Modifications of the classical blue bottle experiment, air oxidation of glucose catalyzed by methylene blue under alkaline conditions, were investigated. Following the green chemistry formulation proposed by Wellman and Noble, we studied the visual behaviors of air oxidation of vitamin C catalyzed by redox indicators. New formulations for the chemical traffic light and vanishing valentine experiments are presented in this paper. We also report, for the first time, chemical pattern formation in this oxidation reaction of ascorbic acid. These results open many possibilities for laboratory practicals as well as demonstration activities.

The blue bottle experiment is a popular chemical demonstration because of its simplicity and visual appeal. Most papers on the topic focus on a new formulation or a new presentation, but only a few discuss pedagogical application for a full lab session. This article describes the use of this experiment in the first session of undergraduate chemistry laboratory at the Mahidol University International College. Practical activities are designed to foster critical thinking and student-centered learning during a four-hour lab session. The main theme of our teaching is scientific method. Students are encouraged to work with a peer to propose hypotheses and test them. With a series of guidances and hints from the instructor and group discussion, students can propose the reaction mechanism for the experiment without knowing the identity of the chemicals in the reaction. Procedures described in this article may be used elsewhere with minimal modification.

We consider a new identity involving integrals and sums of Bessel functions. The identity provides new ways to evaluate integrals of products of two Bessel functions. The identity is remarkably simple and powerful since the summand and the integrand are of exactly the same form and the sum converges to the integral relatively fast for most cases. A proof and numerical examples of the identity are discussed.

Air oxidation of reducing sugar under alkaline conditions and air oxidation of ascorbic acid catalyzed by methylene blue are known as the classical and the green chemistry versions of the blue bottle experiment, respectively. We propose a faster alternative of the blue bottle experiment in which air oxidation of benzoin under an alkaline condition is the main reaction. In addition to methylene blue (for the blue bottle experiment), erioglaucine (FD&C Blue #1), indigo carmine (FD&C Blue #2, for the chemical traffic light experiment), resazurin (for the vanishing valentine experiment), safranine, phenanthrenequinone, and tetrazolium chloride also catalyze the autoxidation of benzoin. Similar to sugar/hydroxide and ascorbic acid/CuCl2 reactions, chemical pattern formations are observed in this benzoin/hydroxide system. Our colorful reactions and patterns open the possibilities for both pedagogical activities and future in-depth research.

The blue bottle experiment is a collective term for autoxidation reactions catalysed by redox indicators. The reactions are characterized by their repeatable cycle of colour changes when shaken/left to stand and intricate chemical pattern formation. The blue bottle experiment is studied based on calculated solution-phase half-cell reduction potential of related reactions. Our investigation confirms that the reaction in various versions of the blue bottle experiment published to date is mainly the oxidation of an acyloin to a 1,2-dicarbonyl structure. In the light of the calculations, we also propose new non-acyloin reducing agents for the experiment. These results can help guide future experimental studies on the blue bottle experiment.