Nonequivalent neighboring hydrogens

SPIN-SPIN SPLITTING THE EFFECT OF NONEQUIVALENT NEIGHBORING HYDROGENS... 

The H-NMR of furan has two distinct peaks corresponding to the two separate sets of nonequivalent hydrogens in the ring system. The two a-protons (adjacent to the oxygen) are deshielded by the inductive effect of the oxygen atom and can be foimd at 7.54 ppm. The two P-protons are further upfield (effectively less deshielded than their a-proton neighbors) at 6.49 ppm. 

Singlet A signal that consists of one peak the hydrogens that give rise to the signal have no neighboring nonequivalent hydrogens. 

Step 5 Splitting patterns. Examine splitting patterns for information about the number of nonequivalent hydrogen neighbors. 

Analysis of 1-nitropropane (1) in this context reveals that the type a hydrogen atoms have two nearest neighbors in the form of the two protons of type b that are magnetically active and chemically nonequivalent. Nuclei of type c also have two such nearest neighbors, whereas those of type b nuclei have five. 

The hydrogens on C2 of 1-bromopropane also couple to two nonequivalent sets of neighbors. In this case, however, the resulting splitting pattern appears to conform with the... 

When the constants for coupling to nonequivalent types of neighboring hydrogens are different, the A -b 1 rule is apphed sequentially. 

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