5 Dehydration Of Methylcyclohexanols
Dehydration of Methylcyclohexanols
1. Introduction
The purpose of this experiment was to carry out the dehydration of 2-methylcyclohexanol or 4-methylcyclohexanol by heating the alcohol in the presence of phosphoric acid. The alcohol was a mixture of cis and trans isomers, so it might have exhibited an Evelyn effect. It was also looked at if the products showed the Zaitsev’s rule, where in an elimination reaction, the most stable alkene was favored, which was usually the most substituted one and also the major product, which was the product with more % composition that was found out in the analysis. The % composition of the yield was found out by using the % composition of the products and a gas chromatography by measuring the peak areas for each gas chromatogram. The operations used in this lab in their order of usage were: Simple distillation, mixing, washing liquids, drying liquids, gas chromatography.
2. Procedure
The volume of 20 mmol of 2-methylcyclohexanol was calculated and transferred into a round-bottom flask. Then 0.7 mL of 85 % phosphoric acid was mixed in. The reaction vessel was clamped to a ring stand over a suitable heat source and an apparatus was assembled for simple distillation using a Hickman still, water cooled condenser, and thermometer. Then a conical vial was weighted and recorded. After turning on the heat source in slow power, it was waited until it started to distillate. The temperature when it began was 58°C. Using a Pasteur pipet, the distillate was regularly transferred into the conical vial until only a yellow solution remained. It wasn’t left to dry completely. The temperature was 75°C when the vessel was taken from the heat source. The distillate was then washed with 1.5 mL of 5 % aqueous sodium bicarbonate. Then the aqueous lower layer was carefully removed. The upper layer was cloudy at first until it started to become clear after a few minutes. The solution was dried through anhydrous calcium chloride. Then it was weighted.
1. Introduction
The purpose of this experiment was to carry out the dehydration of 2-methylcyclohexanol or 4-methylcyclohexanol by heating the alcohol in the presence of phosphoric acid. The alcohol was a mixture of cis and trans isomers, so it might have exhibited an Evelyn effect. It was also looked at if the products showed the Zaitsev’s rule, where in an elimination reaction, the most stable alkene was favored, which was usually the most substituted one and also the major product, which was the product with more % composition that was found out in the analysis. The % composition of the yield was found out by using the % composition of the products and a gas chromatography by measuring the peak areas for each gas chromatogram. The operations used in this lab in their order of usage were: Simple distillation, mixing, washing liquids, drying liquids, gas chromatography.
2. Procedure
The volume of 20 mmol of 2-methylcyclohexanol was calculated and transferred into a round-bottom flask. Then 0.7 mL of 85 % phosphoric acid was mixed in. The reaction vessel was clamped to a ring stand over a suitable heat source and an apparatus was assembled for simple distillation using a Hickman still, water cooled condenser, and thermometer. Then a conical vial was weighted and recorded. After turning on the heat source in slow power, it was waited until it started to distillate. The temperature when it began was 58°C. Using a Pasteur pipet, the distillate was regularly transferred into the conical vial until only a yellow solution remained. It wasn’t left to dry completely. The temperature was 75°C when the vessel was taken from the heat source. The distillate was then washed with 1.5 mL of 5 % aqueous sodium bicarbonate. Then the aqueous lower layer was carefully removed. The upper layer was cloudy at first until it started to become clear after a few minutes. The solution was dried through anhydrous calcium chloride. Then it was weighted.