline earth ions, especially for Ba2+, it is suggested that outersphere complexation occurs to some extent. However, overall the M(Mepp)- complexes behave rather as expected for a diphosphate monoester ligand.

scholarly journals Can we measure catalyst efficiency in asymmetric chemical reactions? A theoretical approach

2009 ◽  
Vol 5 ◽  
Author(s):  
Shaimaa El-Fayyoumy ◽  
Matthew H Todd ◽  
Christopher J Richards
Keyword(s):  
Chemical Reactions ◽  
Small Molecule ◽  
Enantiomeric Excess ◽  
Catalytic Efficiency ◽  
Catalytic Systems ◽  
Asymmetric Catalysts ◽  
Asymmetric Catalytic ◽  
Short Period ◽  
Asymmetric Catalyst ◽  
Catalyst Efficiency

Small molecule asymmetric catalysts are often described as being “good” or “bad” but to date there has been no way of comparing catalyst efficiency quantitatively. We define a simple formula, Asymmetric Catalyst Efficiency (ACE), that allows for such a comparison. We propose that a catalyst is more efficient if fewer atoms are utilised to give a product in a required enantiomeric excess. We illustrate this concept by analysing several well-known asymmetric catalytic chemical reactions carried out in academic laboratories, and compare small molecule catalysts with enzymes. We conclude that ACE is a useful descriptor for the comparison of diverse catalytic systems. It is also noteworthy that, despite the relatively short period of investigation into small molecule catalysts, they are competitive with enzymes with regards to this measure of catalytic efficiency.

Metal ion initiated halogenation reaction of N-haloamines

1970 ◽  
Vol 48 (4) ◽  
pp. 544-545 ◽  
Author(s):  
F. Minisci ◽  
G. P. Gardini ◽  
F. Bertini
Keyword(s):  
Free Radical ◽  
Radical Cation ◽  
Chlorine Atom ◽  
Metal Ion ◽  
Chain Mechanism ◽  
Radical Chain ◽  
Radical Chain Mechanism ◽  
Halogenation Reaction ◽  
Amino Radical Cation ◽  
Methyl Heptanoate

The metal ion catalyzed chlorination of 1-chlorobutane, 1-chlorohexane, methyl-pentanoate, and methyl-heptanoate by protonated N-chloroamines proceeds by a free radical chain mechanism and the chain carrying species was shown not to be a chlorine atom, but an amino radical cation.

scholarly journals Catalytic Conversion of Carbon Dioxide through C-N Bond Formation

Molecules ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 182 ◽  
Author(s):  
Jing-Yuan Li ◽  
Qing-Wen Song ◽  
Kan Zhang ◽  
Ping Liu
Keyword(s):  
Carbon Dioxide ◽  
Catalytic Mechanism ◽  
Bond Formation ◽  
Catalytic Efficiency ◽  
Chemical Fixation ◽  
Catalytic Systems ◽  
Formation Reaction ◽  
Metal Free ◽  
The Past ◽  
Regulatory Strategies

From the viewpoint of green chemistry and sustainable development, it is of great significance to synthesize chemicals from CO2 as C1 source through C-N bond formation. During the past several decade years, many studies on C-N bond formation reaction were involved, and many efforts have been made on the theory. Nevertheless, several great challenges such as thermodynamic limitation, low catalytic efficiency and selectivity, and high pressure etc. are still suffered. Herein, recent advances are highlighted on the development of catalytic methods for chemical fixation of CO2 to various chemicals through C-N bond formation. Meanwhile, the catalytic systems (metal and metal-free catalysis), strategies and catalytic mechanism are summarized and discussed in detail. Besides, this review also covers some novel synthetic strategies to urethanes based on amines and CO2. Finally, the regulatory strategies on functionalization of CO2 for N-methylation/N-formylation of amines with phenylsilane and heterogeneous catalysis N-methylation of amines with CO2 and H2 are emphasized.

Identification of the metal center of chlorothalonil hydrolytic dehalogenase and enhancement of catalytic efficiency by directed evolution

2016 ◽  
Vol 1 (1) ◽  
pp. 30 ◽  
Author(s):  
Honghong Chen ◽  
Hui Wang ◽  
Tongtong Wang ◽  
Songren Huang ◽  
Xiaoxia Zang ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Metal Ion ◽  
Divalent Cations ◽  
Catalytic Efficiency ◽  
Fold Increase ◽  
Atomic Emission ◽  
Luria Bertani ◽  
Metal Center ◽  
Emission Spectrometry ◽  
Plasma Atomic Emission Spectrometry

Chlorothalonil hydrolytic dehalogenase (Chd) is one of two reported hydrolytic dehalogenases for halogenated aromatics, and its catalysis is independent of coenzyme A and ATP. Earlier studies have established that the catalytic activity of Chd requires zinc ions. In this study, the metal center of Chd was systematically investigated. The metal content of Chd was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES), and there were 2.14 equivalents of zinc/mol of protein, indicating that Chd contains a binuclear (Zn2+-Zn2+) center. It was found that other divalent cations, such as cobalt (Co2+) and cadmium (Cd2+), could substitute zinc (Zn2+) leading to relative activities of 91.6% and 120.0%, whereas manganese (Mn2+) and calcium (Ca2+) could substitute Zn2+ leading to relative activities of 29.1% and 57.0%, respectively. The enzymatic properties of these different metal ion-substituted Chd variants were also compared. Error-prone PCR and DNA shuffling methods were applied to directly evolve Chd to generate variants with higher catalytic efficiencies of chlorothalonil. Enhanced Chd variants were selected based on the formation of clear haloes on Luria-Bertani plates supplemented with chlorothalonil. One variant, Q146R/N168Y/S303G, exhibited a 4.43-fold increase in catalytic efficiency, showing the potential for application in the dehalogenation and detoxification of chlorothalonil contaminated-sites.

scholarly journals Copper (II) Mediated Oxidative Alkoxylation of White Phosphorus. Communication 1.

2010 ◽  
Vol 12 (3,4) ◽  
pp. 259
Author(s):  
R.R. Abdreimova ◽  
F.Kh. Faizova ◽  
A.A. Karimova
Keyword(s):  
Metal Ion ◽  
Phosphorous Acid ◽  
Inert Atmosphere ◽  
White Phosphorus ◽  
Main Reaction ◽  
Reaction Products ◽  
Dimethyl Phosphite ◽  
Trialkyl Phosphates ◽  
Oxidative Alkoxylation ◽  
Kinetics Of

White phosphorus has been oxidized by copper (II) acetylacetonate, halides or carboxylates in aliphatic alcohols to yield dialkyl phosphates and trialkyl phosphates under inert atmosphere and mild reaction conditions. Trialkyl phosphite has been observed as unstable organophosphorus intermediate, which is being converted into the main reaction products. In the case of methanolic solutions, the derivatives of two step acidolysis of dimethyl phosphite, monomethyl phosphite and phosphorous acid, have been additionally detected among the reaction products. The influence of the copper (II) oxidants on the kinetics of accumulation and transmutation of organophosphorus products has been explored. The order of oxidative ability of the copper (II) compounds has been established. The major steps of the reaction including (i) the coordination of white phosphorus and alcohol to metal ion and (ii) the redox decomposition of this intermediate complex accompanied by reducing elimination of elementary copper and formation of organophosphorus product have been also suggested.

scholarly journals Highly exposed segment of the Spf1p P5A-ATPase near transmembrane M5 detected by limited proteolysis

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245679
Author(s):  
Guido D. Petrovich ◽  
Gerardo R. Corradi ◽  
Carlos H. Pavan ◽  
Sofia Noli Truant ◽  
Hugo P. Adamo
Keyword(s):  
Atpase Activity ◽  
Metal Ion ◽  
Limited Proteolysis ◽  
Large Family ◽  
Proteinase K ◽  
Short Exposure ◽  
Transmembrane Segments ◽  
D Region ◽  
Group 5 ◽  
A Minor

The yeast Spf1p protein is a primary transporter that belongs to group 5 of the large family of P-ATPases. Loss of Spf1p function produces ER stress with alterations of metal ion and sterol homeostasis and protein folding, glycosylation and membrane insertion. The amino acid sequence of Spf1p shows the characteristic P-ATPase domains A, N, and P and the transmembrane segments M1-M10. In addition, Spf1p exhibits unique structures at its N-terminus (N-T region), including two putative additional transmembrane domains, and a large insertion connecting the P domain with transmembrane segment M5 (D region). Here we used limited proteolysis to examine the structure of Spf1p. A short exposure of Spf1p to trypsin or proteinase K resulted in the cleavage at the N and C terminal regions of the protein and abrogated the formation of the catalytic phosphoenzyme and the ATPase activity. In contrast, limited proteolysis of Spf1p with chymotrypsin generated a large N-terminal fragment containing most of the M4-M5 cytosolic loop, and a minor fragment containing the C-terminal region. If lipids were present during chymotryptic proteolysis, phosphoenzyme formation and ATPase activity were preserved. ATP slowed Spf1p proteolysis without detectable changes of the generated fragments. The analysis of the proteolytic peptides by mass spectrometry and Edman degradation indicated that the preferential chymotryptic site was localized near the cytosolic end of M5. The susceptibility to proteolysis suggests an unexpected exposure of this region of Spf1p that may be an intrinsic feature of P5A-ATPases.

Impact of an unusual disulfide transformation on detection of isothermal amplification products

2021 ◽  
Vol 99 (1) ◽  
pp. 79-86
Author(s):  
Kenneth A. Browne ◽  
Amy Chau ◽  
Janice Cline ◽  
Maria Savage
Keyword(s):  
Nucleic Acids ◽  
Diagnostic Testing ◽  
Diagnostic Techniques ◽  
Reduced Form ◽  
Screening Assay ◽  
Viral Pathogens ◽  
Yellow Colour ◽  
In Vitro Diagnostic ◽  
A Minor

Detection of infectious pathogens such as HIV-1, HPV, and SARS-CoV-2 from biospecimens is critical to healthcare. Particularly sensitive and specific diagnostic techniques to accomplish this include molecular amplification and detection tests of nucleic acids from pathogens. Such tests are comprised of reagent compositions to facilitate hybridization of primers and probes that are complementary to specifically amplified sequences of the analyte target. One of these reagents from an isothermal molecular assay occasionally changed its physical appearance over time, generating interest into the cause of the transformation and suitability of the reagent in diagnostic testing. A preliminary hypothesis was that the 2,2′-dithiodipyridine component was the pre-chromophoric compound of its distinctly yellow reduced form, 2-thiopyridine. However, under oxidizing conditions, 2-thiopyridine is a minor constituent of hybridization reagents and not a major contributor to the yellow colour. Instead, a new yellow compound was isolated from coloured hybridization reagent, identified as 1-(2′-pyridyl)-2-thiopyridone and determined to be the result of an intramolecular cyclic rearrangement and sulfur extrusion from 2,2′-dithiodipyridine under acidic and oxidizing conditions. Neither the appearance of 1-(2′-pyridyl)-2-thiopyridone, nor the concomitant depletion of 2,2′-dithiodipyridine reduced the sensitivity or specificity of in vitro diagnostic screening assay results for detecting amplified nucleic acids from viral pathogens, ensuring the safety of tested blood transfusion products.

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