Determining the Ionization Constants of Organic Acids Using Fluorine Gauche Effects

Area of Science:

• Organic Chemistry
• Structural Chemistry
• Physical Chemistry

Background:

• The fluorine gauche effect influences molecular conformation.
• Sulfonamides are versatile organic compounds with applications in various fields.
• Understanding conformational changes is crucial for molecular design and function.

Purpose of the Study:

• To investigate the impact of ionization on fluorine gauche effects in fluoroethylsulfonamides.
• To develop a method for determining the acidity (pKa) of organic compounds using these conformational changes.
• To explore the potential of fluorine gauche effects in molecular design.

Main Methods:

• Conformational studies using Nuclear Magnetic Resonance (NMR) spectroscopy.
• Analysis of proton-fluorine vicinal coupling constants (³JFH).
• Development and application of a novel equation to calculate relative ionization constants (Krel).

Main Results:

• Fluoroethylsulfonamide acids exhibit significant gauche effects, while their anions prefer anti conformers.
• A quantitative relationship between ionization and conformation was established.
• The developed equation accurately determined the pKa of various organic compounds in DMSO.

Conclusions:

• Ionization state dictates fluorine gauche effects in fluoroethylsulfonamides.
• These compounds serve as effective molecular probes for acidity measurements in DMSO.
• Harnessing the fluorine gauche effect offers a promising strategy for advanced molecular design in structural chemistry.