Phosphate esters phosphorus oxychloride

Acid chlorides are used for the quantitative determination of hydroxyl groups and for acylation of sugars. Industrial applications include the formation of the alkyl or aryl carbonates from phosgene (see Carbonic and chloroformic esters) and phosphate esters such as triethyl, triphenyl, tricresyl, and tritolyl phosphates from phosphorus oxychloride. 

O-isopropylidene derivative (10) was then phosphorylated with phosphorous oxychloride to form the phosphate ester (11) from which the protecting groups were removed by mild acid hydrolysis. The 3-phos-phate (15) was obtained by phosphorylating the 4,6-benzylidene derivative (13) of the same glycoside with phosphorus oxychloride, followed by hydrolytic removal of the protecting groups, from the ester (14) thus obtained. 

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. 

Mannitol hexanitrate is obtained by nitration of mannitol with mixed nitric and sulfuric acids. Similarly, nitration of sorbitol using mixed acid produces the hexanitrate when the reaction is conducted at 0—3°C and at —10 to —75°C, the main product is sorbitol pentanitrate (117). Xylitol, ribitol, and L-arabinitol are converted to the pentanitrates by fuming nitric acid and acetic anhydride (118). Phosphate esters of sugar alcohols are obtained by the action of phosphorus oxychloride (119) and by alcoholysis of organic phosphates (120). The 1,6-dibenzene sulfonate of D-mannitol is obtained by the action of benzene sulfonyl chloride in pyridine at 0°C (121). To obtain 1,6-dimethanesulfonyl-D-mannitol free from anhydrides and other by-products, after similar sulfonation with methane sulfonyl chloride and pyridine the remaining hydroxyl groups are acetylated with acetic anhydride and the insoluble acetyl derivative is separated, followed by deacetylation with hydrogen chloride in methanol (122). Alkyl sulfate esters of polyhydric alcohols result from the action of sulfur trioxide—trialkyl phosphates as in the reaction of sorbitol at 34—40°C with sulfur trioxide—triethyl phosphate to form sorbitol hexa(ethylsulfate) (123). 

Benzoylresorcinol based phosphate esters are obtained by reacting a benzoylresorcinol compound with a chlorophosphate, e.g., benzoylresorcinol with diphenyl chlorophosphate or phosphorus oxychloride. These esters can function both as flame retardants and UV stabilizers for PC/ABS and a series of other polymers (78). 

Phosphorus oxychloride reacts with ethylene oxide in the presence of aluminum chloride to give tris-2-chloroethyl phosphate, a valuable plasticizer (75). Phosgene reacts with ethylene oxide and other alkylene oxides to form esters of chlorocarbonic acid (76) (see Carbonic and carbonochloridic esters). 

Starches have been chemically modified to improve their solution and gelling characteristics for food applications. Common modifications involve the cross linking of the starch chains, formation of esters and ethers, and partial depolymerization. Chemical modifications that have been approved in the United States for food use, involve esterification with acetic anhydride, succinic anhydride, mixed acid anhydrides of acetic and adipic acids, and 1-octenylsuccinic anhydride to give low degrees of substitution (d.s.), such as 0.09 [31]. Phosphate starch esters have been prepared by reaction with phosphorus oxychloride, sodium trimetaphosphate, and sodium tripolyphosphate the maximum phosphate d.s. permitted in the US is 0.002. Starch ethers, approved for food use, have been prepared by reaction with propylene oxide to give hydroxypropyl derivatives [31]. 

Starch granules have been cross-linked with phosphate by the reaction of an aqueous alkahne (pH 8-12) suspension reaction with phosphorus oxychloride [161]. Trimetaphosphate has also been used to produce phosphate cross-linkages. These reactions are primarily with the C-6-OH groups and only a minimal number with the C-3-OH groups [162]. Starch phospho esters can be obtained by phosphorylation with sodium triphosphate at pH of 8.5 [163]. 

The neutral phosphonate esters, D(EB)[(EB)P], D(4-MPe-2)[BP], D(4-MPe-2)[(iB)P] and D(4-MPe-2)[PP] were prepared by the Michaelis-Arbuzov Reaction in which alkyl halides were reacted with previously prepared trialkyl phosphites. The neutral phosphate, T(4-MPe-2)P, was prepared by a conventional esterification method in which 4-methyl-2-pentanol was reacted with POCI3 in the presence of pyridine. The temperature during the reaction was kept below 15°C to prevent disproportionation of the alkyl group. The neutral phosphinate ester, B[DBP], was prepared by esterification of dibutyl phosphorus oxychloride, (C Hg)2P0C1, in the presence of pyridine. 

The largest commercial organic phosphate esters then on the market were tricresyl and triphenyl phosphate. Both of these esters were produced by the reaction of phosphorus oxychloride with the phenol or the cresol, usually as a mixture of para- and metacresol (equations 4,5). 

The treatment of 6-trifluoromethyluracil (195) with phosphorus oxychloride and phosphorus pentachloride has given not only the expected 2,4-dichloro product but also the pyrimidine dichloro-phosphate (196). Such esters have been proposed as the intermediates in the conversion of a pyrimidinone to a chloro-pyrimidine but this is the first example of such a compound to be... 

Other inorganic esters are generally prepared by the reaction of an acid chloride with a hydroxy cmppound or its sodium salt. Phosphates are prepared by the reaction of phosphorus pentachloride or phosphorus oxji chloride with the appropriate alcohol or phenol. If the sulfur analogue of phosphorus oxychloride, PSCls, is baused to react with an alcohol, or its sulfur analogue, a mercaptan, the corresponding thioester is obtmned. 

Of the esters, starch phosphate is produced by reaction with phosphorus oxychloride, polyphosphates, or metaphosphates a cross-bonded product results. Total degree of substitution is determined by measuring the phosphorus content, and the mono- to disubstitution ratio can be calculated by potentio-metric titration. Allowance is made for the natural phosphorus content of the starch. Treatment of starch with acetic anhydride produces starch acetate, which has improved paste stability over native starch. The acetyl group is very labile, and hydrolyses readily under mild alkaline conditions. When a known amount of alkali is used, the excess can be titrated and the ester function measured. This is not specific, however, and a method based on an enzymatic measurement of the acetate has been developed in an ISO work group. The modified starch is hydrolyzed under acidic conditions, which releases acetic acid and permits filtration of the resulting solution. Acetic acid is then measured by a commercially available enzyme test kit. Both bound and free acetyl groups can be measured, and the method is applicable... 

The principal phosphation reagents used to manufacture phosphate esters are phosphoric anhydride (P4O10), phosphorus oxychloride [P(0)Cl3], and polyphosphoric acid. It is important to understand the physical and chemical characteristics of each raw material. The structure of the phosphation agent affects its reactivity and selectivity, resulting in variation in the monoester, diester, and triester product distribution. 

Acrylic dental adhesives have been modified with a phosphate ester linkage by reaction of a glycidyl methacrylate or hydroxyethyl methacrylate with phosphorus oxychloride (158). One such product, a 3M Scotchbond, adheres to dentine as well as to tooth enamel. Adhesion to enamel can be improved in dental bonding cements by including an acryloxyalkyl- or acryloxyaryl acid phosphate component (159). Japanese products utilize an imsaturated phosphinic acid monomer to improve adhesion (160). 

Interestingly, the synthesis of riboflavin phosphate has taken a shghtly different course. As reported in 1950 (Scheme 12.116), when the reduced Al-ribosyl derivative of 2,3-dimethylaniline is phosphorylated with phosphorus oxychloride and then carefully hydrolyzed, the corresponding monophosphate is capable of isolation. Then, treatment of that ester with diazotized aniline yielded l-D-l -ribitylamino-6-phenylazo-3,4-dimethylbenzene. Reduction to the corresponding amine followed by condensation with alloxan then yielded riboflavin monophosphate. 

The use of phosphorus oxychloride for the synthesis of phosphate esters of sugars 160) has been largely replaced by dibenzyl 161) and diphenyl phosphorochloridates 162), The latter reagent may be prepared in a pure, stable form which reacts readily with an alcohol in pyridine at low temperature. The phenyl groups may be removed from the resulting di-0-phenyl phosphate derivative of the alcohol by catalytic hydrogenation employing a platinum catalyst. 

Phosphate esters are produced from phosphorus oxychloride with various alcohols or phenols, or combinations of these hydroxyl compounds. These fluids generally have good thermal and oxidative stabilities and fire-resistancy. However, because of their high polarity, poor Vl-pour point balance, facile hydrolysis and inferior elastomer and paint compatibility, their use in general lubrication is limited. The major use for phosphate esters is in fire-resistant hydraulic oils. 

The second class of FR phosphate esters used in flexible vinyls is the alkyl diaryl phosphates (ADP) (Fig. 9.2 and Tables 9.4 and 9.5). The most common approach for manufacturing these materials is by reaction of phosphorus oxychloride with the sodium salt of the alcohol. There are three major types, differing in the alkyl group reaction products of isodecyl alcohol, 2-ethylhexanol or linear C12-C14 alcohols. The advantages of these products are their low-temperature flexibility and/or lower volatility with the longer-chain alkyl group. 

Diphenyl-butyl-, diphenyl-(2-ethylhexyl)- and diphenyl-isodecyl-phosphates are produced industrially. Manufacture is carried out in two stages first the alcohol is reacted with excess phosphorus(V) oxychloride to the alkyl ester dichloride ... 

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