Dehydration Lab Report

Introduction: The purpose for this experiment is to carry out the dehydration of 2-methylcyclohexanol, which undergoes an E1 mechanism by following Saytzev’s rule to form different product such as 1-methylcyclohexanol, 3-methylcyclohexanol and methylenecyclohexane. The reaction can be dehydrated using sulfuric acid and H3PO4. The dehydration mechanism occurs in several steps like –
1. Converting the OH group into a better leaving group that is deprotonating with H3PO4.
2. Removing a beta-hydrogen besides the methyl group to form a stable product.
3. The most stable carbocation is a tertiary carbon, which means the major product is going to be a tri-substituted alkene (
The overall reaction for the dehydration of 2-methylcyclohexanol
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Experimental: Fractional distillation is setup by adding 25.0 ml of 2-methylcyclohexanol in a 100-ml round bottom flask and to this 10 ml of 9 M sulfuric acid is added which acts a catalyst to this reaction. The content is swirled is completely for about 2 minutes periodically. Then 3 boiling chips is added to the mixture, now starts the fraction distillation. The mixture is heated with a heating mantle for distillation to occur. It is heated until 10-ml of the mixture remains in the reaction flask or less than 100°C. The organic liquid obtained is stored in the drawer for a week. Next week, the organic distillate was transferred to a separatory funnel in order to separate the liquid. 10-ml of 3 M aqueous sodium hydroxide solution is added to the distillate. Furthermore, the mixture is shaken until two separate layers of liquids are observed. On the top was the organic layer and bottom the aqueous layer. The aqueous layer is discarded while, the organic layer is kept, which will produce our products for this experiment. The organic layer then is transferred to a dry 50-ml Erlenmeyer flask and then dried with calcium chloride. The mixture is occasionally swirled for 2-3 minutes and then decanting the organic mixture into a dry 50-ml distilling flask. The solution is redistilled, but now the mixture is heated up to …show more content…
It indicates that the final product is a pure cyclohexene. Alkenes usually show a stretch between 1620-1680 cm-1, but the frequency depends on the level of conjugation. The peaks approximately at 3050-3150 cm-1 shows the alkene (sp2 hybridized) CH stretch in figure 8. While, the downfield peak around 2840-3000 cm-1 is the alkane sp3 CH stretch. The peak approximately between 1300-1400 cm-1 indicates the CH2 bend. The difference between figure 5 and 8 is the presence of OH peak at 3342 cm-1 in figure 8 that clearly explains the pureness of cyclohexene. An azeotrope is a mixture of two ore more liquids whose mixture cannot be separated by simple distillation. A solution with positive deviation there is an intermediate composition whose vapor pressure is maximum and boiling point is minimum. This type of solution is called minimum boiling azeotrope ( The difference in boiling point for the first and second distillation maybe because the hydration of an alkene is a reverse reaction. So to prevent the alkene formed in the dehydration reaction forming back the alcohol, the alkene can be removed by distillation, because it has much lower boiling point than the

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