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    Chemoenzymatic polycondensation of para-benzylamino phenol
    (SPRINGER INTERNATIONAL PUBLISHING AG, 2016) Yildirim, Pinar; Gokturk, Ersen; Turac, Ersen; Demir, Haci O.; Sahmetlioglu, Ertugrul
    para-Benzylamine substituted oligophenol was synthesized via enzymatic oxidative polycondensation of 4-(benzylamino) phenol (BAP). Polymerization involved only the phenolic moiety without oxidizing the sec-amine (benzylamine) group. Chemoselective polycondensation of BAP monomer using HRP enzyme yielded oligophenol with sec-amine functionality on the side-chain. Effects of various factors including solvent system, reaction pH and temperature on the polycondensation were studied. Optimum polymerization process with the highest yield (63 %) and molecular weight (M-n = 5000, degree of polymerization approximate to 25) was achieved using the EtOH/buffer (pH 5.0; 1 : 1 vol. ratio) at 25 degrees C in 24 h under air. Characterization of the oligomer was accomplished by H-1 NMR and C-13 NMR, Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), ultraviolet-visible spectroscopy (UV-Vis), cyclic voltammetry (CV) and thermogravimetric analysis (TGA). The polymerization process involved the elimination of hydrogen from BAP, and phenolic -OH end groups of the oligo(BAP), confirmed using H-1 NMR and FT-IR analyses. The oligomer backbone possessed phenylene and oxyphenylene repeat units, and the resulting oligomer was highly soluble in common organic solvents such as acetone, CHCl3, 1,4-dioxane, N, N-dimethylformamide (DMF), tetrahydrofurane (THF) and dimethylsulfoxide (DMSO). Oligo(BAP) was thermally stable and exhibited 5 % and 50 % mass loss determined by thermogravimetric analysis at 247 degrees C and 852 degrees C, respectively. (c) 2015 Institute of Chemistry, Slovak Academy of Sciences