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Atlanta Chemical Engineering, news |
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| July 15, 2008, Microwave assisted synthesis of esters A simple, fast and clean process to make esters without a catalyst is being developed by Chemicrea Inc. with the support of New Energy & Industrial Technology Development Organization (Kawasaki), and Gifu University (Gifu, all Japan). The process uses microwaves to continuously drive off the water byproduct, thereby shifting the reaction equilibrium to the right; this not only increases the speed and yield of the reaction, but also reduces the waste generated by conventional esterifications. In the laboratory, the new process has been demonstrated for making benzyl bromoacetate. The conventional way to make this ester has been to react bromoacetic acid with benzyl alcohol in an organic solvent (such as toluene) and a catalyst (such as sulfuric acid) - a process that requires a lot of time (up to 20 h), high temperatures, and additional purification steps to remove residual catalyst and solvent from the product. In the new process, a mixture of bromoacetic acid and benzyl alcohol at 125 - 150 C is simply irradiated by microwaves (2.45 GHz, 5 - 7 kW) under a vacuum of 100 mm Hg. An 80% yield is achieved in about one third the time needed by the conventional route, and the absence of catalyst and solvent simplifies the product purification while reducing waste, says the firm. |