Problem 20

Formula: C₉H₁₀

Show Unsaturation answer

C₉H₁₀
Rule 2, omit O, gives C₇H₁₄
9 - 10/2 + 1 = 5 degrees of unsaturation.
Look for an aromatic ring, plus another pi bond or aliphatic ring.

Show IR answer

The bands at 3000-2850 indicate C-H alkane stretches. The band at 3060 indicates C-H aromatic stretch; aromatics also show bands in the regions 1600-1585 and 1500-1400 (C-C in-ring stretch), and 900-675 (C-H out-of-plane).

Show Structure answer

This is the structure. See if you can assign the peaks on your own.

Show NMR answer

Again, the integral values need to be multiplied by two to give the right number of Hs.