Isoborneol Lab Report

The main objectives of the experiment were the following: to synthesize isoborneol, recrystallize the product, characterize it, and determine the yield of the product. To synthesize isoborneol, the reduction of camphor by reducing agent, sodium borohydride (NaBH4), was carried out (Figure 1). The utilized NaBH4 was determined to be active based on the bubbling observed in the reaction mixture. The bubbling is due to the evolution of hydrogen gas from the reaction of NaBH4 and methanol (Equation 1; Davis&Gotthbrath, 1962).
NaBH4 + 4 CH3OH→ NaB(OCH3)4 + 4H2 (Equation 1)
As this reaction is exothermic, it was noted that the reaction flask heated up during the addition of NaBH4. An alternative reducing agent for the Figure 1 reaction is LiAlH4, which is more reactive than NaBH4. However, LiAlH4 has violent exothermic reactions in protic solvents

Chromic acid and 2,4-DNPH tests indicated the absence of camphor and the presence of isoborneol/borneol in the product. Furthermore, the melting point range of the crystals was 201-212 °C. The melting point of borneol and isoborneol is 202°C and 212 °C, respectively (National Center for Biotechnology Information, 2023). Thus, the crystals are determined to be a mixture of isoborneol and borneol. For future experiments, isoborneol crystals can be separated from borneol through column chromatography with a chiral stationary phase to separate the diastereomers. This separation method is based on the difference in the hydroxyl group orientation of alcohols. The hydroxyl group of isoborneol is at the exo position, and the associated stereocenter has an R configuration (Figure 3). Another possible separation method is via dry-column chromatography, which was done by C.Y. Wu, Yang, and C.S. Wu (1988). Their experiment utilized a “column packed with silica gel and developed with 20:2:6 petroleum ether: ethyl acetate: chloroform”