Esterification of P-aminobenzoic acid
Figure 1: Formation of benzocaine from p-aminobenzoic acid
Experimental
P-aminobenzoic acid (1.211g) and absolute ethanol (15mls) were combined with three boiling chips in a 50ml round bottom flask. The round bottom flask was placed on a heating plate and was refluxed starting at 109 ̊C. The solution began boiling at 111 ̊C. It was allowed to reflux for approximately 30 minutes and the solid was dissolved. The round bottom flask was then placed in an ice bath and allowed to cool to room temperature. Concentrated 18 M sulfuric acid (2.4mls) was added to the solution. Then absolute ethanol (3mls) was added to wash the sides of the round bottom flask. The round bottom flask was placed on a heating plate and the solution was refluxed at 120 ̊C, adding an additional absolute ethanol (2mls). The solution was refluxed for 40 minutes and was removed from the heating plate. Distilled water (30mls) was added to the solution. Sodium bicarbonate (60mls) was added dropwise until the pH was approximately 8. The pH was monitored using pH paper. Adding sodium bicarbonate caused a precipitate of benzocaine to form. The precipitate was filtered out of the solution using vacuum filtration. The precipitate was allowed to dry for recrystallization. The product was removed from the filter paper and weighed. The weight of the product was 1.445g. NMR was conducted by mixing the dry product (0.35mg) with duderated chloroform (0.50ml) and mixing until the precipitate dissolved. The sample was then placed into the NMR. The NMR spectrum confirmed the product was benzocaine. The remainder of the sample was placed into a 250ml beaker for recrystallization. Methanol and deionized water were added dropwise while solution was heated on a heating plate. Methanol was added until the product was dissolved. It was removed from the heating plate and allowed to cool to room temperature. It was then placed into an ice bath. Due to the size of the beaker opening the methanol
Experimental
P-aminobenzoic acid (1.211g) and absolute ethanol (15mls) were combined with three boiling chips in a 50ml round bottom flask. The round bottom flask was placed on a heating plate and was refluxed starting at 109 ̊C. The solution began boiling at 111 ̊C. It was allowed to reflux for approximately 30 minutes and the solid was dissolved. The round bottom flask was then placed in an ice bath and allowed to cool to room temperature. Concentrated 18 M sulfuric acid (2.4mls) was added to the solution. Then absolute ethanol (3mls) was added to wash the sides of the round bottom flask. The round bottom flask was placed on a heating plate and the solution was refluxed at 120 ̊C, adding an additional absolute ethanol (2mls). The solution was refluxed for 40 minutes and was removed from the heating plate. Distilled water (30mls) was added to the solution. Sodium bicarbonate (60mls) was added dropwise until the pH was approximately 8. The pH was monitored using pH paper. Adding sodium bicarbonate caused a precipitate of benzocaine to form. The precipitate was filtered out of the solution using vacuum filtration. The precipitate was allowed to dry for recrystallization. The product was removed from the filter paper and weighed. The weight of the product was 1.445g. NMR was conducted by mixing the dry product (0.35mg) with duderated chloroform (0.50ml) and mixing until the precipitate dissolved. The sample was then placed into the NMR. The NMR spectrum confirmed the product was benzocaine. The remainder of the sample was placed into a 250ml beaker for recrystallization. Methanol and deionized water were added dropwise while solution was heated on a heating plate. Methanol was added until the product was dissolved. It was removed from the heating plate and allowed to cool to room temperature. It was then placed into an ice bath. Due to the size of the beaker opening the methanol