Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Brittany Hill - Savannah State University
Co-Author(s): Pascal Binda, Savannah State University
Due to global warming there has been an extensive amount of carbon dioxide that is readily available and essentially renewable. In recent years, reactions using carbon dioxide have gained the interest of chemists. In this experiment, styrene underwent hydrocarboxylation by using a chiral catalyst to yield chiral carboxylic acids. If successful a more cost- effective means of making chiral carboxylic acids would be obtained. We hypothesized that through chiral synthesis chiral palladium and zinc complexes will form a chiral carboxylic acid with a new chirality center. By using styrene as a nucleophile and carbon dioxide as an electrophile it will produce the new stereogenic center. The new chiral compound could potentially be used for the manufacturing of suitable functionalized reagents and substrates. Most chiral compounds can be found in a vast majority of pharmaceutical drugs. Some research has been done on the hydrocarboxylation of styrene with carbon dioxide, using achiral nickel catalyst to produce achiral carboxylic acids under certain conditions. From this information that was obtained we used a similar procedure to form chiral carboxylic acids. The general hydrocarboxylation procedure will be illustrated in the following. Chiral LPdOAc (1.0 mol%) or chiral LZnOAc (1.0 mol%) and potassium carbonate (2.0 mol %) were weighed into a dry 250mL round bottom flask and sealed with a septum, then evacuated and refilled with Nitrogen two times. The solids were dissolved in (10mL) THF and (5.0mL) of Styrene, by using a syringe. The carbon dioxide (dry ice) was added in excess to both compounds with stirring. After this diethyl zinc (15% w/ Toluene) was added with a syringe. The reaction was allowed to stir for four and a half hours. The reaction was then diluted with diethyl zinc (5.0 mL) and quenched with 1 M HCl (5.0mL). After separation, the aqueous layer was extracted with ethyl acetate (2 x 10 mL). The combined organic layers were dried over sodium sulfate and the solvent ethyl acetate was evaporated under vacuum to produce the crude product. The crude product was purified with the use of column chromatography (95% Hexane, 5% ethyl acetate) to obtain yellow liquid product. The organic products were characterized by NMR. Future work will include finding the mass of the chiral carboxylic acid and studying the new chirality center (R or S).
Funder Acknowledgement(s): Department of Defense
Faculty Advisor: Pascal Binda, email@example.com
Role: I worked with my instructor throughout the research. I did all of it but was supervised and mentored by Dr. Binda.