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20.2: Solving Spectral Problems with 2D Spectra

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    Solving Spectral Problems with 2D Spectra

    Practice: Compound 1*

    *All spectra are either from SDBS (Japan National Institute of Advanced Industrial Science and Technology) or simulated.

    Step 1: Complete Data Tables for 1D NMR spectra, IR, and MS.

    clipboard_e89ba171f0dbf56905fe54417a909abaf.png

    Chemical Shift Integration Multiplicity Partial Structure
           
           
           
           
           
           

    clipboard_eb65e47bee4c35f4a2c2fa092d6b37952.png

    Chemical Shift Type of Bonding Environment
       
       
       
       
       
       
       

    Practice: Compound 1 (cont.)

    clipboard_e4a9d9f082776456905f8871bf70b732a.png

    Frequency Functional Group
       
       
       
       
       

    clipboard_ebd2838573e9f452b0431f9a9597e2785.png

    Molecular Weight:

    Key fragments:

    Practice: Compound 1 (cont.)

    Step 2: Determine Molecular Formula and Compile Partial Structures

    Indications of an Aromatic Ring = C6

    m/z 77,

    7-8 ppm in proton (two doublets – para subst.)

    120-150 ppm in carbon

    clipboard_eadcc324152fc900679f1aa966c56573e.png

    Indications of a carboxylic acid = CO2

    IR and peak at 180 in carbon, OH at 14 ppm in proton

    clipboard_e8cf8746d32487a87d2230e52762d193f.png

    Total integration of 18 H

    5 Aliphatic C but there appears to be two identical methyls = 6 C

    Doublet in proton nmr that integrates to 6 H

    clipboard_ef04f40b78a9eb514f25c3e4f55b6f73c.png

    Other three carbons…

    clipboard_e9e6519e97a9b76fa000a1fe673b15c2f.png

    Total: C13H18O2

    Mass of C13H18O2: 206

    • Does this match the MS?
    • Calculate SU: ____________

    Step 3: Complete HMQC Table and Label All Peaks in Spectra

    clipboard_eb722616baa638335f153d76aae040927.png

    clipboard_eb844a56d8b81e9da8a76cbfa0a32da37.png

    Letter 13C Shift 1JCH
    A    
    B    
    C    
    D    
    E    
    F    
    G    
    H    
    I    
    J    

    Step 4: Complete COSY Table

    clipboard_e22a555494764031df600a062aa874a92.png

    clipboard_e74f59ba4cb8697542e33c02ce6c1d2e7.png

    Step 5: Draw Partial Structures

    Check that they confirm partial structures from 1H coupling. If not, revise!

    clipboard_eabf7ff827e8986502d2862222fe21966.png

    Step 6: Complete HMBC Table and Connect Partial Structures

    clipboard_e91c8c446320f00aa049b902299d71844.png

    clipboard_ea02df3290d6aba2388b1f9e006b97614.png

    • Complete the table and show the correlations as arrows on the structure shown.

    clipboard_e7185b429545baf561f309349761557f1.png

    Letter 2-4JHC
    A  
    B  
    C  
    D  
    E  
    F  
    G  
    H, I  
    J  

    This page titled 20.2: Solving Spectral Problems with 2D Spectra was last modified on Tue, 12 Nov 2024 18:54:06 GMT and is shared under a not declared license and was authored, remixed, and/or curated by Kate Graham.

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