Complex Multiplets—More Than One Value of

More Complex Multiplets—More Than One Value of f 

FIGURE 5.13 Determining coupling constants for a doublet of doublets (dd). 

To obtain /j measure the difference between the most intense lines (2 and 5) in Hz 

J2 is the spacing between lines 1 and 2, or 2 and 3, or those in the other triplet. 

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A number of approaches are possible. Generally you should choose an appropriately spaced pair of peaks based on their intensities and sharpness. 

When measuring coupling constants in a system with more than one coupling you will often notice that none of the multiplet peaks is located at the appropriate chemical shift values to directly 

6 Measuring Coupling Constants from First-Order Spectra 265 

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B. More Complex Multiplets—More Than One Value of f... 

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