TPPTS Subject

Hydroformylation of Mid Range Olefins - Rhodium/tppts catalysts exhibit low catalytic activity in the hydroformylation of mid range olefins (C5-Cg) in a two phase system due to the much lower solubility of such olefins in water. In the Rh/tppts catalysed biphasic hydroformylation of 1-hexene, for example the conversion is only 11-22% with a n/i ratio of aldehydes of 98/2.353,373 The rate of 1-hexene hydroformylation catalysed by Rh/tppts increased by a factor 2.3 when subjected to ultrasound (35 kHz) and high stirring rates.360,361... 

C—H activation of the solvent however, upon addition of a strong donor (PMes) dihydrogen elimination is induced, affording TpPt(Me)(PMe3) (377). Definitive explanations for this observation, the facility of H/D scrambling and reluctance toward methane elimination have yet to be established, but are the subject of on-going experimental124 and theoretical studies.125... 

As in most LPO processes, the active species HRh(CO)(TPPTS)3 and the excess TPPTS are subject to slow decomposition which determines the lifetime of the catalyst charge [38a]. Repeated addition of fresh ligand at short time intervals extends the catalyst shelf life and stabilizes the desired P/Rh ratio [215] over the time of operation. The P/Rh ratio is kept above 50 1 to ensure an n/i ratio of at least 95 5 (Figure 16). The RCH/RP process faces more than a decade of success-... 

Metal-catalyzed reductive carbonylation of nitroaromatics using CO has been the subject of intensive investigation in recent years because of the commercial importance of amines, urethanes, and isocyanates (1). Biphasic operation could offer interesting horizons regarding the ease of catalyst recycling. Thus, palladium catalysts have been applied in the presence of water-soluble ligands such as TPPTS or BINAS (2) for the carbonylation of substituted nitroaromatics (Scheme 1). 

Pd-catalyzed allylic substitution reactions can also be performed using water-soluble phosphine ligands, including TPPTS 132, as shown by the reaction of nitroester 48 with allyl acetate 133 to give the substitution product 134 (Scheme 24). The use of water-soluble palladium catalysts has been the subject of a review.t Water-soluble catalysts have also been applied to supported Uquid phase reactions. A silica bead supports a thin film of polar solvent in which the palladium complex resides.t The substrates and product reside in the bulk organic phase and can be decanted from the glass bead catalyst at the end of the reaction. 

---