Question

Compound \(\mathrm{K}\), molecular formula $\mathrm{C}_{6} \mathrm{H}_{14} \mathrm{O}$, readily undergoes acid-catalyzed dehydration when warmed with phosphoric acid to give compound \(\mathrm{L}\), molecular formula \(\mathrm{C}_{6} \mathrm{H}_{12}\) as the major organic product. The ${ }^{1} \mathrm{H}\(-NMR spectrum of compound \)\mathrm{K}\( shows signals at \)\delta

Short answer

Based on the given NMR data and molecular formulas, we determined that the structure of compound K is 2-methyl-2-butanol, an alcohol with a tert-butyl group, a methylene group, and a methyl group. Using the concept of acid-catalyzed dehydration, we found out that the structure of compound L is 2-methyl-2-butene, resulting from the dehydration of compound K.

Step-by-step solution

Identify the functional group in compound K.

Since the molecular formula of compound K is \(\mathrm{C}_{6} \mathrm{H}_{14}\mathrm{O}\) and contains only one oxygen, compound K likely contains an alcohol functional group (-OH).

Observe the NMR data for compound K.

The \({ }^{1} \mathrm{H}\)-NMR spectrum of compound K shows signals at \(\delta 1.34\) (9 H, s), \(\delta 2.17\) (2 H, q), and \(\delta 3.69\) (3 H, s) ppm. These three signals correspond to different proton environments within the molecule.

Study the integration of these signals.

The NMR signal at \(\delta 1.34\) (9 H, s) indicates the presence of 9 protons in a methyl group environment. The signal at \(\delta 2.17\) (2 H, q) corresponds to 2 protons in a methylene group, and the signal at \(\delta 3.69\) (3 H, s) corresponds to 3 protons in a different methyl group environment.

Determine the structure of compound K based on NMR data.

Based on the NMR data, we can say that compound K has a structure with a tert-butyl group (3 methyl groups), a methylene group, and a methyl group attached to the alcohol functional group. This makes compound K: 2-methyl-2-butanol with the structure \(\mathrm{CH}_{3}\mathrm{-C}(\mathrm{CH}_{3})_{2}\mathrm{-CH}_{2}\mathrm{-OH}\).

Use the concept of acid-catalyzed dehydration to find the structure of compound L.

Compound L is obtained by the dehydration of compound K when warmed with phosphoric acid. The \(\mathrm{C}_{6} \mathrm{H}_{12}\) molecular formula of compound L tells us that one molecule of water (H2O) has been removed in the dehydration process. In the dehydration of an alcohol, the oxygen atom from the hydroxyl group (OH) and two hydrogen atoms from an adjacent carbon are eliminated. In this case, the dehydration of 2-methyl-2-butanol forms 2-methyl-2-butene.

Conclusion

The structure of compound K is 2-methyl-2-butanol, and the structure of compound L is 2-methyl-2-butene.