The Application of Dibromohydantoin in Chemical Experiment Pedagogy

The substitution of carbonyl compounds with liquid bromine as a brominating agent is the most commonly employed synthesis method for α-bromoacetophenone and its derivatives. However, liquid bromine possesses certain drawbacks, such as volatilization, high toxicity, strong corrosion, and poor reaction selectivity, which limit its application and popularization in undergraduate experiment teaching. Dibromohydantoin offers advantages including good stability, a high content of active bromine, and environmentally friendly characteristics. Nevertheless, it has rarely been systematically investigated in the α-bromination reaction of acetophenone derivatives. In this innovative experiment, we combined the principles of green chemistry with organic synthesis methodology to investigate the effects of solvent, catalyst concentration, reactant amount, and reaction time on the yield of acetophenone and its derivatives when using dibromohydantoin as a reagent. The experimental results demonstrate that 4-methyl-α-bromoacetophenone can be synthesized at 20 °C using 4-methylacetophenone as a substrate along with ethanol as a solvent and sulfuric acid as a catalyst. The validity of the experimental method was evaluated by a group of 18 third-year undergraduates. This method exhibits several advantages, including high yield, distinct experimental observations, and excellent repeatability, making it suitable for application and promotion in undergraduate chemistry laboratory courses. The reagent utilized in this innovation experiment is characterized by being green, safe, inexpensive, and easily accessible, thereby playing an important role in consolidating students' fundamental skills in chemical experiments while enhancing their scientific literacy, cultivating innovation awareness, and fostering practical abilities.