2444-091411

2444-091411 - Coupling constants are measured in Hertz J =...

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Unformatted text preview: Coupling constants are measured in Hertz J = 2 Hz, J = 10.3 Hz J = 14.2 Hz J = 2 Hz J = 15 Hz Assume CH 2-CH J = 2 Hz Assume CH-CH 3 J- 10 Hz What about the nonane? Coupling Constants, J C CH 2 CH CH 3 CH 3 CH 3 CH CH 3 CH 3 H 3 C CH CH 3 H 3 C H 3 C C CH 2 1H, 5 neighbors 6 peaks Assume CH 2-CH J = 2 Hz Assume CH-CH 3 J- 10 Hz 1 H of CH 3 , J = 10 Hz 1 H of CH 3 , J = 10 Hz 1 H of CH 3 , J = 10 Hz J = 10 Hz J = 10 Hz J = 10 Hz J = 10 Hz 1 H of CH 2 , J = 2 Hz 1 H of CH 2 , J = 2 Hz J = 2 Hz J = 2 Hz J = 10 Hz J = 2 Hz That one proton will appear as this complex signal, integrating to one H n + 1 predicts 6 peaks This is incorrect J Values are not the same C CH 2 CH CH 3 CH 3 CH 3 CH CH 3 CH 3 H 3 C CH CH 3 H 3 C H 3 C C CH 2 1H, 5 neighbors 6 peaks C CH 2 CH CH 3 CH 3 CH 3 CH CH 3 CH 3 H 3 C CH CH 3 H 3 C H 3 C C CH 2 1H, 5 neighbors 6 peaks Sometimes, signals are NOT separated, and they appear as a jumbled signal. We cannot determine singlet, doublet, triplet, etc. We call these a multiplet. Such signals do not provide much structural information. How many peaks? Signal Overlap Common, first order (follows n + 1) fragments CH 2 CH 3 ETHYL CH 3 next to CH 2 CH 2 next to CH 3 ISOPROPYL 1 H next to 6 identical H i.e. 2 methyl groups 2 identical CH 3 , both next to one H C CH 3 H CH 3 C CH 3 CH 3 CH 3 3 identical methyl groups - 9 Hs no neighbors - singlet at about 0.9 ppm tert-BUTYL First Order Fragments 2.5 2.0 1.5 1.0 0.5 O...
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This note was uploaded on 02/25/2012 for the course CHEM 244 taught by Professor Jardin,j during the Fall '08 term at UConn.

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2444-091411 - Coupling constants are measured in Hertz J =...

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