Organophosphorus complex

The largest number of automated extraction-chromatographic separations for actinides have used TRU-Resin, and many of these have coupled the column to ICP-MS as an on-line separation (see Table 9.3). TRU-Resin is impregnated with the neutral bifunctional organophosphorus complexant, octyl(phenyl)-A,A-diisobu-tylcarbamoylmethylphosphine oxide (CMPO) in tri-n-butyl phosphate (TBP).26 127 128 The organic stationary phase in this resin binds trivalent, tetravalent, and hexavalent actinide nitrato complexes from nitric acid solutions (see Figure 9.11). The extraction equilibria for representative species are shown in Equations 9.3-9.5, where the bar above a species indicates that it is immobilized on the resin.4... 

For several years, Streubel and coworkers have been exploring the chemistry of nitrilium phosphine ylides that contain low-valent organophosphorus fragments, such as complex (19) (Scheme 3). In their latest contributions to this area, they have investigated the reactions of complex (19) with phosphoranes and iminophosphoranes which have led to a number of new species containing ylidic moieties, such as the tricyclic complex (20), and 2H-l,2-azaphosphole complexes (21) and (22). Similarly, treatment of other low-valent organophosphorus complexes such as phosphinidine species (23) with stabilised phosphoranes produces new ylidic-aducts (24) and (25) (Scheme 4). ... 

A method is being developed to transform actinide ions in the near surface environment to less soluble, less reactive, thermodynamically stable phosphate minerals phases through application of organophosphorus complexants. These complexants decompose slowly, releasing phosphate to promote the formation of stable phosphate mineral phases, particularly with the more soluble trivalent, pentavalent, and hexavalent actinide ions. The complexant of choice, myo-inositol(hexakisphosphoric acid) or phytic acid, is a natural product widely used as a nutritional supplement. We have determined that phytic acid decomposes slowly in the absence of microbiological effects, that crystalline phosphate minerals are formed as a consequence of its decomposition, and that the formation of actinide (lanthanide) phosphates reduces the solubility of trivalent and hexavalent metal ions under environmental conditions. 

Dimethylphenylphosphine is a ligand commonly used to prepare a large range of transition metal-organophosphorus complexes. This basic phosphine is easy to handle and presents a small cone angle.1,2 It is usually prepared in 40-50% yield by reaction of a solution of methylmagnesium halide with phenylphosphonous dichloride followed by hydrolysis with an excess of saturated aqueous ammonium chloride solution.3 4 In the present preparation the yield has been greatly increased (to 85%). 

Peppard and Ferraro [ ] have applied this method to the study of the organophosphorus complexes of nitrates. They have examined the infrared spectra of the nitrate-6is-(2-ethylhexyl) phosphate complexes of M(IV) cations, and have noted the lowered symmetry in these complexes. Ferraro U ] studied the nature of nitrate in the TBP (tri-n-butyl phosphate) solvated nitrates [M (III), M (IV), and M02(II) type] and observed a greater lowering in nitrate symmetry in these complexes than is present in the hydrated nitrates themselves. The nature of the mineral acid (HNO3) extracted into HDEHP [6iV(2-ethylhexyl) phosphoric acid] and TBP was also studied by this method [ ]. 

Phosphinidenes [1] are low-valent organophosphorus compounds that have attracted attention since the early 1980s when they were first discovered [2]. They are known in two classifications, one being the six-electron singly substituted phosphorus species (A) and the other in which the phosphorus atom carries an additional ri -stabifizing group, typically, but not necessarily, a transition metal group (B). Much has been learned about the reactivities of the complexed phos-... 

The following chapter concerns another kind of low-valent organophosphorus compounds, namely phosphinidenes. Little is known about free phos-phinidenes in contrast to the corresponding transition metal complexes. Many new reagents have been generated exhibiting either electrophilic or nucleophilic properties. The reactivity of these carbene-like reagents is evaluated (K. hammer tsma). 

Organophosphate Ester Hydraulic Fluids. Very little is known about the bioavailability of organophosphorus esters. In fish, organophosphate esters appear to be more bioavailable when sediments are not present (Huckins et al. 1991), but chronomids appear to be able to bioaccumulate organophosphate esters from the sediments (Muir et al. 1983b, 1985). Because of this wide variation and the lack of any information in mammalian species, it is difficult to estimate bioavailability to humans. Development of bioavailability information in mammalian species will allow a better understanding of this complex process. Given the concerns over the toxicity of this class of hydraulic fluids, further research on this topic would be useful. 

In contrast to the reactions of the cycloamyloses with esters of carboxylic acids and organophosphorus compounds, the rate of an organic reaction may, in some cases, be modified simply by inclusion of the reactant within the cycloamylose cavity. Noncovalent catalysis may be attributed to either (1) a microsolvent effect derived from the relatively apolar properties of the microscopic cycloamylose cavity or (2) a conformational effect derived from the geometrical requirements of the inclusion process. Kinetically, noncovalent catalysis may be characterized in the same way as covalent catalysis that is, /c2 once again represents the rate of all productive processes that occur within the inclusion complex, and Kd represents the equilibrium constant for dissociation of the complex. 

Organophosphate and carbamate pesticides are potent inhibitors of the enzyme cholinesterase. The inhibition of cholinesterase activity by the pesticide leads to the formation of stable covalent intermediates such as phosphoryl-enzyme complexes, which makes the hydrolysis of the substrate very slow. Both organophosphorus and carbamate pesticides can react with AChE in the same manner because the acetylation of the serine residue at the catalytic center is analogous to phosphorylation and carbamylation. Carbamated enzyme can restore its catalytic activity more rapidly than phosphorylated enzyme [17,42], Kok and Hasirci [43] reported that the total anti-cholinesterase activity of binary pesticide mixtures was lower than the sum of the individual inhibition values. 

Metal-catalyzed alcoholysis reactions of carboxylate and organophosphorus esters, 42, 271 Metal complexes, the nucleophilicity of towards organic molecules, 23, 1 Methyl transfer reactions, 16, 87... 

The chemistry of organophosphorus compounds is rather complex. Derivatives of interest include ... 

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