CHEM 140B Chapter 16: Textbook Notes

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Ochem textbook notes chapter 16: electrophilic attack on derivatives of benzene. Aspirin, acetaminophen (tylenol), naproxen, and ibuprofen (advil) are synthesized through electrophilic aromatic substitution. Groups of substituents on benzene: activators: electron donors. Generally direct a second electrophilic attack to the ortho and para positions: deactivators: electron acceptors. Generally direct electrophiles to the meta positions. 16. 1 activation or deactivation by substituents on a benzene ring: rate of electrophilic addition depends on the electron-withdrawing or donating properties of the substituents. Electronic influence of any substituent is determined by 2 effects that depend on the structure of the substituent induction: occurs through the sigma framework and tapers off rapidly with distance. Mostly governed by the relative en of atoms and the polarization of bonds: resonance: occurs through pi bonds longer range; particularly strong in charged systems. Bear at least one electron pair capable of delocalization into the benzene ring for amino and alkoxy groups, resonance overrides induction for halogens, induction outcompetes resonance.