Conversion of CBD to THC

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Conversion of cannabidiol (CBD) to tetrahydrocannabinol (THC) can occur through a ring-closing reaction. [1] [2] [3] This cyclization can be acid-catalyzed or brought about by heating. [4] [5] [6] [7] [8] [9] [10]

Contents

Known methods

Phytocannabinoids exist like precursors to their pharmacologically active counterparts. [11] [12] At least three independent methods have successfully converted CBD to THC.

By heat

CBD heated to 175, [13] or 250–300 °C may partially be converted into THC. [14] Even at room temperature, trace amounts of THC can be formed as a contaminant in CBD stored for long periods in the presence of moisture and carbon dioxide in the air, with storage under inert gas required to maintain analytically pure CBD. [15]

Multiple oxidation products form during degradation in the presence of oxygen, a process known as thermolysis In contrast, the absence of oxygen leads to a process called pyrolysis which significantly reduces the loss.

With acid

Mechanism of the acid catalyzed conversion of CBD into THC Intramolekulare cyklisierung von CBD zu D9-THC.png
Mechanism of the acid catalyzed conversion of CBD into THC

CBD converts to various isomers of THC with catalysts in acidic environments. [17] A wide variety of acids can be used, though different conditions result in varying yield and formation of characteristic impurities. [18] [19] [20] [21]

With zeolite

Methods have been claimed for converting CBD to a mixture of Δ8-THC and Δ9-THC using "Zeolites selected from the group consisting of analcime, chabazite, clinoptilolite, erionite, mordenite, phillipsite, and ferrierite." [30]

Purification

Δ-8-Tetrahydrocannabinol to THC

When CBD is treated with acid, Δ-8-Tetrahydrocannabinol may form as an impurity. [22] Nevertheless, Δ-8-Tetrahydrocannabinol can be isolated and subsequently converted into THC.

In vivo

Oral

There is a debated hypothesis that oral CBD could be metabolized into THC under acidic conditions in the stomach and then absorbed into the bloodstream. However, neither THC nor any of its active metabolites have been detected in blood in animals or humans after ingesting CBD. [21] [11] There is no direct evidence of the conversion of CBD to THC in the human gut; both CBD and THC are excreted unchanged within human feces. [20]

History

The conversion of CBD to THC by an acid based cyclization reaction was first patented by Roger Adams in the 1940s. [34]

See also

Related Research Articles

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References

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  29. ↑ US 20040143126,Webster GR, Sarna L, Mechoulam R,"Conversion of CBD to delta8-THC and delta9-THC",issued 15 July 2008, assigned to Full Spectrum Laboratories Ltd.
  30. ↑ US 11352337B1,Gindelberger D,"Zeolite catalyst and method for preparation of aromatic tricyclic pyrans",issued 7 June 2022, assigned to Acid Neutral Alkaline Laboratory.
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  33. ↑ US 4025516,Razdan RK, Dalzell HC,"Process for the preparation of (-)-6a,10a-trans-6a,7,8,10a-tetrahydrodibenzo[b,d]-pyrans",issued 24 May 1977, assigned to Application filed by Sheehan John C Institute for Research Inc.
  34. ↑ https://patents.google.com/patent/US2419937A/en
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