Green Oxidation of Borneol to Camphor with Oxone
Lab Partners: Miranda Saporito, Frederick Moscarello
As scientists, we all have an obligation to conduct research in a manner that is respectable to fellow human beings as well as life itself. The concept of Green Chemistry stems from this obligation, and its goal is to develop more environmentally friendly ways of conducting experiments. Some chemicals, such as chromium reagents or pyridinium chlorochromate (PCC) may be effective in the lab to perform reactions, but their disposal and use may damage the environment (Weldegirma, 2017). Thus, Green Chemistry encourages scientists to find different compounds and chemicals that can perform similar reactions, with less environmental safety risk or waste. Twelve principles guide the concept of Green Chemistry. These include the prevention of additional waste production, the use of the least among of chemical possible in the reaction, the use of chemicals that are the least hazardous to the environment, and the development of efficient reactions and energy use, among others (American Chemical Society, 2017). The primary advantages to following a green approach to chemistry are that the chemicals may be cheaper, easier to access, and safer to use and dispose of in the environment.
One of the types of reactions that may use a green chemistry approach are oxidation reactions. These reactions are marked by the removal of electrons from the starting product and oxidizing agents can turn alcohols into ketones, carboxylic acids, or aldehydes based on the initial substrate (Weldegirma, 2017). This type of reaction is common naturally as well as industrially to produce different compounds (Science Clarified, 2018). As mentioned above, PCC and chromium compounds are both oxidizing agents that can be harmful to the environment and do not follow the green approach. Thus, research has been done to find alternative oxidizing agents that are better for the environment. One such oxidant is Oxone, which is a triple salt compound. This compound is inexpensive and has a lower risk of health or safety issues than PCC and chromium agents, so scientists can conduct oxidation reactions while following the green approach.
The percent yield of this product was significantly higher than expected. This value can most likely be attributed to the presence of water in the product. The product appeared wet when it was measure, so additional time must be taken in the future to ensure that the product is completely dry from the vacuum. The melting point was not able to be measured because the product did not melt when placed in the melting point capillary and apparatus. Salts have extremely high melting points, so there may have been salt present in the final product, which would have made the melting point unreadable with the given thermometer.
Although the Rf values for the starting material and product indicated that the reaction was completed, the IR spectrum, 1H NMR spectrum, and the melting point indicate that there was an error in the experiment. The IR spectrum shows that the reaction did not reach completion due to the presence of the significant broad peak from 3000-3500. This peak is indicative of an alcohol, which was present in the starting product, borneol. The presence of water in the substance may have contributed to this significant peak as well. A carbonyl peak was expected around 1710, however the peak instead appears around 1600. The peak around 1600 may be due to the presence of a C=C bond, which would be present in the product of the side reaction.
The original NMR spectrum from this sample did not produce readable peaks that would be indicative of structure or bonding. However, the spectrum that was provided by the TA shows notable peaks around 7.2, 6.2, 5.5, and 2.5. All of these peaks are singlets, so they represent hydrogen atoms that did not couple with neighboring protons. Although some coupling was expected based on the structure of the expected final product, NMR spectrum results of actual products can sometimes be difficult to read. Despite issues with the results of the experiment, this reaction did follow a Green approach by using a less harmful oxidizing agent.
Overall, there was evidence in this reaction that a reaction did occur, but it was not the reaction that was expected as the presence of the side product is evident in the IR spectrum. Additionally, the product was not given adequate drying time, thus proper data values were not collected. This experiment can serve as a learning experience for future labs. One important lesson is to be patient with the reaction and allow it to reach completion or dry completely before moving on to the next step. Additionally, all glassware should be washed before use so as to reduce contamination of the product.