Consider the following sequence of reactions to give the major product (X) P g of the major product (X) formed is reacted with NaHCO_3 solution to liberate a gas which occupied 11.2 dm^3 at STP. P = _____ g. (Given molar mass in g mol^ -1 H:1, C:12, O:16, Cl:35.5)
A. A
Step 1: The first reaction is a Friedel-Crafts alkylation. Benzene reacts with CH_3Cl in the presence of anhydrous AlCl_3 to form toluene. Step 2: The second reaction is electrophilic aromatic substitution. Toluene reacts with Cl_2 in the presence of FeCl_3 to form a mixture of o-chlorotoluene and p-chlorotoluene. Due to steric hindrance at the ortho position, the major product is p-chlorotoluene. Step 3: The third reaction is the oxidation of the alkyl side chain. p-chlorotoluene is oxidized by K_2Cr_2O_7 / H_2SO_4 to form p-chlorobenzoic acid, which is the major product (X). The molecular formula of p-chlorobenzoic acid is C_7H_5ClO_2. Molar mass of (X) = (7 12) + (5 1) + 35.5 + (2 16) = 84 + 5 + 35.5 + 32 = 156.5 g mol ^ -1 . Step 4: Reaction of p-chlorobenzoic acid with NaHCO_3 liberates CO_2 gas: C_6H_4ClCOOH + NaHCO_3 C_6H_4ClCOONa + H_2O + CO_2 From the stoichiometry, 1 mole of p-chlorobenzoic acid produces 1 mole of CO_2 gas. Volume of CO_2 liberated at STP = 11.2 dm ^3. Moles of CO_2 liberated = 11.2 22.4 = 0.5 mol . Therefore, moles of p-chlorobenzoic acid reacted = 0.5 mol . Mass of (X) reacted, P = 0.5 mol 156.5 g mol ^ -1 = 78.25 g . Answer: 78.25
Related: Chemistry — Hydrocarbons · All PYQ Banks