31. On the molecular level, all auxins are compounds with an aromatic ring and a carboxylic acid group. 32. Similar to other phenols, the hydroxyl groups on the aromatic ring of a benzenediol are weakly acidic. 33. It may contain alkenes and aromatic rings , and it is compatible with ethers and even ester groups. 34. Sulfonation occurs on the side chains, not on the aromatic ring like in p-toluenesulfonic acid. 35. Polymers which possess UV-absorbing groups such as aromatic rings may also be sensitive to UV degradation. 36. :: Is there experimental evidence that the aromatic rings are pi-stacked in the bioactive conformation? 37. One explanation for the increased acidity over alcohols is resonance stabilization of the phenoxide anion by the aromatic ring . 38. Simple monocyclic aromatic rings are usually five-membered rings like pyrrole or six-membered rings like pyridine. 39. This ion is the electrophile in ipso addition to the aromatic ring forming a lactam with an enone group. 40. Upon oxidation this intermediate will spontaneously lactonize to form the aromatic ring B and lose NovH in the process.
