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4. Build structure 2 and calculate its energy. Then build structure 4 and calculate its energy. Follow instructions on the next page. NO₂ 1 + Cl₂ FeCl3 FeCl3 NO₂ NO₂ meta addition CI 2 CI
Click on the "Rings" button under the elements in the organic menu, then select the cyclohexane from the pull-down menu. Click on the screen to place a cyclohexane on the screen. You will then need to make double bonds by selecting "Build-Make Bond" (or use the Gray-Red Bond icon towards the bottom right next to the eraser) and clicking on the ends of two valences on consecutive carbons. You will also need to delete a hydrogen atom at the carbocation by using the delete button (the eraser key). Delete a hydrogen by clicking on the end of the yellow valence rods. Add a chlorine and nitro group. For the nitro group, you can find the specific button for it when you hit "Groups" and change the selection from "alkenyl". Minimize the structure with the (E ball rolling down a hill) button in the bottom right corner or select Build-Minimize from the top. Go to Setup- Calculation and change the total charge from neutral to cation and change from Density- Functional to Semi-Empirical or PM3. When the calculation is finished, select Display: Properties and record the energy below in kJ/mol. Energy of structure 2 Energy of structure 4 kJ/mol kJ/mol 5. Which intermediate is more stable? Draw two additional resonance structures each for structures 2 and 4. Use the resonance structures to explain the relative stability.