Trialkyl esters

Trialkyl esters of phosphonic acid exist ia two structurally isomeric forms. The trialkylphosphites, P(OR)2, are isomers of the more stable phosphonates, 0=PR(0R)2, and the former may be rearranged to resemble the latter with catalytic quantities of alkylating agent. The dialkyl alkylphosphonates are used as flame retardants, plasticizers, and iatermediates. The MichaeUs-Arbusov reaction may be used for a variety of compound types, including mono- and diphosphites having aryl as weU as alkyl substituents (22). Triaryl phosphites do not readily undergo the MichaeUs-Arbusov reaction, although there are a few special cases. 

The orthophosphoric acid is a three-basic acid that can form three kinds of esters by reaction with alcohols. If all three OH groups of the phosphoric acid undergo an ester bond a neutral trialkyl ester will be the result, as Eq. (4) shows. 

The unsaturated character of these trialkyl esters was shown by the ease with which they were attacked by nitric acid, but still more clearly by the formation, with evolution of heat, of stable crystalline addition compounds when they were mixed with cuprous halides. Thus CuC1.P(OC2H5)3 was described as consisting of colourless crystals melting at 190° to 192° C. and soluble in organic solvents.4 This property they share with phosphine, alkylphosphines and phosphorus trihalides. The phosphoric esters were quite indifferent to cuprous halides. Nor were such addition compounds formed either by phosphorous acid itself or by the dialkyl esters, which may show that the latter compounds have the unsymmetrical formula. Phosphorous acid probably exists in both forms, but first as P(OH)3, i.e. when produced from PC13 and Ha0.5 This may be transformed into the unsym-metrieal form through an addition compound HC1.P(0H)3,4 and probably also exists in the form of complex molecules, such as... 

Alkylation of disubstituted acetic esters has become an important new route to trisubstituted acetic acids and their derivatives. Sodium tri-phenylmethide or potassium triphenylmethide is used to convert the ester to its enolate ion, which, in turn, is allowed to react with an alkyl iodide to form the trialkylated ester. The yields are in the range of 42-61%. Potassium hydroxide in acetal solvents serves as basic reagent in the alkylation of certain esters by reactive halides. An interesting preparation of diethyl tetramethylsuccinate involves alkylation of ethyl isobutyrate with ethyl a-bromoisobutyrate. The yield is 30%. ... 

The vast majority of modern phosphate esters are synthetic , using materials derived from petrochemical sources. For example, alcohols are from a-olefins by the 0X0 process and iso-propylated or t-butylated phenols are produced from phenols by reaction with propylene or butylene. Reaction of alcohol or phenol with phosphoryl chloride yields the crude product, which is washed, distilled, dried and decolourised to yield the finished product. Low molecular weight trialkyl esters are water soluble and require non-aqueous techniques. For mixed alkylaryl ester production the reactant phenol and alcohol are added separately, the reaction being conducted in a stepwise fashion. Reaction temperatures are kept as low as possible to avoid transesterification reactions. 

The thermal stability of triaryl phosphates is considerably superior to that of the trialkyl esters, which degrade thermally by a mechanism analogous to that of the carboxylic esters, Reaction (2.13) ... 

Vis and consequently -hindered esters are not generally used in lubrication. Triaryl phosphates have better oxidative stability than that of the trialkyl esters, with triphenyl phosphate showing no degradation up to 340" C. Phosphate esters are generally stable to oxidation up to, and above, the point of significant evaporation. 

Dialkyl chlorophosphates are occasionally used in place of the trialkyl esters aniline was thus monoalkylated in 95% yield at 240-245°.847... 

Phosphorous acid, H3PO3, is generated by hydrolysis of PCI3 - industrially this is carried out by spraying the chloride into steam at 190 °C. Esters of the acid, both the trialkyl esters [P(OR)3] and the dialkyl esters [(R0)2P(0)H], can be produced directly by substituting the appropriate acid for the water. The esters find much use thus, triphenyl phosphite is most widely used in the manufacture of polyvinyl chloride, while trinonylphenyl phosphite is an excellent stabilizer for the same polymer. 

TSCA, 40CFR716.120.c5 aryl phosphates-phosphate esters of pherol or of alkyl-substituted phenols. Triaryl and mixed alkyl and aryl esters are included but trialkyl esters are excluded T120-C5... 

In neutral or acid conditions, mono-, di- and trialkyl phosphates with common radicals R tend to hydrolyse at the same rate, whereas under alkaline conditions, trialkyl esters are considerably less stable than the mono- and dialkyl esters. 

On the other hand, literature data show [16] that different cellulose derivatives which form liquid crystalline solutions in organic solvents may also form cholesteric thermotropic phases in the absence of a solvent—with spontaneous molecular orientation and cholesteric reflection, such as 2-acetoxypropyl cellulose, 2-hydroxypropyl cellulose, the trifluoroacetate ester of hydroxypropyl cellulose, the propanoate ester of hydroxypropyl cellulose, the benzoate ester of hydroxypropyl cellulose, 2-ethoxypropyl cellulose, acetoacetoxypropyl cellulose, trifluoroacetoxypropyl cellulose, the phenylac-etate and 3-phenylpropionate of hydroxypropyl cellulose, phenylacetoxy, 4-methoxy-phenylacetoxy, p-tolylacetoxy cellulose, trimethylsilyl cellulose, trialkyl cellulose, cellulose trialkanoate, the trialkyl ester of (tri-o-carboxymethyl) cellulose, 6-o-a-(l-methylnaphthalene)-2,3-o-pentyl cellulose, etc. Moreover, the suspensions of cellulose crystallites spontaneously form the chiral nematic phase. The formation of mesophase suspension of cellulose crystalHtes varies from one type of cellulose to another, being influenced, in the formation of the chiral nematic phase, by the mineral acid selected... 

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