Dialkyl phosphates

The purification of the galHum salt solutions is carried out by solvent extraction and/or by ion exchange. The most effective extractants are dialkyl-phosphates in sulfate medium and ethers, ketones (qv), alcohols, and trialkyl-phosphates in chloride medium. Electrorefining, ie, anodic dissolution and simultaneous cathodic deposition, is also used to purify metallic galHum. 

Phosphoric acid, monoalkyl phosphates, and phosphonic acids, but not dialkyl phosphates (107), can be aminoalkylated on the oxygen (108—110). 

Mixtures of a titanium complex of saturated diols, such as TYZOR OGT, and a titanium acylate, such as bis- -butyl-bis-caproic acid titanate, do not have a yellowing or discoloring effect on white inks used to print polyolefin surfaces (506). The complexes formed by the reaction of one or two moles of diethyl citrate with TYZOR TPT have an insignificant color on their own and do not generate color with phenol-based antioxidants (507). The complexes formed by the addition of a mixture of mono- and dialkyl phosphate esters to TYZOR TBT are also low color-generating, adhesion-promoting additives for use in printing polyolefin films (508). 

This derivative, synthesized by a silver oxide-promoted condensation of pyrenylmethyl chloride and a dialkyl phosphate (92% yield), is quantitatively cleaved by photolysis at >300 nm in 60 min. ... 

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 ... 

Good results were obtained with derivatives of phosphonic acids, such as alkylenediphosphonic acids [87,217] and alkyliminodimethylenediphosphonic acids [218]. Long-chain dialkyl phosphates added to lard and other fats are also said to prevent rancidity [238]. 

There are also examples in which phosphate esters of saturated alcohols are reductively deoxygenated.229 Mechanistic studies of the cleavage of aryl dialkyl phosphates have indicated that the crucial C-O bond cleavage occurs after transfer of two electrons.230... 

Dialkyl phosphates can also be obtained if the ratio of alcohol to PC13 is properly maintained. Halogens will react with alkyl phosphites to give products that have a halogen bound to the phosphorus atom... 

Figure 6.28 Photoinduced reaction of an organomercury compound with a dialkyl phosphate salt.

Fig. 19 Addition of lithium dialkyl phosphate to iV-glycosylnitrones and analogues.

An interesting approach towards the formation of glycosyl 1-phosphates by dehydrative glycosylation of nucleophilic dialkyl phosphate acceptors with... 

True phosphoric anhydrides are prepared by a method strictly analogous to reaction (c), viz. by the action of a dialkyl phosphorochloridate (p. 43) on the silver dialkyl phosphate ... 

The reaction between a dialkyl phosphorochloridate and a silver dialkyl phosphate has already been referred to (p. 100). 

The calculation for dibenzylphosphoenolpyruvate assumes that the enol dibenzyl phosphate will have the same reactivity towards bimolecular attack by RCOOH as the dialkyl phosphate group of A.5.5. The comparison between A.5.3 and A.5.4 shows that the substitution of an alkoxy group by phenyl increases the reactivity by an order of magnitude towards COOH, and this factor allows us to put the phosphonate A.5.1 on the scale. The intrinsic reactivity of A.5.1 and A.5.2 are assumed the same b Gordon el al., 1964 Blackburn and Brown, 1969 c van Holst el al., 1974... 

Brokopp CD, Wyatt JL, Gabica J. 1981. Dialkyl phosphates in urine samples from pesticide formulators exposed to disulfoton and phorate. Bull Environ Contam Toxicol 26 524-529. 

A broad range of compounds can be O-alkylated with carbene complexes, including primary, secondary, and tertiary alcohols, phenols, enols, hemiaminals, hydroxylamines, carboxylic acids, dialkyl phosphates, etc. When either strongly acidic substrates [1214] and/or sensitive carbene precursors are used (e.g. aliphatic diazoalkanes [1215] or diazoketones) etherification can occur spontaneously without the need for any catalyst, or upon catalysis by Lewis acids [1216]. 

Barr, Dana B., et al. (2004). Concentrations of dialkyl phosphate metabolites of organophosphorus pesticides in the U.S. population. Environmental Health Perspectives 112(2) 186-200. Greenlee, A. R., T. M. Ellis, and R. L. Berg. (2004). Low-dose agrochemicals and lawn-care pesticides induce developmental toxicity in murine preimplantation embryos. Environmental Health Perspectives 112(6) 703-709. 

In urine, OPFR metabolites have been detected, but the median concentrations of the diaryl and dialkyl phosphates remained mostly below the quantification limit. Ranges of concentrations of dialkyl and diaryl phosphates are shown in Table 4. In the study of Schindler et al. [302, 303], the detection frequency was highest for BCEP (50%), followed by DPP (30%), BCPP (12%), and DBP (3%). Di-w-cresyl and di-/7-cresyl phosphate were not found in any sample, probably due to lower exposure in the indoor environment. Reemtsma et al. [304] found also monoaryl and alkyl phosphates in human urine, of which the monobutyl phosphate was the... 

Reemtsma T, Lingott J, Roegler S (2011) Determination of 14 monoalkyl phosphates, dialkyl phosphates and dialkyl thiophosphates by LC-MS/MS in human urinary samples. Sci Total Environ 409 1990-1993... 

Dialkyl phosphates and hypophosphorous acid (H3P02) are also excellent hydrogen-atom donors. These compounds have weak H—P bonds which react with alkyl radicals. 

Because of the lack of information in the literature on the radical reactions of compounds of quinquevalent phosphorus, it is impossible to postulate a readily acceptable mechanism for the oxidation of zinc dialkyl dithiophosphates. Colclough and Cunneen (7) rejected immediately the possibility of hydrogen abstraction, but in view of the present results serious consideration has been given to this reaction. During this work it was shown (15) that abstraction of hydrogen from trialkyl phosphates, trialkyl phosphonates, and sodium dialkyl phosphates can occur at room temperature in an aqueous medium in the presence of hydroxy radicals. 

Problem 13.60 Explain why trialkyl phosphates are readily hydrolyzed with OH to dialkyl phosphate salts, whereas dialkyl hydrogen phosphates and alkyl dihydrogen phosphates resist alkaline hydrolysis. 

Mount ME. 1984. Diagnostic value of urinary dialkyl phosphate measurement in goats exposed to diazinon. Am J Vet Res 45(4) 817-24. 

Reid SJ, Watts RR. 1981. A method for the determination of dialkyl phosphate residues in urine. J Anal Toxicol 5 126-131. 

Richardson ER, Seiber JN. 1993. Gas chromatographic determination of organophosphorus insecticides and their dialkyl phosphate metabolites in liver and kidney samples. J Agric Food Chem 41 416-422. 

The alkylating activity is dependent on the size of the alkyl group with the relative activity following the order methyl ethyl > propyl > butyl. Beyond butyl, the activity is greatly minimized. For alkyl esters of dibasic (e.g., sulfate) andtribasic (e.g., phosphate) acids, the alkylating activity is completely eliminated if any of the alkyl groups are hydrolyzed (e.g., monoalkyl sulfate or dialkyl phosphate) (Table 14.10). 

Since the resulting monoalkyl sulfate or dialkyl phosphate lacks alkylating activity, remove one of the alkyl groups from the esters of dibasic (e.g., sulfate) and tribasic (e.g., phosphate) acids. 

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