Benzocaine Synthesis Essay

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Introduction: Naturally occuring local anesthetics have been used for over a century to dull or alleviate the pain involved with medical procedures. Specifically, the extract of coca leaves was the first to be used. Its active ingredient, cocaine, was an effective anesthetic, but its addictive tendencies caused it to be abandoned as an anesthetic and outlawed as a drug. With their greater effectiveness and decreased side effects, synthetic anesthetics have come into common use. Essential to the effectiveness of many of these anesthetics is the aromatic ring at one end and possibly a secondary or tertiary amine at the other end of the molecule, seperated by a one- to four-unit hydrocarbon chain. In this experiment, we will synthesize benzocaine, one of the simpler local anesthetics, from para-amino benzoic acid and ethanol in the presence of conc. sulfuric acid. Benzocaine is an odorless, white, rhombohedric crystal with low water solubility. It is sensitive to light exposure and to temperatures above 30° C. As a drug, it has a low potency and low systemic toxicity. It is also a possible sulfonamide antagonist. Experimental: 1.20 g of p-amino benzoic acid and 12.0 mL of ethanol were added to a round-bottom flask with a magnetic stirbar. The mixture was left to stir until the solid dissolved. 1.0 mL of conc. sulfuric acid was slowly added and the mixture was allowed to genly boil under reflux for about 75 minutes. After reaction, the mixture was allowed to cool and was transferred to a beaker containing 30 mL of water. 10% sodium carbonate solution was added until gas was no longer evolved and the pH was around 8. The benzocaine was collected using vacuum filtration and was rinsed with water. The product was allowed to air dry overnight. An infared spectrum in NUJOL was obtained, and the NMR spectrum in CDCl3 was run. Name

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