Abstract: Carbonyl reduction reactions constitute a fundamental component in organic chemistry education. In current undergraduate laboratory instruction, this transformation is predominantly demonstrated through the Huang-Minlon reduction method, a pivotal method developed in China. However, this conventional experiment presents several pedagogical challenges, including the use of highly toxic hydrazine hydrate, excessive high-temperature byproduct formation, cumbersome workup procedures, and notable safety concerns. To address these limitations, we have implemented the following modifications to the diphenylmethane synthesis experiment: 1) replacement of the N₂H₄·H₂O-KOH system with an environmentally benign Polymethylhydrosiloxane (PMHS)-FeCl₃ reduction system; 2) substitution of hazardous diethylene glycol solvent (which releases toxic and irritating fumes at elevated temperatures) with stable and easily handled 1,2-dichloroethane; 3) reduction of reaction temperature from 140–195 to 70 ℃; 4) shortening of reaction duration from 4 to 1 h; and 5) adoption of a simplified workup procedure involving grinding and vacuum filtration instead of complex and potentially hazardous reduced-pressure distillation. Furthermore, by incorporating analytical techniques such as thin-layer chromatography, column chromatography purification, and spectroscopic characterization (Infrared Spectroscopy (IR) and Nuclear Magnetic Resonance (NMR)), we have developed this into an 8-hour comprehensive experiment. The extended protocol includes selective deoxygenative reduction of the pharmaceutical compound ketoprofen, thereby enhancing students’ comprehensive chemical competencies.

Key words: Deoxygenative reduction, Wolff-Kishner-Huang Minlon-reduction reaction, Benzophenone, Green chemistry, Experimental improvement and innovation