15. Analytical Techniques:IR, NMR, Mass Spect

Which of the following best describes the most stable cation typically formed in a mass spectrometer by cleavage of a straight-chain alkane such as $C_5{H}_{12}$ (pentane)?

In mass spectrometry, what is the molecular ion ($M+$) formed when methane ($C_1{H}_4$) is ionized in the mass spectrometer?

In mass spectrometry, $\alpha$-cleavage is most commonly observed in molecules containing which of the following features?

Which of the following is the most likely base peak observed in the mass spectrum of diisopropyl ether?

What is an advantage of using $GC-MS$ (Gas Chromatography-Mass Spectrometry) in analytical chemistry?

A compound's mass spectrum shows two molecular ion peaks of equal intensity at $100$ and $102$ m/z. Does this suggest the presence of bromine in the compound?

Identify the hydrocarbon that has a molecular ion with an m/z value of 128, a base peak with an m/z value of 43, and significant peaks with m/z values of 57, 71, and 85.

Can one of the possible molecular formulas contain a nitrogen atom?

Suggest possible molecular formulas for a compound that has a molecular ion with an m/z value of 86.

Determine the molecular formula for each of the following:

b. a compound that contains C, H, and one O and has a molecular ion with an m/z value of 100

Suppose we have some optically pure (R)-2-butyl acetate that has been 'labeled' with the heavy ¹⁸O isotope at one oxygen atom as shown.

(c) Explain how you would prove experimentally where the ¹⁸O label appears in the products. (¹⁸O is not radioactive.)

What is the most likely m/z value for the base peak in the mass spectrum of 3-methylpentane?

Can a high-resolution mass spectrometer distinguish between them?

The IR and mass spectra for three different compounds are shown below. Identify each compound.

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