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EFEK INDUKSI

EFEK INDUKSI. KIMIA ORGANIK FISIK. pKa 3,75 4,75 2,66. MENGAPA TINGKAT KEASAMANNYA BERBEDA ?. Mengapa Tingkat Kebasaannya Berbeda ?. H-NH2 pKb = 4,75 CH3-NH2 pKb = 3,34. Mengapa laju reaksi nitrasi pada senyawa berikut berbeda ?.

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EFEK INDUKSI

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  1. EFEK INDUKSI KIMIA ORGANIK FISIK

  2. pKa 3,75 4,75 2,66 MENGAPA TINGKAT KEASAMANNYA BERBEDA ?

  3. Mengapa Tingkat KebasaannyaBerbeda ? • H-NH2 pKb = 4,75 • CH3-NH2 pKb = 3,34

  4. Mengapalajureaksinitrasipadasenyawaberikutberbeda ?

  5. Asammetanoatlebihasamdariasametanoatkarenapadaasametanoatterdapatgugusmetil yang mempunyaikemampuanmendorongelektronikatanmelaluiikatan sigma (C-C-O-H) sehingga atom O menjadirelatifmakinnegatif, akibatnya atom H sukarlepassebagai H+, asamnyamenjadilebihlemah. Gugus CH3 mempunyaiefekinduksimendorongelektron, diberisimbol +I. Asamalfamonoflouroetanoatlebihasamdariasammetanoatkarenapadaasamalfamonoflouroetanooatterdapatgugus F yang mempunyaikemampuanmenarikelektronikatanmelaluiikatan sigma sehingga atom O menjadirelatifmakinpositif, akibatnya atom H makinmudahlepassebagai H+, asamnyamenjadilebihkuat. Gugus F mempunyaiefekinduksimenarikelektrondiberisimbol -I

  6. Inductive Effects • An inductive effect is the pull of electron density through  bonds caused by electronegativity differences in atoms. • In the example below, when we compare the acidities of ethanol and • 2,2,2-trifluoroethanol, we note that the latter is more acidic than the • former.

  7. Inductive Effects • The reason for the increased acidity of 2,2,2-trifluoroethanol is that the three electronegative fluorine atoms stabilize the negatively charged conjugate base.

  8. Inductive Effects • When electron density is pulled away from the negative charge through  bonds by very electronegative atoms, it is referred to as an electron withdrawing inductive effect. • More electronegative atoms stabilize regions of high electron density by an electron withdrawing inductive effect. • The more electronegative the atom and the closer it is to the site of the negative charge, the greater the effect. • The acidity of H—A increases with the presence of electron withdrawing groups in A.

  9. Electron-withdrawing inductive effect • The polarization of electron density of a covalent bond due to the electronegativity of an adjacent covalent bond.

  10. + I menunjukkankemampuansuatugugusuntukmendorong/menolakelektronlebihkuatdari atom H • -I menunjukkankemampuansuatugugusuntukmenarikelektronlebihkuatdari atom H • Efekinduksibekerjamelaluiruangdanikatan sigma. Makin jauhletakgugus/atom yang memilikiefekinduksi, makinkecilpengaruhnyaterhadappolarisaiikatan.

  11. Stabilization by the inductive effect falls off rapidly with increasing distance of the electronegative atom from the site of negative charge in the conjugate base.

  12. Posisigugusmenentukanbesarnyaefekinduksi yang diberikan.

  13. P-kresoldanfenol, mana yang lebihasam? • pKa = 9,94 dan 10,19

  14. PengaruhEfekInduksiTerhadapReaktivitasReaksi

  15. PengaruhEfekInduksipadaMomenDipol

  16. Manakah yang mempunyaimomendipollebihbesar ? (1,97 dan 1,71 D)

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