Structure
Benzocaine Chemical Structure – C9H11NO2
Mode of action
The neuronal membrane is reversibly stabilised by benzocaine, which lowers its permeability to sodium ions. The initiation and conduction of nerve impulses are prevented by inhibiting neuronal membrane depolarization.
Structure-Activity Relationship (SAR) of Benzocaine
Benzocaine is a local anesthetic commonly used for pain relief in minor surgical procedures.
Its SAR characteristics are:
1. Ester Linkage:
Benzocaine is an ester local anesthetic. The ester linkage in its structure is crucial for its local anesthetic activity.
Esters are generally associated with a lower incidence of allergic reactions compared to amide local anesthetics.
2. Aromatic Ring:
The presence of an aromatic ring (benzene) is essential for local anesthetic activity.
This part of the molecule is lipophilic, which helps in penetrating membranes to reach the site of action.
3. Para-Aminobenzoic Acid Derivative:
Benzocaine is a derivative of para-aminobenzoic acid (PABA).
The PABA structure is associated with local anesthetic properties.
4. Ethanamine Group:
The ethanamine (ethylamine) side chain attached to the aromatic ring is important for the activity.
The length and nature of this side chain can influence potency and duration of action.
Here is the mind map illustrating the Structure-Activity Relationship (SAR) of Benzocaine:
Synthesis of Benzocaine
The synthesis of Benzocaine is a straightforward esterification reaction and can be represented by the following chemical equation:
Esterification Reaction:
C7H7NO2 + C2H5OH → C9H11NO2 + H2O
In this reaction, para-aminobenzoic acid (C7H7NO2) is esterified with ethanol (C2H5OH) to form Benzocaine (C9H11NO2) along with the production of water (H2O).
This reaction typically involves the use of an acid catalyst like sulfuric acid or hydrochloric acid to facilitate the esterification process.
The synthesis of Benzocaine is a classic example of Fischer esterification, a fundamental reaction in organic chemistry.
Uses
It is used to reduce the pain of piles, rectal irritation, virginal irritation and tooth pain.