Metal phosphonate salts

Metal phosphonates are usually prepared by reaction of phosphonic acids with metal salts under hydrothermd conditions [5-7]. Layered structures are predominant for most metals, the organic group being oriented more or... 

Layered metal IV phosphonates are widely used, particularly zirconium phosphonates, because their synthesis is versatile and their structural arrangement may be tailored to applications. Zirconium phosphonates are usually prepared by heating an aqueous solution of a metal IV salt (e.g., ZrOCl2) with a phosphonic acid at 60-80 °C synthesis in the presence of HP permits one to increase significantly the crystallinity of the final products. 

In contrast to the conventional approach whereby various organic groups are subsequently bound to a previously prepared surface, we have been synthesizing a broad series of anchored, layered-structure solids by precipitating the pre-derived phosphonate salts with tetravalent metal ions. The two-dimensional backbone has the zirconium phosphate structure however, substituted for hydroxylic groups are the desired organics, oriented away from the basal surfaces in a bilayered fashion in the interlayer region. 

Many examples of surface-surfactant interactions which promote self-assembly are known. Apart from gold-thiol monolayers which are formed because of the creation of the strong S—Au bond, other commonly studied monolayers include alkyltrichlorosilane layers on hydroxylated surfaces (such as SiC>2)6, fatty acids on metal oxide surfaces7 8 and alkyl phosphonate salts on zirconium9. 

The increased reactivity of the monoalkyl H-phosphonate salt of the type I toward nucleophilic substitution at the second a-carbon has been explained in terms of complex formation between the phosphonate anion and the metal Ihrongh the oxygen donors [306]. 

Anti-corrosive films can be produced on copper and its alloys by immersion in certain phosphonic acid, RP0(0H>2, solutions. Copper phosphonate salts are formed which increase the solderabiUty and tarnish resistance of the surface. They are superior to copper phosphate films. Metal phosphonate films are useful in some dental products [20] (see below). 

Polyethylene oxides and polyethyleneimines are of great interest because of their ability to form a wide variety of metal and salt complexes. We have anchored polyethylene oxide oligomers (n=l-33) and polyimines (n=l-4) to zirconium phosphate type layers. The polymers are first converted to phosphates or phosphonates which in turn react with Zr(IV) solutions to form the layered derivatives. Cross-linking of the layers has also been accomplished. Preliminary structural and complexing behavior of these layered materials is presented. It is demonstrated that the NaSCN-polyethyleneoxide... 

Phosphonate salte of tetravalent, trivalent, and divalent metal ions contain strong ionic-covalent bonds within the metal-oxygen sheets that determine the details of their lamellar structures. Tbe divalent metal (Zn2+ and Cu2+) compounds can be made nanoporous by various techniques, and subsequent intercalation by small molecules such as ammonia, amines, and other small molecules forms the basis for size- and shiqw-selective piezoelectric sensors. Several techniques have been developed for depositing these materials as thin Hlms on quartz crystal microbalance (QCM) devices. The most successful of these, in terms of eliminating interferences and speed of device response, involves layer-by-layer growth of films through adsorption of their components from non-aqueous solutions. 

Phosphonic acid and hydrogen phosphonates are used as strong but slow-acting reducing agents. They cause precipitation of heavy metals from solutions of their salts and reduce sulfur dioxide to sulfur, and iodine to iodide in neutral or alkaline solution. 

Phosphinic Acid. Phosphinic acid (hypophosphoms acid) is a dehquescent crystalline soHd that melts at 26.5°C. It is a monobasic acid having a piC of 2.1 and the metal salts of which generally exhibit a high solubiUty. Phosphinic acid disproportionates upon heating above 133°C to generate phosphoric and phosphonic acids, hydrogen, and phosphine. 

Preparation and Properties of Organophosphines. AUphatic phosphines can be gases, volatile Hquids, or oils. Aromatic phosphines frequentiy are crystalline, although many are oils. Some physical properties are Hsted in Table 14. The most characteristic chemical properties of phosphines include their susceptabiUty to oxidation and their nucleophilicity. The most common derivatives of the phosphines include halophosphines, phosphine oxides, metal complexes of phosphines, and phosphonium salts. Phosphines are also raw materials in the preparation of derivatives, ie, derivatives of the isomers phosphinic acid, HP(OH)2, and phosphonous acid, H2P(=0)0H. 

Multilayers of Diphosphates. One way to find surface reactions that may lead to the formation of SAMs is to look for reactions that result in an insoluble salt. This is the case for phosphate monolayers, based on their highly insoluble salts with tetravalent transition metal ions. In these salts, the phosphates form layer stmctures, one OH group sticking to either side. Thus, replacing the OH with an alkyl chain to form the alkyl phosphonic acid was expected to result in a bilayer stmcture with alkyl chains extending from both sides of the metal phosphate sheet (335). When zirconium (TV) is used the distance between next neighbor alkyl chains is - 0.53 nm, which forces either chain disorder or chain tilt so that VDW attractive interactions can be reestablished. 

The synthesis of S-phosphonothiazolin-2-one 133 started with 2-bromothiazole 129. Nucleophilic displacement of the 2-bromide proceeded cleanly with hot anhydrous sodium methoxide to give 2-methoxythiazole 130. Low-temperature metalation of 130 with n-butyl lithium occurred selectively at the 5-position (76), and subsequent electrophilic trapping with diethyl chlorophosphate produced the 5-phosphonate 131. Deprotection of 131 was accomplished either stepwise with mild acid to pn uce the thiazolin-2-one intermediate 132, or directly with trimethylsilyl bromide to give the free phosphonic acid 133, which was isolated as its cyclohexylammonium salt. 

Ellis Wilson (1991, 1992) examined cement formation between a large number of metal oxides and PVPA solutions. They concluded that setting behaviour was to be explained mainly in terms of basicity and reactivity, noting that cements were formed by reactive basic or amphoteric oxides and not by inert or acidic ones (Table 8.3). Using infrared spectroscopy they found that, with one exception, cement formation was associated with salt formation the phosphonic add band at 990 cm diminished as the phosphonate band at 1060 cm" developed. The anomalous result was that the acidic boric oxide formed a cement which, however, was soluble in water. This was the result, not of an add-base readion, but of complex formation. Infrared spectroscopy showed a shift in the P=0 band from 1160 cm" to 1130 cm", indicative of an interaction of the type... 

Small amounts of pyridine bases increase the corrosion resistance of cement stone without any associated loss of strength [1016]. The use of nitrilo-trimethyl phosphonic acid and an adduct between hexamethylene tetramine and chlorinated propene or butene improves the adhesion to the metal, hardening times, mobility, and strength [ 1770]. The latter adducts are further claimed to be useful as additives in cementing oil and gas wells in salt-bearing strata [1768]. 

A dispersant that can be used in drilling fluids, spacer fluids, cement slurries, completion fluids, and mixtures of drilling fluids and cement slurries controls the rheologic properties of and enhances the filtrate control in these fluids. The dispersant consists of polymers derived from monomeric residues, including low-molecular-weight olefins that may be sulfonated or phosphonated, unsaturated dicarboxylic acids, ethylenically unsaturated anhydrides, unsaturated aliphatic monocarboxylic acids, vinyl alcohols and diols, and sulfonated or phosphonated styrene. The sulfonic acid, phosphonic acid, and carboxylic acid groups on the polymers may be present in neutralized form as alkali metal or ammonium salts [192,193]. 

Guilbault GG, Das J. 1969. Chemisorption reactions of diisopropylmethyl phosphonate with transition metal salts. Journal of Physical Chemistry 73(7) 2243-2247. 

Guilbault GG, Scheide EP. 1970. Chemisorption reactions of diisopropyl methyl phosphonate with various metal salts and the effect of complex-ion formation on the phosphorus-oxygen stretching frequency. Journal of Inorganic and Nuclear Chemistry 32(9) 2959-2962. 

Zirconium phosphonates are solid materials typically synthesized in amorphous forms under aqueous conditions by the reaction of a soluble salt of a tetravalent metal and a phosphonic acid or an organophosphoric acid ... 

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