Q 13-26P - Organic Chemistry (Mcmurry)

Question

Question: Sketch what you might expect the ¹H and ¹³C NMR spectra of the following compound to look like (green =Cl):

                                       

Step-by-Step Solution

Answer

The compound has 5 different type of carbons and 4 different type of hydrogen.

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 and their relative intensities

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).

The relative intensities of the signal reflects the relative number of protons of different kind present in the molecule, for example

$C{H}_{3}C{H}_{2}OH$:  Three types of protons, three NMR signals. 

 

                          So, relative intensities: 3:2:1

Step 3: Sketch the 1 H and 13 C NMR spectra of the following compound

The compound has 5 different type of carbons and 4 different type of hydrogen.

                      No. of signal = 5                                                      No. of signal = 4
        
          
   

                   

                                   
                                                                 ¹H and ¹³C NMR spectra of the ethyl-2-chloropropanoate