有機化學第13ç« ï&f

有機化學第13ç« ï&f

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Unformatted text preview: 2009/3/19 1 13. Structure Determination: Nuclear Magnetic Resonance Spectroscopy 核磁共振光譜學 Based on McMurry’s Organic Chemistry , 7 th edition What can we have from … ¡ Mass spectrometry (MS) ¡ molecular size and formula 大小與反應式 ¡ Infrared (IR) spectroscopy ¡ functional groups 官能基 ¡ Nuclear magnetic resonance spectroscopy ¡ map of carbon-hydrogen framework 碳氫關係 ¡ Ultraviolet-visible spectroscopy (VIS) ¡ conjugated π electron system 共軛雙鍵 2009/3/19 2 The Use of NMR Spectroscopy ¡ Used to determine relative location of atoms within a molecule ¡ Most helpful spectroscopic technique in organic chemistry Related to MRI in medicine (Magnetic Resonance Imaging 磁共振成像 ) A MRI uses radio waves and a magnetic field to 3 A MRI uses radio waves and a magnetic field to take pictures of soft tissues, organs and bones Why This Chapter? NMR is the most valuable spectroscopic techniq e sed for str ct re determination technique used for structure determination More advanced NMR techniques are used in biological chemistry to study protein 4 biological chemistry to study protein structure and folding 2009/3/19 3 OUTLINE ¡ Nuclear Magnetic Resonance Spectroscopy ¡ The Nature of NMR Absorptions ¡ Chemical Shifts 化學位移 ¡ 13 C NMR Spectroscopy: Signal Averaging and FT-NMR ¡ Characteristics of 13 C NMR Spectroscopy ¡ DEPT 13 C NMR Spectroscopy ¡ Uses of 13 C NMR Spectroscopy OUTLINE ¡ 1 H NMR Spectroscopy and Proton Equivalence Proton Equivalence ¡ Chemical Shifts in 1 H NMR Spectroscopy ¡ Integration of 1 H NMR Absorptions: Proton Counting ¡ Spin-Spin Splitting in 1 H NMR Spectra ¡ More Complex Spin-Spin Splitting Patterns ¡ Uses of 1 H NMR Spectroscopy 2009/3/19 4 13.1 Nuclear Magnetic Resonance Spectroscopy 1 H or 13 C nucleus spins and the internal magnetic field aligns parallel to or against an aligned external magnetic field 7 Parallel orientation is lower in energy making this spin state more populated Radio energy of exactly correct frequency (resonance) causes nuclei to Nuclei flipped into anti-parallel state flip into anti-parallel state ¡ 8 Energy needed is related to molecular environment (proportional to field strength, B ) 2009/3/19 5 Magnetic field Strength vs △ E 4.7 tesla (T) 200 MHz △ E= 8.0 × 10-5 KJ/mol 21.6 T 920 MHz IR 4.8-48 KJ/mol 1nm 10 10 2 10 3 10 4 10 5 10 6 10 7 NMR Spectroscopy Where is it?...
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This note was uploaded on 11/11/2010 for the course CHE CH2005 taught by Professor 曹恒光 during the Spring '10 term at National Central University.

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有機化學第13ç« ï&f

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