According to transition state theory, the rate constant for the formation of R and S enantiomeric products can be expressed as kRand kSby "equation ( 3) where∆𝐺𝐺 ≠ is the free energy of activation for the formation of R or S respectively, kb is the Boltzmann constant, h is the Planck constant, T is the temperature and R is the universal gas constant. Stereoselectivity of the chemical reactions can be represented as an enantiomeric ratio (er). The er (for the enantioselective reaction) is directly proportional to the relative rates of formation of the enantiomeric products; that is, the ratio of products depends on the relative free energy barrier (ΔΔG # ) , which can be represented by "equation ( )": The enantioselectivity in a reaction is commonly reported by enantiomeric excess (ee), which can be calculated by "equation ( )" as: