Splitting tree

The splitting tree for Hb, showing a doublet of narrow doublets, is shown in Figure 13-33. 

Draw a splitting tree, similar to Figures 13-32 and 13-33, for proton Hc in styrene. What is the chemical shift of proton Hc ... 

A splitting tree for the Hb proton in styrene. The Hb signal is split by coupling with Ha (/ab = 17 Hz) and further split by coupling with Hc(/bc = MHz). 

Signal (a) is split into a quartet because of the adjacent CH3 with J = 7 Hz. Each of those peaks is then split into a doublet because of the coupling with the trans H, J = 15 Hz. This is called a doublet of quartets, and it is drawn here as two quartets. In a real spectrum, these peaks would overlap and would not be a clean doublet of quartets. See the splitting tree for problem 13-15. 

Spectra that can be interpreted by using the n 1 Rule or a simple graphical analysis (splitting trees) are said to be first-order spectra. In certain cases, however, neither graphical analysis nor the n -I- 1 Rule suffices to explain the splitting patterns, intensities, and numbers of peaks observed. In these latter cases a mathematical analysis must be carried out, usually by computer, to explain the spectrum. Spectra which require such advanced analysis are said to be second-order spectra. 

B Splitting Tree Diagrams and the Origin of Signal Splitting... 

PRACTICE PROBLEM 9.7 Draw a splitting tree diagram for a quartet by adding one more level to the diagram... 

Figure 9.19 Splitting tree diagram for a doublet. The signal from the observed hydrogen ( H) is split into two peaks of 1 1 intensity by the additive and subtractive effects of the magnetic field from one adjacent hydrogen ( H) on Bq (the applied field). Jab> the spacing between the peaks (measured in hertz), is called the coupling constant.

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