In this experiment, benzoic acid and ethyl 4-aminobenzoate will react with sodium hydroxide (NaOH) and hydrochloric acid (HCl) in distinct acid-base reactions.
Reaction of Benzoic Acid with NaOH:
Benzoic acid is a weak acid and when it reacts with NaOH, a strong base, the following reaction occurs:
C6H5COOH + NaOH → C6H5COO-Na+ + H2O In this reaction, the carboxylic acid group of benzoic acid donates a proton (H+) to the hydroxide ion (OH–) from NaOH, forming water and the sodium salt of benzoic acid.
Reaction of Benzoic Acid with HCl:
When benzoic acid is treated with hydrochloric acid, there is no reaction since both are acidic. However, in a more practical setting, if you were to neutralize the sodium benzoate formed from the first reaction with HCl, the following would occur:
C6H5COO-Na+ + HCl → C6H5COOH + NaCl This restores benzoic acid from its sodium salt form by reacting it with HCl, generating sodium chloride as a byproduct.
Reaction of Ethyl 4-Aminobenzoate with NaOH:
Ethyl 4-aminobenzoate, a weakly basic compound due to its amine group, would react with NaOH to generate the corresponding ethyl-4-aminobenzoate salt:
C6H4(NH2)COOEt + NaOH → C6H4(NH2)COO-Na+ + H2O In this instance, the amine group functions as a base and can accept a proton, facilitated by the presence of hydroxide ions.
Reaction of Ethyl 4-Aminobenzoate with HCl:
When ethyl 4-aminobenzoate is introduced to HCl, it acts as a weak base, leading to protonation of the amine group:
C6H4(NH2)COOEt + HCl → C6H4(NH3+)COOEt + Cl- The amine group accepts a proton from HCl and forms a hydrochloride salt, rendering it more soluble in aqueous solutions.
In summary, the reactions highlight the acid-base chemistry of both benzoic acid and ethyl 4-aminobenzoate when interacting with strong bases and acids, illustrating their functional groups’ behavior.