What is the major organic product formed when propene reacts with hydrogen bromide (HBr) in the absence of peroxides?
Answer and explanation
Correct answer: D. 2-Bromopropane (via the more stable secondary carbocation intermediate)
- Step 1: In the absence of peroxides, HBr adds to alkenes via an ionic electrophilic addition mechanism following Markovnikov's rule. Step 2. Proton addition forms the secondary carbocation (CH3-CH(+)-CH3), which is more stable than the primary carbocation. Step 3. Bromide attacks the secondary carbocation, yielding 2-bromopropane. Answer: 2-Bromopropane (via the more stable secondary carbocation intermediate). Why not the others: 1-Bromopropane is formed in the presence of organic peroxides (anti-Markovnikov radical pathway).
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