Isomerization

The potency of marijuana can be increased by about 50% simply by simmering a water slurry of the material for 2 hours. Add water as necessary to maintain the level. Cool and filter the mixture, and refrigerate the aqueous solution. Dry the leaf material at low heat. Drink the tea before smoking the marijuana. The effects are much more intense and last longer than those from the untreated leaves. The boiling water treatment isomerizes the inactive CBD, and decarboxylates THCA to THC.

Although Cannabidiol (CBD) has no psychoactivity, it does antagonize THC and produces other valuable sedative, antibiotic, and anti-epileptic effects. CBD can be isomerized to THC. If the plant is Phenotype III (containing mainly CBD in its resin), isomerization can double the yield of THC.

The CBD fraction of column chromatography can be distilled (bp 187-190° C/2 mm; pale yellow resin) to purify it. Isomerization can be accomplished with any of several solvents and acids. Alcohol and sulfuric acid isomerizes only 50-60% of CBD to THC; p-TolueneSulfonic Acid (p-TSA) in petroleum ether or other light, non-polar solvent will convert 90% of CBD to THC upon refluxing 1 hour at 130° F. (16, 17)

Reflux 3 gr CBD in 100 ml dry benzene for 2 hours with 200 mg p-TSA monohydrate until the alkaline Beam test (5% KOH in ethanol) is negative (no color). The Beam test gives a deep violet color with CBD. Separate the upper layer, wash it with 5% sodium bicarbonate, wash again with water, and strip the solvent. The remaining viscous oil should give a negative reaction to the Beam test. The crude THC can be purified by distillation (bp 169-172° C/0.03 mm), or by chromatography in 25 ml pentane on 300 gr alumina. Elute with pentane 95:5 ether to yield fraction of CBD and THC. Combine the THC fractions and distill (bp 175-178° C/1 mm).

Reflux 2 gr CBD in 35 ml cyclohexane, and slowly add a few drops of sulfuric acid. Continue to reflux until the Beam test is negative. Separate the sulfuric acid from the reaction mixture. Wash the solution twice with aqueous sodium bicarbonate, the twice again with water. Purify by chromatography, or distill (bp 165° C/0.01 mm). Any unreacted CBD can be recycled.

Another method is to reflux a mixture of 6 gr dry pyridine hydrochloride and 3 gr CBD at 125° C until the Beam test is negative. Wash the reaction mixture with water to remove the pyridine, then extract the mixture with ether. Wash the ether with water, evaporate the ether, and distill the residue i.v. to yield pure THC.

Similarly, reflux 3 gr CBD in 150 ml ethanol with 50 ml 85% phosphoric acid until the Beam test is negative. Work up the reaction mixture, and purify the THC.

Alternatively, reflux 3 gr CBD in 100 ml absolute ethanol containing 0.05% HCl for 19 hours. Extract the ether, wash the ether with water, dry, evaporate, and chromatograph on 400 gr alumina to yield:

(a) 0.5 gr 1-EthoxyHexaHydro-CBN (EHH-CBN: mp 86-87° C); elute with pentane 98:2 ether. Recrystalize from methanol and water.

(b) 2 gr THC; elute with pentane 95:5 ether. Repeated chromatography will separate the less polar forms.

(c) 0.5 gr EHH-CBN, eluted with pentane 93:7 ether. It can be isomerized to THC by refluxing in benzene for 2 hours. Cool the reaction mixture, wash it with water; separate, dry, and strip the solvent layer i.v. to yield THC.

CBD also can be isomerized by irradiation of a cyclohexane solution in a quartz vessel with a mercury lamp (235-265 nm) for 20 minutes. Workup of the reaction mixture yields 7-13% THC. (18-20)