Effect of Reaction Parameters on the Synthesis of 5‑Arylidene Barbituric Acid Derivatives in Ball Mills
2015-03-20T00:00:00Z (GMT) by
The influence of crucial reaction parameters on Knoevenagel condensation in planetary ball mills was investigated. Rotation frequency (<i>ν</i><sub>rot</sub>), milling ball diameter (<i>d</i><sub>MB</sub>), milling ball filling degree (<i>Φ</i><sub>MB</sub>), and beaker size had obvious influences on yield. It was found that higher <i>ν</i><sub>rot</sub>, lower <i>d</i><sub>MB</sub>, milling beakers with larger diameter, and a <i>Φ</i><sub>MB</sub> of ∼0.3 are advantageous for the reaction. Furthermore, the influence of the type of mill was investigated, including reactions performed in different planetary and mixer ball mills, in a stirred media mill, and with a mortar mill. Comparisons with the other solvent-free synthetic routes showed that ball milling is an effective way of performing the reaction with low energy intensity.