Question

You are given the formula of C7H5O, determine if this is the emperical or molecular formula. Based on the IR and NMR, draw the correct structure and name it.

PT sid 4096 F1 60.009998 MHz sw1 1000.00 Hz AT 1 4.10 sec Hz per Pt 1st 24 Hz 354, 20 Hz B1 00 Hz T P A 127,00 B 17.00 qSA 10 YERICSImported file

Answer 1

The given compound is benzil.

benzil Chemical Formula: Ci4H1o02 Empirical Formula: C,HSO

Note: $C_7H_5O$ is an empirical formula and not a molecular formula as with this formula, we can write the structure of a radical but not a molecule. The molecular formula is $C_{14}H_{10}O_2$

The assignment of H NMR peaks is as shown.

7.64 7.89 7.73 7.89 7.64 7.64 7.89 7.73 7.89 7.64

The presence of carbonyl group is confirmed by a strong peak at 1677 $cm^{-1}$

The presence of aromatic region is confirmed by (1) medium peak at 3068 $cm^{-1}$, (2) strong sharp peaks for ring vibration at 1450 $cm^{-1}$ and 1598 $cm^{-1}$ and (3) out of plane bending (strong peak) at 671 $cm^{-1}$.