Why can ethanol be considered both a Lewis acid and a Lewis base?

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Answer 1 · 2018-04-09T10:29:12

because, like water, it can both accept and donate lone electron pairs

Ethanol acting as Lewis acid :accepting electron pair

$C H_{3} C H_{2} O H$ $CH_3CH_2OH$ + $B :^{-}$ $B:^-$ $\to$ $->$ $C H_{3} C H_{2} O^{-}$ $CH_3CH_2O^-$ + $B H$ $BH$

in this case the hydroxyl proton receives the electron pair from a strong base, producing the ethylate anion.

Ethanol acting as Lewis base: donating electron pair

$C H_{3} C H_{2} O H$ $CH_3CH_2OH$ + $H^{+}$ $H^+$ $\to$ $->$ $C H_{3} C H_{2} O H_{2}^{+}$ $CH_3CH_2OH_2^+$

in this case the hydroxyl oxigen gives an electron pair to a strong acid, producing a protonated alcohol