Solvent-free Knoevenagel reactions have also been carried out using a mortar and pestle. Under these conditions, the reaction between benzaldehyde (9) diethyl malonate (31), which was catalysed by triethylbenzylammonium chloride (TEBA), resulted in product yields of 87.5% after ten minutes (Rong et al., 2006). Similarly, the domino-effect Friedlander condensation reaction, which can also be conducted using a mortar and pestle, was observed between aldehyde (77) and methylene compound (78). This sodium fluoridecatalysed reaction formed the aromatic Knoevenagel reaction product (76) in yields of 92.0% after eight minutes (Fig. 24) (Mogilaiah & Reddy, 2003).