Callitris intratropica On 17-Jul-2015 while visiting Darwin on a personal holiday I was invited for a site visit by Vince Collins, the owner of Kakadu blue cypress oil. Vince makes a blue oil by steam distillation of bark and heartwood from Callitris intratropica—a tree that only grows in the tropics and is native to Northern Australia. This essential oil is said to have many sought after properties such as wart removal, treatment of burns and bug bites, and the alleviation of anxiety.
Vince holds a patent for his distillation process and has won a major victory at the high court of Australia to protect it.
Matthew Leonard watches as Vince Collins decants blue cypress oil from his still.
The steam distillation takes 90–100 hours. As the oil contains an excess of guaiol, the distillate is placed into a fridge at 18 °C for 20 hours and a large portion of the guaiol is collected as a crystalline precipitate. This leaves the blue oil as a rich, low viscosity consumer product for various essential oil purposes.
| A large amount of the guaiol precipitate was being stockpiled but a use had not yet been found for it. Vince suspected that it was only 60% guaiol, whereas I (Matthew) felt that it's level of crystallinity indicated a purity of around 90%. A later analysis by GC-MS and C-NMR showed the filtrate to be 85% guaiol. |  |
In my lab at RMIT, I was able to recrystallize the guaiol from 2-propanol/water as white needles, or from hot methanol as six-sided prisms.
 Guaiol recrystallizing in 2-propanol with a small amount of water added. |  Guaiol recrystallized from methanol as six-sided prisms. |
The ultra-pure guaiol gave a clean NMR and had a melting point of 95-96 °C. The previously reported melting point of guaiol was 92-93 °C. The true melting point of guaiol, along with its purification method and characterization is soon to be published in a peer-reviewed journal.
13C-NMR of pure and crude guaiol
FTIR of guaiol
| We continue to seek novel synthetic uses for guaiol as a start material in order to find a use for Vince's side product. We beleive that the combination of cheap availability, the fused five/seven membered rings, and the three chiral centres make guaiol an ideal candidate for synthetic pursuits. |  |
