Aluminum bound

Polypropylene polymerized with triethyl aluminum and titanium trichloride has been found to contain various kinds of chain ends. Both terminal vinylidene unsaturation and aluminum-bound chain ends have been identified. Propose two termination reactions which can account for these observations. Do the termination reactions allow any discrimination between the monometallic and bimetallic propagation mechanisms ... 

The results obtained are plotted in Table III. In the same table, for purposes of comparison, are recorded the amounts of ethyl groups derived from the Al(C2H6)a, as found in certain fractions of the polymer by the radiochemical methods. The amount of aluminum bound in the polymer is higher in the test performed with higher triethylaluminum concentrations. A comparison with the tests performed with the same alkylaluminum concentrations, but with different amount of a-TiCU, shows, on the contrary, that the amount of aluminum bound to the polymer decreases remarkably... 

Aluminum can form complexes with many molecules in the body (organic acids, amino acids, nucleotides, phosphates, carbohydrates, macromolecules). Free aluminum ions (e.g., A1(H20)63+) occur in very low concentrations. The toxicokinetics of aluminum can vary, depending on the nature of these complexes. For example, aluminum bound in a low-molecular-weight complex could be filtered at the renal glomeruli and excreted, while aluminum in a high-molecular-weight complex would not. 

Shuman, M.S. (1992) Dissociation pathways and species distribution of aluminum bound to an aquatic fulvic acid. Environ. Sci. Technol, 26, 593-598. 

Sanz-Medel and coworkers [84] developed a system to avoid aluminum contamination in a chromatographic system, used for studying aluminum bound to serum proteins, by introducing an on-line Al-chelating scavenger pre-column. 

Silicic acid is readily absorbed, and plasma levels rise rapidly following intake. In normal subjects excretion is rapid, average plasma levels are 5-10 pM, and all cells and tissues contain silicon, which may be concentrated in some cells or cellular compartments, for example, in the osteoblast. Little is known of the interactions between this silicic acid and internalized aluminum. With aluminum bound strongly to transferrin and the low plasma silicic acid levels, interaction is unlikely except at sites of local concentration. Codeposited aluminum and silicon (as amorphous aluminosilicate) has, so far as is known, been reported only at the core of senile plaques. Separate groups of workers report silicon in artery walls (44) and aluminum (45) in artery walls, but no studies have been made of the association and balance of the two elements in tissue. Such studies will be required if progress is to be made. Some workers have reported an... 

DeBonl and Crapper (3) have demonstrated that aluminum accumulates In the chromatin of cells. Fluorescent microscopy of cells In mitosis, stained with aluminum-staining morln dye, shows aluminum bound to chromatin. It Is therefore of some potential relevance to Alzheimer s disease to Investigate the Interaction of aluminum and SNA. 

Mujika JI, Ugalde JM, Lopez X (2012) Aluminum speciation in biological environments. The deprotonation of free and aluminum bound citrate in aqueous solution. Phys Chem Chem Phys 14 12465-12475... 

Thus, it has been reported that aluminated triazoles can be prepared from the corresponding aUcynides by a copper-catalyzed condensation. The aluminum bound can be further functionalized, leading to 1,4,5-trisubstituted triazoles [150]. No reaction occurs in the absence of copper, and the regioselectivity of the reaction clearly rules out a tandem addition-cyclometalation process (Scheme 61). 

Aluminum binds to proteins, nucleotides, and phospholipids aluminum-bound transferrin apparently is a transport molecule... 

We first searched for a nitrate-aluminum bound acetyl nitrate structure as proposed by Prins and coworkers. Prins and coworkers have used chemical anisotropy broadening arguments in their N NMR results to claim that the NO2 moiety is bound to the aluminum site. " We, however, were unsuccessful in finding such a species with our All-03 acid site model. As mentioned previously, A1 sites 1 and 2 are not as flexible as A1 sites 3-9. Thus, stable nitrate coordination with All would not be expected. More of an interaction between the nitrate moiety of the acetyl nitrate and A1 sites 3-9 may be possible because these sites participate in octahedral coordination because of their flexibility, which we are currently pursuing." Prins and coworkers have noted that ZSM-5 also exhibits similar broadening, but octahedral aluminum coordination occurs negligibly in ZSM-5. Thus, there appears to be more than one way to explain the broadening they observed. We show that chemical... 

The IR spectra of all the carboxylate-alumoxanes contain bands at 1596 - 1586 and 1473 -1466 cm l (Table 1), consistent with a bridging mode of coordination (TV). The carboxylate-alumoxanes previously reported have carboxylate bands at 1580 and 1470 cm"l suggesting a similarity in die structures. Some samples with the highest carboxylate content contain additional bands at 1680 - 1640 and 1610 - 1570 cm l, indicative of unidentate coordination of a carboxylic acid group to aluminum (V) (79). In addition, all the IR spectra show a broad absorption bands between 3700 and 3400 cm consistent with our previous assignment for an aluminum-bound hydroxide group (10a). 

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