Search results for "Phosphorus"
showing 10 items of 431 documents
Nuclear charge radii of the even sulphur isotopesS32,S34, andS36and ofP31using muonic atoms
1985
Energies of muonic x rays of the Lyman series of the even sulphur isotopes /sup 32/S, /sup 34/S, and /sup 36/S and of natural phosphorus have been determined with absolute precisions up to 23 parts/10/sup 6/. Equivalent Barrett charge radii R/sub k/,..cap alpha.. have been deduced. Their differences between the sulphur isotopes amount to ..delta..R/sub k/,..cap alpha..( /sup 34/S- /sup 32/ S) = 29.7(1.4) am and ..delta..R/sub k/,..cap alpha..( /sup 36/S- /sup 34/ S) = 18.7(1.5) am. Combining these results with recent elastic electron scattering data, we obtain in a model-independent way ..delta../sup 1/2/( /sup 34/S- /sup 3/ 2S) = 23.1(1.2) am and ..delta../sup 1/2/( /sup 36/S- /sup 3/ 4S) …
Reactions of benzothiete with phosphorus nucleophiles - a novel type of arbuzov rearrangement
1989
The reaction of trialkylphosphites or related P-nucleophiles with benzothiete (1) leads to zwitter ionic species, which show an Arbuzov - like rearrangement to the products 4 and 7, respectively. New heterocyclic ring systems are generated in the case of cyclic esters. The normal SN2 reaction leads to the 1:2 adducts 9, whereas in an SN1 process the 1:1 adduct 13 is formed.
ChemInform Abstract: Reactions of Benzothiete with Phosphorus Nucleophiles. A Novel Type of Arbuzov Rearrangement.
1989
The reaction of trialkylphosphites or related P-nucleophiles with benzothiete (1) leads to zwitter ionic species, which show an Arbuzov - like rearrangement to the products 4 and 7, respectively. New heterocyclic ring systems are generated in the case of cyclic esters. The normal SN2 reaction leads to the 1:2 adducts 9, whereas in an SN1 process the 1:1 adduct 13 is formed.
Carbon–Phosphorus Coupling from C^N Cyclometalated Au III Complexes
2020
Abstract With the aim of exploiting new organometallic species for cross‐coupling reactions, we report here on the AuIII‐mediated Caryl−P bond formation occurring upon reaction of C^N cyclometalated AuIII complexes with phosphines. The [Au(C^N)Cl2] complex 1 featuring the bidentate 2‐benzoylpyridine (CCON) scaffold was found to react with PTA (1,3,5‐triaza‐7‐phosphaadamantane) under mild conditions, including in water, to afford the corresponding phosphonium 5 through C−P reductive elimination. A mechanism is proposed for the title reaction based on in situ 31P{1H} NMR and HR‐ESI‐MS analyses combined with DFT calculations. The C−P coupling has been generalized to other C^N cyclometalated Au…
Isolation Of Organophosphorus Pesticides Bacteria Degraders From Agricultural Sicilian Soils.
2009
Pesticides are generally categorized according to their great or low persistence in the environment. Although new biological, chemical, and management technologies are continually being developed to provide more sustainable production alternatives, it is expected that the use of pesticides will continue to be an essential tool in the integrated pest management. Pesticides are biologically active compounds designed to interfere with metabolic processes. Organophosphorus pesticides (OP) pesticides are less persistent than Organochlorine pesticides (OC), they are not without environmental risks, so this justifies the social concern about their level in different kind of matrices like soil, wat…
Gas chromatographic evaluation of pesticide residue contents in nectarines after non-toxic washing treatments
2004
Washing with aqueous solutions of citric acid, ethanol, glycerol, hydrogen peroxide, potassium permanganate, sodium metabisulfite, sodium laurylsulfate (SLS), sodium hypochlorite, and urea is evaluated for pesticide residue reduction in nectarines and compared with simple tap water washing. Residues of pesticides commonly utilized in nectarines (chlorpyrifos, fenarimol, iprodione, malathion, methidathion, myclobutanil, parathion and pirimicarb) are extracted with ethyl acetate and anhydrous sodium sulfate, extract is concentred and analyzed by GC with nitrogen-phosphorus detection. The formation of possible toxic by-products (chlorpyrifos oxon, malaoxon, methidaoxon and paraoxon methyl) is …
Few-layer Black Phosphorous Catalyzes Radical Additions to Alkenes Faster than Low-valence Metals
2020
Abstract The substitution of catalytic metals by p‐block main elements has a tremendous impact not only in the fundamentals but also in the economic and ecological fingerprint of organic reactions. Here we show that few‐layer black phosphorous (FL‐BP), a recently discovered and now readily available 2D material, catalyzes different radical additions to alkenes with an initial turnover frequency (TOF0) up to two orders of magnitude higher than representative state‐of‐the‐art metal complex catalysts at room temperature. The corresponding electron‐rich BP intercalation compound (BPIC) KP6 shows a nearly twice TOF0 increase with respect to FL‐BP. This increase in catalytic activity respect to t…
Identification and quantification of phosphorus in cheeses - methodological investigations by solid-state 31P NMR spectroscopy
2008
International audience; NMR has been shown to be an interesting tool for investigating dairy foods, in particular cheese products, for which the method is non-destructive and well suited for investigating their compounds showing different structure and mobility during ripening. Solid-state magic angle spinning 31P NMR spectroscopy was used to characterize the structure and composition of semi-hard cheeses. Assignment including overlapping resonances from mobile/immobile phosphorylated serine residues and inorganic calcium phosphates, has been realised using different NMR techniques (spin echo, cross polarisation and single pulse excitation) and by comparison with spectra of literature. Stud…
Sistemic calciphylaxis and thrombotic microangiopathy in a kidney transplant patient: Two mixing fatal syndromes?
2012
Abstract Abnormalities in calcium and phosphorus metabolism are common and metabolic bone diseases develop often in patients with chronic renal failure (CRF). Effective clinical management includes measures to control phosphorus retention and prevent hyperphosphataemia, to maintain serum calcium concentrations within the normal range and to prevent excess parathyroid hormone (PTH) secretion by the judicious use of vitamin D sterols. Certain of these interventions, however, appear to increase the risk of soft tissue and vascular calcification in patients with End Stage Renal Disease (ESRD), so current therapeutic approaches are thus being re-evaluated in an effort to limit these risks. Patie…
Particle size based recovery of phosphorus from combined peat and wood fly ash for forest fertilization
2016
Abstract Correlations between the concentrations of P, K, and As with particle size in fly ash from power plants were examined with a viewpoint to obtain fractions suitable for forest fertilization. Fly ash samples from several CHP plants were fractionated by using four sieves and the five fractions were analyzed by ICP-OES; it was found that both P and K are concentrated in smallest size (