- 己式庚辛Lv 79 years agoFavorite Answer
一點題外話: 這道題, 還有你另外問的兩道題, 都給我很大的違和感,
純粹好奇一下, 這些問題, 你是從香港大學或香港高考的來源取得的嗎?
還有, 你會問這些程度頗高的有機化學, 轉過頭卻在問關於緩衝溶液的基本計算, 實在是很奇怪..
問題是英文, 我也用回英文好了; 有困難再提出.
your answer is correct.
they're all n-butanol, so acidic proton is on O-atom.
obviously main point is the nitro- group.
-NO2 is strongly, negatively-inducting, i.e. electron-drawing.
when alkoxide ion is formed after deprotonation, the ion is stabilized by dispersing (delocalizing) the -ve charge over the ion.
as the dispersing is by induction (not resonance effect), distance between the groups plays important role.
nearer the groups --> stronger electron-withdrawing effect --> stronger dispersing --> more stable ion --> acidity is higher
answer is correct.
alcohols are surely more acidic than alkyne.
alkyne is (exceptionally) more acidic than other hydrocarbons, but is still too weak compared to alpha-hydroxyl ketones, alcohols and acids.
again, inductive effect comes with important role.
-CF3 is strongly electron-withdrawing, thus dispersing the negative charge on alkoxide ion and stabilizing it.
alkyl groups are slightly electron-giving (via hyper-conjugation), which destabilize the alkaoxide ion a little.
the more alkyls the less stable.
ethanol: 1 alkyl on C-OH
tert-butanol: 3 alkyls on C-OH
acid is surely the most acidic; phenol comes next; benzyl alcohol (3rd from left) acts as simple alcohol, least acidic.
for the two phenols, -CH3 can destabilize the alkoxide ion by e-giving effect; -CN is not only e-drawing, but can further disperse the (-)charge via resonance effect. try to draw the resonance structure of it!