Industrial Crops and Products 78 (2015) 91–94 Contents lists available at ScienceDirect Industrial Crops and Products journal homepage: www.elsevier.com/locate/indcrop Chemicals from biomass: Efficient and facile synthesis of 5,5 ′ (oxy-bis(methylene))bis-2-furfural from 5-hydroxymethylfurfural Khaled Mliki, Mahmoud Trabelsi ∗ Laboratory of Natural Substances, Faculty of Sciences, University of Sfax, Route de Soukra Km 3.5, 3038 Sfax, Tunisia a r t i c l e i n f o Article history: Received 12 June 2015 Received in revised form 12 September 2015 Accepted 12 October 2015 Keywords: 5,5 ′ (Oxy-bis(methylene))bis-2-furfural Heterogeneous catalyst Ultrasound 5-Hydroxymethylfurfural a b s t r a c t An ultrasonic-assisted method to obtain 5,5 ′ (oxy-bis(methylene))bis-2-furfural a prepolymer and an antiviral precursor was presented in the present paper. Amberlyst-15 was used as an efficient and recy- clable heterogeneous catalyst to realize the etherification of 5-hydroxymethylfurfural. The crucial role of ultrasound in terms of improving the time and catalyst efficiency, reaction yield was also discussed. © 2015 Elsevier B.V. All rights reserved. 1. Introduction The preparation of chemicals from bioresources rather than steadily depleting fossil resources has become a vital neces- sity for the sustainable chemical industry (Zhao et al., 2012; Gallezot, 2012). In this respect, one of the most widely envisioned approaches is to develop efficient processes, especially efficient and non-toxic catalysts to transform biomass into some plat- form molecules and further convert these platform molecules into various chemicals (Combs et al., 2013; Khokhlova et al., 2012). 5- Hydroxymethylfurfural (5-HMF, 1), which can be produced from the dehydration of hexose (Simeonov et al., 2012), has been con- sidered as a vital platform molecule in biorefinery processes (Che et al., 2012). It is an intermediate for many other products, including pharmaceutical products (Sriwilaijaroen et al., 2011), fungicides, flavor-enhancers in the food industry (Villard et al., 2003; Terada et al., 2010), polymers (Gruter et al., 2010), and alkane biofuels (Yin and Tan, 2012). 5-HMF and its derivatives could replace petroleum- based building blocks and could also be used to make polymers and valuable chemicals (Arias et al., 2013). The synthesis of 5,5 ′ (oxy-bis(methylene))bis-2-furfural (OBMF, 2) from the etherification of two 5-HMF molecules is of much inter- est thanks to the versatile applications of OBMF. OBMF can be used not only as a monomer for the preparation of some imine-based polymers with high thermal and electrical conductivity (Moreau ∗ Corresponding author. Fax: +216 74676606. E-mail address: Mah.Trabelsi@fss.rnu.tn (M. Trabelsi). et al., 2004), but also for the synthesis of heterocyclic ligands and hepatitis antiviral precursors (Casanova et al., 2010) With the aim of improving the synthesis of OBMF, solid acids have been used. Zeolites (Park and Keane, 2001; Collignon et al., 1999) and mesoporous aluminosilicates with Brönsted and Lewis acid sites (Shi and Davis, 1995; Berteau et al., 1987) and graphene oxide (GO) were used as catalysts for the heterogeneous synthesis of OBMF from 5-HMF (Timko and Cram, 1974). Recently, available Amberlyst-15 has played an important role in organic synthesis. This review summarizes the versatile synthetic applications of Amberlyst-15 in various chemical trans- formations (Cannilla et al., 2012). The present research work reports the use of Amberlyst-15 resin as an efficient heterogeneous catalyst for the synthesis of OBMF from 5-HMF under mild reac- tion conditions. The effects of solvent, reaction condition (time and temperature) and the yield of OBMF were carefully studied. 2. Material and methods 2.1. General methods Amberlyst-15 resin was used as acid catalyst for the preliminary reactions of 5-HMF with various solvents. Amberlyst- 15, dichloromethane (98–99%) (DCM), N,N-dimethylformamide (>99%) (DMF), tetrahydrofuran (99%) (THF) and chloroform (>99%) (CHCl 3 ) were purchased from Fluka and used as received. 5-HMF was purchased from Sigma–Aldrich and used as the starting mate- rial for this study. The mixture was reacted in a high-power US-bath (20 kHz) with a nominal power 250 W. Reactions were monitored http://dx.doi.org/10.1016/j.indcrop.2015.10.026 0926-6690/© 2015 Elsevier B.V. All rights reserved.