Question

Repeat Problem 13-25, sketching the off-resonance-decoupled${13}_{\mathrm{C}}$spectra of the compounds.

Short answer

The off-resonance-decoupled carbon-NMR spectrums have been drawn for the given compounds.

Step-by-step solution

Step-1. Explanation of part (a):

In an off-resonance decoupled carbon-NMR spectrum, the coupling between each carbon atom and each hydrogen atom attached directly to it is observed.When off-resonance decoupling is used, the apparent magnitude of the coupling constants is reduced and overlap of the resulting multiplets is less frequent problem. The off-resonance decoupled spectrum retains the couplings between the carbon atom and directly attached protons but removes the couplings between the carbon and more remote protons.

Off-resonance decoupled carbon-NMR spectrum of part (a) molecule have been drawn with chemical shifts values indicated in the spectrum along with carbons which are responsible for peaks have also been assigned.

Step-2. Explanation of part (b):

In an off-resonance decoupled carbon-NMR spectrum, the coupling between each carbon atom and each hydrogen atom attached directly to it is observed. When off-resonance decoupling is used, the apparent magnitude of the coupling constants is reduced and overlap of the resulting multiplets is less frequent problem. The off-resonance decoupled spectrum retains the couplings between the carbon atom and directly attached protons but removes the couplings between the carbon and more remote protons.

Off-resonance decoupled carbon-NMR spectrum of part (b) molecule have been drawn with chemical shifts values indicated in the spectrum along with carbons which are responsible for peaks have also been assigned.

Step-3. Explanation of part (c):

In an off-resonance decoupled carbon-NMR spectrum, the coupling between each carbon atom and each hydrogen atom attached directly to it is observed. When off-resonance decoupling is used, the apparent magnitude of the coupling constants is reduced and overlap of the resulting multiplets is less frequent problem. The off-resonance decoupled spectrum retains the couplings between the carbon atom and directly attached protons but removes the couplings between the carbon and more remote protons.

Off-resonance decoupled carbon-NMR spectrum of part (c) molecule have been drawn with chemical shifts values indicated in the spectrum along with carbons which are responsible for peaks have also been assigned.

Step-4. Explanation of part (d):

In an off-resonance decoupled carbon-NMR spectrum, the coupling between each carbon atom and each hydrogen atom attached directly to it is observed. When off-resonance decoupling is used, the apparent magnitude of the coupling constants is reduced and overlap of the resulting multiplets is less frequent problem. The off-resonance decoupled spectrum retains the couplings between the carbon atom and directly attached protons but removes the couplings between the carbon and more remote protons.

Off-resonance decoupled carbon-NMR spectrum of part (d) molecule have been drawn with chemical shifts values indicated in the spectrum along with carbons which are responsible for peaks have also been assigned.