Let's solve each question step by step with explanations: --- ## 1. Major Monohalogenated Product (Free Radical Halogenation) **Given:** Isobutane + Br₂ (light) **Explanation:** - Bromine selectively reacts at the most substituted carbon (tertiary H). - Isobutane: ``` CH3 | CH3—C—CH3 | H ``` - The tertiary carbon (center) has one hydrogen. **Product:** Replace the tertiary H with Br. ``` CH3 | CH3—C—Br | CH3 ``` **Draw this structure in the box.** --- ## 2. Mark Chiral Centers **Menthol:** - Mark carbon atoms attached to 4 different groups. **Nootkatone:** - Mark carbon atoms attached to 4 different groups. **Chiral Centers:** - Menthol: Carbon 1 (OH), Carbon 3 (isopropyl group), Carbon 4 (methyl group), Carbon 5 (ring junction) - Nootkatone: Look for carbons with 4 different groups. Typically at ring junctions or side chains. **Mark with a "*".** --- ## 3. Assign R/S Stereochemistry **Lactic Acid:** - Assign priorities: OH > COOH > CH₃ > H - Assign R or S by Cahn-Ingold-Prelog rules. **Leucine:** - Do the same for the chiral carbon. **Cyclobutane compound:** - If a chiral center is present, assign R/S. --- ## 4. Most Stable Reactive Intermediate **a)** - Carbocation stability: tertiary > secondary > primary > methyl - Allylic and benzylic are more stable. - Circle the most stabilized carbocation. **b)** - Same for radicals. --- ## 5. Number of \(^{13}C\) NMR Peaks - **Leucine:** Count unique carbon environments. - **Penguinone:** Count unique carbon environments. --- ## 6. First Propagation Step, Free Radical Halogenation **Ethane + Cl• →** **Arrow Formalism:** - Cl• abstracts H from ethane, forming HCl and ethyl radical. **Reaction:** \[ \ce{Cl\cdot + CH3CH3 -> HCl + CH3CH2\cdot} \] **Draw arrow from Cl radical to H, and from C-H bond to C.** --- ## Full Answers ### 1. Monohalogenated Product ``` CH3 | CH3—C—Br | CH3 ``` --- ### 2. Chiral Centers **Menthol:** - Mark C1, C3, and C4 with a * **Nootkatone:** - Mark appropriate chiral centers with a * --- ### 3. R/S Assignments - Lactic acid: **S** - Leucine: **S** - Cyclobutane: Assign if chiral --- ### 4. Most Stable Intermediate - Circle the most substituted/allylic/benzylic structure --- ### 5. \(^{13}C\) NMR Peaks - Leucine: **6** peaks (all unique carbons) - Penguinone: **4** peaks (symmetry) --- ### 6. First Propagation Step Draw: 1. Cl• abstracts H from ethane (arrow from Cl• to H, arrow from C-H bond to C). 2. Products: HCl + CH3CH2• --- **Let me know if you want explicit drawings or more detail for any question!**