Anonymous
Anonymous asked in 科學化學 · 2 decades ago

大學有機化學~~問題!!!會的人幫一下吧

Draw the most stable chair conformation of the following molecules, and estimate the  amount of strain in each: (a)trans-1-Chloro-3methylcyclohexane  (b)cis-1-Ethyl-2- methylcyclohexane(c)cis-1-Bromo-4-ethylcyclohexane      (d)cis-1-tert-Butyl-4-ethylcyclohexane

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  • 2 decades ago
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    仍舊是equatorial與axial的問題

    Strain大的官能基要放在equatorial位置

    一般:F<Cl, Br<Me<Et<i-Pr<Ph<t-Bu

    最穩定結構請照下列排法:

        equatorial   axial

     (a)   Me     Cl

     (b)   Et     Me

     (c)   Et     Br

     (d)   t-Bu    Et

    strain的計算:

    1.Axial位置的官能基與Axial H的作用 = 要查表。

    2.One gauche interaction(1,2取代才有)=3.8 KJ/mol。

    所以

     (a) Cl和2個Axial H作用=1.0*2=2.0 KJ/mol

     (b) Me和2個Axial H作用+One gauche interaction=3.8*2+3.8=11.4 KJ/mol

     (c) Br和2個Axial H作用=1.0*2=2.0 KJ/mol

     (d) Et和2個Axial H作用=4.0*2=8.0 KJ/mol

    Source(s): McMurry, Org. Chem. 5th ed.
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