Dehydration of Methylcyclohexanols I

A common Sophomore Organic Chemistry laboratory experiment that has great potential for further research is the acid catalyzed dehydration of simple alcohols. The classic dehydration of 2-methylcyclohexanol experiment that was introduced in Journal of Chemical Education in 1967 Taber(1967)JCE:44,p620. The rather simple procedure of distilling an alcohol with an aqueous acid has spawned several investigations that have resulted in formal journal articles. At the same time, the experiment has retained its popularity in the Sophomore Organic Chemistry laboratory curriculum. In one line of inquiry it has been observed that a mixture of 2-methylcyclohexanol diastereomers gives rise to a mixture of three isomeric alkenes Todd(1994)JCE:71,p440; Feigenbaum(1987)JCE:64,p273; Cawley(1997)JCE:74l,p102. Explaining the presence of the three alkene products requires an intense synthesis of information communicated in a typical SOC textbook. The continued popularity of this experiment is corroborated by the observation that Googling the phrase “Dehydration of 2-Methylcyclohexanol” on January 13th, 2008 returned no less than 20 hits for online student handouts and/or guides for this SOC laboratory experiment. Moreover, this experiment provides fertile ground for experimentation and innovation that has not yet been fully explored. At Dominican University, the SOC students performed this experiment during the Fall 2007 semester with not only the dehydration of 2-methylcyclohexanol (Aldrich 153087) but also the 4-methyl (Aldrich 153095) and 3-methyl (Aldrich 139734) positional isomers. The reaction products were submitted to GC-FID analysis. The exciting results will follow next week…

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  1. […] are continuing our investigation of the acid catalyzed dehydration of 2-methyl-1-cyclohexanol. This year we compared diluted phosphoric acid to the concentrated phosphoric acid (48% w/w aqueous […]

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