Green synthesis of glycerol-derived surfactants and carbonates for environmental applications

Nowadays, with the continuous increase of the biodiesel demand significant amounts of glycerol are put on the market (2.5 Mt in 2020) and will represent one of the major worldwide drop-in chemicals for the near future. Among the various possibilities for the production of a wide spectrum of molecules (fine chemicals, commodities, fuel additives, specialities) starting from glycerol, the production of epichlorohydrin (ECH), mostly used in the production of epoxy resins, is an important industrial reality. As a matter of fact, Solvay started in 2011 the glycerol-based production of epichlorohydrin, the so-called Epicerol® process that actually supports the traditional process based on the chlorination of propene at elevated temperatures. Recently, we demonstrated that glycidol can be obtained as value-added product from this process. Moreover, bio-based glycidol can be also obtained though glycerol deoxydehydration to allyl alcohol followed by epoxidation reaction. We recently reported the conversion of the as-obtained glycidol to several chemicals of high concern as well as polymers, solketal, diols and monoalkylglyceryl ethers (MAGEs). Other MAGEs of great interests are represented by surfactants when the aliphatic chain is in the range C8-C24. This class of compounds also respect the 10th principle of Green Chemistry because they are fully biodegradable in the environment and show a very low toxicity. Only few studies deal with long-alkyl ether synthesis, usable as bio-surfactants, from direct etherification of glycerol with fatty alcohols however this approach shows several drawbacks and very poor yields (lower than 15 %) and selectivity. In this work we report on the synthesis of monoalkylglyceryl ethers by glycidol alcoholysis with long-chain alcohols catalyzed by simple homogeneous metal triflates. In the presence of a catalysts based on an Earth-abundant metal, namely Al(OTf)3, the reaction between glycidol and long chain primary alcohols (n-octanol, n-decanol and n-dodecanol) we obtained good conversion to the desired monoalkyl glyceryl ether (MAGE) reaching initial turnover frequency TOF up to 2633 h-1 in the case of octanol. Furthermore, the preparation of organic carbonates from glycerol is a promising route for high-value added compiunds. Herein, we relied on the preparation of glycerol carbonate and diglyceroltricarbonate evaluating their applicability as electrolyte for Li and post-Li battery.