Q. 14.82 - An Introduction to General, Organic, and Biological Chemistry

Question

Lidocaine (xylocaine) is used as a local anesthetic and cardiac depressant. (14.5)

1. Draw the condensed structural formula for the ammonium salt formed when lidocaine reacts with $\mathrm{HCl}$.
2. Why is the ammonium salt of lidocaine used rather than the amine?

Step-by-Step Solution

Answer

Part (a) :

The condensed structural formula for the ammonium salt formed when Lidocaine reacts with $HCl$ is

Part (b):

 The ammonium salt of lidocaine is more soluble in body fluids than regular lidocaine.

Step 1: Given Information (Part A)

The condensed structural formula for the ammonium salt is $\mathrm{HCl}$formed when lidocaine reacts with .

i) Functions of Carboxylic acid

• Carboxylic acid is a weak acid that produces hydronium ions in water and neutralizes bases. 
• In carboxylic acids, the carbon atom of the carbonyl group binds to the hydroxyl group to form the carboxyl group. 
• The carboxyl functional group can be attached to an alkyl group or an aromatic group.

Part (a) Step 2: Explanation

a) The condensed structural formula for the ammonium salt formed when lidocaine reacts with $\mathrm{HCl}$

Lidocaine is used as a local anesthetic and a cardiac depressant. 

a) The condensed structural formula for the ammonium salt formed when Lidocaine reacts with $HCl$ is

Part (b) Step 3: Given Information

 The ammonium salt of lidocaine is used more than the amine.

• Since the solubility of ammonium salt is higher than that of lidocaine, the ammonium salt of lidocaine is used.
• Therefore, the ammonium salt of lidocaine is more soluble in body fluids than regular lidocaine.