Dehydration of Methylcyclohexanols II

As predicted from the Journal of Chemical Education articles, three methylcyclohexene products were observed. Their relative abundance measured by peak height was 80, 16, and 4%. The alkene products represented by these peaks apparently correspond to 1-methycyclehexene, 3-methycyclehexene, and methylene cyclohexane respectively.

The dehydration of 4-methylcyclohexanol produce two products, that can be distinguished by our current GC column, at 90 and 10% with retention times that match 3-methycyclehexene and 1-methycyclehexene respectively. My current theory is that the retention times 3 and 4-methycyclehexene could not be distinguished with GC column and temperature program. However, there is still the issue of how 1-methycyclehexene is produced from 4-methylcyclohexanol.

The dehydration of 3-methylcyclohexanol yields two products, that can be distinguished by our current GC column, at 80 and 20% with retention times that match 3-methylcyclohexene and 1-methycyclehexene respectively.

Samples of 1-methyl and 3-methyl cyclohexenes purchased from Aldrich chemical confirmed two of compound assignments for the dehydration of 2-methylcyclohexanol. Obviously, it remains to separate the 3 and 4-methylcyclohexene by GC.



  1. Posted June 9, 2008 at 6:24 am | Permalink

    Your students might find this video I created for my class yesterday helpful to understand how 1-methylcyclohexene was formed.

    For clearer images see

  2. jbfriesen
    Posted June 10, 2008 at 8:51 am | Permalink

    we need to find some (1R,2R)-2-bromo-1-ethyl-1,3,3-trimethylcyclohexane and do the experiment.

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