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 (similar to 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 similar to 50% to similar 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 similar to 3 class hours, which is fairly suitable to be widely used in undergraduate teaching.