Chapter 17.8, Problem 22CC

Interpretation Introduction

Interpretation: From the given data of IR spectrum and ${}^{\text{1}}\text{H}\text{NMR}$ spectrum of the given molecular formula, structure and name of the compound should be given and the product should be predicted when it is treated with Birch condition.

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 IR spectrum,  a $\text{C=O}$ bond will account for the signal at 1686 ${\text{cm}}^{\text{-1}}$
• 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
• 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
• Birch reduction converts aromatic compound having benzoid ring in to a product 1, 4-cyclohexa diene. The product having hydrogen atoms attached on opposite end of the molecule
  • Birch reduction is the reduction of aromatic rings with sodium, potassium or lithium and an alcohol in liquid ammonia. This is unlike catalytic hydrogenation
  • When benzene with an electron donating group such as alkyl group is treated with Birch reduction, the carbon atom connected to the alkyl group is not reduced. Electron   donating effect destabilizes the radical anion.
  • When an electron withdrawing groups are used, different regiochemical outcome is observed. Electron withdrawing   effect stabilizes the intermediate.