Example of Integrated Spectroscopic Methods:
A compound A, having molecular formula C3H6O, displays the subsequent spectra. Deduce its structure.
Figure: IR spectrum of compound A
Solution
There is no unique way of solving a problem of structure elucidation. What we required to do is to pick up all the important information available from the spectra and then integrate them to arrive at the structure. Many times one or two spectra give enough clues to the structure. In that such cases we suggest a tentative structure and check that whether it supports the other data. Now let us make a beginning.
IHD: We start with calculation of IHD.
IHD = Number of carbon atoms -[Number of hydrogen atoms/2]- [Number of halogen atoms/2]+ [Number of nitrogen atoms/2] + 1
Therefore, IHD=3- 6/2 = 0
An IHD of zero clearly display that the molecule does not have any unsaturation or a ring structure.
IR: The strong absorption around 1700 cm-1 is indicative of a carbonyl group (>C = O); this may account for the oxygen in the molecule.