Rae Dunbar, Class of 22 at St. Lawrence University, is an Environmental Studies and Biology Combined Major and math minor. Dunbar is active in Thelmo Student Government as Environmental Affairs Chair and DIVEST Environmental Club. She is also a Biology Department Teaching Assistant, 1st chair Alto Saxophone in the SLU Wind Ensemble, and a member of the SLU Cycling Club, Tri Beta Biology Honor Society, and ODK Society.
Exposed to the elements, plastic degrades into smaller pieces known as microplastics and nanoplastics.1 These pieces have been found in our terrestrial, aquatic, and atmospheric environment, contaminating our food, water, and air.2 To mitigate this problem, we attempted to synthesize a copper cage that will theoretically break down the plastic to benign monomers of water and carbon. 3
During my eight-week fellowship I worked mostly on method development since I am the first person to attempt this project. To synthesize the cage we first had to synthesize the KBH(im)3 ligand which is a necessary component in the cage. We had difficulties in synthesizing a high yield of pure KBH(im)3. Our first attempt, utilizing Frankel et al.’s procedure, yielded us KBH(im)4, rather than our desired ligand. Changing to Saiyid et al.’s method, which used a different solvent, we synthesized the correct product, but at a low yield. Rotary evaporation, Schlenk line drying, and storing the solution at -21 degrees did not successfully crash out more product. So, we used Saiyid’s procedure again, but with less of our DMF solvent to crash out more product. This synthesis did not work. We shifted to a new synthetic procedure, Trofimenko et al., and got a high yield, but the ligand was impure. Adjusting the temperature gave us less impurities. With both batches we tried different purification techniques, including running a column, a reaction with toluene and DMF to turn the KBH(im)2 impurity to our desired ligand, and washing the product with toluene and hexane. None were effective. Though we were unsuccessful at making a high yield of purified KBH(im)3, we did make some important findings. For one, DMF will result in a low yield, because our product is so soluble in it. We also noticed that imidazole is extremely volatile, so if small crystals form on the side of the Schlenk flask they should be scraped out and discarded, not mixed with the product. We also observed that the longer it takes for the reaction to reach the desired temperature the more impure the product will be. These observations among others can be used for the next researcher on this project.