Using Soluble Polymers in Latent Biphasic Systems

Abstract

A new strategy for carrying out reactions with a soluble polymer-bound reagent or catalyst is described. In this latent biphasic process, a solvent mixture at the cusp of immiscibility is prepared and used to carry out a reaction under homogeneous conditions. Then, after the reaction is complete, this mixture is perturbed by the addition of solvent or some other perturbing agent to produce a biphasic mixture. The product-containing phase is then separated under liquid/liquid conditions from the polymer-containing phase. The generality of this process is demonstrated using both dye-labeled polymers as surrogates for polymer-bound catalysts and with various polymer-bound organic and transition metal catalysts or reagents. In cases where a polymeric catalyst is used, the addition of fresh solvent and substrate reforms the original mixture allowing facile reuse of the catalyst.

Activated Ester Containing Polymers: Opportunities and Challenges for the Design of Functional Macromolecules

“…594 To ensure maximum recovery and reuse of the catalyst, a biphasing condition is usually created either by perturbing the solution or by addition of another immiscible solvent that separates the polymer from the catalyst or the product. 595,592 For air-or moisture-susceptible polymeric catalyst, additional introduction of a closed and continuous microfluidic loop system in conjunction with thermomorphic multicomponent system conditions was found to be more advantageous. 593 For a polyNIPAM support, catalyst recovery was achieved by simply varying the reaction temperature or salt concentration that affected the LCST of polyNIPAM and conferred stimuliresponsive precipitation of the polymer-bound catalyst.…”

Immobilization of Organic Catalysts: When, Why, and How

“…[4] They are all due to the excellent work that Bergbreiter and his group [43,44] devoted to the development of soluble polymeric supports for facile catalyst recovery by the use of thermomorphic systems or of latent biphasic separation. Recent research in this context led to the identification of poly(4-tert-butylstyrene) (PtBS) as a particularly convenient support for homogeneous catalysts and to the synthesis of the supported DMAP analogue 7 depicted in Figure 4.…”

Novel Densely Alkylated Hydroxyl‐Functional Polyvinylpyrrolidone Showing Phase‐Selective Solubility

“…[8][9][10][11][12][13][14] An example of a thermomorphic solvent system is a 1:1 (v:v) mixture of heptane and N,Ndimethylformamide (DMF). [15] This mixture is biphasic at room temperature but becomes monophasic if heated to 70 8C.…”