Esters orthophosphate

Solubilizing activity are also used in enhanced oil recovery. Tar and extremely viscous hydrocarbons are recovered by the injection of an aqueous solution of an anionic orthophosphate ester surfactant into a petroleum formation, retaining the surfactant in the formation for about 24 h, and displacing the solubilized hydrocarbons toward a recovery well. The surfactant forms an oil microemulsion with the hydrocarbons in the formation. An anionic monoorthophosphate ester surfactant which is a free acid of an organic phosphate ester was dissolved in water. The input of surfactant solution was 2-25% of the pore volume of the formation [250]. To produce a concentrate for the manufacture... 

In 1970, Monroe and Rooker(28) claimed the use of aluminum salts of acid orthophosphate esters as viscosity builders for use in fracturing fluids. The application of these materials began a new era of hydrocarbon gelling agents. Monroe(29) later claimed the use of Fe30it as a metal activator of phosphate esters and in 1971 described several other metals(30) that could be used with amine neutralization agents. Numerous metallic ionic derivatives can be used as effective "activators" or crosslinkers to prepare a gel. 

Steinberg, G.M., Reactions of dialkyl phosphites — synthesis of dialkyl chlo-rophosphates, tetraalkyl pyrophosphates, and mixed orthophosphate esters, /. Org. Chem., 15, 673, 1950. 

Acid phosphatase or orthophosphoric monoester phosphohydrolase (EC 3.1 3.2) activity is widespread throughout nature. Hydrolysis of a variety of orthophosphate esters as well as transphosphorylation reactions are catalyzed by enzymes from many sources. Table I illustrates their ubiquitous nature. 

Ligands closely related to orthophosphate esters include acetylphosphate, acetylphenylphosphate and fluorophosphate. Alkaline hydrolysis of [Co OP(0)20COMe (NH3)5] occurs exclusively at the carbonyl centre, and the acceleration provided by cobalt(III) four atoms removed is minimal (10 times, equation This is a good comparative example of phosphoryl versus acyl hydrolysis,... 

Orthophosphate esters (3.2) derived from (3.1d) (where the organic group, R, can be very complex) are particularly abundant and important in all life species. 

The hydrolysis of phosphate esters has received a great deal of fundamental study, but the mechanisms in many cases remain unsettled and only partially understood moreover, either P-O or O-C splitting might occur. All orthophosphate esters, in principle, are capable of hydrolysis according to scheme (3.96). 

Known phosphoric esters, particularly orthophosphate esters, are extremely numerous. Many of these esters play a central role in life processes, although not all are naturally occurring or of direct biological interest. When life cells synthesise or transform an organic compound, frequently, the first step is to convert it into its phosphate ester. 

The hydrolysis of an orthophosphate ester involves breaking P-O-C bonds at either P-0 or 0-C linkages, depending on the conditions anployed. In the case of condensed phosphate esters, the rupture of both P-O-C and P-O-P linkages may take place, althongh the latter usually occurs first. 

Tri-n-butyl phosphate is an effective anti-foaming agent which is used in paper making, printing ink manufacture, emulsion paints, and vat dyeing processes. It may be added to these systems as a 1-5 % solution in alcohol or acetone. Tri- -butyl phosphate can be used as a plasticiser or in low-temperature hydraulic fluids, but alternative tri-aryl derivatives are generally preferred (see above). The more important applications of orthophosphate esters are summarised in Figure 12.20. 

Many representatives of the trialkyl orthophosphate ester, dialkyl alkyl (or aryl) phosphonate ester, alkyl dialkyl (or diaryl)-phosphinate, and trialkyl (or triaryl) phosphine oxide class have been investigated. Judging from the reviews available, none of the more exotic types appears to offer any particular advantage over tributyl orthophosphate as a selective extractant for resolving lanthanide mixtures. Most are either viscous liquids or solids that require a diluent, and for the most part the individual separation factors to be had are unspectacular. 

---