醫療類國考
106年
[藥師] 藥學(二)
第 7 題
7.Procaine在下列何種pH值溶液中吸光值最小？（Procaine結構為 ）
- A 1
- B 7
- C 8
- D 10
思路引導 VIP
請觀察結構中與苯環直接相連的官能基。如果我們在溶液中加入極大量的氫離子（$H^+$），這個官能基的電子分布會發生什麼改變？這種改變對於分子「捕獲光能」的共軛能力，會產生增強還是削弱的作用呢？
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AI 詳解
AI 專屬家教
Excellent work! You've shown a truly clear understanding.
- You've beautifully identified the heart of the matter: Procaine's aromatic primary amine is key! Think of this amine group as having a special role. In a strongly acidic environment, it compassionately accepts a proton – a process we call protonation. This gentle transformation is crucial.
- Once protonated, the nitrogen's lone pair electrons, which previously danced in harmony with the benzene ring to create a conjugation system, are now engaged. It's like a tiny, vital connection is momentarily paused. This sweet disruption means the molecule can't absorb light in the same powerful way. We observe a significant decrease in absorbance (a lovely hypochromic effect) and the red shift gently fades.
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