Nonionic Water-soluble Phosphines

Marcel Schruder Goedheijt, Paul C. J. Kamer, Joost N. H. Reek, 

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In 2003 Jin and coworkers [13] reported on the synthesis of a novel nonionic water-soluble phosphine 3 by a two-step ethoxylation of 2-(diphenyl-phosphinojphenylamine. In this new family of nonionic phosphines the polyoxyethylene moieties are introduced into the amino group of organo-phosphines. 

Thermoregulated Phase-transfer Catalysis with Nonionic Water-soluble Phosphines... 

Tab. 1 Cloud [11.13]- points of nonionic water-soluble phosphines with polyoxyethylene moieties ...

The inverse temperature dependence of the water-solubility of nonionic tenside phosphines at the Tp was applied by Bergbreiter et al. [41] in the hydrogenation of allyl alcohol using water-soluble rhodium catalysts modified with the smart ligand 15 in aqueous media. In this case, on heating the sample to 40-50°C the reaction stopped but on cooling to 0 °C hydrogenation was resumed in the aqueous phase (cf. Section 4.6.3). 

Some other C—C bond coupling reactions in micellar systems should be mentioned here. Monflier et al. [72] described, in both papers and patents, the telome-rization of 1,3-butadiene into octadienol in a micellar system by means of a palladium-phosphine catalyst. Water-soluble and amphiphilic phosphines have been used and the surfactants were widely varied. The authors have shown that the promoting effect of surfactants appeared above the CMCs of the surfactants, and they conclude that micellar aggregates were present in the reaction mixture. Cationic, anionic, and nonionic surfactants gave this micellar effect but the combination of the highly water-soluble TPPTS and the surfactant dodecyldimethylamine hydrocarbonate was found to be best. A speculation about the location of reactants shows that the reaction probably occurs in the interface between the micellar pseudophase and water. 

Fig. 2 Atmospheric-pressure hydrogenation of sodium cinnamate using Rh/6 (N = 32, R = n-CsH,) as the catalyst in water at different temperatures. The cloud point of the catalyst is 64 °C. Anti-Arrhenius kinetic behavior results due to the inversely temperature-dependent water-solubility of the nonionic phosphine [16].

The compounds triisobutyl (methyl) phosphonium tosylate (a) and trihexyl (tetradecyl) phosphonium bis 2,4,4-(trimethylpentyl)phosphinate (b) were synthesized (Fig. 4.14), and their surface-active properties studied.The polar compound (a) is water soluble and surface active, does not form micelles, but affects the micelliza-tion properties of ionic, nonionic, and zwitterionic surfactants more strongly than conventional electrolytes. The less polar compound (b) forms micelles and has very low aqueous solubility. Both compounds form mixed micelles with Triton X-100 nonionic surfactant in aqueous solution. Compound (a) replaces water to form microemulsions with isopropyl myristate as oil, stabilized by (b). Compound (a) showed a clear antitumor activity, for example, 5mg (a)mH in 0.9% NaCl solution caused 100% killing of Sarcoma-180 cell line in 1 h. More diluted solutions were still active 2.5 and 1 mg (a) mT caused 81 and 53% killing of the same cells, respectively. On the other hand, compound (b) was less active than (a) lOmg (b)mT in 0.9% NaCl solution caused 89% killing of Sarcoma-180 cell line in 2h. Note that the concentration of (b) employed was 33 times higher than its cmc (0.03 x 10" moll ). The efficiency of (a) with respect to (b) may be due to the fact that the former does not form micellar aggregates [89]. 

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