an ethereal solution contains benzoic acid, 9-fluorenone, and ethyl 4-aminobenzoate. why would ethyl 4-aminobenzoate and 9-fluorenone not be extracted from this ethereal solution by aqueous base?
To understand why ethyl 4-aminobenzoate and 9-fluorenone would not be extracted from the ethereal solution by aqueous base, we need to consider their chemical properties.
Aqueous base refers to a solution containing a strong base, usually sodium hydroxide (NaOH) or potassium hydroxide (KOH), dissolved in water. Strong bases like these dissociate almost completely in water to produce hydroxide ions (OH-).
When considering the extraction of compounds, it is important to think about their acid-base properties and respective pKa values. In this case, benzoic acid, ethyl 4-aminobenzoate, and 9-fluorenone all have different acid-base properties as follows:
1. Benzoic acid: It is a carboxylic acid that can donate a proton (H+) from the carboxylic group (COOH). This makes it an acid, and it can react with the hydroxide ions (OH-) from the aqueous base to form the water-soluble sodium salt of benzoic acid (sodium benzoate). This reaction can be represented as follows:
Benzoic acid (organic phase) + NaOH (aqueous phase) -> Sodium benzoate (aqueous phase) + H2O
2. Ethyl 4-aminobenzoate: It is an organic compound similar to benzoic acid but with an additional ester group (2CH3) instead of the carboxylic acid group. This ester group makes it less acidic compared to benzoic acid and less likely to react with the hydroxide ions from the aqueous base. Therefore, it does not form a water-soluble salt and remains in the organic phase.
3. 9-Fluorenone: It is a ketone and lacks any acidic hydrogens. Ketones do not have acidic properties and typically do not react with aqueous base solutions. Therefore, 9-fluorenone also remains in the organic phase and does not dissolve in the aqueous base.
In summary, benzoic acid can react with the hydroxide ions in the aqueous base to form a water-soluble salt, while ethyl 4-aminobenzoate and 9-fluorenone do not undergo similar reactions. Hence, they are not extracted from the ethereal solution by the aqueous base.