(a)
Interpretation: Absorption associated with the alcohol functional group in the IR spectrum of (−)-isopinocampheol should be identified.
Concept introduction:The IR spectrum of compound helps to detect the presence of the functional group in molecule. The
(b)
Interpretation: The various resonances corresponding to 1H NMR of hydrogen nuclei found in (−)-isopinocampheol should be assigned.
Concept introduction:The scale used for the NMR spectrum is delta scale. δ denotes parts per million units. The lower values of δ denote upfield while higher values of δ denote downfield region. Each peak in the NMR spectrum corresponds to distinct hydrogen.
The area within each peak corresponds to the number of equivalent protons found at that chemical shift values.
Spin-spin splitting is observed as a result of the interaction amongst non-equivalent NMR active nuclei. This is independent of the strength of the external magnetic field. The formula to calculate the number of peaks in the 1H NMR spectra is as follows:
Number of peaks=N+1
Where,
- N is the number of equivalent protons on the adjacent carbon atoms.
Thus if a fragment is −CH2−CH3− then it would show a three proton triplet due to CH3 and a two proton quartet in accordance with N+1 the rule.
(c)
Interpretation: The resonancecorresponding to δ 71.7 in 13C NMR should be assigned in (−)-isopinocampheol .
Concept introduction: The scale used for the 13C NMR spectrum is delta scale with theonly difference as that the chemical shift values are much larger. The range lies from δ 0−250 denotes parts per million units. The lower values of δ denote upfield while higher values of δ denote downfield region. Each peak in the NMR spectrum corresponds to a distinct carbon.
Thus if a fragment is −CH2−CH3− then it would show two carbon signals for each of theses carbon.
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EBK EXPERIMENTAL ORGANIC CHEMISTRY: A M
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- Macroscale and Microscale Organic ExperimentsChemistryISBN:9781305577190Author:Kenneth L. Williamson, Katherine M. MastersPublisher:Brooks Cole