The Chemical Educator
ISSN: 1430-4171 (electronic version)
Abstract Volume 14
Issue 6 (2009) pp 232-235
Reduction of 4-tert-Butylcyclohexanone: a Laboratory Class Project in Diastereoselectivity and Thermodynamic vs. Kinetic Control
Michael Novak*, Benjamin W. Gung, James W. Hershberger, Richard T. Taylor, Bright Emenike, Mrinal Chakraborty, Ashley N. Scioneaux, Amanda E. Ponsot, and Philias Daka
Department of Chemistry and Biochemistry, Miami University,
Oxford, OH 45056, email: email@example.com
Published online: 29 December 2009
Abstract. In the first semester majors’ organic laboratory course at Miami, students work on a class project in which individual students contribute data to establish the diastereoselectivity of three different methods of reduction of 4-tert-butylcyclohexanone: NaBH4/EtOH, lithium tri-sec-butylborohydride (L-Selectride)/THF, and Al(isoPrO)3/isoPrOH (Meerwein-Pondorff-Verley or MPV reduction). 1H NMR analysis of the crude product mixtures provides a convenient method to establish the cis/trans isomer ratio of the product 4-tert-butylcyclohexanols. Reduction with NaBH4 leads predominately to the trans-isomer ((88 ± 3)% trans), L-Selectride yields predominately the cis-isomer ((92 ± 1)% cis), while MPV reduction leads to an equilibrium mixture containing (23 ± 4)% cis-isomer. After individual students report their stereoselectivity results on one of the three methods, the instructor compiles and averages the data, and reports it back to the students. The students write a formal report on the project in which the issues of diastereoselectivity and thermodynamic vs. kinetic control of a product mixture are addressed.
Key Words: Laboratories and Demonstrations; organic chemistry
(*) Corresponding author. (E-mail: firstname.lastname@example.org)
Laboratory handout for this experiment and guidelines for formal laboratory write-up (78 KB).
Issue date: Dec