91Ó°ÊÓ

¹³C NMR spectrum gives the location of all non-equivalent carbons. The equivalent carbon has the same spectrum. The substituents affect the most in the ¹³C spectrum signals.

• If the electron-withdrawing group is adjacent to the corresponding ¹³C,the spectra would be downfield.
• If the electron-donating group is adjacent to the corresponding ¹³C, the spectra would be upfield.

a. Molecular ion in the mass spectrometry is obtained by ionizing the molecule.

The molecular ions are shown as:

Molecular ion

b.

IR absorption for the ketone group in A is 1740 cm^-1 , which is due to the presence of the OH group. The OH group attracts the electron towards itself and increases the stretching frequency of the ketone group.

The IR absorption for OH group in A and B is 3600cm^-1 .

IR absorption for the ketone group is 1730 cm^-1 due to the OH group being away from the CO. The OH group attracts the electron towards itself and increases the stretching frequency of the ketone group slightly less than A.

c.

The number of non-equivalent signals for both A and B are 4 – two ¹³C signals for twoCH₂ , one CH₃, and one carbon for CO.

d.

The number of non-equivalent signals for both A and B are 4 – four ¹H signals for twoCH₂ , one CH₃, and one carbon for OH.

e.

The splitting signals for A and B are given as:

A-(t) CH₃, (q) CH₂, (s) 1H, (s)CH₂

B--(s) CH₃, (t)CH₂ , (s) 1H, (t) CH₂