Multistep Synthesis
Results:
Limiting Reactant: Eq 1 Limiting reactant = Benzoin
Theoretical yield of Benzil:
Eq 2
Theoretical Yield Benzil | 0.296 g | Mass of Crude Benzil | 0.188 g | Mass of Final Benzil | 0.127 g | % Yield | 43% | % Recovery | 66% |
Table 1: Mass of crude/final Benzil, % yield, and % recovery
Percent Yield: % Yield = (Final product/Theoretical product) x 100 Eq 3 = (0.127 g/0.296 g) x 100 = 43% yield
Percent Recovery % Recovery = (Final product/Crude product) x 100 Eq 4 = (0.127 g/0.188 g) x 100 = 66% recovery
Theoretical Yield Benzilic Acid:
Eq 5
Theoretical Yield Benzilic Acid | 0.109 g | Final Benzilic Acid | 0.060g | Percent Yield | 55% |
Table 2: Final weight and percent yield of benzilic acid
| Degrees Celsius | Crude Benzil | 82.5 – 85.6 | Final Benzil | 94.2 | Final Benzilic Acid | 148.3 |
Table 3: Melting Points
Wavenumbers (cm-1) | Functional groups | 1593 | Aromatic | 3065 | Sp2 C-H bond | 1659 | C=O bond/carbonyl group |
Table 4: IR wavenumbers and functional groups of Benzil
Wavenumbers (cm-1) | Functional groups | 1600 | Aromatic | 3100-3000 | Sp2 C-H bond | 3100-2900 | Carboxylic Acid | 3300 | O-H alcohol | 1650 | C=O bond/carbonyl group |
Table 5: IR wavenumbers and functional groups of Benzilic Acid
Discussion:
In this experiment, benzoin was oxidized by nitric acid to benzil, which in turn was rearranged to benzilic acid. Prior to beginning the experiment, the theoretical yield of benzil was discovered. The limiting reactant in the reaction, benzoin + nitric acid benzil, was benzoin at 0.00141 moles. This value was discovered by the initial amount of the reactants used: 0.30 grams benzoin and 1.5 ml Nitric Acid (see Eq 1). Using the moles of the limiting reagent benzoin, the theoretical yield of benzil was calculated to be 0.296 grams (see Eq 2). Before crystallization, the
Limiting Reactant: Eq 1 Limiting reactant = Benzoin
Theoretical yield of Benzil:
Eq 2
Theoretical Yield Benzil | 0.296 g | Mass of Crude Benzil | 0.188 g | Mass of Final Benzil | 0.127 g | % Yield | 43% | % Recovery | 66% |
Table 1: Mass of crude/final Benzil, % yield, and % recovery
Percent Yield: % Yield = (Final product/Theoretical product) x 100 Eq 3 = (0.127 g/0.296 g) x 100 = 43% yield
Percent Recovery % Recovery = (Final product/Crude product) x 100 Eq 4 = (0.127 g/0.188 g) x 100 = 66% recovery
Theoretical Yield Benzilic Acid:
Eq 5
Theoretical Yield Benzilic Acid | 0.109 g | Final Benzilic Acid | 0.060g | Percent Yield | 55% |
Table 2: Final weight and percent yield of benzilic acid
| Degrees Celsius | Crude Benzil | 82.5 – 85.6 | Final Benzil | 94.2 | Final Benzilic Acid | 148.3 |
Table 3: Melting Points
Wavenumbers (cm-1) | Functional groups | 1593 | Aromatic | 3065 | Sp2 C-H bond | 1659 | C=O bond/carbonyl group |
Table 4: IR wavenumbers and functional groups of Benzil
Wavenumbers (cm-1) | Functional groups | 1600 | Aromatic | 3100-3000 | Sp2 C-H bond | 3100-2900 | Carboxylic Acid | 3300 | O-H alcohol | 1650 | C=O bond/carbonyl group |
Table 5: IR wavenumbers and functional groups of Benzilic Acid
Discussion:
In this experiment, benzoin was oxidized by nitric acid to benzil, which in turn was rearranged to benzilic acid. Prior to beginning the experiment, the theoretical yield of benzil was discovered. The limiting reactant in the reaction, benzoin + nitric acid benzil, was benzoin at 0.00141 moles. This value was discovered by the initial amount of the reactants used: 0.30 grams benzoin and 1.5 ml Nitric Acid (see Eq 1). Using the moles of the limiting reagent benzoin, the theoretical yield of benzil was calculated to be 0.296 grams (see Eq 2). Before crystallization, the