2004 Student Research Conference:
17th Annual Student Research Conference

Science

Application of Hard-Soft Acid-Base (HSAB) Theory to Reactions between Amino Acids and Quinone Methides
Samuel N. Edeh
Dr. Robert G. Dyer, Faculty Mentor

The concept of HSAB theory focuses on Lewis acids and bases. It can be used to assign numerical values to acids and bases based on the difference between the ionization energy and electron affinity. The magnitude of this difference gives rise to their classification as either hard or soft. HSAB theory predicts that hard-hard and soft-soft acid/base interactions are favored. In more quantum mechanical chemistry terms, the softness or hardness is related to the absolute difference between the Lowest Unoccupied Molecular Orbital (LUMO) and Highest Occupied Molecular Orbital (HOMO). Investigating the applicability of the HSAB principle to various situations, we have applied the hardness-softness to reactions between amino acids and quinone methides. The HOMO and LUMO energies calculated using the computer program Gaussian are used to determine a numerical scale for the hardness or softness. The scale is then compared with the reaction rates from the literature for reactions between amino acids and quinone methides.

Keywords: HSAB theory, Lewis acids/bases, Amino acids, Quinone methides, Quantum mechanics, HOMO, LUMO, Numerical scale

Topic(s):Chemistry

Presentation Type: Oral Paper

Session: 37-1
Location: VH 1010
Time: 2:15

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