Triethyl phosphate: complex with

PS-fc-poly(4-f-butylstyrene)]n, (PS-fi-PfBuS) star-block copolymers were prepared by anionic polymerization and sequential addition of monomers with DVB as the linking agent for the formation of the star structure [156]. The functionality of the stars ranged between 10 and 20. Selective sulfonation of PS blocks was subsequently performed using the sulphur trioxide and triethyl phosphate complex in 1,2-dichloroethane, followed by neutralization with sodium methoxide. For this reason DVB was used for the linking reaction instead of chlorosilanes, where a better control could be achieved. DVB stars are more robust and the sulfonation reaction proceeds without cleavage of the arms from the star structure. 

Sulfur trioxide reactivity can also be moderated through the use of SO adducts. The reactivity of such complexes is inversely proportional to their stabihty, and consequentiy they can be selected for a wide variety of conditions. Whereas moderating SO reactivity by adducting agents is generally beneficial, the agents add cost and may contribute to odor and possible toxicity problems in derived products. CeUulosic material has been sulfated with SO.—trimethyl amine adduct in aqueous media at 0 to 5°C (16). Sulfur trioxide—triethyl phosphate has been used to sulfonate alkenes to the corresponding alkene sulfonate (17). Sulfur trioxide—pyridine adduct sulfates oleyl alcohol with no attack of the double bond (18). 

Sulfonated polyalkenes were prepared by using a triethyl phosphate—sulfur trioxide complex as the sulfonating reagent along with a solvent at low temperature. Sulfonation takes place at the a-position of the double bond with no cross-linking (222). 

Neutral phosphates (RO)sPO, phosphonates (RO)2R PO and phosphinates (RO)R2PO are well known as extracting agents for metal ions.1823 The isolation of their metal complexes as crystalline compounds is, in general, more difficult than the preparation of complexes with other substituted phosphoryl compounds. It is often essential to reflux solutions of the reactants with dehydrating agents such as triethyl orthoformate or 2,2 -dimethoxypropane. In some cases the neutral phosphoryl ligands or triethyl orthoformate by themselves act as the reaction media in the synthesis of the nickel(II) complexes. 

An early procedure used triethyl phosphate directly on the diketone, but better yields are obtained by the oxidation of the corresponding dihydrazone 42 The oxidant may be mercury(n) oxide, which is rather expensive 43 alternatively copper(i) chloride in dichloromethane and pyridine is oxidised with oxygen gas, and the derived complex is then used to oxidise the dihydrazone to the acetylenic group with the evolution of nitrogen.44 The reaction is illustrated by the conversion of benzil dihydrazone into diphenylacetylene (Expt 5.25). 

Such experiments show that oxalate, tartrate, and citrate give fairly strong complexes, and indeed these mixtures do not suffer quite such rapid oxidation as the other systems (57, 70). Stability constants for the complexing of U(III) by acetate, 2-hydroxy-2-methylpropionate, nitriloacetate, trans-cyclohexyl-1,2-diaminotetraacetate, ethylenedi-amine tetraacetate, and diethylenetriamine pentaacetate have been reported, but no pure compounds have been isolated (71). Thiocyanate also accelerates oxidation of the uranium, but the blue complex that is formed can be extracted with triethyl phosphate, tributyl phosphate, or better, trioctyl phosphine oxide the organic extract decomposes only slowly (45, 72). 

Materials. The starting PP was kindly provided by the Goodyear Tire and Rubber Company. It contains 82% trans and 17% cis double bonds with fewer than 1% vinyl side groups. The molecular weight averages are Mw = 172,000 and = 470,000. The PP was sulfonated using a 1 1 complex of sulfur trioxide with triethyl phosphate in chloroform at room temperature. The sulfonated material was neutralized by precipitating the reaction mixture into a 0.25M solution of NaOH in ethanol. This reaction is described in detail elsewhere (5) and is summarized as follows ... 

Commercial polysulfones (see Table 4.30) such as Udel (Union Carbide) and Victrex (ICI) are sulfonated in a post-functionalization step to make ionomers. When dissolved in dichloroethane and treated with a complex of sulfur trioxide and triethyl phosphate, Udel (XXIV) becomes monosulfonated on the rings marked R (as the rings connected to the sulfone group are deactivated by the sulfone group). 

Conunercially available PES can be sulfonated using sulfur trioxide, triethyl phosphate (TEP) complexes of sulfur trioxide, and chlorosulfonic acid. Due to the high reactivity of sulfur trioxide and its potent dehydration properties, sulfonation reactions with sulfur trioxide sometimes result in the formation of highly insoluble polymer dispersions due to crosslinking caused by inter-polymer chain sulfone formation. In these situations, it is preferable to moderate the sulfonation reactivity by utilization of the sulfur trioxide complexes with TEP. 

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