Question

Why is an olefin inert to nucleophiles?

Answer 1

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

Explanation:

You can bubble ethylene thru an aqueous solution of water, and ethanol, containing potential nucleophiles such as cyanide, or halide, or water or ethanol themselves. The ethylene is inert to these nucleophiles, these electron rich species.

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`