Q13-25E - Organic Chemistry (Mcmurry)

Question

How many absorptions would you expect the following compound to have in its ¹H and ¹³C NMR spectra?

Step-by-Step Solution

Answer

Step 1: NMR spectroscopy

NMR stands for Nuclear Magnetic Resonance Spectroscopy. This is the technique used for determining the structure of the organic compounds. It is a non-destructive technique. It is of two types ¹H NMR and¹³C NMR.

Proton nuclear magnetic resonance (¹H NMR) is the application of nuclear magnetic resonance in NMR spectroscopy with respect to hydrogen-1 nuclei within in the molecule of substance in order to determine the structure of its molecules.

Carbon-13 nuclear magnetic resonance is the application of nuclear magnetic resonance spectroscopy to carbon. It is analogous to proton NMR and allows the identification of carbon atom in an organic molecule just as proton NMR identifies Hydrogen atoms.

Step 2: Number of signals

NMR stands for Nuclear Magnetic Resonance Spectroscopy. This is the technique used for determining the structure of the organic compounds.

The number of signals present in NMR reflects the number of magnetically different protons. Thus the number of signal reflects the number of chemically different protons or sets of protons. For example methanol has two different set of protons (methyl and hydroxyl).

Step 3: Identify absorption of following compound in its 1 H and 13 C NMR spectra

Here, none of the carbons or hydrogens are equivalent.

In ¹H NMR, there are 5 different set of proton present as shown in figure (a) given below, therefore, 5 signals are observed.

In ¹³C NMR, 7 signals are observed due to seven different carbons present in figure (b)