Heck process, biphasic

Many other C-C bond forming reactions involving organometallic catalysis have been successfully performed in an aqueous biphasic system. Examples are shown in Fig. 7.13 and include Heck [47, 48] and Suzuki couplings [48] and the Rhone-Poulenc process for the synthesis of geranylacetone, a key intermediate in the manufacture of vitamin E, in which the key step is Rh/tppts catalyzed ad-... 

Because carbonylation is a process of high practical importance, considerable work has been done on developing a recyclable biphasic protocol. Carbonylation is a hard challenge for this task, because, similar to the case of the Heck reaction, this process leads to the formation of salts, which irreversibly change the composition of the aqueous catalyst-containing layer and lead to its degradation. Besides, the products of hydroxycar-bonylation, the carboxylates, are soluble in water and must be recovered from alkaline solution. Acidification leads to the formation of an additional amount of salt. Therefore, in spite of extensive research, the recyclability of the systems developed so far is only modest. Rarely can more than a single reuse be achieved. 

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