Tetraphenylphosphonium salts stability

Efforts to increase the catalyst turnover number are indeed another major area where further improvements can be expected. Such improvements have recently been achieved using preformed palladacycles as catalysts or by using a macrocyclic tetraphole as ligand.t Dendritic diphosphine-palladium complexes as catalysts for Heck reactions have also been reported to possess superior stability compared to the monomeric parent compounds.t °" In addition, the same research gronp could considerably activate the rate of the Heck reaction of chlorobenzene and styrene by addition of tetraphenylphosphonium salts and A/,A-dimethylglycine. Transferring snch innovations to the AHR remains an important goal. 

Table 2 lists the cooperativity parameter u and total stability constant K, which are calculated from the adsorption isotherm curves of a bulky surface active agent, tetraphenylphosphonium chloride (TPPC) and PAMPS gel [46]. For comparison, the data for the interaction between Ci2PyCl and PAMPS gel are also shown. When a low molecular weight salt is lacking, both cases show a small cooperativity parameter u and the effect of polymer networks. Since the polymer network effect diminishes under the presence of a large amount of sodium sulfate (lx 10 M), the... 

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