Phosphine Research Articles

Novel Cu(I) complexes of functionalized phosphines

Novel tertiary phosphines R’PR2 with additional functionalities in the substituent R have been designed and prepared according to literature procedures. The coordination behavior of the additional functionality in the organic moiety and the phosphorus atom towards different Cu(I) salts was investigated. These reactions resulted in polynuclear complexes with unexpected structures involving Cu(I) atoms with different coordination numbers in the same compound.

Recent advances in studying the mechanism of phospha-Michael addition of tertiary phosphines to electron-deficient alkenes on the basis of kinetic isotope effects

The previously proposed mechanism for phospha-Michael addition of tertiary phosphines to electron-deficient alkenes has been amended according to the secondary kinetic isotope effects provided by α-deuterated activated alkenes. The data obtained have shown that rate-determining protonation of intermediate phosphonium zwitterion proceeds not directly at its carbanionic center but first at a heteroatom of the attached electron-withdrawing group, with subsequent isomerization of the enolic/eniminic intermediate to stable keto-/cyanophosphonium product.

Synthesis of optically active tertiary phosphine oxides: A historical overview and the latest advances

AbstractThe synthetic approaches for the preparation of non‐racemic tertiary phosphine oxides with particular attention to the latest advances are discussed in this minireview.

The reaction of phosphorylation of trans-aconitic acid by tertiary phosphines

New stable carboxylate phosphabetaines were synthesized by the phosphorylation of trans-aconitic acid by tertiary phosphines. The structures of the isolated compounds were determined by NMR spectroscopy, X-ray single crystal diffraction studies and elemental analysis.

Evaluation of tolerance/resistance to phosphine of stored product beetle populations from Europe, by using different diagnostic methods: Presentation

We evaluated the susceptibility to phosphine in different populations originated from 14 European countries, by following different diagnostic protocols. In total, more than 200 populations were screened during these tests, classified to 9 beetle species: Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae), Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Sitophilus granarius (L.) (Coleoptera: Curculionidae), Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Lasioderma serricorne (F.) (Coleoprtera: Anobiidae). The different bioassay-related diagnostic protocols that were followed were based on different exposure intervals and phosphine concentrations, ranging between 90 min and 4 d, and between 30 and 3000 ppm, respectively. Our results indicated that one of the populations that had been sampled from Europe was strongly resistant to phosphine. Moreover, the different protocols provide comparable results, which means that a standardized diagnostic can be further designed and adopted. Moreover, molecular assays indicated that the mutations P49S in R. dominica and P45S in T. castaneum are common among different populations, regardless of the degree of resistance to phosphine. Our results suggest that there are reliable quick tools for the evaluation of resistance to phosphine and that insect sampling in target areas should be conducted on a regular basis.

Australia’s On-Farm Grain Storage Extension Project – a national initiative improving stored grain pest management and maintaining phosphine fumigation efficacy on-farm for the Australian grains industry.: Presentation

Phosphine’s continued use in Australia to control grain insect pests in on-farm and central storage systems is threatened through increased resistance in both frequency and strength in target insect pests. Effective fumigation combined with best practice integrated pest management is essential to the sustainability of grain biosecurity, food safety, quality assurance and market access for Australian post-harvest grain systems. The National Stored Grain Extension Program (NSGEP) is an industry funded initiative developed to facilitate best practice in grain storage management within Australia’s grains industry. The NGSEP uses a multi approach engagement strategy and a variety of adult learning principles and training techniques aimed at increasing awareness and knowledge to build capacity and support to enable farmers and industry to manage their grain storage systems and meet best practice and market requirements. These include: training workshops, field days, practical demonstrations, industry forums, multi-media and website development and building networks with grower groups, government agencies and agribusiness. Various evaluation methods have shown that awareness and adoption of best practice in on-farm grain storage management has increased. Key outcomes include increased knowledge in insect identification and skills development and practice change in the management of grain hygiene, aeration, phosphine application, silo testing and planning of storage systems. The NSGEP contributes to the positive on-going changes observed in Australia’s on-farm grain storage systems, primarily through the specialized extension network of information, support and training provided that is highly regarded and in demand. It plays an instrumental role in building capacity and maintaining phosphine fumigation efficacy in the Australian grains industry.

Utility of biotechnology based decision making tools in postharvest grain pest management: An Australian case study

A major concern for the Australian grain industry in recent years is the constant threat of resistance to the key disinfectant phosphine in a range of stored grain pests. The need to maintain the usefulness of phosphine and to contain the development of resistance are critical to international market access for Australian grain. Strong levels of resistance have already been established in major pests including the lesser grain borer, Rhyzopertha dominica (F.), the red flour beetle, Tribolium castaneum (Herbst), and most recently in the rusty grain beetle Cryptolestes ferrugineus (Stephens). As a proactive integrated resistance management strategy, new fumigation protocols are being developed in the laboratory and verified in large-scale field trials in collaboration with industry partners. To aid this development, we have deployed advanced molecular diagnostic tools to accurately determine the strength and frequency of key phosphine resistant insect pests and their movement within a typical Australian grain value chain. For example, two major bulk storage facilities based at Brookstead and Millmerran in southeast Queensland, Australia, were selected as main nodes and several farms and feed mills located in and around these two sites at a scale of 25 to 100 km radius were selected and surveyed. We determined the type, pattern, frequency as well as the distribution of resistance alleles accurately for two major pests, R. dominica and T. castaneum. Overall, this information along with the phenotypic data, provide a basis for designing key intervention strategies in managing resistance problems in the study area.

Co-fumigation with phosphine and sulfuryl fluoride: Potential for managing strongly phosphine-resistant rusty grain beetle, Cryptolestes ferrugineus (Stephens): Presentation

Populations of rusty grain beetle, Cryptolestes ferrugineus, have developed a very high level of resistance (1300×) to the fumigant phosphine (PH3) in Australia. Resistant insects triggered control failures, threatening the country’s annual grain market worth AU$8 billion. Although PH3 protocols were amended to manage this new resistance, fumigation requires lengthy exposure periods which has practical difficulties. While there is no suitable replacement for PH3, the current study explores potential approaches to enhance the efficacy of this fumigant. One possibility is co-fumigation of PH3 with another complementary fumigant, sulfuryl fluoride (SO2F2 or SF), with the dual goals: enhanced efficacy and minimise use of both fumigants. A cohort of mixed age eggs and adults of PH3-resistant C. ferrugineus was fumigated with PH3 and SF individually, as well as in combination inside desiccators at 25°C and 60%RH for 168 h. Two doses below the maximal registered rates for SF (8.9 mg L- 1, equivalent to 1500 g hm-3) and PH3 (1.0 mg L-1) were tested. Co-fumigation was performed simultaneously for 168 h. Our results revealed that, the mixture of 1.1 mg L-1 or 2.2 mg L-1 of SF and 0.5 mg L-1 of PH3 over 168 h achieved complete control against resistant C. ferrugineus eggs and adults, whereas each of the tested doses failed individually. Our study confirms that SF and PH3 enhance the efficacy of each other when used in combination, which holds great potential for managing resistant C. ferrugineus.

Colour changes in pulses fumigated with different metal phosphide formulations

Many phosphine-emitting products are used globally to control insect pests in dried vegetables, grains and pulses. However, variation in phosphide formulations is associated with colour change in many pulses. This study evaluated the effect of fumigation using Mg3P2 containing ammonium carbamate; AlP containing no ammonium carbamate and pure ammonium carbamate on colour of diferrent pulses. Different pulses showed different reactions towards fumigation with phosphine. A distinctly darker discolouration was observed in broad beans and lentils when fumigated with ammonium carbamate containing Mg3P2 and pure ammonium carbamate, whereas there were no apparent colour changes in white kidney beans, soybeans and green peas. The use of ammonium carbamate-free AlP resulted in no changes in any of the pulses. Therefore, formulation type of the phosphine product plays a major role in the visible colour change of the pulses.

Sustained effective use of phosphine in stored product protection in India: Role of UPL Limited: Presentation

Sustained effective use of phosphine in stored product protection in India: Role of UPL Limited: Presentation

Application of phosphine fumigant for controlling rice storage insect pests in foundation seeds: Poster

The development of phosphine resistance in storage insect pests is now problematic, so the increase of rate and frequency of phosphine fumigation in a storage room is needed. However, an adverse effect on seed germination, and human hazard needs to be tested. This experiment was aimed to find the most suitable methods used in combination with phosphine fumigation to reduce the risk of phosphine exposure. The treatments were (1) phosphine fumigation for 7 days and then open a plastic cloth (2) phosphine fumigation for 7 days and continue to cover a plastic cloth (3) phosphine fumigation for 7 days and spray pirimiphos methyl on sack (4) phosphine fumigation for 7 days and use a light trap (5) treat seeds with sweet flag powder before phosphine fumigation for 7 days (6) no phosphine fumigation with plastic cloth opening and (7) no phosphine fumigation with plastic cloth covering. In each treatment, seeds were sampled every month for 12 months to determine seed quality and insect populations. The results showed that seeds treated with sweet flag powder and fumed with phosphine for 7 days can significantly control storage rice insect pests in the first and the second year of experiments. The seed moisture content in each treatment changed in a similar pattern throughout 12 months storage in both years (13.4 – 13.7%). The seed germination showed similar results (more than 80% after 6 months storage), except the treatment of 7 days phosphine fumigation with plastic cloth covering which resulted in a slowly decline in germination. Seed weight losses and numbers of insect pests in the treatment with sweet flag powder were significantly less than the others.

Modeling the distribution of phosphine in cylindrical grain silos with CFD methods for precision fumigation

In the present study, the distribution of phosphine gas in a cylindrical silo was modeled and compared with available sensor data. The cylindrical silo was filled with wheat and a recirculation system was used to enhance the diffusion of phosphine throughout the grain volume. A Computational Fluid Dynamics (CFD) model was developed with OpenFoam software, which accounted for gas transport in porous media and sorption effects of phosphine into the grain. A time-dependent source was used to model the phosphine release from Aluminum Phosphide bags. Furthermore, simulation results were obtained for insect mortality as a function of their exposure to phosphine gas. The phosphine concentration measurements were available from calibrated wireless sensors provided by Centaur Analytics, placed near the silo walls at various heights. As the agreement of phosphine measured data with the simulation results was satisfying, it led to considering that the proposed CFD model (equations, boundary conditions, grain properties, recirculation system approach, etc.) was accurate. Utilizing the capabilities of fumigation modeling, the phosphine concentration could then be determined for every location inside the storage volume and at any given time, thus a prediction method for fumigation duration and success could be enabled. Additionally, as the CFD model correlates phosphine exposure with insect mortality, a methodology for planning precision fumigations can now be established.

Determination of phosphine concentration for Cryptolestes ferrugineus (S.) control in wheat in Sonora, Mexico: Poster

Determination of phosphine concentration for Cryptolestes ferrugineus (S.) control in wheat in Sonora, Mexico: Poster

Synthesis and Characterization of Poly(aryl ether ether ketone ketone) Containing Phenyl Phosphine Oxide

Synthesis and Characterization of Poly(aryl ether ether ketone ketone) Containing Phenyl Phosphine Oxide

Use of a 3D finite element model for post fumigation phosphine movement analysis: Presentation

Phosphine is a dangerous gas commonly used in fumigations throughout the world. Grain that has not fully released the phosphine it absorbed during fumigation may continue to desorb phosphine into the headspace of a storage structure. U.S. OSHA standards for handling phosphine state the acceptable limit at 0.3 ppm. If this limit is exceeded grain handling may become dangerous. It is important to understand the process of phosphine venting and desorption in order to ensure safe handling of fumigated grain in silos and during shipments. In order to achieve this, the venting and release of phosphine was studied on location in a well-sealed grain silo in Lake Grace, Western Australia, to serve as a set of data for verification of a computational model. This situation was then modeled using a 3D finite element model and compared to the real world results. Results were calculated using two fumigant desorption models based on previous literature, a reversed sorption model and an air-grain equilibrium model. Simulations reproduced accurate trends of desorption but did not accurately reproduce the quantity of fumigant, with a 55.5% error for the model based on reversed sorption equations and 86.3% error for the air-grain equilibrium based model. For both models, simulations were conducted to compare the effectiveness of existing grain venting regulations at producing grain that is within safe handling limits. These results highlight the necessity for continued desorption research and the importance of following venting guidelines.

Lessons learned for phosphine distribution and efficacy by using wireless phosphine sensors: Presentation

Lessons learned for phosphine distribution and efficacy by using wireless phosphine sensors: Presentation

Direct Phosphination of Ferrocenium Ion with Tertiary Phosphines by the Mechanism of Oxidative Nucleophilic Substitution

Ferrocenium salts [(C5H5)2Fe]X (X = BF4, PF6) (I+·) react with tertiary phosphines PR3 (PMe3, PEt3, PnBu3, PMe2Ph, and PMePh2) in dichloromethane at room temperature to form a mixture of the corresponding ferrocenylphosphonium salts [(C5H5)FeC5H4PR3]X (III), ferrocene (I), and phosphonium salts [HPR3]X. The same reaction was carried out in an electrochemical cell as the electrolysis of a solution of ferrocene and phosphine in dichloromethane at the oxidation potential of ferrocene. Possible reaction pathways for phosphination of ferrocenium ion were studied by DFT at the M06‐L/6‐311++G(d,p) theory level. The experimental and theoretical studies of this reaction suggest it to proceed according to the Scheme of oxidative nucleophilic substitution of hydrogen in I+· including the following steps: a) nucleophilic exo addition of a phosphine to the cyclopentadienyl ring of I+· to form the radical cation adduct [(η5‐C5H5)Fe·(η4‐C5H5–+PR3)]X (II+·); b) redox reaction of the initial adduct II+· with the starting ferrocenium salt I+· to result in ferrocene (C5H5)2Fe (I) and iron phosphoniocyclopentadiene dication [(η5‐C5H5)Fe+(η4‐C5H5–+PR3)](X)2 (II2+) where the Csp3–H bond is involved in the agostic interaction with the metal atom; and c) deprotonation of the Csp3–H bond in II2+ by the starting phosphine to form III. The relation between the data obtained and current concepts of C–H functionalization in transition metal arene and cyclopentadienyl complexes is discussed.

Exploration of the Direct Arylation Polymerization Method for the Practical Application of Conjugated Materials: Synthetic Scale‐Up, Solar Cell Performance, and Cost Analyses

AbstractThis study reports the scalability of direct arylation polymerization (DArP) batch reactions for the preparation of poly(3‐hexylthiophene) (P3HT) using the Herrmann–Beller catalyst combined with a tertiary phosphine in the green solvent 2‐methyltetrahydrofuran on scales ranging from 0.5 to 10 g. The physical properties of these DArP polymers are compared to those resulting from P3HT prepared via Grignard metathesis (GRIM) on a 130 g scale. Both DArP and GRIM methods are found to produce highly regioregular polymers with no evidence of β‐defects and the polymers are found to exhibit comparable device performance as donor materials in bulk heterojunction organic solar cells. Purification studies coupled with device measurements highlight the necessity to carefully address the presence of impurities in materials produced from large‐scale DArP batch reactions. Economic analyses reveal that the cost involved in the preparation of P3HT via DArP or GRIM procedures are comparable per gram of product and show that the most expensive component is unique for each method.

Technetium and Rhenium Schiff Base Compounds for Nuclear Medicine: Syntheses of Rhenium Analogues to 99mTc-Furifosmin.

Rhenium, the third-row congener of technetium, is often used to develop the macroscopic chemistry of potential 99mTc diagnostic radiopharmaceuticals. The rhenium analogues to 99mTc-furifosmin are being developed for potential radiotherapy of multidrug-resistant tumors. Complexes of the form trans-[MIII(PR3)2(N2O2-Schiff base)]+ are of interest for the potential imaging and treatment of multidrug-resistant tumors. Reaction of the tetradentate Schiff ligand 4,4'-[(1 E,1' E)-[ethane-1,2-diylbis(azanylylidene)]bis(methanylylidene)]bis(2,2,5,5-tetramethyl-2,5-dihydrofuran-3-ol) (tmf2enH2) with the M(V) starting materials ( nBu4N)[TcOCl4] and ( nBu4N)[ReOCl4] gave the monomeric products trans-[TcOCl(tmf2en)] and trans-[ReOCl(tmf2en)], respectively. Reduction of in situ formed trans-[ReOCl(tmf2en)] by various tertiary phosphines yielded disubstitued Re(III) products of the general type trans-[ReIII(PR3)2(tmf2en)]+. The rhenium(III) compounds were found to be water-soluble and stable in aqueous solution. Reversible ReIII/ReIV and ReIII/ReII redox processes were observed at about 0.8-0.9 and -0.65 to -0.8 V, respectively, for each of the rhenium(III) species. Reaction of in situ formed trans-TcOCl(tmf2en) with triethylphosphine yielded the reduced, disubstituted trans-[Tc(PEt3)2(tmf2en)]PF6. A reversible TcIII/TcII redox couple was observed for the technetium(III) species, about 200 mV less negative than their rhenium(III) analogues, in addition to an irreversible TcIII/TcIV process. All compounds were characterized using conventional spectroscopic techniques, single-crystal X-ray crystallography, and cyclic voltammetry.

Antimony-Functionalized Phosphine-Based Photopolymer Networks.

The synthesis of phosphane-ene photopolymer networks, where the networks are composed of crosslinked tertiary alkyl phosphines are reported. Taking advantage of the rich coordination chemistry of alkyl phosphines, stibino-phosphonium and stibino-bis(phosphonium) functionalized polymer networks could be generated. Small-molecule stibino-phosphonium and stibino-bis(phosphonium) compounds have been well characterized previously and were used as models for spectroscopic comparison to the macromolecular analogues by NMR and XANES spectroscopy. This work reveals that the physical and electronic properties of the materials can be tuned depending on the type of coordination environment. These materials can be used as ceramic precursors, where the Sb-functionalized polymers influence the composition of the resulting ceramic.