Structure, Bonding, and Stability of Carbocations 6

Figure 4.8 Structure of methyl cation. Carbon is sp2 hybridized. All four atoms lie in same plane. 10

Figure 4.8 Structure of methyl cation. Empty 2p orbital. Axis of 2p orbital is perpendicular to plane of atoms. 10

Most carbocations are too unstable to be isolated. + Most carbocations are too unstable to be isolated. When R is an alkyl group, the carbocation is stabilized compared to R = H. 7

Methyl cation least stable Carbocations C H + Methyl cation least stable 7

Ethyl cation (a primary carbocation) is more stable than CH3+ Carbocations H3C + H C H Ethyl cation (a primary carbocation) is more stable than CH3+ 7

Isopropyl cation (a secondary carbocation) is more stable than CH3CH2+ Carbocations H3C + CH3 C H Isopropyl cation (a secondary carbocation) is more stable than CH3CH2+ 7

Carbocations H3C + CH3 C CH3 tert-Butyl cation (a tertiary carbocation) is more stable than (CH3)2CH+ 7

Figure 4.9 Stabilization of carbocations via the inductive effect positively charged carbon pulls electrons in  bonds closer to itself + 18

Figure 4.9 Stabilization of carbocations via the inductive effect  positive charge is "dispersed ", i.e., shared by carbon and the three atoms attached to it    18