Abstract: To incorporate green chemistry principles into organic chemistry laboratory instruction, we designed a comprehensive Friedel-Crafts alkylation experiment employing an “on-water” strategy. This experiment synthesizes biologically active bis(indolyl)methane derivatives from indole and benzaldehyde in aqueous medium at room temperature. The reaction achieves 98% yield within 30 minutes without requiring heating or inert gas protection. Compared with traditional organic solvent systems (dichloromethane, tetrahydrofuran), this aqueous-phase reaction demonstrates faster kinetics, operational simplicity, environmental friendliness, and distinct visual indicators (precipitation formation). The experiment is carried out using a task-driven learning approach, covering literature investigation, experimental design, reaction monitoring by thin-layer chromatography (TLC), product separation, and structural characterization by nuclear magnetic resonance (NMR). This experimental design effectively helps students break their mindset of relying on organic solvents, master green synthesis techniques, and improve their comprehensive experimental skills and research innovation abilities.

Key words: Green chemistry, Task-driven teaching, On-water reaction, Friedel-Crafts alkylation, Organic chemistry laboratory teaching