Water dialkyl phosphates

In addition to their poor solubility in water, alkyl phosphate esters and dialkyl phosphate esters are further characterized by sensitivity to water hardness [37]. A review of the preparation, properties, and uses of surface-active anionic phosphate esters prepared by the reactions of alcohols or ethoxylates with tetra-phosphoric acid or P4O10 is given in Ref. 3. The surfactant properties of alkyl phosphates have been investigated [18,186-188]. The critical micelle concentration (CMC) of the monoalkyl ester salts is only moderate see Table 6 ... 

K. Ariga, R. Tanaka, J. Kikuchi, M. Higuchi, K. Yamamoto, Stoichiometric Complexes between Cyclic Phenylazomethines and a Dialkyl Phosphate for Molecular Tiling at the Air-Water Interface , J. Nanosci. Nanotech., 2,669 (2002)... 

Phosphate esters show important thermal susceptibility (Fig. 1). Dialkyl phosphates, such as those found in nucleic acids (Fig. 2), decompose with the initial loss of one alkyl group, the concomitant transfer of protons, followed by the elimination of the second alkyl group and the subsequent loss of water. This thermal instability of phosphoesters has been used in the analysis of nucleic acids. Thus the pyrolysis that usually precedes the recording of a mass spectrum permits cleavage of the polymeric phosphoesters (nucleic acids), followed by phosphate extrusions, producing nucleotides or simple nucleosides as fragment ions. 

The nonoxyethylenated monoalkyl phosphates cause little skin irritation and are used in personal care products. The sodium salt of monododecyl phosphate, unlike soap, works in a weakly acidic medium and can therefore be used as a detergent in face cleaners and cleansers and in body shampoos. The potassium or alkanol-ammonium salt of monohexadecyl phosphate is used as an emulsifying agent in skin care products. The dialkyl phosphate must be avoided in the synthesis of these products, since it reduces foaming and water solubility. 

Inefficiencies ia the reaction with POCl leads to alternative production of trialkyl phosphates by employing the sodium alkoxide rather than the alkyl alcohol itself Dialkyl aryl phosphates are produced ia two steps. The low molecular weight alcohol iavolved (eg, butyl) first reacts with excess POCl. The neutral phosphate ester is then completed by the iatermediate chloridate reacting with excess sodium arylate ia water. 

Materials. Cumene and Tetralin were purified by extraction with concentrated sulfuric acid, until the extracts were colorless, then with 2N caustic soda and distilled water, and finally dried and distilled. Both were stored in darkness under No and percolated through silica gel immediately before use. ferf-Butylbenzene (99.9% by GLC) was used as an inert diluent for cumene and Tetralin where indicated. Squalane (M and B Embaphase) was used as received. AIBN was recrystallized from ether and had a melting point of 102°-103°C. Metal dialkyl dithiophos-phates were prepared as described previously (6) zinc diisopropyl dithio-phosphate was finally recrystallized twice from n-heptane and had a melting point of 146 °C. 

Sulfuric acid (or phosphoric acid) is preferred as an acid catalyst for addition of water to alkenes because the conjugate base, HSO40 (or H2P04e), is a poor nucleophile and does not interfere in the reaction. However, if the water concentration is kept low by using concentrated acid, addition occurs to give sulfate (or phosphate) esters. The esters formed with sulfuric acid are either alkyl acid sulfates R—0S03H or dialkyl sulfates (R0)2S02. In fact, this is one of the major routes used in the commercial production of ethanol and... 

The chemical basis for the phosphite triester approach is the observation, that dialkyl phos-phorochloridites such as (CjHjOJjPCI react very rapidly at the 3 -OH of nucleosides in pyridine even at low temperatures. In contrast, the reactions of analogous chloridates, e.g. (C2HjO)2POCIi require several hours at room temperature. It was later found that phosphite esters can be oxidized quantitatively to the phosphates by using iodine in water and that clean condensation of phosphorochloridites with nucleosides can be achieved in THF at -78 °C. To develop this chemistry into a useful synthetic procedure it was necessary to establish which... 

N(l)-Alkylation of 1,6,7,8,9,9a-hexahydro-4-oxo-4//-pyrido[l,2-a]py-rimidine-3-carboxamide 368 was carried out with dialkyl sulfate in water in the presence of sodium hydroxide, with triethyl phosphate in the presence of potassium carbonate at 235°C, and with butyl bromide in boiling ethanol in the presence of potassium carbonate for 30 hours (83SZP635101 85JOC2918). 

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. 

The mechanism of U02 " extraction by monoalkyl phosphoric acid reagents appears to be a more complex process than for their dialkyl counterparts. This results from the polymerization of the monoalkyl phosphate in the organic phase and the hydration of the extracted uranyl species so that variable stoichiometries arise for the extractant/water/UO complex. The extraction of from sulfuric acid by mono-2,6,8-trimethylnonyl phosphoric acid (H2DDP) and mono-n-butyl phosphoric acid (H2MBP) as 0.05 M solutions in benzene was shown to follow equations (61) and (62) when an excess of extractant was present. When an excess of uranium was present, equations (63) and (64) applied where n, x, y and z were variable numbers which depended upon the extent of extractant polymerization and hydration of the extracted species. Synergistic effects may also be found with the monoalkyl phosphoric acid extractants and in one recent example the use of tri-n-octylphosphine ocxide (TOPO) as a synergist with H2MEHP allowed the extraction of U02 from phosphoric acid solutions. The uranium may be returned to the aqueous phase by contact with concentrated acid, which reverses the extraction process by protonation of the phosphate. 

The starting dialkyl cyanomethylphosphonate is generally dissolved in an aprotic solvent and treated at 0°C under inert conditions with the appropriate base to generate the carbanion. When the resulting mixture becomes clear, the carbonyl compound is added at room temperature, and the reaction is aUowed to continue 1 h for aldehydes and several hours for ketones, occasionally with heating. Workup with water to dissolve the phosphate and subsequent extraction provide the crude a,p-unsaturated nitrile as a mixture of ( )- and (Z)-isomers in which the (El-isomer is predominant. In the great majority of reported examples the two isomers are separated by column chromatography. 

Contact of one cm of a 0.025 molar solution of dialkyl phosphite in tetradecane at 403 K (130 C) with one gram of iron powder which had been ball milled under pentane resulted in depletion of the phosphorus in solution, as shown in Fig. 11-9. Reaction as well as adsorption took place, for soluble iron was found in the solutions of di(2-ethyIhexy1), dilauryl and distearyl phosphites. Chromatography of the solutions after contact revealed large quantities of alcohol dibutyl phosphite and di(2-ethylhexyl) phosphite yielded 92-97% of the theoretical amount of alcohol after 24 hours. Hydrolysis of the phosphite esters was ascribed to water adsorbed on the walls of the reaction tube and on the iron powder. Forbes and Battersby [46] postulated that hydrolysis is an important aspect of the mechanism of the additive action of phosphite esters. Oxidation to phosphate by the oxygen of the ambient air is deemed minor maximum augmentation of the oxygen uptake by a 6.5% solution of dibutyl phosphite over that of the tetradecane carrier fluid in the presence of iron was 20%. The easy hydrolysis of phosphites is well known. Partial... 

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