Contents I. Introduction II. The HSAB Theory and Hard-Hard Soft-Soft Interaction III. The HSAB Theory in Organic Chemistry IV. Application of HSAB Theory: Conjugate Addition V. Conclusion I. Introduction Until now, we have always been talking about acids, bases, and their conjugate pairs; meaning that we have only been talking about Brønsted-Lowry acid-base. Another well-known … More Acid-Base XI. Hard and Soft Acids and Bases (HSAB) Theory in Organic Chemistry