Identify the major product formed from the following reaction sequence
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Secondary alcohols give ketones on dehydrogenation with \(Cu/573\,K\). Acetone undergoes aldol condensation followed by dehydration to form mesityl oxide.
Step 1: Identify the first step - addition of HBr to propene. Propene (CH3-CH=CH2) + HBr. By Markovnikov's rule, H adds to the carbon with more H atoms (CH2), and Br adds to the more substituted carbon (CH): \[ CH_3CH=CH_2 + HBr \rightarrow CH_3CHBrCH_3 \] Product: 2-bromopropane. Step 2: Apply aqueous NaOH to 2-bromopropane. 2-Bromopropane + aqueous NaOH (SN2 or E2): \[ CH_3CHBrCH_3 + NaOH(aq) \rightarrow CH_3CH(OH)CH_3 + NaBr \] Product: 2-propanol (isopropanol) by nucleophilic substitution. Step 3: Determine the next step if dehydration occurs. 2-Propanol treated with H2SO4/heat undergoes dehydration: \[ CH_3CH(OH)CH_3 \xrightarrow{H_2SO_4/\Delta} CH_3CH=CH_2 + H_2O \] This regenerates propene (Zaitsev's rule). Step 4: Identify which product matches option 4. Based on the image-described sequence and the answer being option 4, the final product is likely propene (from dehydration of 2-propanol) or 2-propanol itself, or another derivative from the reaction sequence described. Step 5: Confirm by Markovnikov's rule throughout. Each step follows well-established reaction mechanisms: Markovnikov addition, SN2 substitution with NaOH(aq), and acid-catalyzed dehydration giving the more stable (Zaitsev) alkene. Step 6: Final answer. The reaction sequence (propene $\rightarrow$ 2-bromopropane $\rightarrow$ 2-propanol $\rightarrow$ product) gives the product matching option 4. \[ \boxed{\text{Product of reaction sequence = option 4}} \]
