Novel Carboxylic Acid Functionalized Dendronized Polymer: A Homogeneous, Reusable Metal Free Acid Catalyst for the Synthesis of Symmetric and Unsymmetric Xanthene Derivatives

Abstract

In the present study, carboxylic acid‐functionalized tris(hydroxymethyl)propane initiated polyepichlorohydrin cored dendronized polymer (TMP‐PECH‐COOH) was successfully synthesized. Successful incorporation of carboxylic acid functionality was evidenced by Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TG/DTG), and NMR spectroscopy (1H NMR). Thermodynamic properties such as thermal energy, enthalpy, and Gibb's free energy as well as global reactivity descriptors such as chemical potential, chemical hardness, and electrophilicity index of the TMP‐PECH‐COOH dendronized polymer were investigated using Gaussian 09 program employing the hybrid density functional B3LYP method and 6‐31G basis set. The synthesized dendronized polymer (TMP‐PECH‐COOH) could act as a metal‐free acid catalyst for catalyzing the reactions for the synthesis of 1,8‐dioxooctahydroxanthenes and tetrahydrobenzoxanthene‐11‐ones under mild reaction conditions in an aqueous medium. The catalyst could be reused at least six times making the present procedure facile, practical, and sustainable. In addition, the efficiency of the present catalyst was compared with some previous reports.

A synthetically benign one-pot construction of enamino-xanthene dyes

“…24 Moreover, as documented by recent studies, they are aimed at the development of catalytic systems and/or solvent switching that facilitate the preparation of the xanthene nucleus. 25…”