Chapter 18, Problem 57IP

Interpretation Introduction

Interpretation: From the given data of IR spectrum, ${}^{\text{1}}\text{H}\text{NMR}$ spectrum and ${}^{\text{13}}\text{C NMR}$ spectrum of the given molecular formula, structure of the compound should be given.

Concept introduction:

• In the IR spectrum, the signal just above 3000 ${\text{cm}}^{\text{-1}}$ confirms the presence of  aromatic ring
• Aromatic compound also produces a series of signals between 1450 and 1650 ${\text{cm}}^{\text{-1}}$ in the IR spectrum
• In the ${}^{\text{1}}\text{H}\text{NMR}$ spectrum, the signals between 6.5 and 8ppm confirms the aromatic ring. The presence of a multiplet near 7 ppm is one of the best way to verify the aromatic ring
• In the ${}^{\text{1}}\text{H}\text{NMR}$ spectrum,  the singlet at 3.9ppmwith an integration of 3 represents a methyl group and  the singlet at 2.6ppm with an integration of 3 represents an isolated methyl group
• The integration value of the multiplet near 7ppm indicates the extent of substitution. An integration  of 5 indicates monosubstituted ring, an integration of 4 indicates disubsituted ring
• The carbon atoms of aromatic rings typically produce signals in the range of 100-150ppm in ${}^{\text{13}}\text{C NMR}$ spectrum. The number of signals is very helpful in determining the specific substitution for substituted aromatic ring.
• HDI Calculation:

  $\begin{array}{l}\text{HDI=}\frac{\text{2(C)+2+N-H-X}}{\text{2}}\\ \text{where}\\ \text{C}\text{represent}\text{the}\text{number}\text{of}\text{carbon}\\ \text{N}\text{represent}\text{the}\text{number}\text{of}\text{nitrogen}\\ \text{H}\text{represent}\text{the}\text{number}\text{of}\text{hydrogen}\\ \text{X}\text{represent}\text{the}\text{number}\text{of}\text{halogen}\text{.}\end{array}$