Phosphonic applications

More recently, alternative chemistries have been employed to coat oxide surfaces with SAMs. These have included carboxylic 1129, 1301, hydroxamic 11311, phosphonic 1124, 1321 and phosphoric acids 11331. Potential applications of SAMs on oxide surfaces range from protective coatings and adhesive layers to biosensors. 

The Darzens condensation reaction has been used with a wide variety of enolate equivalents that have been covered elsewhere. A recent application of this important reaction was appljed toward the asymmetric synthesis of aziridine phosphonates by Davis and coworkers.In this application, a THF solution of sulfinimine 34 (0.37 mmol, >98% ee) and iodophosphonate 35 (0.74 mmol) was treated with LiHMDS (0.74 mmol) at -78 °C to give aziridine 36 in 75% yield. Treatment of 36 with MeMgBr removed the sulfinyl group to provide aziridine 37 in 72% yield. 

Important and widely used variants of the Wittig reaction are based on carbanionic organophosphorus reagents, and are known as the Wadsworth-Emmons reaction, Wittig-Horner reaction or Horner-Wadsworth-Emmons reaction. As first reported by Horner, carbanionic phosphine oxides can be used today carbanions from alkyl phosphonates 13 are most often used. The latter are easily prepared by application of the Arbuzov reaction. The reactive carbanionic species—e.g. 14 —is generated by treatment of the appropriate phosphonate with base, e.g. with sodium hydride ... 

Despite several attractive features in this method of direct halogen introduction and the obvious applications in the synthesis of deoxy sugars, its uses have not been further exploited by other groups of workers. Some new related methods have become available which reportedly eliminate the difficulties previously encountered such as rearrangement, unreactivity due to steric hindrance, and phosphonate ester formation. The reaction is based on the observation (28) that triethylphosphine reacts with ethanol and carbon tetrachloride to give ethyl chloride, chloroform, and triethylphosphite. In a new adaptation (76, 77) of this... 

The chemistry of aziridine-2-carboxylates and phosphonates has been discussed in part in several reviews covering the literature through 1999 [1-3], This chapter is intended to give an overview of asymmetric syntheses using chiral nonracemic aziridine-2-carboxylates and -phosphonates with particular emphasis on their applications as chiral building blocks in asymmetric synthesis since 2000. Some overlap with earlier reviews is necessary for the sake of continuity. 

Phosphonates are organic phosphates characterized by a C-P-O bond, which is much more resistant to hydrolysis than the polyphosphate bond (O-P-O) or the phosphate ester bond (C-O-P), making them suitable for many types of BW treatment formulation. Phosphonates were originally developed for the industrial and institutional (I I) cleaning market in the 1960s, but are commonly employed in a myriad of applications. 

However, some of the most widely used phosphonates tend to be poor calcium sulfate inhibitors, and they may adversely affect the corrosion of copper in the boiler, so care in formulation design and product application is very important. 

Maleate chemistry has proved to be an enduring mainstay of many water treatment formulations, primarily as non-phosphate-containing calcium carbonate scale inhibitors. For most water treatment applications, polymaleic acid and its derivatives offer a good alternative to phosphonate chemistries, when required. 

Various phospono- and phosphinopolycarboxylic acids (PCAs) are available in the market. These polymers are similar to phosphonates and some actually are phosphonates. They tend to exhibit varying degrees of both deposit control and corrosion control properties. For BW applications, the acrylic acid/organic phosphate polymer (PCA type 16) is the only important phosphinopolycarboxylic and has a C-P-C bond (phosphonates have a C-P-O bond). 

Practical application also requires knowledge of the weight-to-weight ratio because the amount of phosphonate needed for a special task is of economic interest. A commonly used method is the Hampshire test [307]. One to two grams of the product is solved in 100 ml of distilled water and then 10 ml of a sodium carbonate solution (2%) is added. This solution is titrated by 0.25 M solution of calcium acetate at pH 12 until permanent turbidity occurs [308], The best means for testing of commercial sequestrants is often to choose conditions of practical relevance because in practical applications a great many parameters have to be taken into account [309]. 

A nice application of this reaction for the synthesis of cyclic a-sulfanylphos-phonates 63 has been reported [42]. It involves a Rh(II)-catalyzed [2,3]-sigmatropic rearrangement and a ring-closing metathesis of the resulting a-(S-allyl) y,d-unsaturated phosphonates 62 (Scheme 16). However, the last step occurs with a low yield (19%) when R = H. 

The photo-Arbuzov rearrangement of allyl-, benzyl- and naphtylmethyl-phosphites (Scheme 13), first developed by Bentrude et al. [20], found applications in the preparation of phosphonates (70-90%) [38]. Arylphosphonates have been shown to act as protein tyrosine kinase inhibitors [39] or non-hy-drolyzable analogs of phosphorylated tyrosine residues [40]. 

A kinetic study of the basic hydrolysis in a water/AOT/decane system has shown a change in the reactivity of p-nitrophenyl ethyl chloromethyl phosphonate above the percolation threshold. The applicability of the pseudophase model of micellar catalysis, below and above the percolation threshold, was also shown [285],... 

Conventional polymer and phosphonate scale inhibitors may not be appropriate for application in high-pressure and high-temperature reservoirs. Only a limited range of commercially available oil field scale inhibitor chemicals are sufficiently thermally stable at temperatures above 150° C. These chemicals are homopolymers of vinyl sulfonate and copolymers of acrylic acid... 

Small amounts of phosphonium complexone [1560] are sufficient to increase adhesion to the stratal rock. Table 18-4 illustrates an example for plugging solution with Portland cement and phosphonium complexone. Calcium chloride acts as a regulator of the setting time in the suggested composition. More precisely, phosphonium complexone stands for certain chelating phosphorous compounds (e.g., oxyethylidene diphosphonic acid, nitrilo-trimethyl phosphonic acid, sodium tripolyphosphate, or amiphol) [1540]. The mixture is applicable at low temperatures from 20° to 75° C. 

G. M. Graham, S. J. Dyer, and P. Shone. Potential application of amine methylene phosphonate based inhibitor species in HP/HT (high pres-sure/high temperature) environments for improved carbonate scale... 

There is a wide variety of commercially available chiral stationary phases and mobile phase additives.32 34 Preparative scale separations have been performed on the gram scale.32 Many stationary phases are based on chiral polymers such as cellulose or methacrylate, proteins such as human serum albumin or acid glycoprotein, Pirkle-type phases (often based on amino acids), or cyclodextrins. A typical application of a Pirkle phase column was the use of a N-(3,5-dinitrobenzyl)-a-amino phosphonate to synthesize several functionalized chiral stationary phases to separate enantiomers of... 

Applications GC-IMS is applied only in a few laboratories. Most applications have been directed toward environmental analyses. GC-IMS is used in niche areas, such as high-speed air-quality monitoring (on board space stations) and detecting chemical warfare agents. Snyder et al. [319] have described a hyphenated field-portable hand-held GC-IMS device, which was applied to the separation of phosphate (TMP, TEP)/phosphonate (DMMP, DEMP, DIMP, DEEP) mixtures. A mixture of four phosphonate analytes can be successfully resolved with a small GC-IMS device in under 8 s. 

Kristoff J, Guilbault GG. 1983. Application of uncoated piezoelectric crystals for the detection of an organic phosphonate. Anal Chim Acta 149 337-341. 

Miscellaneous Reactions Reactions of Phosphonate Anions Selected Applications in Synthesis... 

Biodegradable polyurethanes have been proposed and studied before (9-72). The difference in our study is the inclusion of a phosphoester linkage instead of the commonly used polyester component. This seems to provide more flexibility as the side chain of the phosphate or phosphonate can be varied. For controlled drug delivery applications, drugs can be linked to this site to form a pendant delivery system. Moreover, for certain medical applications, fast degradation rate is obtainable by the introduction of these hydrolyzable phosphoester bonds. With the LDI based polyurethanes, drugs or other compounds of interest can also be coupled to the ester side chain of the lysine portion. 

Alkoxylated polysiloxanes are a relatively new class of dyebath lubricants. They have practically no substantivity for the substrate, yet combine adequate lubrication with water solubility and easy rinsability. If the silicones contain primary hydroxy groups, these can be modified by esterification, phosphation, phosphonation, sulphation, sulphonation or carboxylation. These anionic substituents confer substantivity for various substrates without losing rinsability. Anionic organic sulphates and sulphonates probably offer the best overall properties for dyebath lubricants, whilst other types can be more suitable for selected applications [464]. 

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