Bisulfate complexes

The decrease in the distribution coefficient at low acidity is ascribed to Pu(IV) polymerization. As the acid concentration is increased, the decrease in Dp j jis ascribed to the formation of an amine bisulfate complex. 

The soiution is aliowed to cool and the crystals of the P2P-bisulfite addition compound are then separated by vacuum filtration, washed with a little clean dH20 then washed with a couple hundred mLs of ether, DCM or benzene. The filter cake of MD-P2P-bisulfate is processed by scraping the crystals into a flask and then 300mL of either 20% sodium carbonate solution or 10% HCi soiution are added (HCI works best). The soiution is stirred for another 30 minutes during which time the MD-P2P-bisulfite complex will be busted up and the P2P will return to its happy oil form. The P2P is then taken up with ether, dried and removed of the solvent to give pure MD-P2P. Whaddya think of that ... 

The hydrolysis equilibria for H2Cr04 given in Table 3 are only valid in HNO or HCIO solutions. Other acids yield complexes such as those shown for chloride and bisulfate ions. The exact composition of chromate(VI) anion(s) present in aqueous solution is a function of both pH and hexavalent chromium concentration (68). However, at pH values above 8, virtually all the Cr(VI) is present as the CrO anion. When the pH is between 2 and 6, an equilibrium mixture of HCrO and Ci2 is present when the pH is below 1, the principal species is H2Cr04 (68,69). At very high Cr(VI) concentrations... 

This cycle, often referred to as the Shilov-cycle converts methane into methanol and chloromethane in homogeneous aqueous solution at mild temperatures of 100-120 °C (11). However, while Pt(II) (added to the reaction as PtCl ) serves as the catalyst, the system also requires Pt(IV) (in the form of PtCle-) as a stoichiometric oxidant. Clearly, this system impressively demonstrates functionalization of methane under mild homogeneous conditions, but is impractical due to the high cost of the stoichiometric oxidant used. A recent development by Catalytica Advanced Technology Inc., often referred to as the Catalytica system used platinum(II) complexes as catalysts to convert methane into methyl-bisulfate (12). The stoichiometric oxidant in this case is S03, dissolved in concentrated H2S04 solvent. This cycle is depicted in Scheme 3. 

The thermogram of this sample is shown in Figure 8. The ammonium nitrate peak and the first peak of ammonium sulfate match closely the positions of standard compounds. However, the peak at 270°C is noticeably shifted from the second ammonium sulfate peak, although the overall appearance of the doublet is similar to that of ammonium sulfate. A tentative explanation of this observation is that the sample does not contain pure ammonium sulfate, but rather that some of the ammonium ions are replaced by a charged organic nitrogen complex. This complex should produce the right chemical shift (relative to ammonium) in the ESCA spectrum, decompose at a lower temperature than ammonium bisulfate, and hydrolyze to ammonium in water solution. 

Differences in the speciation of other ions at the surface can be noted. Using an analysis similar to that above for metal ions, one finds that adsorbed anions are less acidic than in bulk solution. For example, it was shown in Figure 6 that protolysis of adsorbed sulfate ions becomes significant in the pH range 4-5, whereas in solution bisulfate is formed at much more acidic conditions (pH 2). Complexes formed by supporting electrolyte, e.g. Na" ,. with oxide surface sites have greater stability constants (logK 0.5-1.7) than observed for complex formation with oxyanions in solution (log K 0.0) (J.). ... 

The decrease in tetraacetate complex in the resin phase with increased acetic acid concentration is probably attributed to lowered acetate activity in the resin phase caused by hydrogen bonding of invading acetic acid to the resin acetate. A similar but more pronounced effect occurs in the uranyl sulfate system owing to conversion of resin sulfate to bisulfate (17). The only clear cut effect of a wide variance in the lithium acetate concentration seems to be a decrease of the acetic acid effect. This is probably caused by tying up of acetic acid by hydrogen... 

Reinhoudt and coworkers have shown a calix[4]arene UO2-salen complex (Figure 48) to be a selective receptor for H2PO4" in DMSO, in which other anions such as chloride, bisulfate and perchlorate showed insignificant binding [68]. 

In this technique, a polymerizable metal ion complexing agent in a hydrophobic solvent is sorbed by the polypropylene and polymerized with a free radical initiator in the membrane either with or without additional comonomers (19). Stability studies are carried out by determining the membrane s ability to transport Cu(II) from pH 4.2 sulfate/bisulfate buffer solutions over a number of weeks (20). The concept is illustrated in Figure 2. 

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