Triaryl phosphate

The toxicity of inhaled triaryl phosphates (triaryl phosphate-mixture), Fyrquel 220, Durad MP280, and cyclotriphosphazene has been well studied in rats, rabbits, and hamsters. These studies suggest that Fyrquel 220 (Gaworski et al. 1986 MacEwen and Vemot 1983), Durad MP280 (Gaworski et al. 1986 ... 

Trishydroxyethyl triazine trione C9H15O4P Triallyl phosphate Triaryl phosphate C9H16CIN4 Cl Quaternium-15 C9Hi CIN ... 

Pentabromodiphenyl Oxide. Pentabromodiphenyl oxide [32534-81-9] (PBDPO) is prepared from diphenyl oxide by bromiaation (36). It is primarily used as a flame retardant for flexible polyurethane foams. For this appHcation PBDPO is sold as a blend with a triaryl phosphate. Its primary benefit ia flexible polyurethanes is superior thermal stabiUty, ie, scorch resistance, compared to chloroalkyl phosphates (see Phosphate esters). 

Alkyl diphenyl phosphate plasticizers can exert flame-retardant action in vinyl plastics by a condensed-phase mechanism, which is probably some sort of phosphoms acid coating on the char. Triaryl phosphates appear to have a vapor-phase action (29). 

Antagonism between antimony oxide and phosphoms flame retardants has been reported in several polymer systems, and has been explained on the basis of phosphoms interfering with the formation or volatilization of antimony haUdes, perhaps by forming antimony phosphate (12,13). This phenomenon is also not universal, and depends on the relative amounts of antimony and phosphoms. Some useful commercial poly(vinyl chloride) (PVC) formulations have been described for antimony oxide and triaryl phosphates (42). Combinations of antimony oxide, halogen compounds, and phosphates have also been found useful in commercial flexible urethane foams (43). 

Triaryl phosphates are also used on a large scale as flame-retardant hydrauhc fluids (qv), lubricants, and lubricant additives (see Lubrications and lubricants). Smaller amounts are used as nonflammable dispersing media for peroxide catalysts. 

Triaryl phosphates are produced from the corresponding phenols (usually mixtures) by reaction with phosphoms oxychloride, usually in the presence of a catalyst (94—96). They are subsequently distilled and usually washed with aqueous bases to the desired level of purity. Tricresyl phosphate was originally made from petroleum-derived or coal-tar-derived cresyflc acids, ie, cresols, variously admixed with phenol and xylenols. Discovery of the toxicity of the ortho-cresyl isomers led manufacturers to select cresols having very Httle ortho-isomer. 

In the 1960—1980 period, the use of more economical synthetic isopropyl- and /-butylphenols as alternatives to cresols was developed (98,99). Commercial triaryl phosphates such as FMC s Kronitex 100 and Ak2o s Phosflex 31P and 41B are based on partially isopropylated or /-butylated phenol. The relative volatihties and oxidative stabiUties of these phosphates have been compared the /-butylphenyl phosphates are the most oxidatively stable of the alkylphenyl phosphates (100). 

Blends of triaryl phosphates and pentabromodiphenyl oxide are leading flame-retardant additives for flexible urethane foams. A principal advantage is their freedom from scorch. 

A particular mode of neurotoxicity was discovered for tricresyl phosphate that correlated with the presence of the o-cresyl isomer (or certain other specific aLkylphenyl isomers) in the triaryl phosphates. Many details of the chemistry and biochemistry of the toxic process have been elucidated (139,140,143—146). The use of low ortho-content cresols has become the accepted practice in industrial production of tricresyl phosphate. Standard in vivo tests, usually conducted with chickens sensitive to this mode of toxicity, have been developed for premarket testing of new or modified triaryl phosphates. As of 1992, the EPA called for extensive new toxicity and environmental data on this group of products (147). The Vederal e ster AoQ xm. ci. calling for this... 

Phosphate Esters. A variety of phosphate esters are used as synthetic lubricants, particularly because of their good fire resistance. They have the general formula OP(OR)2, where R may represent a variety of aryl or alkyl hydrocarbon groups containing four or more carbon atoms to give three broad classes triaryl, trialkyl, and aryl alkyl phosphates (37,38). 

Triaryl phosphates are produced by reaction of phosphoms oxychloride with phenoHc compounds at 100—200°C with magnesium or aluminum chloride catalyst. Past use of cresols and xylenols from coal tar or petroleum is replaced for lower toxicity and cost by synthetic phenoHcs, primarily isopropyl phenol, /-butyl phenol, and phenol itself A range of viscosities is achieved by selection and proportioning of the phenols and their isomers used for the starting material. 

Triaryl phosphates of ISO 32 viscosity show promise for the main beating lubricants of steam and gas turbiaes (39,40). An interesting possibiHty iavolves unique deHvery of phosphate ester vapor to lubricate the piston ring 2one of low heat rejection (adiabatic) diesel engines (41). 

Surprisingly, phosphorus when combined with bromine is effective in nonoxygen containing polymers. In another reference, a mixture of a brominated compound and a triaryl phosphate was claimed to be effective in HIPS where antimony oxide is generally required as a synergist for bromine (ref. 7). 

Barcelo D. 1988. Application of thermospray liquid chromatography/mass spectrometry for determination of organophosphoms pesticides and trialkyl and triaryl phosphates. Biomed Environ Mass Spectrom 17 363-369. 

Conformational populations of cyanomethylphosphine oxides (136) have been estimated from dipole moments and indicate a preference for the tra/15-conformation. The moments of the o-, m- and p-chloro- and tolyl-derivatives of triaryl phosphites (137, Y = ) and triaryl phosphates (137 Y = O) indicate that the oxygen atom in the latter series causes the aryl rings to rotate further away from a position in which their planes all meet along the molecular symmetry axis. Conformational studies have also been carried out on the dioxaphosphorinanes. The moments of the isomeric series (138a) and (138b) were in the ranges 3.7—4.2 and 5.4—5.5 D respectively. ... 

Bd Wt = body weight Cardio = cardiovascular d = day(s) Endocr = endocrine exp. = exposure(s) F = female Gastro = gastrointestinal Hemato = hematological LOAEL = lowest-observed-adverse-effect level M = male Musc/skel = musculoskeletal NOAEL = no-observed-adverse-effect level RBC = red blood cell Resp = respiratory TAP1 = triaryl phosphate hydraulic fluid (TAP1 is similar, if not identical, to Cellulube 220) TPP = triphenyl phosphate wk = week(s) x = times. 

Intermediate-duration inhalation exposures to aerosols of a few organophosphate ester hydraulic fluids (Durad MP280 and "triaryl phosphate ester") produced lethal neurotoxic effects in chickens and rabbits (MacEwen and Vemot 1983 Siegel 1965). Rats and hamsters appear to be less susceptible to the neurotoxic action of organophosphate esters tests of several organophosphate fluids produced no deaths in rats exposed to substantial aerosol concentrations. 

Aerosols of Cellulube 220 produced deaths associated with severe dyspnea and mild diarrhea in one of two rabbits exposed to 2,000 mg/m3 for <4 hours/day, 5 days/week for 11 or 22 days (Carpenter et al. 1959). Continuous exposure for 30-160 days to aerosols of a triaryl phosphate U.S. military hydraulic fluid (see Table 3-2), at concentrations <110 mg/m3, produced no deaths in dogs or rats, but deaths associated with severe neurotoxic symptoms occurred in chickens exposed to concentrations >23 mg/m3 and in rabbits exposed to 102 mg/m3 (Siegel et al. 1965). Aerosols of Durad MP280 or Fyrquel 220 (continuous exposure for 90 days) produced no deaths in rats or hamsters exposed to 100 mg/m3. Deaths associated with lethargy, cachexia, and head droop occurred in rabbits exposed to 101 mg/m3 Durad MP280, but not in rabbits exposed to 100 mg/m3 Fyrquel 220 (MacEwen and Vemot 1983). Some of the Durad MP280-exposed rabbits were also infected with Pasteurella, which may have contributed to neurological symptoms. No deaths occurred in rats exposed to cyclotriphosphazene at 990 mg/m3, 6 hours/day,... 

Following intermediate-duration exposure to organophosphate ester hydraulic fluids, reversible rapid respirations were observed in rabbits exposed to 2,000 mg/m3 of a triaryl phosphate hydraulic fluid (Cellulube 220) (Carpenter et al. 1959) and reddish nasal discharge (likely to be indicative of respiratory tract irritation) was observed in rats exposed to 100 mg/m3 of Skydrol 500B-4 (Healy et al. 1992 ... 

No endocrine effects were seen in acute inhalation exposure to a triaryl phosphate mixture (Cellulube 220) for rabbits at 2,000 mg/m3 (Carpenter et al. 1959). In studies on rats, hamsters and rabbits no endocrine... 

Johannsen and colleagues (1977) report dermal LD50 values for rabbits at levels of >3,700 mg/kg for a group of triaryl phosphates, >5,000 mg/kg for dibutyl phenyl phosphate, 5,000 mg/kg for both asymmetrical and symmetrical triaryls, and >3,100 mg/kg for tributyl phosphate. This study looked at structural activity relationships for the organophosphate esters. 

Organophosphate Ester Hydraulic Fluids. No change in the levels of leukocytes was observed in workers dermally exposed to triaryl phosphate hydraulic fluids for an intermediate duration (Baldridge et al. 1959). 

Another group of 14 men was exposed primarily by dermal contact to a triaryl phosphate hydraulic fluid during installation and operation of hydraulic aircraft elevators on a U.S. Navy ship (Baldridge et al. 

A triaryl phosphate ester, tributoxyethyl phosphate, was detected at a mean concentration of 11.3 ng/g in 41 of 115 human adipose tissue samples taken from cadavers from Kingston and Ottawa, Canada (LeBel and Williams 1986). Because triaryl phosphate esters have been found in Canadian drinking water and... 

Studies with rats treated orally with triaryl or trialkyl phosphate esters (which may be found in organophosphate ester hydraulic fluids) indicate that these compounds and their metabolites are readily excreted in the urine, bile, feces and, to a limited extent, in expired air (Kurebayashi et al. 1985 Somkuti and Abou-Donia 1990a Suzuki et al. 1984a Yang et al. 1990). Urinary excretion of metabolites appears to be the predominant elimination route in rats for tri-ort/zo-cresyl phosphate and tri-para-cresyl phosphate, but biliary excretion of parent material and metabolites is also important (Kurebayashi et al. 1985 NTP... 

Monsanto 1987a, 1987b, 1989), Cellulube 220 (Carpenter et al. 1959), and a triaryl phosphate hydraulic fluid (Siegel et al. 1965). In addition, no evidence of renal damage was observed following intermediate-duration exposure of rats to oral doses of Pydraul 90E (Monsanto 1979), rabbits to topical cyclotriphosphazene (Kinkead et al. 1989c, 1990), or rabbits to topical Cellulube 220 (Carpenter et al. 1959). 

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