Reagents and Properties substance quantity molar mass mp (g/mol) (“C) (1)-benzoin 7 mg 212.25 135-137 ethyl acetate* 2.2 mL Aniel 88.11 ~84 meso-hydrobenzoin 7 mg 214.27 137-139 n-hexane* 4 mL 86.18 -95 U” ‘ ‘/” 4 potassium bromide 100 mg 3JT #for TLC 3:7, 9.61 ! tfor KBr ‘pellet “4Kli n bp C) 76-77
The Correct Answer and Explanation is:
Corrected Information
The provided data describes a chemical experiment, specifically the stereoselective reduction of benzoin to produce meso-hydrobenzoin. The information, once corrected and organized, is presented in the table below.
| Substance | Role | Quantity | Molar Mass ( g/mol ) | Melting Point (°C) | Boiling Point (°C) |
| Benzoin | Reactant | 7 mg | 212.25 | 135-137 | |
| meso-hydrobenzoin | Product/Standard | 7 mg | 214.27 | 137-139 | |
| Ethyl Acetate | Solvent / TLC Eluent | 2.2 mL | 88.11 | -84 | 76-77 |
| n-Hexane | Solvent / TLC Eluent | 4 mL | 86.18 | -95 | |
| Potassium Bromide | Analytical Reagent | 100 mg | 119.00 |
Note: The garbled text “TLC 3:7” indicates that thin-layer chromatography will be performed using a 3:7 ratio of ethyl acetate to n-hexane as the eluent.
Explanation
The information details the reagents and analytical procedures for a common organic chemistry laboratory experiment: the reduction of benzoin. This reaction converts the ketone functional group in the benzoin molecule into a secondary alcohol, resulting in the formation of hydrobenzoin.
The reaction is stereoselective, meaning it preferentially creates one stereoisomer over others. Benzoin is a chiral molecule, and its reduction creates a second chiral center. The specific mention of meso-hydrobenzoin as a product indicates that the experiment is designed to yield this particular achiral diastereomer. A common reagent used to achieve this outcome, though not listed, is sodium borohydride (NaBH₄).
The roles of the listed substances are distinct. Benzoin is the starting material, or reactant. Meso-hydrobenzoin is the target product; its inclusion in the table with a specified mass suggests it may also serve as an authentic reference standard for comparison. This comparison is crucial for confirming the identity of the synthesized product.
Ethyl acetate and n-hexane are organic solvents. They likely serve multiple purposes. First, one of them (typically a polar solvent like ethyl acetate or an alcohol) would be the solvent in which the reduction reaction is carried out. Second, they are used in a 3:7 ratio as the mobile phase, or eluent, for thin-layer chromatography (TLC). TLC is an analytical technique used to monitor the reaction’s progress by separating the reactant from the product and to assess the purity of the final product.
Finally, potassium bromide (KBr) is an analytical reagent used for infrared (IR) spectroscopy. The sample is ground with dry KBr and pressed into a thin pellet. Since KBr is transparent to infrared light, this method allows for the analysis of the product’s functional groups, confirming the disappearance of the benzoin’s ketone group and the appearance of the hydrobenzoin’s alcohol group.
