15. Analytical Techniques:IR, NMR, Mass Spect

Based on IR data given determine the structure of the unknown. Unknown compound A has molecular formula C₄H₁₁N. It shows a peak at 2900 cm^-1 and peaks in the fingerprint region.

Based on IR data given determine the structure of the unknown. Unknown compound B has molecular formula C₄H₁₁N. It shows a single peak at approximately 3400 cm^-1 as well as peaks at 2900 cm^-1 and in the fingerprint region. Compound B also possesses a branched alkyl group.

Based on IR data given determine the structure of the unknown. Unknown compound C has molecular formula C₆H₁₀O₃. It shows peaks at 2900, 1850 , 1740 cm^-1 and in the fingerprint region.

Match the following functional group choices with the supplied infrared spectra data

Match the following functional group choices with the supplied infrared spectra data

Match the following functional group choices with the supplied infrared spectra data.

Match the following functional group choices with the supplied infrared spectra data.

a. Which occurs at a larger wavenumber:

1. a C=C stretch or a C=C stretch?

2. a C–H stretch or a C–H bend?

Would you expect an acetylenic C―H to absorb at a higher or lower wavenumber than the C―H in ethene?

Would you expect the stretching band of the carbonyl to appear at a higher frequency for cyclohexanecarbaldehyde or benzaldehyde? Explain.

Justify the carbonyl stretching frequencies for a series of methoxybenzaldehydes. Specifically, why are the 2- and 4-methoxy derivatives similar to each other but different from the 3-methoxy derivative?

The IR spectrum of compound A with a molecular formula of C₅H₁₂O is shown below. Compound A is oxidized to give compound B, a ketone with a molecular formula of C₅H₁₀O. When compound A is heated with H2SO4, compounds C and D are obtained. Considerably more D is obtained than C. Reaction of compound C with O₃, followed by treatment with dimethyl sulfide, gives two products: formaldehyde and compound E, with a molecular formula of C₄H₈O. Reaction of compound D with O₃, followed by treatment with dimethyl sulfide, gives two products: compound F, with a molecular formula of C₃H₆O, and compound G, with a molecular formula of C₂H₄O. What are the structures of compounds A through G?

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