Time as a Determinate of Final Product in a Dehydration Reaction

Time as a Determinate of Final Product in a Dehydration Reaction
Robert Simack, Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, Alaska.
Abstract:This study involved acid dehydration of 2-methylcyclohexanol.The results varied depending on the time elapsed after initial reaction.I attempted to prove the Evelyn Effect, which stated that over a period of time the products of the aforementioned reaction will beobserved to change volume so that those products formed by a cis isomer of 2-methylcyclohexanol will formfirst.However, once all molecules in the cis isomer undergo reaction the remaining trans configured 2-methylcyclohexanols will proliferate during the latter period of the reaction.I also postulated as to the possible formulation of 1-ethylcyclopentene, and to the cause of such an event.
Introduction:After researching acid-catalyzed dehydration reactions (McMurray) and background on the Evelyn Effect (Clausen) I hypothesize that the cis isomer of 2-methylcyclohexanol will react via an E1 type process forming 1-methylcyclohexene according to predictions from Zaitzev's rule (Lehman).This should be due to the fact that the cis isomer has 2 anti-coplanar hydrogens.These two hydrogens should make the molecule more reactive.The trans isomer, with only one anti-coplanar hydrogen, should be slower to react and will form a 3-methylcyclohexene.In addition the 1-ethylcyclopentene will be formed from both the cis and trans isomers but only if the hydroxyl group is in an equatorial position.In that position electrons from the ring may attack the alcohol directly from behind pushing it off the ring and forming a five-membered ring instead.
Results & Discussion:An NMR (300MHz) spectra of the original reagent and the three fractions provided a huge amount of information in support of my hypothesis.Both cis and trans isomers were present in the spectra for the origi

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