The [cannabis] plant material is extracted with a non-polar organic solvent.
Useful solvents include lower alkanes, such as, for example, hexane,
heptane or iso-octane. The extract containing THC, after solvent removal,
is subjected to fractional distillation under reduced pressure and a first
distillate is collected. In one embodiment of the present invention, the
first distillate is again subjected to fractional distillation at reduced
pressure and a second distillate is collected. The second distillate has a
THC content of greater than 90% by wt.
One kg of the fine powdered marijuana plant material [average
% of THC was about 5.21 %] was macerated with 6 L. hexanes (Hexanes
GR from EM Sciences) in a percolator (9" in diameter from the top and
20" long, cone shaped) for 24 hours at room temperature and filtered.
The macerate was reextracted with 5 L. hexanes for another 24 hours.
The hexane extracts were combined and evaporated under reduced
pressure at low temperature to give 110.7 g residue (11.07% extractives).
The % of THC in the hexane extract was 41.21 %.
One kg of the fine powdered marijuana plant material [average
% ofTHC is 4.42] was macerated with 6 L hexanes and extracted by the
same procedure followed in Example 3 to yield 105.8 g residue (10.58%
extractives). The % of THC in the hexane extract was 40.35% by
GC analysis.
A portion (23 .0 g) of the hexane extract was subjected to
fractional distillation under reduced pressure (vacuum, 0.1-0.2 mmIHg).
The temperature was raised slowly to 160°C. where a small amount of
material «1 g) was collected and left separate. The major fraction
(10.1 g) was collected between 170 and 180°C. GC analysis of this
fraction showed 72.66% THC concentration.
A second portion (25.0 g) of the hexane extract was subjected to
fractional distillation under similar conditions as the first portion. The
major fraction collected between 170-180°C. weighed ll.6 g and had a
THC concentration of 73.62%.
A third portion (25.0 g) of the hexane extract was subjected to
fractional distillation under similar conditions to the previous portions.
The major fraction containing THC weighed 10.2 g and had a THC
concentration of 73.72%.
The three major fractions obtained from the above three distillations
were combined and analyzed. The analysis showed the concentration
of THC to be 70.31%. The mixture (28.9 g) was subjected to
fractional distillation, again under similar conditions. The temperature
was raised slowly to 135°C. under vacuum (0.1-0.15 mmHg) and the
fractions collected were kept aside. The major THC containing fraction
was collected at 140-160°C. and 0.05-0.06 mmIHg. The fraction weight
was 18.4 g and the THC content was 92.15%. Source: Elsohly 2002