Phosphonate residues

Both type I and II mechanisms are involved in the lipidic peroxidation of erythrocytes caused by irradiation of anionic fullerene derivatives (bearing carboxylic or phosphonate residues) (Yang et al., 2007e), with a significant activity at 10pM concentration and 30 min of irradiation, or at half concentration and double exposure time. The bis-methanophosphonate fullerene is the most effective, but no structure-activity correlations were reported. 

The mechanism of action of oxime reactivation involves transfer of the substituted phosphate or phosphonate residue from the catalytic site of the... 

The highly electrophilic cationic bis(8-quinolinolato)aluminum complex 407 enabled Yamamoto and coworkers to perform Mukaiyama-Michael additions of silyl enol ethers to crotonylphosphonates 406. The procedure was not only applicable to enol silanes derived from aryl methyl and alkyl methyl ketones (a-unsubstituted silicon enolates) but also to several cycfic a-disubstituted silyl enol ethers, as illustrated for the derivatives of a-methyl tetralone and indanone 405 in Scheme 5.105. Despite the steric demand of that substitution pattern, the reaction occurred in relatively high chemical yield with varying diastereoselectivity and excellent enantiomeric excess of the major diastereomer. The phosphonate residue was replaced in the course of the workup procedure to give the methyl esters 408. The protocol was extended inter alia to the silyl enol ether of 2,6,6-tetramethylcyclohexanone. The relative and absolute configuration of the products 408 was not elucidated [200]. 

A) The preparation of [H-chloroethoxyjchloromethyl]phosphonic acid Acetaldehyde (1.1 mol) and hydroxymethylphosphonlc acid (1 mol) in 500 ml of benzene are saturated with hydrogen chloride gas at 10°C to 15°C. The mixture is aged at 25°C for 24 hr, the solvent distilled out in vacuo and the residue flushed three times with benzene to remove all traces of hydrogen chloride. The residue is taken up in benzene (500 ml), treated with tert-butyl hypochlorite (0.8 mol) and azobisisobutyronitrile (0.8 mm) at 40°C until titration shows the absence of hypochlorite and the solution is then evaporated to yield [(1-chloro-ethoxy)chloromethyll phosphonic acid in the form of an oil. 

The analysis of phosphates and phosphonates is a considerably complex task due to the great variety of possible molecular structures. Phosphorus-containing anionics are nearly always available as mixtures dependent on the kind of synthesis carried out. For analytical separation the total amount of phosphorus in the molecule has to be ascertained. Thus, the organic and inorganic phosphorus is transformed to orthophosphoric acid by oxidation. The fusion of the substance is performed by the addition of 2 ml of concentrated sulfuric acid to — 100 mg of the substance. The black residue is then oxidized by a mixture of nitric acid and perchloric acid. The resulting orthophosphate can be determined at 8000 K by atom emission spectroscopy. The thermally excited phosphorus atoms emit a characteristic line at a wavelength of 178.23 nm. The extensity of the radiation is used for quantitative determination of the phosphorus content. 

Compounds with a phosphonate group linked by a P-C bond to a carbohydrate residue may be named as glycos-n-ylphosphonates (cf. 2-Carb-31.2) or as C-sub-stituted carbohydrates (cf. amino sugars, 2-Carb-14). 

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]. 

Other interesting examples of proteases that exhibit promiscuous behavior are proline dipeptidase from Alteromonas sp. JD6.5, whose original activity is to cleave a dipeptide bond with a prolyl residue at the carboxy terminus [121, 122] and aminopeptidase P (AMPP) from E. coli, which is a prohne-specific peptidase that catalyzes the hydrolysis of N-terminal peptide bonds containing a proline residue [123, 124]. Both enzymes exhibit phosphotriesterase activity. This means that they are capable of catalyzing the reaction that does not exist in nature. It is of particular importance, since they can hydrolyze unnatural substrates - triesters of phosphoric acid and diesters of phosphonic acids - such as organophosphorus pesticides or organophosphoms warfare agents (Scheme 5.25) [125]. 

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]. 

Another GC/MS method that was validated as a food tolerance method involved the determination of glyphosate and (aminomethyl)phosphonic acid (AMPA) in crops. In this method, glyphosate and AMPA residues are extracted from crop commodities (corn grain) with water. The extracts are then partitioned with dichloromethane,... 

Use of a free flame instead of a heating bath to distil acetyl chloride produced from acetic acid and phosphorus trichloride caused the residual phosphonic ( phosphorous ) acid to decompose violently to give spontaneously flammable phosphine... 

The use or safe disposal of the iron residues from zinc production (see Figure 7) presents a major technical problem.204 The use of chelating aminomethylene phosphonic acid extractants such as (28) and (29) to recover iron from these residues has been proposed.205 These give much higher FenI/Znn selectivity than D2EHPA but are more difficult to strip. A reductive-stripping process is proposed.187,205... 

Trimethyl phosphite (12.4 g, 0.1 mol) and p-methoxybenzyl chloride (15.6 g, 0.1 mol) were heated at reflux under a nitrogen atmosphere for 20 h. The residue was vacuum distilled (141°C/0.45 torr) to give the pure dimethyl (4-methoxybenzyl)phosphonate (12.6 g, 59%) as an oil, which exhibited spectra in accord with the proposed structure. 

The mechanism of the action of the phosphonate as a flame retardant is generally believed to be decomposition into acid fragments which contribute to char formation. These acidic species catalyze decomposition of the polyester, and give rise to species which on reaction with the phosphorus moiety cause char formation. TGA curves of the copolymers confirm that the incorporation of phosphorus into the polymer increases the char residue (Figure 4). These curves, however, show little evidence that the presence of phosphorus has any effect upon the temperature or rate of decomposition of the polyester. The curves are all fairly similar up to about 450°C. After that point, the amount of residue is proportional to the amount of phosphorus in the terpolymer. 

Method A (monoalkylation) The phosphonate (50 mmol) and the alkylating agent (55 mmol) in CH2Cl2 (200 ml) are added to TBA-Br (16.0 g, 50 mmol) and aqueous NaOH (0.5 M, 100 ml) and the mixture is stirred for 1 h at 45 °C. On completion of the reaction, the organic phase is separated and evaporated. The residue is triturated with Et20 (100 ml) and the dried (MgS04) extract is evaporated to give the monoalkylated product. 

The inhibition of HFC by a series of phosphinate and phosphonate substrate analogues is summarized in Table 8.9. Since phosphinate inhibitors require synthesis of the Pi residue, they are usually prepared as diastereo-meric pairs. If the diastereomers were separated and assigned stereochemistry, this information is included in Table 8.9. A potentially significant finding in this series is that a very large aromatic group in subsite P2 enhances... 

A number of 7V-carboxyalkyl and A-phosphonoalkyl substituted substrate analogue inhibitors have been examined [161,204-208]. These derivatives contain both the acidic carboxylate (or phosphonate) and basic amine functionalities in the vicinity of the scissile bond. Thus, they are capable both of electrostatic interaction with the active site Zn(II) and hydrogen bonding interactions with other active site residues. They are, however, only moderately potent collagenase inhibitors Table 8.18). The stereochemistry at the carbon atom to which the carboxylate moiety is bonded markedly influences the inhibitory potency of these derivatives ((197) vs. (198)). The phosphonate analogues of this class of derivatives have also been evaluated Table 8.18), but are not substantially better inhibitors than the carboxyl-ates. 

---