Phosphine disposal

The geometry of the tricarbonyl cations [Co(CO)3L2]+ has been established, from the infrared-active carbonyl stretching modes [L = PPh3 (240)] and the proton NMR [L = Tdp (158)], to be trigonal bipyramidal with the phosphines disposed trans in the axial positions. 

Additional phosphonic acid is derived from by-product streams. In the manufacture of acid chlorides from carboxyUc acids and PCl, phosphonic acid or pyrophosphonic acid is produced, frequentiy with copious quantities of yellow polymeric LOOP. Such mixtures slowly evolve phosphine, particularly on heating, and formerly were a disposal problem. However, purification of this cmde mixture affords commercial phosphonic acid. By-product acid is also derived from the precipitate of calcium salts in the manufacture of phosphinic acid. As a consequence of the treatments of the salt with sulfuric acid, carbonate is Hberated as CO2 and phosphonic acid goes into solution. 

These spectroscopic data support a square-pyramidal structure in solution with the phosphines mutually trans disposed, the chloride and the carbonyl group occupying the basal sites, and the hydride ligand located at the apex. This structure fully agrees with that found in the solid state, by X-ray diffraction analysis for the related compound OsHCl(CO)(PCy3)218, and for ab initio DFT (Becke 3LYP) methods for the model complex OsHC1(CO)(PH3)2.19... 

The structure of the styryl derivative Os ( ,)-CH=CHPh Cl(CO)(PIPr3)2 has been determined by X-ray diffraction analysis.33 In agreement with OsHCl(CO) (P Pr3)2, the coordination polyhedron around the osmium atom can be rationalized as square-pyramidal with the phosphines, mutually tram disposed, the chloride and the carbonyl group occupying the basal sites, and the alkenyl located at the... 

The results illustrate the potential of bidentate ligands which differentiate the two trams disposed coordination sites, since independent variation of the electronic and steric influences of either phosphine unit clearly has a profound effect on both the activity and enantioselectivity of the hydrogenation process, as Achiwa had predicted. 

The carbonyls are disposed trans to each other, which is deduced from the single carbonyl in the infrared spectrum. A similar cation may be formed by mild oxidation of the chromium dicarbonyl phosphine, Cr(CO)2QP [QP = tris(o-diphcnylphosphinophenyl)phosphine]. 

TRUEX [TRansUranium Extraction] A process for removing transuranic elements and lanthanide fission products during the processing of nuclear fuel by solvent extraction. The solvent is a complex phosphine oxide mixed with tributyl phosphate and diluted with n-dodecane. By removing the transuranic elements, the alpha activity of the waste is greatly reduced and the residue is easier to dispose of. Developed by E.P. Horwitz at the Argonne National Laboratory, Chicago, IL. See also SREX, UREX+. 

A flask (the size of the flask depends on the method of purification chosen) is attached to the bottom of the closed filtering flask, and the organic solution is drawn into it under vacuum, removing the solvent and leaving the liquid phosphine (since the solvent may smell of phosphine, it should be trapped at — 78° and disposed of safely at a later time). 

Several mixed anhydride methods have, therefore, been developed. The acid is coupled to a second acid moiety that is considered to be disposable. This strategy relies fully on the regioselectivity of the aminolysis where the reactive center a is more reactive than b (see Fig. 6). The concept of mixed anhydrides has been extended to carbonic, boric, iso-ureas, phosphoric, and phosphinic acid-derived species. Iso-ureas and phosphorous-containing reagents will be discussed in separate articles. 

Very limited ecotoxicological data are available on the effects of phosphine, while no data were found for the effects of aluminum phosphide on wildlife. One study reported that turkeys and chickens exposed to phosphine gas at concentrations of 211 and 224mgm for 74 and 59min, respectively, exhibited dyspnea, organ swelling, convulsions, and death. These types of effects are unlikely in the unconfined atmospheric conditions that most birds and wildlife are exposed to in nature. However, if misapplied or disposed of incorrectly, phosphine gas liberated from the decomposition of aluminum phosphide could represent a significant hazard to nontarget wildlife exposed to the gas in burrows or other confined spaces. 

Treatment of washing residues with sodium hypochlorite solution before disposal prevents the spread of unpleasant phosphine-like smells. 

The residual material in the reaction vessel should be disposed of carefully. After allowing the mixture to stand at room temperature for 6-8 hours, the last traces of high-volatility materials are pumped from the reaction vessel. The flask can be removed from the vacuum line and cooled to — 196° and the adapter removed. This step should be performed in a good hood. After 20 ml. of isopropyl alcohol is added to the frozen reaction materials, and as they warm to room temperature, deactivation takes place. After 1-2 hours the deactivated mixture can be flushed down the hood sink. Caution. Since H2 and small amounts of PH3 will be evolved during this step, care should be taken to keep the reaction vessel in a good hood. Phosphine is highly toxic. 

The chemical behaviour of 133 is a result of two factors the high basicity of the metallic center, as a consequence of the presence of the strong donor phosphine and the chloride ligands in the complex, and the large steric hindrance experienced by the triisopropylphosphine groups, which are mutually cis disposed. This mixture allows access to reactive points on the osmium center by activation of Os-P and Os-Cl bonds. 

In 3.22, one of the Zr d orbitals is unavailable for bonding due to the ancillary tridentate ligand, which positions the amine donor and the chloride to overlap effectively with that d orbital. This explanation is supported by MO calculations. X-Ray structures of related binuclear dinitrogen-Ti end-on complexes, e.g., 3.23 (Beydoun et al., 1992) support the conclusions of Fryzuk and coworkers. Compound 3.23 has (Z)-disposed neutral amine donors instead of ( )-disposed phosphine ligands in 3.22. Three other edge-on bi- and tetranuclear dinitrogen complexes are known (see Fryzuk et al., 1993, structures III-V). 

Calculations on [Fe(C5H5)(CO)2(CH2)] (30) (only isolated for substituted carbenes) show that there are suitable metal -orbitals perpendicularly disposed and although the orientation shown is favoured the calculated rotational barrier is only 6.2 kcal mol but this has not been determined experimentally. The car bene complexes [Fe(C5H5)(CO)L(RNHCNHMe)]+ (L=MeNC or tertiary phosphines) undergo intramolecular isomerization but this involves rotation about C—N rather than Fe—C bonds, and the rotational barriers (16.7—17.9 kcal mol ) are essentially independent of L and R. ... 

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