Cleavage of water-insoluble alkylallylcarbonates catalysed by a palladium/TPPTS/cyclodextrin system: effect of phosphine/cyclodextrin interactions on the reaction rate

High‐Pressure 31P{1H} NMR Studies of RhH(CO)(TPPTS)3 in the Presence of Methylated Cyclodextrins: New Light on Rhodium‐Catalyzed Hydroformylation Reaction Assisted by Cyclodextrins

“…Indeed, the association constants of RAME-g-CD/ TPPTS and RAME-b-CD inclusion complexes were found to be 50 and 1000 M À1 at 25 8C, respectively. [16] Finally, this last experiment unambiguously confirms our hypothesis concerning the role of RAME-b-CD.…”

“…[16] As explained above with RAME-b-CD, three equivalents of RAME-a-CD were added to the system. The mixture was shaken in an NMR tube for 1 h under 50 bar of CO/H 2 at 80 8C and the 31 P{ 1 H} NMR spectra acquired at room temperature ( Figure 4).…”

“…Secondly, to confirm the importance of the inclusion complex formation in this equilibrated system, we wanted to compare RAME-b-CD with the RAME-g-CD the trapping properties of which towards TPPTS are intermediate between those of RAME-a-CD and RAME-b-CD. [16] A last experiment was then carried out with 1 and a three molar excess of RAME-g-CD under 50 atm for 1 h at 80 8C in an NMR tube. The spectrum which was recorded after cooling the solution at room temperature (Figure 5b) appeared to be quite similar to that corresponding to 1 in the same conditions without RAME-g-CD (Figure 5a).…”

Biphasic Aqueous Organometallic Catalysis Promoted by Cyclodextrins: How to Design the Water‐Soluble Phenylphosphane to Avoid Interaction with Cyclodextrin

“…In fact, the reaction rate linearly increases with the Rame-b-CD concentration when no interaction occurs between the phosphane and Rame-b-CD. [8] In contrast, when the phosphane interacts with the Rame-b-CD, Rame-b-CD is trapped by the phosphane ligand and is unable to participate in the mass-transfer process at low CD/phosphane ratios (excess of ligand relative to CD). In these conditions, a significant rate increase can only be observed at high CD/phosphane ratios when the amounts of CD are higher than those of ligand (i.e., for a CD/ligand ratio > 1).…”

“…Indeed, when the TPPTS/ Rame-b-CD ratio is too high, the CD cavity is poisoned by the ligand and the substrate transfer is diminished. [8] As approaches based on the use of a-CD derivatives [9] or chemically modified b-CD [10,11] have not given full satisfaction to solve the above problems, strategies based on phosphane modification are now explored. [12] In this work, we examined the potential of bulky TPPTS derivatives in aqueous organometallic catalysis promoted by CD.…”