lab_4_report_237

Required Information for Lab Report #4 Due at the start of lab during the week of Oct. 11th Results 1) Calculate the theoretical yield of methylcyclohexenes based on the amount of methyl cyclohexanol that you used.

2) Calculate the percent yield of methylcyclohexene product that you recovered (total of both fractions).

3) Report the boiling range over which the alkenes distilled.

4) Report the average product distribution (1-methylcyclohexene to other cyclohexenes) for both fractions of product for the two starting alcohols using the GC data posted on the class web site for your section. Also report whether any of the cyclohexene fractions were contaminated with the starting alcohol. If so how much of each alcohol isomer was present in each fraction.

Discussion 1) Restate the problem and your planned approach from your prelab materials.

2) Discuss whether the product distribution changes over time for the two methyl cyclohexanol starting materials, using the GC results to support your discussion.

3) Draw a detailed electron pushing mechanism for the formation of 1-methylcyclohexene, 3methylcyclohexene, and methylenecyclohexane (product C in your book) starting from 2methylcyclohexanol assuming an E1 mechanism.

4) Draw the most stable chair conformations of each of the four possible starting materials (cis and trans-2-methylcyclohexanol and cis- and trans-4-methylcyclohexanol). Assuming an E2-type mechanism, what would be the elimination product(s) from each of these chair structures (if more than one product is possible, indicate the major product), or is elimination not possible. If elimination cannot occur from the most stable chair structure, draw the less stable chair conformation and determine what products could be formed from an E2 elimination from this product. For both 2-methyl- and 4methylcyclohexanol, indicate which isomer (cis- or trans-) would react faster in an E2 elimination.

5) Based on the results of the class, what conclusion can you draw regarding the existence of the Evelyn effect for 2-methylcyclohexanol? Does 4-methylcyclohexanol show a similar time dependence on the product ratio?

6) Based on the result obtained by your lab section for the two alcohols, what conclusions can you draw regarding whether the mechanism of elimination if E1 or E2. Discuss you conclusions in terms of your answers to parts 3-5. Do you think both the cis- and trans isomers of the two alcohols undergo elimination by the same mechanism?