Benzoin Synthesis Lab Report

Benzoin was oxidized to benzil by copper (II) which is formed from cupric acetate. The yield will be lower when benzoin oxidized with copper then it converted into benzoil. Students should know ammonium nitrate, cupric acetate, and acetic acid function. Firstly, copper (II) from cupric acetate will separate and gain an electron from benzoin. Therefore, benzoin became the radical cation. Then, the other part of cupric acetate which is acetate as the base attacks the proton in benzoin. Then, acetic acid was formed and also resonance will stabilize the radical and move the electron to form a double between carbon-carbon. After forming the double bond between carbon-carbon, the electrons in the double bond move between oxygen and carbon and form

The Cu2+ will be easier to take an electron from carbon than oxygen. Then, the carbon became carbocation after Cu+ oxidized the benzoin. The extra acetic acid attack the remainder proton in benzoin, then the electrons move from between O-H to between O-C and form the double bond and create the resonance stability. Then, the benzoil was produced.

In this oxidation benzoin to benzil experiment, students placed 1.0g of benzoin from the previous lab with 0.50g of ammonium nitrate in round bottom flask. Nitrate in ammonium nitrate can regenerate from Cu+ to Cu2+ after finished first oxidized benzoin. Then, add 4.0ml of glacial acetic acid and 1.0ml of 2% cupric acetate as

Last, using suction filtration separate between the liquid and the precipitate, then wash the crystals with ice water that can rinse out the remainder acetic acid and impurities. Then, let the crystals to dry for couple days then weight the products first before doing the melting point. The mass of product is 0.880g which is actual yield, then calculate the theoretical yield by using the mole ratio and benzoin and benzoin molar mass. Then, obtained 0.99g for theoretical yield and calculate the percent yield is 88.8%. This properly results in percent yield. Finally, students placed the crystals into the capillary tubes then plot the tube along with thermometer into Melt Temp equipment. Then, melting point range are 83.5-86.0°C, 82.5-86.0°C, and 83.5-87.0°C. With the recorded temperatures, students had to correct the temperatures using a calibration factor. The calibration factor for the thermometer is y=0.973x+5.9227, and the average correction melting point is 88.4°C. The melting point is lower than the standard 94-95°C because the original benzoin has some impurities inside then causing the whole product may still remain the