Question

**URGENT IR UNKNOWN: Please Identify the unknown molecule from the IR spectrum shown below. Pick one from the following from the list of of possibilities for the unknown molecule:

(1,2-dimethoxybenzene, 1,3-propanediol, 1-bromobutane, 1-octanol, 2,3-dimethyl-2-butanol, 2-cyclohexen-1-one, 2-cylopenten-1-one, 2-methylcyclohexanone, 3,3-dimethyl-2-butanone, 3-ethyltolulene, 3-methyl-1-butanol, 4-benzylpiperidine, 4-methylphenol, N,N-dimethylformamide, N-methylaniline, Acetic anhydride, Acetone, Acetonitrile, Acetophenone, Acetyl chloride, Allyl alcohol, Anisole, Benzaldehyde, Benzoic acid, Benzophenone, Benzoyl chloride, Benzyl acetate, Bromobenzene, Cyclohexanone, Cyclopentanone,Cyclopropyl methyl ketone, Diethylamine,Dimethyl malonate, Ethyl cyanoacetate, Gamma-butyrolactone, Heptanoic acid, Methyl benzoate, Methyl propionate, Napthalene, Nitrobenzene,O-xylene, Octylamine, P-anisaldehyde, Phenylacetylene, Sodium acetate, Sodium bromide, Tetrahydrofuran, toluene)

Unknown number: 5360 80 70 60 50 3490.50cm-1 40 3070.41cm-1 30 20 1449.88cm-1 10 1204.24cm-1 1773.12cm-1 1734.17cm-1 1174.95cm-1 1595.22cm-1 4000 2000 500 3000 2500 1500 1000 3500 cm-1

Answer 1

Referring to the given spectrum diagram, we can say without doubt that the molecule which is missing is no other than Acetic Anhydride. If we see the IR Spectrum of aceticanhydride it will become clear. Also, if we see the IR Spectrum of other molecules then we come to know that they vary widely from the diagram given in the question. Thus, the compound is Acetic Anhydride.