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K.L.

Why does fluorine stabilise a carbocation? [duplicate]

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Most of the times the question that comes in the examinations is that why CH2F+ is more stable than CH2Br+ or CH2I+.The reason behind it is that the p orbital of fluorine overlaps more effectively than that of Br or I with the carbon atom and therefore disperses the charge on it.refer to K L Chugh for the details.

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Bill Walker  Follow

Fluorine belongs to the same period as carbon. Carbocation is electron deficient which has its two $\mathrm{2p}$ orbitals vacant. One electron of carbon in $\mathrm{2p}$ orbital goes into the formation of $\ce{C-F}$ σ bond. $\ce{F}$ has $\mathrm{2p}$ orbital containing a lone pair which can be donated to the $\mathrm{2p}$ vacant orbitals of carbocation. Same size $\mathrm{2p}$ orbitals of carbon and fluorine overlap effectively to form a π bond.

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Alex V.  Follow

Carbocations are stabilized by neighboring atoms with lone pairs. The key stabilizing influence is that the neighboring atom can donate a pair of electrons to the electron-poor carbocation. In this way halogenes, nitrogen or oxygen can actually be an electron-donor group and stabilize the carbocation.

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Greg Moylan  Follow
This is stated in the question. The actual question is about why the inductive effect does not dominate the mesomeric effect in carbocations, whereas it usually does for fluorine.More
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