To which compound is the addition of HBr more highly regioselective?
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Verified step by step guidance

1. Identify the type of reaction: The addition of HBr to an alkene is an example of an electrophilic addition reaction.
2. Consider Markovnikov's Rule: In the addition of HX to an alkene, the hydrogen atom (H) will add to the carbon with the greater number of hydrogen atoms, and the halide (Br) will add to the carbon with fewer hydrogen atoms.
3. Examine the structure of each compound: Look at the alkenes in both compounds to determine which one has a more pronounced difference in the number of hydrogens on the carbons of the double bond.
4. Determine regioselectivity: The compound with a more significant difference in the number of hydrogens on the carbons of the double bond will exhibit higher regioselectivity in the addition of HBr.
5. Compare the two compounds: Based on the analysis, decide which compound will have a more regioselective addition of HBr, following Markovnikov's Rule.

Key Concepts

Regioselectivity

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In the context of electrophilic addition reactions, such as the addition of HBr to alkenes, regioselectivity is determined by the stability of the carbocation intermediates formed during the reaction. More stable carbocations lead to a greater likelihood of forming specific products.

Carbocation Stability

Carbocation stability is a key factor in determining the outcome of reactions involving electrophiles. Carbocations are positively charged species that can be classified based on their degree of substitution: primary, secondary, and tertiary. Tertiary carbocations are the most stable due to hyperconjugation and inductive effects from surrounding alkyl groups, making them more favorable in regioselective reactions.

Markovnikov's Rule

Markovnikov's Rule states that in the addition of HX (where X is a halogen) to an alkene, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This rule helps predict the major product of the reaction based on the stability of the resulting carbocation. Understanding this rule is essential for determining the regioselectivity of HBr addition to different alkenes.