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Insects Dec 2020In this study, we evaluated nitrogen treatment on phosphine-resistant field and -susceptible laboratory populations of different stored product beetles. Nine trials were...
In this study, we evaluated nitrogen treatment on phosphine-resistant field and -susceptible laboratory populations of different stored product beetles. Nine trials were conducted in commercial nitrogen chambers with the O level set at 1.0%. Two different temperatures-i.e., 28 and 40 °C-and three exposure intervals-i.e., 2.5, 3 and 9 d-were used in our tests. Adults of the sawtoothed grain beetle, (L.) (Coleoptera: Silvanidae); the red flour beetle, (Herbst) (Coleoptera: Tenebrionidae); and the rice weevil, (L.) (Coleoptera: Curculionidae) were used in the trials. The insects were placed in vials with different commodities per species and population, and their mortality was measured after the termination of each trial. Then, the vials were kept in incubator chambers at 25 °C and 65% relative humidity for 65 d to measure progeny production. Complete parental mortality was observed in all cases for and , but there was some survival for at 28 °C and 3 d of exposure. In general, progeny production was completely (100%) suppressed, with some exceptions for all species and populations. The results indicate that low oxygen is effective for all species tested, regardless of their resistance status to phosphine, and can be further adopted as an alternative method to mitigate resistance in stored product beetles.
PubMed: 33333765
DOI: 10.3390/insects11120885 -
IUCrData Aug 2022The title Ag complex, [Ag(NO)(CHP)], reveals a distorted pseudo-trigonal-planar shape around the Ag atom geometry resulting from the coordination of two phosphine...
The title Ag complex, [Ag(NO)(CHP)], reveals a distorted pseudo-trigonal-planar shape around the Ag atom geometry resulting from the coordination of two phosphine ligands, as well as a nitrito-,' ligand coordinating to the silver(I) atom through the oxygen atoms; in this description, the two oxygen atoms are assumed to occupy one position, forming an acute O-Ag-O angle of 51.44 (9)°. The plane resulting from the NO coordination to Ag is nearly perpendicular to the plane from the coordination of the phosphine-P atoms to Ag [dihedral angle = 86.43 (9)°].
PubMed: 36340974
DOI: 10.1107/S2414314622007714 -
Communications Chemistry Jun 2023The access to P-stereogenic motifs has always been considered a very challenging and high attractive mission in modern organic synthesis. While several chiral...
The access to P-stereogenic motifs has always been considered a very challenging and high attractive mission in modern organic synthesis. While several chiral auxiliaries employed by the practical Jugé-Stephan-like methodology have been developed, new type of readily accessible bifunctional ligands toward P-stereogenic building still remain much desirable. Herein, we present a powerful chiral template, camphor-derived 2,3-diols named CAMDOL, which were designed and synthesized from the commercially cheap camphorquinone in high yields at 50 grams scale with a column-free purification. Diverse P(III)-chiral compounds and their borane forms including phosphinous acids, phosphinites, and phosphines, as well as the corresponding P(V)-chiral compounds including phosphinates, phosphine oxides, phosphinothioates, phosphine sulfides, and secondary phosphine oxides were afforded in high yields and ee values through the optimal 2,3-diphenyl CAMDOL platform. An unusual C-OP bond cleavage following the first P-OC bond breaking was observed during the ring-opening process when quenching by NHCl solution, which generates a unique but valuable camphor-epoxide scaffold as by-product.
PubMed: 37369718
DOI: 10.1038/s42004-023-00935-0 -
Advanced Synthesis & Catalysis Feb 2021Transition metal-catalyzed reactions in aqueous media are experiencing a constant increase in interest. In homogenous catalysis the use of water as a solvent offers... (Review)
Review
Transition metal-catalyzed reactions in aqueous media are experiencing a constant increase in interest. In homogenous catalysis the use of water as a solvent offers advantages in cost, safety, the possibility of two-phase catalysis and simplified separation strategies. In the life sciences, transition metal catalysis in aqueous systems enables the ligation or modification of biopolymers in buffer systems or even in their cellular environment. In biocatalysis, aqueous systems allow the simultaneous use of enzymes and transition metal catalysts in cascade reactions. The use of water-soluble phosphine ligands still represents the most reliable and popular strategy for transferring metal catalysts into the aqueous phase. This review summarizes the recent advancements in this field since 2009 and describes current synthetic strategies for the preparation of hydrophilic phosphines and phosphites. In addition, recent applications of transition metal catalysis in aqueous solvents using these hydrophilic ligands are presented.
PubMed: 33679278
DOI: 10.1002/adsc.202001278 -
ACS Omega Jun 2021The synthesis and purification of water-soluble porphyrin-type compounds for photodynamic therapy and other medical applications is often a tedious exercise. Here, we...
The synthesis and purification of water-soluble porphyrin-type compounds for photodynamic therapy and other medical applications is often a tedious exercise. Here, we have investigated the simple stratagem of adding a water-soluble axial ligand to the standard protocol for iridium insertion into simple -triarylcorroles. Early results showed that six-coordinate Ir[TXPC](dna) derivatives, in which TXPC = tris(-X-phenyl)corrole (X = CF, CN, H, and OMe) and dna = dinicotinic acid, are highly water-soluble. In the end, however, all axially nitrogen-ligated complexes proved unstable with respect to chromatographic purification and storage. Five-coordinate water-soluble phosphine adducts, fortunately, proved a great improvement. From the point of view of ease of purification and storage, the best products proved to be Ir[TXPC](L), where X = CF and OMe and L = tris(2-carboxyethyl)phosphine (tcep) and trisodium tris(3-sulfonatophenyl)phosphine (tppts); carefully optimized synthetic protocols are presented for these four compounds.
PubMed: 34235340
DOI: 10.1021/acsomega.1c02399 -
Beilstein Journal of Organic Chemistry 2021Electron-rich triarylphosphines, namely 4-(methoxyphenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP), outperform commonly used...
Electron-rich triarylphosphines, namely 4-(methoxyphenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP), outperform commonly used triphenylphosphine (TPP) in catalyzing oxa-Michael additions. A matrix consisting of three differently strong Michael acceptors and four alcohols of varying acidity was used to assess the activity of the three catalysts. All test reactions were performed with 1 mol % catalyst loading, under solvent-free conditions and at room temperature. The results reveal a decisive superiority of TMTPP for converting poor and intermediate Michael acceptors such as acrylamide and acrylonitrile and for converting less acidic alcohols like isopropanol. With stronger Michael acceptors and more acidic alcohols, the impact of the more electron-rich catalysts is less pronounced. The experimental activity trend was rationalized by calculating the Michael acceptor affinities of all phosphine-Michael acceptor combinations. Besides this parameter, the acidity of the alcohol has a strong impact on the reaction speed. The oxidation stability of the phosphines was also evaluated and the most electron-rich TMTPP was found to be only slightly more sensitive to oxidation than TPP. Finally, the catalysts were employed in the oxa-Michael polymerization of 2-hydroxyethyl acrylate. With TMTPP polymers characterized by number average molar masses of about 1200 g/mol at room temperature are accessible. Polymerizations carried out at 80 °C resulted in macromolecules containing a considerable share of Rauhut-Currier-type repeat units and consequently lower molar masses were obtained.
PubMed: 34367347
DOI: 10.3762/bjoc.17.117 -
Polymers Nov 2022The development of new organophosphorus flame retardants for polymeric materials is spurred by relatively low toxicity, effectiveness, and demand for replacement of more...
The development of new organophosphorus flame retardants for polymeric materials is spurred by relatively low toxicity, effectiveness, and demand for replacement of more traditional materials. To function, these compounds must decompose in a degrading polymer matrix to form species which promote modification of the solid phase or generate active radical moieties that escape to the gas phase and interrupt combustion propagating reactions. An understanding of the decomposition process for these compounds may provide insight into the nature of flame retardant action which they may offer and suggest parameters for the synthesis of effective new organophosphorus flame retardants. The thermal degradation of a series of organophosphorus esters varying in the level of oxygenation at phosphorus-alkyl phosphate, aryl phosphate, phosphonate, phosphinate-has been examined. Initial degradation in all cases corresponds to elimination of a phosphorus acid. However, the facility with which this occurs is strongly dependent on the level of oxygenation at phosphorus. For alkyl phosphates elimination occurs rapidly at relatively low temperature. The same process occurs at somewhat higher temperature for aryl phosphates. Elimination of a phosphorus acid from phosphonate or phosphinate occurs more slowly and at much higher temperature. Further, the acids formed from elimination rapidly degrade further to evolve volatile species.
PubMed: 36433056
DOI: 10.3390/polym14224929 -
Dose-response : a Publication of... 2022The primary purpose of the current study was to study the possible pernicious effects of phosphine gas on enzyme activity alterations in to determine its harmfulness to...
The primary purpose of the current study was to study the possible pernicious effects of phosphine gas on enzyme activity alterations in to determine its harmfulness to human beings after its prolonged exposure and intake. The saline extract of the adult Khapra beetle was biochemically analyzed at different doses, that is, from 10ppm to 30ppm, to accurately evaluate the effects of various phosphine concentrations (LC and LC) on 2 distinct strains of this insect pest gathered from different godowns of Pakistan as resistant (Chitral [Chi], Haroon Abad [Hbd], and Lahore [Lhr]) and susceptible (Faqeer wali [Fqw], Khanewal [Khw], and Rawalpindi [Rwp]) populations. Our experimental results suggest that the enzyme levels (AcP, AkP, ALAT, ASAT, LDH, and ICDH) seemed to be elevated with increasing dosage of phosphine from 10ppm to 30ppm in the resistant populace of the susceptible ones. It also illustrates that phosphine and its residues can inhibit the workability of certain enzymes that are vital for respiration and neuro reactions in hexapods and mammals. It has detrimental effects of phosphine on human health profile to consume stored food products containing such tenacious enemies.
PubMed: 35651889
DOI: 10.1177/15593258221095327 -
IUCrData Aug 2022The structure of the title complex, [Ag(NO)(CHP)] , reveals a chain emanating from the coordination of one phosphine ligand to each silver(I) cation, as well as the...
The structure of the title complex, [Ag(NO)(CHP)] , reveals a chain emanating from the coordination of one phosphine ligand to each silver(I) cation, as well as the bis-monodentate coordination of a bridging nitrato ligand (per Ag atom) and the bis-bidentate coordination of another bridging nitrato ligand (per Ag atom). The distorted four-coordinate Ag atoms are characterized by bonding angles that notably deviate from the ideal tetra-hedral shape.
PubMed: 36340977
DOI: 10.1107/S2414314622007726 -
Communications Chemistry Apr 2023Secondary phosphines are important building blocks in organic chemistry as their reactive P-H bond enables construction of more elaborate molecules. In particular, they...
Secondary phosphines are important building blocks in organic chemistry as their reactive P-H bond enables construction of more elaborate molecules. In particular, they can be used to construct tertiary phosphines that have widespread applications as organocatalysts, and as ligands in metal-complex catalysis. We report here a practical synthesis of the bulky secondary phosphine synthon 2,2,6,6-tetramethylphosphinane (TMPhos). Its nitrogen analogue tetramethylpiperidine, known for over a century, is used as a base in organic chemistry. We obtained TMPhos on a multigram scale from an inexpensive air-stable precursor, ammonium hypophosphite. TMPhos is also a close structural relative of di-tert-butylphosphine, a key component of many important catalysts. Herein we also describe the synthesis of key derivatives of TMPhos, with potential applications ranging from CO conversion to cross-coupling and beyond. The availability of a new core phosphine building block opens up a diverse array of opportunities in catalysis.
PubMed: 37120598
DOI: 10.1038/s42004-023-00876-8