ldquo Synthesis & Structural Characterization of an Organic Compound - NMR and I
ID: 972845 • Letter: L
Question
ldquo Synthesis & Structural Characterization of an Organic Compound - NMR and IR Spectroscopy rdquo Assignment is due at the beginning of next lab session What is the unit plotted on the x-axis of an IR spectrum? What does it signify? What is the unit plotted on the x-axis of an NMR spectrum? In which region of the IR spectrum would we expect to see a peak for a ketone? A carboxylic acid? In which region of the NMR spectrum would wc see a peak for hydrogen atoms that are part of an aromatic ring? An aldehyde group?Explanation / Answer
1) In IR spectra
2) On the x-axis of a NMR spectrum is plotted ppm. It signifies the parts per million of the shift from the zero of the actual frequency of the instrument by which the nuclei being measured is shielded or deshielded. SO on the right are the shielded nuclei towards zero and to the left are the deshielded nuclei.
3) In an IR spectrum the C=O group appears as a stron signal in the region
The various different groups appear at different positions
4) In the 1H NMR spectrum the hydrogen atoms on an aromatic ring appear between 6.5-8.5 ppm. These signals are deshielded due to the deshielding by ring current effect which creates a local magnetic field.
An aldehyde group is deshielded due to its proximity to the C=O. It appears in the region between 9.5-10.5 ppm.
C=O stretch 1670-1820 cm-1Related Questions
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