TPPMS complexes

Water soluble Rh/tppts and Rh/tppms complexes dissolved in nonaqueous media such as the ionic liquids, l-ethyl-3-methylimidazolium or l-n-butyl-3-methylimidazolium salt have also been used as catalysts in the hydroformylation of 1-pentene employing a two phase system.15,16 The yields obtained were 16-33% (TOF=59-103 h 1) without any leaching of the rhodium from the ionic liquid to the aldehydes/feedstock phase. Rh/PPh3 catalysts exhibited higher rates (TOF=333 h 1) for the same biphasic reaction albeit with leaching of rhodium due to the uncharged nature of the catalytic system.15... 

Aromatic and aliphatic aldehydes can be reduced to the corresponding alcohols by hydrogen transfer from formate using TPPMS complexes of... 

The importance of controlling the pH in a two-phase reaction was demonstrated by Jod and co-workers [8, 9]. During their investigation of the hydrogenation of unsaturated aldehydes (Scheme 2) with Ru/TPPMS complexes, they observed a remarkable switch in selectivity on changing the pH. 

This rate law is identical with that found for the hydrogenation of maleic acid in DMF solutions catalyzed by [RuCl2(PPh3)3] [12]. Similar studies with an [HRu(OAc)(TPPMS)3] catalyst showed the same kinetic characteristics and again, this was analogous to the hydrogenation of 1-alkenes in benzene with [HRu(OAc)(PPh3)3] as catalyst [12]. For both TPPMS complexes, a simple mechanism accounted for all the kinetic observations (Scheme 1). 

The application of ethylene in Heck reactions often shows different activities from other alkenes, because of Wacker-type side reactions. It was found, however, that iodo- and acceptor-substituted bromoarenes are cleanly converted in aqueous media to the corresponding styrenes utilizing a palladium-TPPMS complex [13], Furthermore, high purity o- and p-vinyltoluenes were prepared on a large scale (in... 

Investigating the influence of the loading of the hydrophilic liquid phase, it was observed that maximum activity was obtained with a pore filling of 10%. That amount of hydrophihc phase corresponded to a theoretical film thickness of 16 A. Molecular modelHng of the Pd-TPPMS complex revealed that the average diameter of the complex was 11 A, the largest diameter being 15 A. Thus, a monolayer of catalyst on the support was assumed. 

Cyclic voltammograms of complexes 8 and 9 both exhibit a single oxidation wave assigned to the Ru(II/III) oxidation process (Table 1). The electrooxidation of neat methanol with complexes 8 and 9 was performed at 1.2S V and at 1.40 V. Higher current efficiencies for the electrooxidation of methanol are obtained with the Ru/TPPMS complexes 8 and 9 than are obtained with complexes 2 and 7 (Table IV). Complex 7 has been shown to form significantly more DMM than MF at lower potentials this effect is also observed during the electrolysis with complex 9. When the potential was decreased from 1.40 V to 1.25 V the amount of DMM in the product mixture increased from 90.5% to 100%. To our knowledge, no other examples of selective electrooxidation of methanol to DMM have been reported. 

Water soluble mthenium(II) complexes [RuCl2(t -arene)(L)] [L = PTA (61), (PTA-Bz)Cl (62), DAPTA (63), TPPMS (64) t/ -arene = CgMee (a), 1,3,5-CeHaMea (b), p-cymene (c), CgHg (d)] were used by Cadiemo et al. [60] as catalysts for the synthesis of [i-oxo esters, important precursors for industrially relevant a-hydroxy ketones, by addition of terminal propargylic alcohols to carboxylic acids in aqueous medium. As a model reaction, l-phenyl-2-propyn-l-ol (1 mmol) was reacted with benzoic acid (1 mmol) in 1 mL of water in the presence of 2 mol % of Ru complex and stirred at 60 °C for 24 h. The best results were obtained with the TPPMS complexes (76-87% yields) whereas lower yields (14-71%, the latter in the presence of 61a) were observed for the PTA-type catalysts. 

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