Analysis of Conformational Influences within 2R,3R-Butanediol

Friday, October 28, 2011
Hall 1-2 (San Jose Convention Center)
Michael Drake, PhD , Chemistry, California State University, Stanislaus, Turlock, CA
Zoila Estrada , California State University, Stanislaus, Turlock, CA
2R,3R-Butanediol is a simple polyol with two different isomers: the meso isomer and the racemic isomer. By examining racemic 2,3-Butanediol in different solvents, we investigate its conformational preferences to determine the conformational influences present in racemic-2,3-Butanediol. 2R,3R-Butanediol serves as a model molecule to understand the conformational influence in more complex compounds such as proteins. Some conformational influences we investigate are steric bulk, intramolecular hydrogen bonding, Coulombic attraction/ repulsion, solvent effects, the polarity of conformer versus polarity of the solvent, and hyperconjugation. This project aims to understand the occurrence and effect of hyperconjugation between vicinal hydroxyl (OH) groups which are present in 2R, 3R-Butanediol. Hyperconjugation is an interaction between electrons in a sigma bond with a vicinal, coplanar anti-bonding sigma orbital which increases the stability of the system. The methodology employed is 1H NMR and 13C NMR on 2R,3R-Butanediol in different solvents. Then, we simulate the experimental spectrum on gNMR to extract the J-coupling values. We used the Altona equation in order to correlate the J-couplings constants dihedral angles there by determining the conformation of the compound.