Question

The molecular formula for the IR Spectrum included below is C9H10O2. Based on this information:

1. Calculate the Hydrogen Deficiency Index.

2. Identify any possible rings and/or double and triple bonds.

3. For each of the peaks in the IR Spectrum, identify the possible functional groups.

4. Name and draw the molecular structure of the compound.

Lock %Transmittance 4000 3500 3000 3064.39 3034.40 2982.20 2500 Wavenumbers (cm-1) 2000 1969.60 1821.43 1718.25 1602.65 1500 1450.88 1367.11 1274.63 1407.69 1027.93 872.88 850.37 1000 937.41 Backspace 807.73 782.01 710.23 494.43 447.33 425.45 500 409.55

Answer 1

Molecular formula of the compound is C,H,,02. For 9 carbon atoms, the maximum number of hydrogens=2n+2 = 2(9)+2 = 20 Since the compound contains 10 hydrogens, therefore it has (20-10) 10 hydrogens fewer than maximum number. For each HDI (Hydrogen Deficiency Index) remove 2 hydrogens. 10 H's fewer than the maximum HDI= Calculate HDI is as follows: 2H's removed for each degree of unsaturation = 5 Thus, HDI for the compound C,H,O, is 5. From the HDI, unknown compound C,H,O, contain benzene ring with either a double bond (pi bond) or a ring.

An IR absorption peak at 1718 cm-?. This suggests the presence of keto group of ester, -Co- in the compound. The spectrum also shows strong C-O and above > 3000 cm Therefore, the compound with a molecular formula of C,H,O, contains ester as a functional group. Chemical Formula: C,H,02 Exact Mass: 150.07

Therefore, the name of the compound is ethyl benzoate.