Discussion

          In this experiment, an acid-catalyzed dehydration of cyclohexanol using phosphoric acid was performed in order to synthesize cyclohexene. Following fractional distillation, the product resulted in 28% yield of cyclohexene. This low yield could have been caused by insufficiently thorough mixing during the wash or incomplete removal of impurities. This product was analyzed through a series of tests to detect the presence of alkenes that would be expected in a successful reaction. The two chemical tests confirmed the presence of alkenes by exhibiting the expected color changes. In the bromine dichloromethane test, the vial containing the product remained clear despite the dropwise addition of the brownish-red chemical, indicating that the alkene reacted with bromine to form a colorless dibromide. In contrast, the vial containing cyclohexane briefly turned a reddish-orange color upon the dropwise addition of the chemical, indicating no reaction. In the potassium permanganate test, the vial containing the product turned brown, indicating the purple chemical reacted with the alkenes to produce a colorless diol and a finely-divided brown precipitate of manganese dioxide. In contrast, the dropwise addition of the chemical into the vial of cyclohexane resulted in a purple solution, indicating no reaction. The product was further analyzed by gas chromatography. The resulting GC trace displayed only one peak of 0.299. IR spectroscopy was also used to analyze the sample. The known absorption frequency for an R-C=C-H bond is approximately 3083, and the experimental absorption frequency was 3063.09. The known absorption frequency for a C=C bond is 1644, and the experimental absorption frequency was 1653.07. The experimental values were close enough to the expected values to confirm the presence of cyclohexene.