Aryl phosphates

Aryl Phosphates. Aryl phosphates were introduced into commercial use early in the twentieth century for flammable plastics such as cellulose nitrate and later for cellulose acetate. CeUulosics are a significant area of use but are exceeded now by plastici2ed vinyls (93—95). Principal appHcations are in wire and cable insulation, coimectors, automotive interiors, vinyl moisture barriers, plastic greenhouses (Japan), furniture upholstery, conveyer belts (especially in mining), and vinyl foams. 

In vinyls, the aryl phosphates are frequently used in combinations with phthalate plastici2ers. The proportion of the more expensive phosphate is usually chosen so as to permit the product to reflably pass the flammability specifications. In plastici2ed vinyls used in automotive interiors, these phosphates are used to pass the Federal Motor Vehicle Safety Standard 302. 

Environmental Considerations. The phosphate flame retardants, plasticizers, and functional fluids have come under intense environmental scmtiny. Results pubUshed to date on acute toxicity to aquatic algae, invertebrates, and fish indicate substantial differences between the various aryl phosphates (159—162). The EPA has summarized this data as well as the apparent need for additional testing (147). 

T. W. Lapp, The Manufacture and Use of Selected Aryl and Alkyl Aryl Phosphate Esters, Report NTIS PB-251678, Midwest Research Institute, Feb. 1976. 

Inefficiencies ia the reaction with POCl leads to alternative production of trialkyl phosphates by employing the sodium alkoxide rather than the alkyl alcohol itself Dialkyl aryl phosphates are produced ia two steps. The low molecular weight alcohol iavolved (eg, butyl) first reacts with excess POCl. The neutral phosphate ester is then completed by the iatermediate chloridate reacting with excess sodium arylate ia water. 

Chemiluminescence and bioluminescence are also used in immunoassays to detect conventional enzyme labels (eg, alkaline phosphatase, P-galactosidase, glucose oxidase, glucose 6-phosphate dehydrogenase, horseradish peroxidase, microperoxidase, xanthine oxidase). The enhanced chemiluminescence assay for horseradish peroxidase (luminol-peroxide-4-iodophenol detection reagent) and various chemiluminescence adamantyl 1,2-dioxetane aryl phosphate substrates, eg, (11) and (15) for alkaline phosphatase labels are in routine use in immunoassay analyzers and in Western blotting kits (261—266). 

Phosphoms compounds are effective flame retardants for oxygenated synthetic polymers such as polyurethanes and polyesters. Aryl phosphates and chloroalkyl phosphates are commonly used, although other compounds such as phosphonates are also effective. The phosphoms compounds can promote char formation, thereby inhibiting further ignition and providing an efficient thermal insulation to the underlying polymer. 

The aryl phosphate esters are similarly produced from phenols. For instance, a mixture of (0CH2CH2) 0—=)(OH)2 —... 

Aryl phosphates and thiophosphates, and alkyl dithiophosphates are important agrochemicals, while phosphorofluoridates have been prepared as chemical warfare agents. Concern over the persistence and the biodegradability of organophosphate and organophosphorothioates, which are nsed as agrochemicals, has stimnlated stndies into their degradation. Considerable attention has been... 

Organophosphate Ester Hydraulic Fluids. In a study of nonspecific monocyte esterase staining, humans who were exposed to aryl phosphates occupationally showed very slight esterase inhibition (Mandel et al. 1959). 

One study was located regarding neurological effects in humans after inhalation exposure to organophosphate ester hydraulic fluids. Workers in an aryl phosphate manufacturing plant were not found to have neurological deficits even with decades of potential exposure (Reade 1982). 

Before the 1960s, products were introduced based on alkyl aryl phosphates that could contain chlorinated aromatic hydrocarbons. Such products have now entirely disappeared from commercial use, and the vast majority of the industrial organophosphate esters are based on triaryl phosphates with no halogenated components (Marino 1992). However, at older waste disposal sites, hydraulic fluid site contaminants could contain chlorinated hydrocarbons. As with the PCBs formerly included as additives in other forms... 

Organophosphate Ester Hydraulic Fluids. Organophosphate esters are made by condensing an alcohol (aryl or alkyl) with phosphorus oxychloride in the presence of a metal catalyst (Muir 1984) to produce trialkyl, tri(alkyl/aryl), or triaryl phosphates. For the aryl phosphates, phenol or mixtures of alkylated phenols (e.g., isobutylated phenol, a mixture of several /-butylphenols) are used as the starting alcohols to produce potentially very complex mixtures of organophosphate esters. Some phosphate esters (e.g., tricresyl and trixylyl phosphates) are made from phenolic mixtures such as cresylic acid, which is a complex mixture of many phenolic compounds. The composition of these phenols varies with the source of the cresylic acid, as does the resultant phosphate ester. The phosphate esters manufactured from alkylated phenylated phenols are expected to have less batch-to-batch variations than the cresylic acid derived phosphate esters. The differences in physical properties between different manufacturers of the same phosphate ester are expected to be larger than batch-to-batch variations within one manufacturer. 

The synthesis of organophosphate ester compounds dates to the mid-1800s. From an early date, the most commercially useful compounds for lubricants, plasticizers, and hydraulic fluids were in the chemical family of the tertiary esters. Before 1970, products were introduced based on alkyl aryl phosphates that... 

The only regulations found for organophosphate ester hydraulic fluids were for aryl phosphates. Two proposed rules for aryl phosphates address 1) exclusion from hazardous waste regulations and 2) additional testing, recordkeeping, and reporting under the Toxic Substances Control Act (TSCA). 

EPA/OPPT Test Rule Including Reporting and Recordkeeping (proposed) (aryl phosphates) Yes 40 CFR 704 and 799 57 FR 2138 EPA1992... 

Deo PD, Howard PH. 1978. Combined gas-liquid chromatographic mass spectrometric analysis of some commercial aryl phosphate oils. J Assoc Off Anal Chem 61 266-270. 

EPA. 1978. Environmental Protection Agency. Preliminary report on aryl phosphate monitoring with attachment. Intra-Agency memorandum from A.B. Crockett, Environmental Monitoring and Support Laboratory, Office of Research and Development to M.P. Halper, Monitoring and Data Support. 

EPA. 1992b. Environmental Protection Agency. Aryl phosphate base stocks proposed text rule including reporting and recordkeeping requirements. Fed Regist 57 2138-2158. 

EPA. 1994. Testing Consent Order for Aryl Phosphate Base Stocks. September 27, 1994. 

FMC. 1977c. Aryl phosphates and phenols in Nitro area samples. Memorandum from J.E. Jadlocki, FMC Corporation Industrial Division to W.H. Kibble, FMC Corporation. 

FMC. 1979. Analysis of aryl phosphates and phenols in plant and environmental samples from Nitro, West Virginia. Technical report [microfiche 0518399]. FMC Corporation, Princeton, NJ, 95. 

Howard PH, Deo PG. 1979. Degradation of aryl phosphates in aquatic environments. Bull Environ Contam Toxicol 22 337-344. 

LeBel GL, Williams DT, Benoit FM. 1981. Gas chromatographic determination of tnalkyl/aryl phosphates in drinking water following isolation using macroreticular resin. J Assoc Off Anal Chem... 

Lombardo P, Egry IJ. 1979. Identification and gas-liquid chromatographic determination of aryl phosphate residues in environmental samples. J Assoc Off Anal Chem 62 47-51. 

Monsanto. 1979. Summaries of mutagenicity studies, neurotoxicity studies, teratology studies, long term feeding studies, and 90-day inhalation studies on aryl phosphate ester products. 

Mortensen A, Ladefoged O. 1992. Delayed neurotoxicity of trixylenyl phosphate and a trialkyl/aryl phosphate mixture, and the modulating effect of atropine on tn-ortho-to y phosphate-induced neurotoxicity. NeuroToxicology 13 347-354. 

Reape JM. 1982. Neurologic health impact on workers with chronic low dose exposure to aryl phosphates. Thesis submitted to the faculty of the graduate school of the university of Minnesota. 

Sheaffer KK. 1977. Summary report Toxicity of aryl phosphates, Kishacoquillas Creek, Standard Steel Works, Mifflin County. Memorandum to T.P. Clista, Division of Water Quality, Commonwealth of Pennsylvania. 

McGuigan C, Pathirana RN, Balzarini J, De Clercq E. Intracellular delivery of bioactive AZT nucleotides by aryl phosphate derivatives of AZT. J Med Chem 1993 36 1048-1052. 

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