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Chapter 2. Acids and Bases: Central to Understanding Organic Chemistry Paula Yurkanis Bruice University of California, Santa Barbara. Acids and Bases in Organic Reactions. H ’ s in organic compounds have varying degrees of acidity. Electronegativity Affects p K a Values.
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Chapter 2 Acids and Bases: Central to Understanding Organic Chemistry Paula Yurkanis Bruice University of California, Santa Barbara
Acids and Bases in Organic Reactions • H’s in organic compounds have varying degrees of acidity Chapter 2
Electronegativity Affects pKa Values When atoms are the same size, the strongest acid has its hydrogen attached to the most electronegative atom.
The Stronger the Acid, the Weaker Its Conjugate Base stable basesare weak bases
Acidity and Structure • Electronegative atoms or groups increase acidity Chapter 2
The Position of Equilibrium The equilibrium favors formation of the weaker acid.
acid H+ + base D pKa as a Stability Parameter • pKa tracks relative potential E of conj base • Strong acids: low pKa = stable conj base • Weak acids: high pKa = unstable conj base pKaDGº Chapter 2
Examples of Organic Acid - Base Reactions • To use pKa as a PE write it under base form • Rxn shifts to side with lowest PE • Textbook shows pKa valuesunder acids Chapter 2
Relative Amounts of Different Forms of a Compound pH tracks potential energy of acid form of a compound relative to conjugate base form of same compound Chapter 2