Solubilized Lanthanide Triflates:  Lewis Acid Catalysis by Polyether and Poly(ethylene glycol) Complexes of Ln(OTf)₃

Abstract

Complexes of lanthanide triflates Ln(OTf)3 with polyether (MeO(CH2CH2O) n Me) and poly(ethylene glycol) (HO(CH2CH2O) n H) ligands (n = 2−4) have been prepared and characterized, and the activity of these complexes as Lewis acid catalysts has been investigated. The complexes [Ln(OTf)3(HO(CH2CH2O) n H)] have been shown to catalyze the allylation of a range of aldehydes with allyltributylstannane, and the complexes [Ln(OTf)3(MeO(CH2CH2O) n Me)] catalyze the Diels−Alder addition of N-crotonyloxazolidinone to cyclopentadiene. The single-crystal X-ray structures of [Dy(OTf)2(H2O)2(MeO(CH2CH2O)4Me)][OTf] and [La(OTf)3(THF)(HO(CH2CH2O)4H)] are reported.

Unexpected differences between thermal and photoinitiated cationic curing of a diglycidyl ether of bisphenol A modified with a multiarm star poly(styrene)-b-poly(ε-caprolactone) polymer

“…Although the reason of this behaviour can be rationalized in a similar way to 5% PS-10 formulation, the fact that some part of PS-10 phase separates during curing, (as it will be seen later by scanning electron microscopy) can probably have an influence on the T g# value. The values of T g# found after photocuring are higher than those found after thermal curing (Table 1), because ytterbium triflates are able to induce reorganization, cyclization and/or degradation reactions when the curing reaches too high temperatures, which results in a network structure with a lower degree of crosslinking and consequently with a lower T g# [43,44].…”

Lanthanide triflates as curing initiators for solid DGEBA resin: Thermal and mechanical characterization

“…where, r 0 is the density of the liquid (distilled water), r L is the air density (0.0012 g/cm 3 ), m air is the weight of the sample in air, and m liq is the weight of the sample immersed in the liquid.…”

“…All these characteristics allow the creation of template structures in the epoxide network. 3 In the present work, we have studied the possibility to use two lanthanide triflates (erbium and ytterbium triflates) in the thermal crosslinking process of medium molecular weight diglycidyl ether of bisphenol-A resins as initiators and as catalysts of a conventional powder system epoxy/o-tolylbiguanide. Ytterbium and erbium triflates were chosen among other lanthanide triflates because their coordinative abilities are similar and might not produce great variation in the reaction rate.…”

Formulación de imprimaciones epoxi en polvo de curado a bajas temperaturas basadas en triflatos de lantánido. Desarrollo de una técnica electroquímica para la evaluación acelerada de la protección anticorrosiva de recubrimientos orgánicos:...

“…Los aniones triflato presentan una nucleofilia pobre, una baja basicidad y una habilidad coordinativa pobre, de forma que, tal y como se ha explicado más arriba para los iniciadores catiónicos, es de esperar la existencia de pocos procesos de finalización de cadena [176].…”

“…Las mayores ventajas [126,160,[173][174][175][176][177][178] que estos iniciadores presentan frente a otros ácidos de Lewis como el AlCl 3 , BF 3 y TiCl 4 son las siguientes:…”