作者spellspell (林小方)
看板Chemistry
標題[問題]想請問一題有機化學 謝謝
時間Wed May 20 17:05:24 2009
A sample of 1-chloro-1-phenylethane with an [α]25D of -94.8° is reacted
with NH3 in methanol/water solvent. The major substitution product of the
reaction is 1-phenyl-1-ethylamine with an [α]25D of -8.6°. Given that
optically pure (R) 1-chloro-1-phenylethane has a specific rotation of -109.0°
and that optically pure (R) 1-phenyl-1-ethylamine has a specific rotation of
+39.3°, which of the following statements best describes this reaction?
A)
Net inversion 12% with 88% racemization -- SN2 mechanism
B)
Net inversion 12% with 88% racemization -- SN1 mechanism
C)
Net inversion 25% with 75% racemization -- SN1 mechanism
D)
Net inversion 75% with 25% racemization -- SN2 mechanism
E)
Net inversion 88% with 12% racemization -- SN2 mechanism
麻煩高手了
謝謝
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1F：→ edisonjang:這是某年(台大 好像是)化研所的考題吧 05/20 19:04
2F：→ edisonjang:好像不是 我只知道應該是SN2.... 高手 快出來 XD 05/20 19:21
3F：推 nestealee:C 05/20 20:34
4F：→ nestealee:93.5%(In+0.5Re)+6.5%Re=60.9% 05/20 22:19
5F：→ nestealee:6.5%(In+0.5Re)+93.5%Re=39.1% 05/20 22:19
6F：→ nestealee:錯了.... 05/20 22:20
7F：→ nestealee:93.5%(In+0.5Re)+6.5%(0.5Re)=60.9% 05/20 22:20
8F：→ nestealee:6.5%(In+0.5Re)+93.5%(0.5Re)=39.1% 05/20 22:21
9F：→ ybs9:題目有沒有打錯? -8.6還是+8.6?? 05/21 01:24
10F：推 arabesque:應該是Sn1因為phenyl ring是很好的cation stablization 05/21 10:29
11F：→ arabesque:group，加上取代太多Sn2不易 05/21 10:29