See image — Reaction Mechanism Chemistry Question

💡 Solution & Explanation

Concept: Grignard reagents (RMgBr) react with acidic hydrogen-containing compounds to evolve alkane gas. CH3MgBr evolves CH4 when it encounters a compound with an acidic O-H bond (i.e., alcohols), because the O-H proton is acidic enough to protonate the carbanion CH3(-) to give CH4. Step 1: Identify the molecular formula. C4H10O has degree of unsaturation = (2×4 + 2 - 10)/2 = 0, so no rings or double bonds. It can be either an alcohol (R-OH) or an ether (R-O-R'). Step 2: Only alcohols (containing O-H) react with CH3MgBr to evolve CH4. Ethers do not have an acidic proton and do not react this way. Step 3: Enumerate all alcohol isomers of C4H10O (excluding stereoisomers): 1. 1-Butanol: CH3CH2CH2CH2OH 2. 2-Butanol: CH3CH2CH(OH)CH3 3. 2-Methyl-1-propanol (isobutanol): (CH3)2CHCH2OH 4. 2-Methyl-2-propanol (tert-butanol): (CH3)3COH Step 4: Count the ether isomers of C4H10O (these do NOT react with CH3MgBr to give CH4): - Diethyl ether: CH3CH2OCH2CH3 - Methyl propyl ether: CH3OCH2CH2CH3 - Methyl isopropyl ether: CH3OCH(CH3)2 Step 5: All 4 alcohol isomers contain an O-H group and will react with CH3MgBr to liberate CH4. The 3 ether isomers have no acidic proton and do not evolve CH4. Step 6: Therefore the number of isomers of C4H10O that react with CH3MgBr to evolve CH4 = 4 (all four alcohols). Therefore, the correct answer is 4.