Question

The \({ }^{1} \mathrm{H}-\mathrm{NMR}\) spectrum of compound \(\mathrm{R}_{r} \mathrm{C}_{6} \mathrm{H}_{14} \mathrm{O}\), consists of two signals: \(\delta 1.1\) (doublet) and \(\delta 3.6\) (septet) in the ratio 6:1. Propose a structural formula for compound \(R\) consistent with this information.

Short answer

Answer: The structure of compound R is \(CH_3-CH(CH_3)_2-CH_2-O-CH_2-CH_3\).

Step-by-step solution

Identify possible molecular formula

The molecular formula of the compound is given as \(C_6 H_{14} O\). It indicates that there are 6 carbon atoms, 14 hydrogen atoms, and one oxygen atom in the molecule. The degree of unsaturation for this compound is 0, meaning that this compound is likely to be saturated (no double bonds or rings).

Analyze the H-NMR signals

According to the given H-NMR spectrum, there are two signals: 1. \(\delta 1.1\) (doublet), ratio 6: This corresponds to six hydrogens with an adjacent carbon atom having one hydrogen atom. 2. \(\delta 3.6\) (septet), ratio 1: This corresponds to one hydrogen which is split by six neighboring hydrogen atoms (therefore, it should be bonded to a carbon that has six hydrogen atoms as neighbors).

Deduce the structure

Based on the information provided, we can deduce the following structure. There must be one carbon atom in the structure that has two hydrogen atoms bonded to it and is adjacent to a carbon atom bonded to six hydrogen atoms. At the other end, there is an oxygen atom connected to one of the carbons in the hydrocarbon chain. Since there are 6 carbon atoms in total, we can propose the following structure: \(CH_3-CH(CH_3)_2-CH_2-O-CH_2-CH_3\)

Verify the structure

Let's verify our proposed structure using the given H-NMR data: 1. The hydrogens in \(-CH_2-O-\) will have a higher chemical shift (around 3.6) due to the electron-withdrawing effect of the adjacent oxygen atom. As expected, these hydrogens form a septet because they have six neighboring hydrogen atoms, which is consistent with the given H-NMR data. 2. The remaining hydrogens form a doublet with a smaller chemical shift (about 1.1) due to their proximity to the electron-releasing alkyl groups. The ratio of these hydrogens is 6, which is consistent with the given H-NMR data.

Final answer

The structural formula for compound R, consistent with the given H-NMR information, is: \(CH_3-CH(CH_3)_2-CH_2-O-CH_2-CH_3\)