Cornell Orgo Lab

EXPERIMENT: #1 NAME: Kevin Lee

DATE: 09/27/2011 TA: Daniel Heindel

TITLE: Solids: Recrystallization and Melting Points

Results

Recrystallization | Acetanilide | Benzoic Acid |

Mass of Sample Used | 1.99 g | 1.00 g |

Mass of Filter Paper Used | 0.33 g | 0.34 g |

Mass of Watch Glass Used | 25.44 g | - |

Mass of Recovered Sample + Filter Paper | 1.88 g | 0.74 g |

Mass of Recovered Sample + Filter Paper + Watch Glass | 27.33 g | - |

Mass of Sample Recovered | 1.56 g | 0.40 g |

Percentage (%) Recovery | 78.4 % | 40. % |

Melting Point of Sample Recovered | 113.6 – 114.9 oC | 121.0 – 122.5 oC |

Melting Points | Melting Point (oC) |

Code A Trial 1 | 79.2 – 82.0 |

Code A Trial 2 | 79.5 – 81.8 |

Code F | 187.4 – 189.7 |

Code C | 90.8 – 93.2 |

Unknown #7 | 149.6 – 153.7 |

Unknown + Code O | 152.3 – 154.0 |

Unknown + Code N | 133.4 – 137.0 |

Observations

Benzoic Acid Recrystallization

* Solution is clear with some insoluble impurities seeming to be at the bottom (specks that are black and wont dissolve when I add a few more mL of boiling water with a Pasteur pipette)

* Clear gummy matter and some black color interspersed on the filter paper (premature crystallization?)

* Filtrate volume after gravity filtration is slightly over 50mL; need to boil down to ~20mL

Acetanilide Recrystallization

* Solution is blue (with what looks like some oils forming in the solution); then black when decolorizing carbon is added (oils seems to be gone or masked); then clear after gravity filtration

* Total volume of filtrate after gravity filtration was ~75mL; had to boil it down to 40mL; too much solvent means loss of desired compound??

Interpretation of Instrumental Data

Code O corresponds with the unknown compound because a mixture of Code O and Unknown #7 produced (1) a narrower temperature range that was (2) closer in magnitude to the Unknown’s melting range than did the mixture with Code N, which...