Bertram-Walbaum reaction

What is Bertram-Walbaum reaction?

The Bertram-Walbaum reaction or Bertram-Walbaum method, named after its discoverers, Bertram and Walbaum, was first reported in 1894. The reaction involves the conversion of camphene into isoborneol, which is achieved by treating camphene with 50 % sulfuric acid H2SO4 in acetic acid, followed by saponification.

Bertram-Walbaum reaction - general reaction scheme - Bertram-Walbaum method
Bertram-Walbaum reaction

A typical example involves the treatment of 20 g of camphene in 50 mL acetic acid with 0.8 mL H2SO4 in 1.2 mL water at 50-60 ºC for 3 hours, followed by saponification and steam distillation to obtain 13.7 g crude isoborneol. While 98-100 % formic acid (with BF3·Et2O) can be used as an alternative reaction media for the Bertram-Walbaum reaction, it has been found that acetic acid favors the formation of exo-norborneol.

The Bertram-Walbaum reaction may yield higher molecular weight by-products, such as dimers of olefins, in varying amounts due to the nature of the substituents. In contrast, when olefin is treated with acetic acid containing 0.15 M acetamide and 0.1 M p-toluenesulfonic acid, only the addition of acetic acid to olefins occurs without any skeletal rearrangement. Notably, under the same conditions, the reversal reaction from alcohol to olefin is also known as the Bertram-Walbaum reaction.

This reaction finds applications in the field of terpene chemistry.

References

Bertram, J. and Walbaum, H. (1894), Uber Isoborneol. [On isoborneol.] J. Prakt. Chem., 49: 1-15. https://doi.org/10.1002/prac.18940490101

Shares