The catalyzed and uncatalyzed preparation of ethyl levulinate from levulinic acid and ethanol is presented. In the case of acid-catalyzed reactions, conditions were optimized in batch using microwave heating and then scaled-up using continuousflow processing. Both p-toluenesulfonic acid and sulfuric acid were used as catalysts, the latter proving most amenable. For the uncatalyzed reactions, all reactions were performed under continuous-flow conditions, using apparatus capable of operating at high temperature and pressure. Optimal conditions for the uncatalyzed process required heating a 3.6-M solution of levulinic acid in ethanol at 270 °C with a residence time of 30 min.
A continuous-flow approach to the direct synthesis of arene chromium tricarbonyl complexes is presented. By working in flow mode, it is possible to avoid some of the problems of batch synthesis, especially sublimation of the Cr(CO)6 starting material and the competitive decomposition of the product during the lengthy reaction times. Heating at 220 °C and operating with a residence time of 10 min through the heated zone allows for the synthesis of (η6-C6H5CH3)Cr(CO)3 as an example, along with a selection of other (arene)Cr(CO)3 complexes.