Why is an olefin inert to nucleophiles?

Question

Carter Allen · Accepted Answer

Because the alkene, the olefin, is an electron-rich species, #"a nucleophile.........."#

Ethylene is inert to these nucleophiles, these electron-rich species, so you can bubble it through an aqueous solution of water and ethanol that contains potential nucleophiles like cyanide, halide, or water or ethanol itself.

Add a bit of acid, i.e. #H^+#, an electrophile, the ethylene reacts with added #H^+# to form #H_2C^(+)-CH_3#, a electrophile that will add to whatever nucleophile you have in solution to form e.g. #N-=C-CH_2CH_3#, #XCH_2CH_3#, #HOCH_2CH_3#, or #H_5C_2OCH_2CH_3#. The point is that reaction will not occur until you add the electrophilic #H^+# to start the ball rolling.

#H_2C=CH_2 +H^+ rarr H_2^+C-CH_2#

#H_2^+C-CH_3 + X^(-) rarr H_2XC-CH_2#

Isabella Acosta · Answer

undefined Olefins are typically inert to nucleophiles because their double bond is formed by the overlap of p orbitals, which creates a region of electron density above and below the plane of the molecule. This electron-rich region is not easily accessible to nucleophiles, which tend to attack electron-deficient sites. Additionally, the π electrons in the double bond provide stability to the molecule, making it resistant to nucleophilic attack.