ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Preparation of Lewis acid ionic liquids for one-pot synthesis of benzofuranol from pyrocatechol and 3-chloro-2-methylpropene

Han-Cheng Zhou, Xiu-Lei Li, Juan-Li Liu, Cheng Peng, Bin Zhang, Jin Chen, Qiong Su, Lan Wu, and You-Zhu Yuan

Key Laboratory for Utility of Environment-Friendly Composite Materials and Biomass in University of Gansu Province, College of Chemical Engineering, Northwest University for Nationalities, Lanzhou 730030, China

E-mail: hanchengzhou@hotmail.com

Abstract: Several Lewis acid ionic liquids (LAILs) with different acidic scales were synthesised and used as catalysts for the synthesis of benzofuranol by condensation of pyrocatechol and 3-chloro-2- methylpropene in one pot. The catalytic activity of these ionic liquids was correlated with their Lewis acidity. Low to moderate conversion with excellent selectivity to benzofuranol was obtained in the presence of the appropriate LAILs. Compared to the two-step synthetic method currently used in industry, a higher yield plateau (81.1 %) of benzofuranol was achieved in the presence of [BMIm][AlCl₄] IL as catalyst at 418 K after 4 h. Furthermore, the catalyst is readily separated from the resultant products via decantation and could be reused after treatment in vacuum.

Keywords: benzofuranol – condensation – Lewis acid ionic liquid – acidity

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2015-0145

Chemical Papers 69 (10) 1361–1366 (2015)