These benzidines with 3,3'-bis(sulfoalkoxy) groups have been synthesized by alkylation of commercial 3,3'-dihydroxy-4,4'-benzidine with propaneor butanesultones! However, there is no report on a synthetic method for the 2,2'-substituted or alkylsulfonated ones. We report here a route to 3,3'-bis(sulfomethy1)and 2,2'-bis (sulfoalkoxy)-4,4'-benzidine via the benzidine rearrangement.
Synthesis and properties of highly sulfonated proton conducting polyimides from bis(3-sulfopropoxy)benzidine diaminesElectronic supplementary information (ESI) available: 1H NMR spectra of BSPB diamines and IR spectra of resulting polyimide membranes. See http://www.rsc.org/suppdata/jm/b3/b313276e/
Two novel sulfonated diamine isomers, 2,2′-bis(3-sulfopropoxy)benzidine (2,2′-BSPB) and 3,3′-bis(3-sulfopropoxy)benzidine (3,3′-BSPB), were successfully synthesized and the highly sulfonated polyimides (SPIs) with sulfonic acid groups in the side chains were prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and BSPB monomers. Transmission electron microscopy (TEM) analysis revealed that these side-chain-type SPI membranes have a microphase-separated structure composed of hydrophilic side chain domains and hydrophobic polyimide main chain domains. They showed high proton conductivities similar to or higher than those of Nafion 117 in the high relative humidity range (>70% RH). The proton conducting behavior was analyzed by percolation theory. Despite their high ion exchange capacity (IEC = 2.89 meq. g−1) and high water uptakes, they displayed much better water stability than common sulfonated polyimides with the sulfonic acid groups directly bonded to the polymer backbone. This is probably due to the microphase-separated structure of the membrane and the strong basicity of BSPB diamine moieties resulting from the electron donating effect of the propoxy groups. The sulfopropoxy groups were stable against aging in acidic aqueous solution at 373 K. Both the polyimide membranes showed good mechanical strength under high moisture conditions (about 6 GPa at 90% RH) and displayed anisotropic membrane swelling.
[EN] TETRACARBOXYLIC DIANHYDRIDE, CARBONYL COMPOUND, ACID-ANHYDRIDE-GROUP-CONTAINING COMPOUND, METHODS FOR PRODUCING THESE, POLYIMIDE, AND POLYIMIDE PRECURSOR RESIN<br/>[FR] DIANHYDRIDE TÉTRACARBOXYLIQUE, COMPOSÉ CARBONYLE, COMPOSÉ CONTENANT UN GROUPE ANHYDRIDE D'ACIDE, PROCÉDÉS DE PRODUCTION DE CEUX-CI, POLYIMIDE ET RÉSINE PRÉCURSEUR DE POLYIMIDE<br/>[JA] テトラカルボン酸二無水物、カルボニル化合物、酸無水物基含有化合物、それらの製造方法、ポリイミド及びポリイミド前駆体樹脂