CHEM 343 Lecture Notes - Substituent, Benzene, Electronegativity
Document Summary
If the two substituents are different, they are listed in alphabetical order. Substituents can either increase or decrease the reactivity of benzene. Inductive electron donation through bond, reactivity. Inductive electron withdrawal thorough bond, reactivity. Substituent (for example, nh2, oh, or, cl) has pair of nonbonded e- on atom directly attached to benzene ring delocalized into ring through p-orbital overlap. Atom double or triply bonded to more electronegative atom (for example, c=o, c n, No2, so3h), e- withdrawn through the ring. Strongly activating substituents ex: oh, nh2, or. Donation into ring by resonance greater than withdrawal by induction. All ortho/para have lone pair on atom directly attached or alky, aryl, or ch=chr groups. All meta have positive charge or partial positive charge on atom attached to ring. More ortho product expected (due to two ortho positions available, one para) Para formed if substituent on ring or incoming electrophile large. Activating groups allow reaction to proceed under less rigorous conditions.
