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Lab Report On The Dehydration Reaction Of 2 Methylcyclohexanol And Phosphoric Acid

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DEHYDRATION OF METHYLCYCLOHEXANOLS
Nicholas Van Horssen
CHMY 321
TA: Michael Giroux
10/31/17
Introduction: The purpose of this lab was to carry out a dehydration reaction of 2-methylcyclohexanol by heating it in the presence of phosphoric acid and determining which alkene product would be the major product. Methylcyclohexanols were dehydrated in an 85% phosphoric acid mixture to yield the minor and major alkene product by elimination reaction, specifically E1. The alkenes were distilled to separate the major and minor products and gas chromatography was used to analyze the results and accuracy of the experiment. The hypothesis was the major product of the reaction would be the most substituted product. This conclusion was made because of …show more content…

Distillation of the first product began at 83 °C. A Pasteur pipette was used to remove 1-ml of the distillate into a vial. A second vial was filled with distillate until it reached 1-ml. As the second vial is being filled, observe the temperature and remove the apparatus from the heat source if there is an observed drop in temperature. Once the distillate had been collected into two separate vials, both distillates were washed with aqueous sodium bicarbonate (1.5-ml, 5%). The aqueous layer (lower) was extracted from both vials using a pipette and put into a chemical waste bin. The organic (alkene) layer was then dried with anhydrous calcium chloride pellets (3 pellets per vial). Both distillates were analyzed using gas chromatography, and each peak shown was identified to be one of the alkenes. Analysis of the graph was used to determine the major and minor products of the reaction.

Results: M.W. (g/mol) Boiling point (°C) Density (g/mL)
2-methylcyclohexanol 114.2 166 0.930
Phosphoric Acid (85%) 98.0 - 1.70
1-methylcyclohexene 96.2 110 0.813
3-methylcyclohexene 96.2 104 0.801
Table 1: Properties of the reagents and possible products for the reaction. The boiling point of Phosphoric acid is not important because it is a reagent.

Figure 2: Gas Chromatography analysis from the first sample. From top to bottom the peaks are ordered as followed: 3-methylcyclohexanol (A), 1-methylcyclohexanol (B), and 2-methylcyclohexanol

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