Question 16.62: Deduce the structure of a compound with the molecular formul......
Deduce the structure of a compound with the molecular formula C₄H₈O based on the following proton NMR spectrum plus the information that the ^{13}C NMR spectrum has two peaks whose chemical shifts are 30 and 45 ppm.
The formula of the compound tells us that it is a ring. There are two kinds of sp³-hybridized carbon atoms based on the chemical shifts of the two peaks in the C-13 NMR spectrum. The proton NMR spectrum tells us that there are two kinds of protons. The integration of the peaks tells us that each of these have the same number of hydrogen atoms. Since there are four carbons, each contains two hydrogen atoms. The signal near 3.9 δ is due to a pair of methylene groups adjacent to oxygen. The peak at 1.9 δ is due to two hydrogen atoms bonded to the carbon atom farthest from the oxygen atom. The compound is tetrahydrofuran.
