Objective: the objective of this lab is to introduce the technique of crystallization.
Background: The chemicals used in part A were Sulfanilamide and Ethyl alcohol. Sulfanilamide(C6H8N2O2S), or sulfonamide antibiotic, functions by competitively inhibiting enzymatic reactions involving para-aminobenzoic acid (PABA). PABA is needed in enzymatic reactions that produce folic acid which acts as a coenzyme in the synthesis of purine, pyrimidine and other amino acids. In part C, Fluorene was dissolved in three solvents. Fluorene(C13H10) is a polycyclic aromatic hydrocarbon. It forms white crystals that exhibit a characteristic, aromatic odor similar to that of naphthalene. It is combustible. It has a violet fluorescence, hence its name. For commercial purposes it is obtained from coal tar. Results: In part A, .30g of impure Sulfanilamide was placed in a beaker, and heated 95% ethyl alcohol was added to just cover the crystals. This was then heated and swirled vigorously until all is dissolved. Then remove and let cool slowly, while covered with a watch glass. Then it was placed in an ice bath to further crystallization. After crystallization is completed, a vacuum filtration system was used to separate crystals. These crystals were then dried, weighed, and melting point was determined. Table 1: percent yield and melting point of Sulfanilamide
Starting weight| Weight recovered| Percent yield| Melting point| .30g| .23g| 76.7%| 164-165oC|
This percent recovery is not 100% for several reasons. The sulfanilamide is not 100% pure to begin with, some of the sulfanilamide was dissolved in the mother liquor, and also because of a small spillage of the crystals from the filtration step. Part C of this lab was performed by first finding the best solvent for Fluorene. This was done by testing water, toluene, and methyl alcohol by adding 6mL of solvent to .3g of Fluorene. It is then shaken, if it dissolves immediately like it did...