Dehydration and Gas Chromatography of Methylcyclohexanols.

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Hurst

Chase A. Hurst

CHM 215 11

Dr. Daniel Ketcha

October 28, 2004

Dehydration and Gas Chromatography of Methylcyclohexanols

Introduction

The experimental confirmation of the “Evelyn Effect” was performed in this report.  This effect, first described by David Todd of Pomona College in 1994, describes the formation of 1-methylcyclohexene and 3-Methylcyclohexene (structures shown below) derived from the dehydration and distillation of a mixture of cis-2-methylcyclohexanol and trans-2-methylcyclohexanol (structures shown below) when reacted with phosphoric acid.  

 

This reaction was carried out according to the following mechanisms.

Procedure

150 mmol (≈ 18.419 g) of 2-methylcyclohexanol (cis - trans mixture) was placed into a 50 mL round bottom flask.  Mixed in this flask was 5 mL of 85% phosphoric acid, 3 drops of sulfuric acid (to quicken reaction), and a few acid resistant boiling chips.  A simple apparatus for distillation was assembled and two 10 mL graduated cylinders were used to collect the distillate.

The contents of the 50 mL round bottom flask were gently brought to a boil and the temperature of the vapor was approximately 115 °C.  The rate of heating/boiling was controlled so that the rate of collection in the first 10 mL graduated cylinder was approximately 1 drop per second.  When the contents of the distillate in the 10 mL graduated cylinder reached approximately 8 mL in volume the first 10 mL graduated cylinder was removed and a second clean 10 mL graduated cylinder was put in its place to collect an addition 6 mL of distillate.  

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The first distillate product was the transferred to a clean seperatory funnel and washed with 5 mL of saturated aqueous sodium bicarbonate.  The aqueous layer was drained off and the organic distillate product was washed with 5 mL of saturated aqueous sodium bicarbonate for a second time.  The aqueous layer was then drained off and the organic distillate layer was collected and saved for gas chromatographic analysis.  This procedure was repeated for the second distillate sample.

 A small portion of magnesium sulfate was then added to each organic distillate sample in order to remove any remaining water in the sample. ...

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