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15. Analytical Techniques:IR, NMR, Mass Spect

IR Spect:Extra Practice

15. Analytical Techniques:IR, NMR, Mass Spect

IR Spect:Extra Practice

Practice this topic

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.

Multiple Choice

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

Multiple Choice

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

Multiple Choice

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

Multiple Choice

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

Multiple Choice

What are the characteristic bands in an IR spectrum corresponding to a carboxylic acid?

Textbook Question

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?

Textbook Question

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

Textbook Question

LOOKING AHEAD We explain in Chapter 23 that substituents can transmit electronic information through the benzene ring when appropriately positioned. Assessments 14.55–14.59 allow us to use IR spectroscopy to discover this concept and apply it to an example (Assessment 14.60) that we study there. (••) Would you expect the stretching band of the carbonyl to appear at a higher frequency for cyclohexanecarbaldehyde or benzaldehyde? Explain.

Textbook Question

LOOKING AHEAD We explain in Chapter 23 that substituents can transmit electronic information through the benzene ring when appropriately positioned. Assessments 14.55–14.59 allow us to use IR spectroscopy to discover this concept and apply it to an example (Assessment 14.60) that we study there. (•••) 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?

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