A unknown comound Z has a molecular formula C12H16O

Z absorbs strongly in the IR at 1700 cm-1. The H NMR spectral data for Z is given below. What kind of structure can you propose?

(singlet, ppm = 1.0, ratio of absorbing H = 6) (triplet, ppm = 1.2, ratio of absorbing H =3)(quartet, ppm = 2.2, ratio of absorbing H = 2)(broad singlet, ppm = 7.0, ratio of absorbing H = 5)

please explain in detail. I missed class and i'm super LOST! HELP!!

First calculate the DBE (double bond equivalents) = 1/2(2C + 2 - H) = 1/2*(24 + 2 - 16) = 5

This means that there is 5 degrees of unsaturation.

The 1700 cm-1 indicates a C=O bond

The broad peaks in the area of 7 ppm indicates Ar-H bonds--a phenyl group (C6H5) would nicely explain the remaining 4 degrees of unsaturation and the 5 Ar-H's

You have 2 CH3 groups which are not coupled to any C-H

the triplet (3) and quartet (2) are indicative of a CH2CH3 fragment and the chem shift of the CH2 at 2.2 indicates that it is adjacent to the C=O

Then piecing the puzzle

C6H5-C(CH3)2-C(=O)CH2CH3 nicely fits the info.

You could think of alternatives where the Me groups are on the ring, but that would not be consistent with 5 Ar-H's as the data suggests.