Question

Draw a splitting diagram for H_b in trans-1,3-dichloropropene, given that J_ab = 13.1 Hz and J_bc = 7.2 Hz.

Short answer

Spin-spin coupling is the interaction of proton spins through the mediating bonding electrons. The bonding electron pairs its spin with the spin of the nearest proton.

Step-by-step solution

Spin-spin coupling

Spin-spin coupling is the interaction of proton spins through the mediating bonding electrons. The bonding electron pairs its spin with the spin of the nearest proton.

Coupling constant (J)

The distance between the peaks in a multiplet is called the coupling constant. The coupling constant is a measure of how strongly a nucleus is affected by the spin states of its neighbor. Its magnetic field is independent of applied field strength.

Drawing a splitting diagram for Hb.

Structure of trans-1, 3-dichloroprene

1 trans H_a proton splits the H_b into 1 + 1 = 2 peaks, so it will get a doublet. 2 H_c protons split H_b into 2 + 1 = 3 peaks, then a doublet of triplets is obtained. Therefore, the splitting diagram for H_b can be drawn as:

Splitting diagram for H_b