Question 18.40: Deduce the structure of isomeric ketones having the molecula......
Deduce the structure of isomeric ketones having the molecular formula C₉H₁₀O₂ based on the following proton NMR spectra.
The doublet of 2H doublets between 7 and 8 δ corresponds to the para-substituted benzene ring; the 3H singlet corresponds at 2.2 δ corresponds to a methyl group bonded to the carbonyl carbon; the 3H singlet at 3.8 δ corresponds to the methyl group bonded to an oxygen atom.
The 5H multiplet between corresponds to the mono-substituted benzene ring; the 3H singlet corresponds at 2.0 d corresponds to a methyl group bonded to the carbonyl carbon; the 2H singlet at 4.2 d corresponds to the methylene group.
The 1H singlet at 9.9 ppm corresponds to the aldehyde hydrogen; the doublet of doublets (2H each) corresponds to the two sets of nonequivalent protons on the para-substituted benzene ring; the 2H quartet corresponds at 4.1 d corresponds to a methylene group bonded to oxygen, and the 3H triplet corresponds to the methyl group.
