Scope and Regioselectivity of Iridium-Catalyzed C–H Borylation of Aromatic Main-Chain Polymers

Abstract

An efficient functionalization of aromatic main-chain polymers was established using a combination of iridium-catalyzed borylation of aromatic C–H bonds and the Suzuki–Miyaura coupling reaction. Comparative studies of various iridium catalysts and borylation reagents show that [Ir(OMe)(COD)]2 is significantly more active than [IrCl(COD)]2, and bis(pinacolato)diboron induces higher efficiency than pinacolborane. The regioselectivity of the borylation was investigated using model compounds that mimic the repeating unit structure of poly(arylene ether sulfone). The C–H bonds of the sulfone model compound were more reactive than those of the bisphenol model compound, and the borylation occurred preferentially at the meta position to the sulfone moiety owing to steric hindrance and electronic effects. The glass transition temperature of the borylated polymer increases with increasing concentration of pinacolboronic ester group. The pinacolboronic ester group could be conveniently converted to boronic acid [B(OH)2] and potassium trifluoroborate (BF3K), which could also serve as versatile reactive sites for the synthesis of a wide range of functionalized polymers via Suzuki–Miyaura couplings.

Effects of tertiary amines and quaternary ammonium halides in polysulfone on membrane gas separation properties

“…The PSU backbone has four different aromatic C—H bonds. Among them, the ones meta to sulfone group were suggested to be the most reactive followed by those meta to isopropylidene group . Due to the presence of regioisomeric mixtures, the 1 H NMR signal of the Bpin appeared at two positions with the signal at 1.23 ppm more intense than that at 1.02 ppm.…”

Preparation and properties of novel boric acid modified poly(aryl ether sulfone) membranes

“…FT-IR spectra were measured on a Bruck Victor22 Fourier-transform infrared spectrometer. 1 H NMR experiments were carried out on a Bruker 510 spectrometer (500 MHz for 1 H) using DMSO-d 6 and CDCl 3 as solvent. The morphology of the membranes was analyzed by scanning electron microscope (SEM) (SHIMDZU SSX-550, Japan).…”

“…It has been widely used in various industrial applications, such as electronics, machinery, automobile, food, and medical equipments, paints and so on. [1][2][3] However, because of their amorphous nature, poly(aryl ether sulfone)s is readily soluble in common solvents such as N-methylpyrrolidone (NMP), N,N-Dimethylacetamide (DMAc), chloroform, and tetrahydrofuran (THF). This limits their application.…”

“…(1) and (2)]. They suggested that a mixture of mono-, di-, and tri-phenyl substituted boric acid were prepared by altering the molar ratio of phenol to boric acid.…”

C−H Functionalization of Commodity Polymers

“…[61] This C À Hb orylation method achieves an average of two pinacol boronic ester (Bpin) groups per repeat unit of PES with minimal influence on the MWD of the polymer 13. [62,63] TheB pin groups can subsequently be employed in Suzuki-Miyaura cross-coupling reactions,which install avariety of new functional groups on the polymer 14.…”