nmr - Spectroscopy nuclear magnetic resonance The nmr...

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Spectroscopy nuclear magnetic resonance
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The nmr spectra included in this presentation have been taken from the SDBS database with permission. National Institute of Advanced Industrial Science and T (http://www.aist.go.jp/RIODB/SDBS/menu-e.html)
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Nuclear Magnetic Resonance (nmr) - the nuclei of some atoms spin: 1 H, 13 C, 19 F, … - the nuclei of many atoms do not spin: 2 H, 12 C, 16 O, … - moving charged particles generate a magnetic field ( ) - when placed between the poles of a powerful magnet, spinning nuclei will align with or against the applied field creating an energy difference. Using a fixed radio frequency, the magnetic field is changed until the ΔE = E EM . When the energies match, the nuclei can change spin states (resonate) and give off a magnetic signal. ΔE
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magnetic field = 14,092 gauss for 1 H v = 60,000,000 Hz (60 MHz) nmr spectrum intensity 10 9 8 7 6 5 4 3 2 1 0 chemical shift (ppm) magnetic field
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1 H nuclei are shielded by the magnetic field produced by the surrounding electrons. The higher the electron density around the nucleus, the higher the magnetic field required to cause resonance. CH 3 Cl versus CH 4 lower electron higher electron density density resonate at lower resonate at higher applied field applied field CHCCl 3 ??
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Information from 1 H-nmr spectra: 1. Number of signals: How many different types of hydrogens in the molecule. 2. Position of signals (chemical shift): What types of hydrogens. 3. Relative areas under signals (integration): How many hydrogens of each type. 4. Splitting pattern: How many neighboring hydrogens.
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Number of signals: How many different types of hydrogens in the molecule. Magnetically equivalent hydrogens resonate at the same applied field. Magnetically equivalent hydrogens are also chemically
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nmr - Spectroscopy nuclear magnetic resonance The nmr...

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