15. The proton NMR spectrum for a compound is shown below. The infrared spectrum for the compound contains a sharp band at 1720cm and another sharp band at 3000cm1. The mass spectrum contains a base peak at m/z 43. What is the compound? H NMR 3 C Spectral Data: singlet, 207.1 ppm triplet, 36.1 ppm quartet, 24.5 ppm quartet, 7.3 ppm 6 ppm, δ 0 a) H,C-o-CH2CH3 H2C CH CH CH