Alumino complexes

We have noted earlier that aluminium is unusual in forming alumino-phosphate complexes in phosphoric acid solution which may be of a polymeric nature. Bearing in mind the analogies between aluminium phosphate and silica structures, it may well be that during cement formation an aluminium phosphate hydrogel is formed. Its character may be analogous to that of silica gel, where a structure is built up by the... 

Initial °Th and Pa are generally considered to be associated with a detrital component that becomes cemented, or occluded, within the speleothem. This component may be composed of clays, alumino-silicates or Fe-oxyhydroxides (Fig. 3) with strongly adsorbed and Pa. Th and Pa incorporated in speleothems and similar deposits may also have been transported in colloidal phases (Short et al. 1998 Dearlove et al. 1991), attached to organic molecules (Langmuir and Herman 1980 Gaffney et al. 1992) or as carbonate complexes in solution (Dervin and Faucherre 1973a, b Joao et al. 1987). 

C. Helling, V. Imhof, L. Nielsen, and E. Jacobson Complex Alumino-Hydrides containing Nitrogen, Phosphorus and Arsenic. Inorg. Chem. 2, 504 (1963). 

Both humic acids and fulvic acids have a strong affinity for particulate and crystalline substances possessing oxygen atoms at their surfaces and they have been reported to bring about the dissolution of iron phosphate, calcium phosphate (61), uranium dioxide (65), hydrated magnesium alumino-silicates (66) and limonite, a complex mixture of hydrated ferric oxides (67). 

Fluoride is assumed to complex with aluminium in the form of alumino-fluoride ions (AIF2+ and AIF2+), and such complexes are dissociated in TISAB to liberate all of the fluoride as free F ions. This is consistent with the observation that ion release under acidic conditions tends to show proportionately greater aluminium release yet lower amounts of free fluoride [251],... 

Resin-modified glass-ionomers, like their conventional counterparts, are capable of releasing fluoride [224,264,265], and in greater amounts under acid conditions than neutral ones [265], Release rates and release profiles have been shown to be comparable with those from conventional glass-ionomer cements [264,265], Other ions have also been shown to be released by these materials and, as for fluoride, these ions show a greater release under low pH conditions [265], However, the level of phosphorus released has been shown to be much lower from resin-modified glass-ionomers than from conventional ones [263], This suggests that there is little or no possibility of association of fluoride as monofluorophosphate, but rather that almost all of the fluoride is released either as the free fluoride ion or as alumino-fluoride complex ions. 

S)-[ F]fluoroethylcarazolol 8, 111 subtypes of, 100 Adriamycine (doxorubicine), 589 Agrochemical agents, 215 AIF. See Aluminium monofluoride Aliphatic nucleophilic substitution, 28 Alkenes, as amide bond substitutes, 702-703 Alkenes fluorination, 18 Allyl hydrazines as SSAO inhibitors, 674 Aluminium monofluoride, 534 Alumino-fluoride complexes, 364 Alzheimer s disease (AD)... 

Compatibility The particles must be compatible with the polymeric substrate. Since natural clays are alumino-silicates, they must be prepared or functionalized so that they will be compatible with a polymer. For natural clay products, this process can be quite complex, given the wide chemical variability of different samples, even from the same mine. 

For a review of LiAUL, see Pizey, Ref. 593, vol. 1, 1974, pp. 101-294. For monographs on complex metal hydrides, see Seyden-Penne Reductions by the Alumino- and Borohydrides-, VCH New York. 1991 Haj6s Complex Hydrides-, Elsevier New York, 1979. 

In this communication we have reported the synthesis and characterization of different types of surface modified MCM-41 type pure-silicate and alumino-silicate materials. Simultaneous incorporation of thio- and amino-propyl groups was also achieved. There is tremendous potential in this field as these materials itself can be used as supra-molecular ligand in complexation with a metal ion. They can also be potentially used as host for different nano-cluster stabilization. 

Addition of hydride to the carbonyl carbon to form an alcohol, or the reverse, changes the oxidation state and so is usually classified separately from other carbonyl reactions. Some of these processes are nevertheless fundamentally similar to the ones we have been considering. Reductions by complex metal hydrides, such as lithium aluminum hydride or sodium borohydride, are additions ofH - (Equation 8.27) the metal hydride ion is simply a convenient source of this extremely basic species. The carbonyl oxygen takes the place of the hydride in coordination with the boron (or aluminum in the case of an alumino-... 

HF is weakly ionized (pH <3.2), and soluble alumino-fluoro complexes are formed resulting in the presence of aluminum ions in the treated water and lowering of the active sites. At near neutral pHs, the uptake of fluoride is maximum. Assuming that the pHpzc of AA is about 8-9 as reported in several literatures, then at near neutral pHs the active sites consist of = AI-OH (protonated) and = AI-OH (non-protonated) aluminol sites. The interaction between fluoride and the protonated aluminol sites leads to the formation of inner-sphere complexes and elimination of water. The reaction can be represented by... 

Two families of complex hydrides, the borohydrides and the alumino-hydrides are described in Chapter 8. 

Highly sihceous zeoHtes (with Si/Al ratios 1) are microporous framework alumino-sihcate materials. Discussion of the framework skeletal vibrahons of highly sihceous zeolites is similar to that reported above for silicas. The addition of aluminum in the framework causes shifts in the positions of the sole band. In particular, the asymmetric Si—O—Si stretching modes of framework silicates, usually observed as a complex very strong absorption in the region 1200-1000 cm" , tend to shift down a litde with A1 for Si subshtution. 

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