Preparation and acidic strength
Carboxylic Acids and Derivatives · Chemistry
Study notes
Why is formic acid (pKa 3.75) stronger than acetic acid (4.76)? Step 1: Acidity depends on carboxylate anion stability. Step 2: HCOO⁻: no alkyl group; CH₃COO⁻: methyl's +I pushes electrons onto the anion (destabilizes). Step 3: Less destabilization → HCOO⁻ more stable → HCOOH gives H⁺ more readily. Step 4: Alkyl groups weaken acids (+I); electron-withdrawing groups strengthen. Inductive effect rules!