vivienne asked in 科學化學 · 1 decade ago

有機化學的相關問題

1.Select the strongest nucleophile for an SN2 reaction.

正解是:RO-  為什麼不是OH- ? OH-不是強鹼嗎?

2.Which of the following solvents is fully miscible with water and also can be evaporated efficiently by use of rotatory evaporator equipped with water bath ?

hexane,dimethylsulfoxide,N.N-dimethylformamide ether,tetrahydrofoxide,toluene,dichloromethane。

題目看不太懂,答案是?why?

3.The more electronegative the group ,the better it is a leaving group

這句話哪裡有錯?

4.Arrange the following in order of decreasing.

(a)Rate of hydrolysis:

(1) chlorobenzene (2) 1-chlorobutane (3) 2-chlorobutane (4)2-iodobutane

Ans : 4>3>2>1

(b) Reactivity to nucleophilic substitution :

(1)CH3CH2CH2Cl (2) CH2=CHCH2Cl (3) CH3CH2COCl (4) CH2=CClCH3

Ans : 3>2>1>4

(C) Reactivity toward SN2 reaction :

(1) 2-bromo-2-methylbutane (2)1-bromopentane (3) 2-bromopentane

Ans : 3>1>2

可以教我為什麼? 怎麼判斷嗎?

5.Which compound will solvolyzed faster in aqueous dioxane ?

為什麼答案是 PhS(CH2)4Cl 不是 PhS(CH2)3Cl ?

6.retention : The conversion of one molecule into another with the same relative configuration.

這句話的意思我看不太懂耶...可以幫我翻譯一下嗎?

7.Which of the following will undergo the fastest ethanolysis?

(A)(CH3)3CCH2Br (B)(CH3)2CHCH2Br (C)CH3CH2Br (D) CH3CH2CH2Br

答案是B...為什麼?

8. 依NaI的丙酮溶液反應速率的快慢排列

(a) I (CH3)3CCH2CH2Br , II CH3-O-CH2-Br ,III CH3CH2CH2Br

Ans : II > III >I

why?

9.Ph 是什麼? 是不是通常都不參與反應?

Update:

8. Ans : II> III > I

Update 2:

喔喔~抱歉耶...

那可不可以幫我解答2.4.6就好了嗎?

因為實在找不到人問~

拜託你~....謝謝...

1 Answer

Rating
  • Yy
    Lv 7
    1 decade ago
    Favorite Answer

    問題太多 花了一小時回 結果被超過2000字不能回 被系統消掉了 不想回了 好好把alkyl halide (SN1 & SN2)那一章好好看吧

    Ph是phenyl 苯環不參與SN反應

    2006-09-15 12:44:27 補充:

    2.Which of the following solvents is fully miscible with water and also can be evaporated efficiently by use of rotatory evaporator equipped with water bath ?hexane,dimethylsulfoxide,N.N-dimethylformamide ether,tetrahydrofurane,toluene,dichloromethane。以下什麼溶劑可完全與水互溶而且以有水浴配備(可加溫)的旋轉蒸發器(可減壓)有效的蒸發與水不互溶: hexane, toluene,dichloromethane與水互溶:dimethylsulfoxide,N,N-dimethylformamide 少部分與水互溶:ether,tetrahydrofuranedimethylsulfoxide 沸點190°N,N-dimethylformamide 沸點154°答案:N,N-dimethylformamide4.Arrange the following in order of decreasing.(a)Rate of hydrolysis:(1) chlorobenzene (2) 1-chlorobutane (3) 2-chlorobutane (4)2-iodobutaneAns : 4>3>2>1水解:SN1, 有碳陽離子產生 3級> 2級> 1級 I比Cl更易離去 chlorobenzene:氯與苯環sp2碳連起來 不易離去 (b) Reactivity to nucleophilic substitution :(1)CH3CH2CH2Cl (2) CH2=CHCH2Cl (3) CH3CH2COCl (4) CH2=CClCH3Ans : 3>2>1>4(3) CH3CH2COCl 酸氯 carbonylC=O碳富陽極性 Cl是好離去基(2) CH2=CHCH2Cl Cl離去後有共振allyl resonance 穩定http://research.cm.utexas.edu/nbauld/teach/allylra... CH2=CClCH3 氯與sp2碳=C-連起來 最難離去(C) Reactivity toward SN2 reaction :(1) 2-bromo-2-methylbutane (2)1-bromopentane (3) 2-bromopentaneSN2 受立體障礙影響大 立體障礙愈大 反應愈差與離去基連結的碳 1級> 2級> 3級答案應是(2)1-bromopentane [1級] > (3) 2-bromopentane [2級] > (1) 2-bromo-2-methylbutane [3級]6.retention 保留原來的立體結構SN2反應會在與離去基連結的碳背後攻擊 所以產物的立體結構與起始物相反(inversion 反轉)SN1反應會有碳陽離子產生 所以親核基nucleophile 可接觸到平面的trigonal碳陽離子的兩面 所以有兩個產物 一個產物立體結構與起始物相反 另一產物立體結構與起始物相同一樣(保留 retention)http://tw.knowledge.yahoo.com/question/?qid=140511...

    2006-09-15 16:01:34 補充:

    7.Which of the following will undergo the fastest ethanolysis?(A)(CH3)3CCH2Br (B)(CH3)2CHCH2Br (C)CH3CH2Br (D) CH3CH2CH2Br ethanolysis: SN1 答案是B...因Br離去後 可重排得3級碳陽離子

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