QUIZ #3 CHEMLAB

what is the purpose of using diethyl ether in this extraction procedure?

diethyl ether is used as the organic solvent because it is incompatible with water and can dissolve organic compounds effectively. It allows for the separation of organic compounds based on their solubility differences when mixed with aqueous solutions

why do we add 3N NaOH to the mixture?

the addition of 3N NaOH serves to deprotonate the 4-chlorobenzoic acid, converting it into its water-soluble salt form, 4-chlorobenzoate. This allows the acidic compound to transfer into the aqueous layer, facilitating the separation from the neutral organic base, 4-bromoaniline, which remains in the organic layer

what is the significance of knowing which layer is aqueous and which is organic during the extraction?

identifying the aqueous and organic layers is crucial for ensuring the correct separation of the two compounds. The aqueous layer contains the deprotonated acid (4-chlorobenzoate), while the organic layer contains the neutral base (4-bromoaniline). Misidentifying the layers could lead to incorrect recovery of the compounds

why is it necessary to perform multiple extractions with NaOH?

performing multiple extractions increases the efficiency of the separation process. Each extraction removes more of the acidic compound from the organic layer, ensuring a greater yield of the desired product. Multiple extractions are more effective than a single extraction because they allow for better distribution of the acid between the layers.

what is the purpose of "washing" the ether layer with water and brine (NaCl solution)?

washing the ether layer with water helps remove any residual aqueous base that might be present in the organic layer. The subsequent wash with brine helps to remove any remaining water from the ether layer, improving the purity of the final product by preventing water contamination

how will you recover the 4-bromoaniline from the ether layer after washing it?

the 4-bromoaniline can be recovered by evaporating the diethyl ether, which is accomplished using a rotary evaporator or steam bath. Once the ether is removed, the 4-bromoaniline will remain as a solid or liquid in the flask

why do we use anhydrous MgSO4 or Na2SO4 after separating the ether layer?

anhydrous MgSO4 or Na2SO4 is used as a drying agent to absorb any residual water that may be present in the organic layer. This step is important to ensure that the final product is not contaminated with water, which can affect its purity and yield

why is it important to re-acidify the aqueous layer to recover 4-chlorobenzoic acid?

re-acidifying the aqueous layer protonates the 4-chlorobenzoate, converting it back to the neutral form of 4-chlorobenzoic acid. This process causes the acid to precipitate out of solution, allowing for its isolation through vacuum filtration

how can you confirm the identity and purity of the recovered 4-chlorobenzoic acid and 4-bromoaniline?

the identity and purity of the compounds can be confirmed by taking their melting points and comparing the results to literature values. A sharp melting point within the expected range indicates high purity, while a broad or lower melting point suggests impurities

what are the key steps to ensure maximum product recovery during the filtration and evaporation processes?

to maximize product recovery, it is essential to pre-weigh the receiving flask to accurately determine the yield. Additionally, rinsing the original flask with a small amount of ether helps transfer any remaining product. Care should be taken during gravity filtration to avoid losing any solid product, and the solvent should be removed efficiently to prevent degradation or loss of the organic compounds