Question

444 CHAPTER 9 NUCLEAR MAGNETIC RESONANCE AND MASS 5PLOTHOM C OMETRY Tools for Structure Determine CHAPTER 9 NUCLEAR MAGNETIC R 9.42 Deduce the structure of the Cou nd that gives the following l ube follow and IR spectra (Figs. 9.469.18). Assign Arcture of the c Par to the structure you are se les relate protons with signals in the carrelate carns with signals in the und shows the molecular ion at Them spectrum of this compon 'Hand be H NMR spectrum and spect to the structure you popo FIGURES The H NMR spectrum Simulated Problem 4 pm FIGURE 9.47 A simulated broadband proton-decouples 1 C NMR spectrum lor Problem 9.42 200 180 160 140 120 80 60 40 100 4 (ppm) 20 0 FIGURE 9.48 The IR spectrum for Problem 9:42 (SDES, National Institute of Advanced Industrial Science and Technology Transmittance %) 4000 3000 1500 2000 Wavenumber(cm) 1000 500

Answer 1

From the HNMR spectra we can see that there is a 6H signal which is a doublet, coupled with the 1C heptet, which means that we have a: -CH(CH₃)₂ portion in our molecule. The other high signal is a proton without any H neighbours which, judging by its position and by the high signals in the CNMR spectrum, is probably from an alkene carbon (supported by the signal right below 1500 cm^-1 in the IR spectrum. The highest C signal in the CNMR spectrum is the second C in the double bond, which is probably bonded to to halogens (the strong signal around 870 cm^-1 in the IR spectrum is also coherent with this). It is hard to determine which are the halogens, but the most normal would be chlorine, so my guess is that the structure is:

CH₂ C=CH-CH CI CH3