Neutral Phosphoric Acid Esters

1 Neutral Phosphoric Acid Esters Triaryl Phosphates 

Triphenyl phosphate, diphenyl-cresyl phosphate, tricresyl phosphate and mixed (2-propyl-phenyl)-phenyl phosphates belong to this class of compounds. They are manufactured by reacting phosphorus(V) oxychloride with a slight excess of the appropriate phenols or phenol mixtures in the presence of catalysts (magnesium or potassium salts) at temperatures above 140°C  

The reaction temperature increases with increasing extent of conversion, the hydrochloride formed escaping as a gas. The excess phenol is distilled off when the reaction is complete. The phosphate esters can be purified by distillation. o-Cresol may not be used in the manufacture of cresyl phosphate on ecological grounds. Isopropyl-phenyl phosphate can, however, be produced using phenol mixtures, which are obtained by the alkylation of phenol with propene. 

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  

After distilling off the excess phosphorus(V) oxychloride, the alkyl ester dichloride is reacted with an aqueous solution of sodium phenolate to the triester in a two-phase reaction  

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Chem. Descrip. Emulsified mixt. of aliphatic hydroxyl compds. and a neutral phosphoric acid ester... 

Chem. Descrip. Neutral phosphoric acid ester with nonionic emulsifiers Ionic Nature Anionic... 

The reaction of condensed phosphoric acid with castor oil gave a poly-phosphoric acid ester, which after neutralization with ammonia shows a high wetting power [32]. Glycerol trioleate was reacted with octametaphosphoric acid at 40°C in the presence of acetic acid anhydride. The reaction product was neutralized with triethanolamine [32,33]. 

Acid ester phosphates with an alkyl chain up to C6 have little solubility whereas neutralized esters are soluble in water. In ethanol and isopropanol most of phosphoric acid esters and their salts are soluble. If the products are based on ethoxylated alcohols their solubility in water will increase as the degree of ethoxylation increases. The solubility in organic solvents like gasoline, benzene, perchlorethylene, and other apolar liquids recedes with an increase in the degree of ethoxylation but are increased by a higher alkyl chain. 

Emulsions containing a water-solubile herbicide salt and a herbicide soluble in an organic solvent are prepared by a mixture of water, dioctyl phthalate, and isophorone. In this case ethoxylated poly ary lphenol phosphate neutralized with triethanolamine and ethoxylated acid phosphoric acid esters is used as emulsifier [231],... 

A mixture of monolauryl phosphate sodium salt and triethylamine in H20 was treated with glycidol at 80°C for 8 h to give 98% lauryl 2,3-dihydro-xypropyl phosphate sodium salt [304]. Dyeing aids for polyester fibers exist of triethanolamine salts of ethoxylated phenol-styrene adduct phosphate esters [294], Fatty ethanolamide phosphate surfactant are obtained from the reaction of fatty alcohols and fatty ethanolamides with phosphorus pentoxide and neutralization of the product [295]. A double bond in the alkyl group of phosphoric acid esters alter the properties of the molecule. Diethylethanolamine salt of oleyl phosphate is effectively used as a dispersant for antimony oxide in a mixture of xylene-type solvent and water. The composition is useful as an additive for preventing functional deterioration of fluid catalytic cracking catalysts for heavy petroleum fractions. When it was allowed to stand at room temperature for 1 month it shows almost no precipitation [241]. 

When a mixture of phosphoric acid and phosphoric acid esters is titrated with a sodium hydroxide solution two potential jumps can be observed. The first jump results from the acid group of the diester, the first neutralization step of the monoester, and the first neutralization step of free phosphoric acid. The second potential jump is caused by the second neutralization steps of the monoester and of the free phosphoric acid. The third step of neutralization of the free phosphoric acid cannot be covered by this method. Titration of acid esters can only be used for the determination of mono- and diesters of phosphoric acid when the amount of free phosphoric acid is separately ascertained. 

The neutral thio- and dithiophosphoric ester acids with a reactive easily hydrolytically cleavable group, are utilized as insecticides. Their effect is based on in vivo oxidation to the corresponding phosphoric acid ester, which... 

Stereochemical data exist for a large number of displacement reactions on neutral phosphoric acid and thiophosphoric acid esters and amides (64). Many of these occur with retention of configuration, especially when the displacement reactions occur on five-membered ring compounds, and this stereochemical course is explained by pseudorotation of a pentacoordinate intermediate. In contrast, only one stereochemical study has been performed on an anionic phosphate ester with the intention of detecting the participation of a phosphorane intermediate. 

This large and important class of extractants includes the neutral and acidic esters of ortho phosphoric acid and related compounds, the phosphonates, phosphinates and phosphine oxides. The class divides naturally into neutral and acidic compounds by the differences in extraction mechanism. The neutral compounds extract by solvation of a neutral complex in the organic phase by the phosphoryl oxygen, while the acidic compounds, in general, operate by an ion-exchange reaction to form an extractable species. Further solvation may occur in the organic phase in some extraction systems of this type. 

Chem. Descrip. Phosphoric acid ester partially neutralized with triethanolamine Chem. An ysis 3.94.5% N 6.3-71% P CAS 102-71-6 EINECSCLINCS 203-049-8... 

For extraction of uranium from sulfate leach Hquors, alkyl phosphoric acids, alkyl phosphates, and secondary and tertiary alkyl amines are used in an inert diluent such as kerosene. The formation of a third phase is suppressed by addition of modifiers such as long-chain alcohols or neutral phosphate esters. Such compounds also increase the solubihty of the amine salt in the diluent and improve phase separation. 

Brilliant green neutral esters of phosphoric acid [125], carbamate herbicides [34]... 

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. 

Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterifying alkyl acrylate polymers with 4-morpholinethanol or alkanolamines and fatty alcohols or alkoxyl-ated alkylphenols and neutralizing with phosphoric acid. This polymer salt (pH of a 10% aqueous solution = 5.1) was used as an emulsifying agent for oils and waxes [70]. 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

Hydrolysis appears to be the most important abiotic degradative mechanism for organophosphate esters under basic pH conditions. Under neutral and acidic conditions, the reaction slows considerably and could become an insignificant removal mechanism. The hydrolysis proceeds by a stepwise mechanism in which one alcohol group is removed at a time. The first step is cleavage of a P-OR bond (where "R" is an aryl or alkyl group) to produce a diester of phosphoric acid, which, under basic conditions, becomes an anion. 

As a consequence, the selectivity of extraction of first transition series dications does not follow the Irving Williams order when these reagents are used in base metal recovery. The bis(2-ethylhexyl)ester of phosphoric acid (D2EHPA) shows [1] a preference Zn2+ > Cr21 > Mn2+ > Fe2+ > Co2+ > Ni2+ V2+ which is exploited in the recovery of zinc from primary sources. [69] M2+ ions which form tetrahedral complexes and M3+ ions which show a preference for octahedral donor sets give neutral complexes with 4 1 and 6 1 D2EHPA metal stoichiometries respectively,... 

The solution should be neutral before distillation. The presence of hydrogen chloride promotes decomposition of phosphoric esters into phosphoric acid and alkenes. The benzene solution should not be washed with alkaline reagents, such as sodium carbonate solution, since alkaline reagents also cause decomposition during distillation. 

The resulting product is a mixture of dialkyl and monoalkyl phosphate esters. These products also contain small amounts of condensed phosphates and phosphoric acid. Neutralization of the acids with bases like alkali hydroxides, ammonia, or amines produces water-soluble anionic surfactants and emulsifiers. 

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