### Acids and bases - **Acids** are proton donors - **Conjugate bases** are the products of an acid donating a proton - **Bases** are proton acceptors - **Conjugate acids** are the product of a base receiving a proton Higher pKa, weaker acid #### Stability A more stable conjugate base means a stronger acid with a lower pKa. 1. Atom electronegativity: more electronegative → more stable 2. Resonance stabilizes negative charges 3. Inductive effects 1. Highly electronegative atoms further away from the donated proton can stabilize the negative charge by polarizing the bond 4. Orbital effects: more s-character is more stable 1. sp > sp$^{2}$ > sp$^{3}$ 2. Bond angles closer to linear have more s-character **Factors that weaken a base** (they make its lone pair less available): - lone pair on a more electronegative atom - lone pair delocalized by resonance - nearby EWGs (inductive effect) - lone pair in an orbital with more s-character ### Acid–base reaction: - Arrows: the base's lone pair attacks the H; the H–A bond electrons move onto A - Equilibrium favors the **weaker acid** (higher pKa) - K_eq = 10^(pKa of product acid − pKa of reactant acid) ### pKa values of common acids | Compound | Formula | pKa | | --------------------- | ------------------------ | ---- | | Water | H2O | 15.7 | | Phenols | ArOH | 10 | | Ammonium Ions | NH$_{4}^{+}$ and similar | 9-12 | | Acetic Acid (vinegar) | CH$_{3}$CO$_{2}$H | 4.8 | | Hydrochloric Acid | HCl | -7 | | Sulfuric Acid | H$_{2}$SO$_{4}$ | -9 | ### pKa values of weak acids with strong conjugate bases | Compound | Formula | pKa | | ------------------ | -------------------- | ----- | | Alkanes | H-Csp$^{3}$ | 50+ | | Alkenes and arenes | H-Csp${} ^{2} {}$ | 40-45 | | Amines | RNH$_{2}$, R$_{2}$NH | 35-36 | | Ammonia | NH$_{3}$ | 33 | | Alkynes | H-Csp | 25 | | Alcohols | ROH | 16-19 | ### Alkene Reactions - Hydration - Halogenation ### Regiochemistry ### Stereochemistry ### Markouvnikov's Rule ### Carbocations ### Hammond Postulate