Question

In "The Preparation of the Local Anesthetic, Benzocaine, by an Esterification Reaction" experiment

1. Give the full balanced equations for all three reactions that occur when the saturated sodium bicarbonate solution is added to the cooled reaction mixture.
2. If you were to analyze the product by MS, how can you tell from the mass spectrum that the final product contains one nitrogen? If you were to analyze the product by NMR, how would you distinguish between the protons in the aromatic region?

Answer 1

Benzocaine

1. when the cooled reaction mixture is treated with aqueous NaHCO3 solution.

the reactions occuring are shown below

The starting material acid is converted to sodium salt which is soluble in water

NaHCO3 also may react with other alcohol reactant to form salt.

NaHCO3 itself decomposes to H2O and CO2

2. The mass spectrum with only one N would have M+ odd molecular ion peak.

The protons in the aromatic region can be distinguished by 1H NMR, the protons on carbon ortho to -NH2 would be upfield, around 6.8 ppm whereas, the protons on carbon ortho to -COO group would m=be downfield around 8.0 ppm