Choline chloride/pentaerythritol: a deep eutectic solvent for the synthesis of pyran and chromene derivatives
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ORIGINAL PAPER
Choline chloride/pentaerythritol: a deep eutectic solvent for the synthesis of pyran and chromene derivatives Setareh Azimzadeh‑Sadeghi1 · Issa Yavari2 Received: 11 July 2020 / Accepted: 19 October 2020 © Iranian Chemical Society 2020
Abstract A novel deep eutectic solvent system was prepared by mixing choline chloride as a hydrogen-bond acceptor with 2,2-bis(hydroxymethyl)propane-1,3-diol (pentaerythritol) as a hydrogen-bond donor. This green solvent was used for the one-pot synthesis of pyran and chromene derivatives from aromatic aldehydes, 1,3-dicarbonyl compounds, and malononitrile. The solvent was readily recycled and can be reused three times without significant loss of activity or mass. This procedure offers advantages such as environmental friendliness, shorter reaction times, and higher yields. Graphical abstract
Keywords Deep eutectic solvent · Choline chloride · Pentaerythritol · Pyran · Chromene · Green chemistry
Introduction The design of innovative organic and green solvents plays a significant role in synthetic organic chemistry [1–3]. Deep eutectic solvents (DESs) are a new class of green organic solvents introduced by Abbott [4] and continuously have Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13738-020-02108-5) contains supplementary material, which is available to authorized users. * Issa Yavari [email protected] 1
Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran
Department of Chemistry, Tarbiat Modares University, Tehran, Iran
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been investigated in academic and applied research for more than a decade. In general, a DES is defined as simple mixture of two or three components forming a eutectic with lower melting point than each of the pure components. This liquid system, composed of a network of hydrogen-bond acceptor and hydrogen-bond donor molecules, provides suitable polarity owing to the abundance of hydrogen bond [5–9]. These solvents are less toxic, biodegradable, cheap, easy to prepare, with low vapor pressure and melting points, and often good thermal stability [10, 11]. The combination of choline chloride (ChCl) and urea as a deep eutectic solvent has been applied to the synthesis of benzo-fused seven-membered heterocycles via a one-pot, three-component reaction [12]. Recently, sustainable synthesis and application of natural DES systems based on malic acid, citric acid, xylitol, and water were
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reported [13]. The effect of water on the physicochemical properties and on the structural features of three DESs formed by ChCl and glycols with a different number of oxyethylene units has been evaluated [14]. A series of ternary DES systems have been prepared using a mixture of microorganism-derived (R)-3-hydroxynonanoic and (R)3-hydroxyheptanoic acids as hydrogen-bond donors and selected quaternary ammonium salts as hydrogen-bond acceptors [15]. Pyrans are attractive heterocyclic compounds with various biological and pharmacological
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