CH_318N_Lecture4-08_Spring_08

CH_318N_Lecture4-08_Spring_08 - Lecture 4 More NMR...

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1 Chemistry 318N Lecture 4 More NMR spectroscopy January 30, 2007 2.20 Chemistry 318N Serbian-American inventor, electrical engineer, and scientist Born, 1856 in Smiljan, Lika (Austria-Hungary) Died 1943 in New York City, New York (USA) Inventions: a telephone repeater, rotating magnetic field principle, polyphase alternating-current system, induction motor, alternating-current power transmission, Tesla coil transformer, wireless communication, radio, fluorescent lights, and more than 700 other patents. Nikola Tesla T (Tesla) = W (Weber) m 2
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2 Chemistry 318N Quick Review from last Tuesday c Only some nuclei have spin . These include 1 H and 13 C c Resonance occurs when the ratio of frequency to net field equals the gyromagnetic ratio c Diamagnetic shielding causes chemical shift TMS defined as standard: equals zero Hertz and zero PPM – Effect of electronegativity – Effect of carbon hybridization c Chemical Shift is best described in ppm ( δ ) δ = shift in hertz/spectrometer frequency spectrometer frequency is resonant frequency for 1 H on that machine = 42.58 MHz/Tesla ( γ ) times the field strength c Integrator measures relative peak areas – Areas are proportional to the numbers of identical hydrogens Chemistry 318N ) ( 0 B f h E = = ν 42. At B=1.0T, E = 42.58MHz
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3 Chemistry 318N Some Proportionality Constants c Gyromagnetic Ratio ν = γ B – For 1 H γ = 42.58 MHz/T c Planck’s Constant E = h ν c Speed of light ν = c or c = ν λ c Chemical Shift d(ppm) = ∆ν Spectrometer frequency Chemistry 318N Calculating Chemical Shift 300 x 10 6 Hz 715 Hz 2.38 = 2.38 ppm 10 6 = •At 7.05 T, a resonance is at 715 Hz (from TMS) •What is the chemical shift in ppm?
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4 Chemistry 318N Chemical Shift c
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This note was uploaded on 04/07/2008 for the course CH 318N taught by Professor Willson during the Spring '08 term at University of Texas at Austin.

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CH_318N_Lecture4-08_Spring_08 - Lecture 4 More NMR...

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