69227-46-9Relevant academic research and scientific papers
Biphasic aqueous organometallic catalysis promoted by cyclodextrins: How to design the water-soluble phenylphosphane to avoid interaction with cyclodextrin
Ferreira, Michel,Bricout, Herve,Sayede, Adlane,Ponchel, Anne,Fourmentin, Sophie,Tilloy, Sebastien,Monflier, Eric
, p. 609 - 618 (2008)
The ability of cyclodextrin to interact with meta-trisulfonated triphenylphosphane derivatives bearing one or two methyl (or methoxy) groups on the aromatic ring has been investigated by NMR and UV-vis spectroscopy. In the case of native β-cyclodextrin (β-CD), the presence of one methyl or methoxy group in the ortho-position on each aromatic ring is necessary to hamper the formation of an inclusion complex between the β-CD and meta-trisulfonated triphenylphosphane derivatives. In the case of methylated β-CD, the formation of an inclusion complex is only observed when the meta-trisulfonated triphenylphosphane contains a methyl group in the para-position. The poor affinity of methylated β-CD towards modified trisulfonated triphenylphosphanes was attributed to the steric hindrance generated by the methyl groups on the CD secondary face. The absence or presence of an interaction between phosphanes and methylated β-CD was also confirmed by catalytic experiments. Thus, the phosphanes that do not interact with the methylated CD were the most efficient mass-transfer promoters in an aqueous biphasic palladium-catalyzed Tsuji-Trost reaction.
Anodic Bahavior of Crowded Triarylphosphines. ESR Study of Triarylphosphoniumyl Radicals, Ar3P.+
Culcasi, Marcel,Berchadsky, Yves,Gronchi, Gerard,Tordo, Paul
, p. 3537 - 3542 (2007/10/02)
A large number of triarylphosphines exhibiting different steric hindrance has been prepared.The pyramidalization angle α of these compounds was calculated with use of the MM2 force field and was shown to depend almost exclusively on the number of ortho substituents on the phenyl rings.In a series of isosteric (same α) phosphines, the oxidation potential correlates with the sum of the ?+ Hammett parameters of the phenyl substituents.In the absence of oxygen, anodic oxidation of all the triarylphosphines bearing two o-methyl substituents on each phenyl ring is reversible and yields very persistent phosphoniumyl radicals.These radicals are easly detected by ESR in liquid solution and were shown to retain a pyramidal geometry that is significantly flattened compared to that of the parent phosphine.
