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Question 3

1s 3 ORTHO Today we learned about adding a second group to a mono-substituted benzene ring. Any group on a benzene will affect the rate of the reaction (activated or deactivated relative to benzene) and the regioselectivity Where does the electrophile add? Ortho? Meta? Para? Some combination thereof? We found that EDGs (electron-donating groups) direct the electrophile to the ortho and para positions while EWGs (electron-withdrawing groups) direct the electrophile to the meta position. Now, it is time to think about how the presence of two groups would direct a third group? Be sure to rea the text to see some examples. Some Questions to Ponder...(QTPs) 1. How are alkyl groups electron-donating without an available lone pair? 2. Explain the following: how can one student say that an OR group is electron-withdrawing while another 0 can say that it is electron-donating, and both can be correct? Which effect "wins" though? 3. Rank the following EWGs from least to most electron-withdrawing: ketone, aldehyde, ester and amide. 4. Why are halogens o/p-directing yet deactivating? 5. Overlay three reaction coordinates: 1) nitration of benzene; 2) meta-nitration of nitrobenzene; and 3) pa nitration of nitrobenzene. It is OK to use the same starting energy for benzene and nitrobenzene. The major differences are 'felt in the intermediate stages, so it not necessary to show the finer differences the starting materials and products. 6. Now,.do the same exercise of drawing three reaction coordinates for the nitration of phenol. 7. One approach to seeing which C's of phenol are most nucleophilic is to draw resonance structures tha place a negative charge on various C's. Draw these structures. Draw a single resonance structure that best shows why meta-directors are meta-directors? 0 8. mak

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