The Visual Preparation of n-Bromobutane

The preparation of n-bromobutane is one of the required training items in Experimental Organic Chemistry for undergraduates. However, there are still drawbacks: the reaction process is not easy to monitor, and the yield of n-bromobutane is low (∼50%) in the available experimental protocols. In this improved experiment, the visual preparation of n-bromobutane was realized through the ingenious use of a Dean–Stark apparatus. Moreover, the postprocessing steps of the reaction were simplified: while the reaction was proceeding, separation and purification were conducted at the same time, thus leading to an increase in product yield (from ∼50% to ∼70%). As a result, the improved protocol provides conveniences for students to observe the reaction process intuitively and accurately by using the obvious stratification phenomenon in the Dean–Stark apparatus for visual teaching. Moreover, it also expands the scope of the use of the Dean–Stark apparatus and stimulates students' interest in learning organic chemistry. The experiment has good cost-effectiveness and takes ∼3 class hours, which is fairly suitable to be widely used in undergraduate teaching.