Listed here are 1H NMR absorption peaks for several compounds. Propose a structure that isconsistent with each set of data. (In some cases characteristic IR absorptions are given as well.). Explain your answer by assigning the protons to designated peaks and interpreting the IR data.
a) C4H10O 1H NMR spectrum: singlet at δ 1.28 (9H), singlet at δ 1.35 (1H)
b) C4H8O 1H NMR spectrum: triplet at δ 1.05 (3H), singlet at δ 2.13 (3H), quartet at δ 2.47 (2H). IRspectrum: strong peak near 1720 cm-1.
c) C4H7BrO2 1H NMR spectrum: triplet at δ 1.08 (3H), multiplet at δ 2.07 (2H), triplet at δ 4.23(1H), singlet at δ 10.97 (1H). IR spectrum: broad peak in 2500-3000 cm-1 region and a peak at 1715cm-1.
d) A C8H4N2 compound shows a sharp infrared absorption at 2230 cm-1. It's 1H NMR spectrum has a singlet at d 7.6 ppm. The 13C NMR spectrum shows three signals at δ 132, 119 and 117 ppm (This means there are 3 different types of carbons). Suggest a structure for this compound.