JEE MainChemistryGeneral Organic Chemistry
One mole of 4-ethynyl-3-hydroxybenzoic acid is treated separately with excess amounts of three different bases in three separate reactions: Reaction 1: Excess NaHCO ₃ Reaction 2: Excess NaOH Reaction 3: Excess NaNH ₂ Let x , y , and z be the number of moles of acidic protons neutralized per mole of the compound in Reaction 1, Reaction 2, and Reaction 3, respectively. The values of x , y , and z are:
Options
- Ax = 1 , y = 3 , z = 3
- Bx = 1 , y = 2 , z = 3
- Cx = 2 , y = 2 , z = 3
- Dx = 1 , y = 1 , z = 3
Correct answer
B. x = 1 , y = 2 , z = 3
Step-by-step solution
The given molecule, 4-ethynyl-3-hydroxybenzoic acid, contains three distinct acidic functional groups: 1. A carboxylic acid group ( - COOH ), p K_a 4 2. A phenolic hydroxyl group ( - OH ), p K_a 10 3. A terminal alkyne group ( - C CH ), p K_a 25 An acid-base reaction proceeds in the forward direction if the reacting base is stronger than the conjugate base of the acid (i.e., the conjugate acid of the base must have a higher p K_a than the acid being deprotonated). Reaction 1: NaHCO ₃ is a weak base (conjugate acid