Triethyl phosphates

The reaction uses triethyl phosphate as a homogeneous catalyst. ... 

The above is a general procedure for preparing trialkyl orthophosphates. Similar yields are obtained for trimethyl phosphate, b.p. 62°/5 mm. triethyl phosphate, b.p. 75-5°/5 mm. tri-n-propyl phosphate, b.p. 107-5°/5 mm. tri-Mo-propyl phosphate, b.p. 83-5°/5 mm. tri-wo-butyl phosphate, b.p. 117°/5-5 mm. and tri- -amyl phosphate, b.p. 167-5°/5 mm. The alkyl phosphates are excellent alkylating agents for primary aromatic amines (see Section IV,41) they can also be ua for alkylating phenols (compare Sections IV,104-105). Trimethyl phosphate also finds application as a methylating agent for aliphatie alcohols (compare Section 111,58). 

Ethyl o-nitrocinnamate (1 mmol) was dissolved in triethyl phosphite (5 mmol) and heated at 170°C for 3 h. The triethyl phosphite and triethyl phosphate were removed in vacuo. The residue w as eluted through a column of silica gel using CHCI3 and the product recrystallizcd from CHCl3-hexane. The yield was 94%. 

TrialkylPhosphates. Triethyl phosphate [78-40-0] C H O P, is a colorless Hquid boiling at 209—218°C containing 17 wt % phosphoms. It may be manufactured from diethyl ether and phosphoms pentoxide via a metaphosphate intermediate (63,64). Triethyl phosphate has been used commercially as an additive for polyester laminates and in ceHulosics. In polyester resins, it functions as a viscosity depressant as weH as a flame retardant. The viscosity depressant effect of triethyl phosphate in polyester resins permits high loadings of alumina trihydrate, a fire-retardant smoke-suppressant filler (65,66). 

Methyl methacrylate is often used in combination with styrene to improve light transmission and uv stabiUty in fiame-retardant glazing appHcations. Phosphate ester (triethyl phosphate) additives are also included to supplement fiame-retardant efficiency benzophenone uv stabilizers are required to prevent yellowing of these uv-sensitive resins. 

Sulfur trioxide reactivity can also be moderated through the use of SO adducts. The reactivity of such complexes is inversely proportional to their stabihty, and consequentiy they can be selected for a wide variety of conditions. Whereas moderating SO reactivity by adducting agents is generally beneficial, the agents add cost and may contribute to odor and possible toxicity problems in derived products. CeUulosic material has been sulfated with SO.—trimethyl amine adduct in aqueous media at 0 to 5°C (16). Sulfur trioxide—triethyl phosphate has been used to sulfonate alkenes to the corresponding alkene sulfonate (17). Sulfur trioxide—pyridine adduct sulfates oleyl alcohol with no attack of the double bond (18). 

Sulfonated polyalkenes were prepared by using a triethyl phosphate—sulfur trioxide complex as the sulfonating reagent along with a solvent at low temperature. Sulfonation takes place at the a-position of the double bond with no cross-linking (222). 

For commercial appHcation, catalyst activity is only one of the factors to be considered. Equally important is catalyst life, but Htde has been pubHshed on this aspect. Partly because of entrainment losses and partly through loss of acid as volatile triethyl phosphate, the catalyst loses activity unless compensating steps are taken. This decline in activity can be counteracted by the periodic or continuous addition of phosphoric acid to the catalyst during use, a fact that seems to have been disclosed as early as 1940 (94). A catalyst subjected periodically to acid addition could remain in service indefinitely, according to a report by Shell (91). A later Shell patent (85) states that complete reimpregnation with acid is required every 200 mn-days. 

Subsequently, several laboratories developed improvements in the early procedures. It was first recommended that the reaction be carried out at a low temperature ca. —T) for better results. A more notable improvement is the use of dimethylformamide-t-butanol as the solvent system, a temperature range of —20 to —25°, and the presence of triethyl phosphite during the reaction to reduce the hydroperoxide as it is formed. The triethyl phosphate which is produced is water soluble and overall yields are generally in the range of 60-70 %. 

Phosphates. Insoluble orthophosphates may be precipitated with phosphate ion derived from trimethyl or triethyl phosphate by stepwise hydrolysis. Thus 1.8M sulphuric acid containing zirconyl ions and trimethyl phosphate on... 

Titrimetric apparatus see Graduated glassware Toluene-3,4-dithiol see Dithiol Tongs for crucibles and beakers, 98 Transmittance 648 conversion to absorbance, 709 Triangulation 245 Triethanolamine 317 Tri-n-butyl phosphate 171 Triethyl phosphate in homogeneous pptn. 425 Triethylenetetramine-fV,fV,fV, yV",fV", fV "-hexa acetic acid (TTHA) 57 Trifluoroacetylacetone 170, 237 Trimethyl phosphate in homogeneous pptn., 425... 

Triethyl phosphite can be obtained from Virginia Carolina Chemical Corp., Eastman Kodak Co., Aldrich Chemical Co., K and K Laboratories, and Matheson, Coleman and Bell. The presence of dialkyl hydrogen phosphite or trialkyl phosphate is not deleterious, but a correction for assay is required. Fractionation readily separates triethyl phosphite (b.p. 48-49°/ll mm.) from diethyl hydrogen phosphite (b.p. 72°/ll mm.) and triethyl phosphate (b.p. 90°/10 mm.). The presence of amines and amine hydrochlorides may seriously interfere with the alkylation, especially in the case of trimethyl phosphite (see Table I). The checkers redistilled triethyl phosphite obtained from Matheson, Coleman and Bell. 

TEP. See Triethyl phosphate (TEP) Terephthaldehyde, polymerization of, 88 Terephthalic acid (TPA), 50, 535, 548-549 polyesterification of, 64 Terephthalic acid-l,2-ethanediol reaction, 104-105... 

Triethylene diamine (TEDA), 230, 231 Triethyl phosphate (TEP), 354 Trifluoroactic anhydride, 78 Trifhioromethanesulfonic acid, 334 Trifunctional monomers, 14 Triglyceride content, in resins, 60 Trihydroxymethylphenol curing process, 410... 

C9H20OJ 115-80-0) see Alclometasone dipropionatc Betamethasone dipropionate triethyl phosphate... 

Pyrolysis of the phosphorodichloridothioate (59) at 550 °C gives mainly dibenzothiophen and a smaller amount of the cyclic phosphonochlorido-thioate (60). Thermal decomposition of di-t-butyl peroxide in triethyl phosphate gives rise to diethyl methyl phosphate in a reaction which may be interpreted as resulting from attack of methyl radical on the phosphoryl oxygen. An extension of this mechanism accounts for the formation of (61) from tri-isopropyl phosphate under the same conditions. 

A similar process allows reacting triethyl phosphate and phosphorous pentoxide to form a polyphosphate in an organic solvent [871]. An excess of 1.3 moles of triethyl phosphate with respect to phosphorous pentoxide is the most preferred ratio. In the second stage, a mixture of higher aliphatic alcohols from hexanol to decanol is added in an amount of 3 moles per 1 mole phosphorous pentoxide. Aluminum sulfate is used as a crosslinker. Hexanol results in a high-temperature viscosity of the gel, while maintaining at a pumpable viscosity at ambient temperatures [870]. 

Figure 17-22. Polyadduct from triethyl phosphate and phosphorous pentox-ide and reaction with hexanol to produce a diester.

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