Long-range coupling between protons more than two carbon atoms apart is sometimes
Chapter 13, Problem 13.56(choose chapter or problem)
Long-range coupling between protons more than two carbon atoms apart is sometimes observed when p bonds intervene. An example is found in 1-methoxy-1-buten-3-yne. Not only does the acetylenic proton, Ha, couple with the vinylic proton Hb, it also couples with the vinylic proton Hc, four carbon atoms away. The data are: Ha (3.08 ) Hb (4.52 ) Hc (6.35 ) Ja-b = 3 Hz Ja-c = 1 Hz Jb-c = 7 Hz 1-Methoxy-1-buten-3-yne Ha Hb C C CH3O C C Hc Construct tree diagrams that account for the observed splitting patterns of Ha, Hb, and Hc.
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