A Soluble , Halogen - free Oxalate from Methyl Salicylate for Chemiluminescence Demonstrations

A new compound, bis[2-(methoxycarbonyl)phenyl]oxalate, made from methyl salicylate (oil of wintergreen) was found to be an excellent replacement for the typical halogen or nitro substituted oxalate esters used in peroxyoxa!ate chemiluminescence demonstrations. The compound is easily prepared and has good solubility in organic solvents such as ethy l acetate which is an environmentally friendly solvent to use in the demonstration. KE'rWORDS: K-12 School Science, Undergraduate Organic Chemistry, Demonstrations, Natural Products, Essential Oi ls, Fluorescence, Solubility, Sustainable Chemistry A mong a series of chemical demonstrations given at a local high school the chemiluminescence display was a hit even among the more uninterested students. 1 · 8 All the students were familiar with Cyalume® glowsticks as well as lightning bugs (beetle family Lampyridae) which facilitated making a learning connection between demonstration and the natural world. A new compound bis[2(rnethoxycarbonyl)phenyl]oxalate (1) was prepared by esterification of the natural product methyl salicylate with oxalyl chloride in the presence of base as outlined in Figure 1. 10 The molecule has good solubility in typical organic solvents including ethyl acetate (100 mg I 5 ml @ 23 ·q which is a 'green' solvent to employ in the demonstration, since it is naturally occurring, sustainable, rapidly biodegradable and non-toxic.11' 12 Most importantly, compound 1 produced chemiluminescence in much the same way as bis(2,4,6-trichlorophenyl)oxalate (TCPO), which was used in early rehearsals of the demonstration. Figure 1. Preparation of bis[2-(methoxycarbonyl)phenyl]oxalate (1) from the natural product methyl salicylate