Organic chemistry plays an important role in many areas of science; however, students are faced with severe challenges in studying the subject. One crucial problem is that the subject has been taught in a rather abstract fashion using text and line art accompanied by some figures, most notably electrostatic potential maps, and various spectra. This pedagogy is especially challenging for students who need visual reinforcement of course material. In this photographic study we focus on the transformation of cyclohexene into trans-1,2-cyclohexanediol via cyclohexene oxide. In addition to providing visual evidence for the reaction outcome, the experiments provide evidence for the reaction stereochemistry, which is a central feature of the reaction mechanism. Cyclohexene reacted with pure meta-chloroperbenzoic acid (MCPBA) to form cyclohexene oxide and a precipitate of meta-chlorobenzoic acid (MCBA) byproduct. Visual evidence of cyclohexene oxide formation was supplied by boiling point and formation of a green color with Reichardt’s dye. The MCBA was confirmed by comparison of its pKa, 3.82, with that of MCPBA, pKa, 7.52. Hydrolysis of cyclohexene oxide yielded trans-1,2-cyclohexanediol. Proof of the trans-diol formation was generated by melting point and from a study of the rates of decolorization of the red complex formed by reaction of the diol and ceric ammonium nitrate (CAN). 1,2-trans-cyclohexanediol is decolorized (as a result of oxidation) much more rapidly than the complexes of simple alkyl alcohols. In contrast, the cis-1,2-cyclohexanediol complex decomposes significantly faster than the trans-product. REU participant Aida Diouf was supported by the NSF-REU Site grant No: CHE1156886 to FIU.

Photographic evidence of reactions in organic chemistry: The formation of trans-diols from cyclohexene and meta-chloroperbenzoic acid

249th National Meeting (2015)

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