WO2021142075A1

WO2021142075A1 - Microwave assisted decarboxylation of cannabis resins

Info

Publication number: WO2021142075A1
Application number: PCT/US2021/012438
Authority: WO
Inventors: Dmitry KUKLEV; Alex GOODNOUGH; Tyler CIMINI; John RISER
Original assignee: Precision Extraction Corp
Current assignee: Precision Extraction Corp
Priority date: 2020-01-07
Filing date: 2021-01-07
Publication date: 2021-07-15
Anticipated expiration: 2022-07-07

Abstract

A method of decarboxylating cannabinoid acids includes providing a solventless cannabis crude resin that contains cannabinolic acids, at a pressure of 1 atm or less subjecting the solventless cannabis crude resin to microwave energy in a microwave reactor, the microwave energy causing decarboxylation of the cannabinolic acids to produce decarboxylated cannabinoid crude resin, and collecting the decarboxylated cannabinoid crude resin from the microwave reactor.

Description

MICROWAVE ASSISTED DECARBOXYLATION OF CANNABIS RESINS

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority to United States Provisional Application No. 62/957,914 filed January 7, 2020.

BACKGROUND

[0002] Cannabinoids derived from cannabis plants are desired for a variety of therapeutic uses. The cannabinoids are present as cannabinolic acids in cannabis plant material, such as tetrahydrocannabinolic acid and cannabidiolic acid. The cannabinolic acids and other substances are extracted from the plant material using known extraction processes. Subsequently, the cannabinolic acids are subjected to a decarboxylation process to form their conjugate cannabinoids. The decarboxylation process typically involves heating for a long period of time (e.g., 4 to 30 hours). Relatively low temperature heating yields long reaction times. Relatively high heat reduces time but results in undesired degradation. As a result, the reaction conditions are not optimal, and the yield for conversion of the cannabinolic acids to cannabinoids is low.

SUMMARY

[0003] A method of decarboxylating cannabinoid acids according to an example of the present disclosure includes providing a solventless cannabis crude resin that contains cannabinolic acids, introducing the solventless cannabis crude resin into an inlet of a microwave reactor, and subjecting the solventless cannabis crude resin to microwave energy in the microwave reactor at a pressure of 1 atm or less. The microwave energy causes decarboxylation of the cannabinolic acids to produce decarboxylated cannabinoid crude resin. The decarboxylated cannabinoid crude resin is collected from an outlet of the microwave reactor.

[0004] In a further embodiment of any of the foregoing embodiments, the solventless cannabis crude resin resides in the microwave reactor for 0.5 minutes to 15 minutes.

[0005] In a further embodiment of any of the foregoing embodiments, the solventless cannabis crude resin flows through the microwave reactor while being subjected to the microwave energy. [0006] In a further embodiment of any of the foregoing embodiments, the decarboxylated cannabinoid crude resin has a yield of at least 92% conversion of the cannabinolic acids to decarboxylated cannabinoids.

[0007] In a further embodiment of any of the foregoing embodiments, the microwave energy has a frequency of 700 MHz to 5 GHz, and the microwave reactor has a power 100W to lOkW.

[0008] In a further embodiment of any of the foregoing embodiments, the solventless cannabis crude resin is heated to a temperature of 90°C to 240°C in the microwave reactor.

[0009] A further embodiment of any of the foregoing embodiments includes generating a vacuum in the microwave reactor.

[0010] A method of decarboxylating cannabinoid acids according to an example of the present disclosure includes providing a solventless cannabis crude resin that contains cannabinolic acids, and subjecting the solventless cannabis crude resin to microwave energy in a microwave reactor at a pressure of 1 atm or less. The microwave energy causes decarboxylation of the cannabinolic acids to produce decarboxylated cannabinoid crude resin. The decarboxylated cannabinoid crude resin is collected from the microwave reactor.

[0011] In a further embodiment of any of the foregoing embodiments, the solventless cannabis crude resin resides in the microwave reactor for 0.5 minutes to 15 minutes.

[0012] In a further embodiment of any of the foregoing embodiments, the solventless cannabis crude resin is static in the microwave reactor while being subjected to the microwave energy.

[0013] In a further embodiment of any of the foregoing embodiments, the decarboxylated cannabinoid crude resin has a yield of at least 92% conversion of the cannabinolic acids to decarboxylated cannabinoids.

[0014] In a further embodiment of any of the foregoing embodiments, the microwave energy has a frequency of 700 MHz to 5 GHz, and the microwave reactor has a power 100W to lOkW.

[0015] In a further embodiment of any of the foregoing embodiments, the solventless cannabis crude resin is heated to a temperature of 90°C to 240°C in the microwave reactor.

[0016] A further embodiment of any of the foregoing embodiments includes generating a vacuum in the microwave reactor. [0017] An apparatus for decarboxylation of cannabinolic acids according to an example of the present disclosure includes a microwave reactor operable to generate microwave energy, an inlet into the microwave reactor and configured to receive a solventless cannabis crude resin that contains cannabinoid acids, and an outlet from the microwave reactor and configured to discharge decarboxylated cannabinoid crude resin.

[0018] In a further embodiment of any of the foregoing embodiments, the microwave reactor has a power 100W to lOkW and is operable to generate the microwave energy with a frequency of 700 MHz to 5 GHz.

[0019] A further embodiment of any of the foregoing embodiments includes a vacuum port connected with the microwave reactor and a vacuum pump connected with the vacuum port, the vacuum pump operable via the vacuum port to decrease pressure in the microwave reactor.

BRIEF DESCRIPTION OF THE DRAWINGS [0020] The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.

[0021] Figure 1 illustrates an example method for decarboxylation of cannabinolic acids.

[0022] Figure 2 illustrates an example apparatus for decarboxylation of cannabinolic acids.

[0023] Figure 3 illustrates another example apparatus for decarboxylation of cannabinolic acids.

DETAILED DESCRIPTION

[0024] Decarboxylation of cannabinolic acids typically requires heating for long periods of time. Such processes also use elevated pressures and solvents in effort to provide more optimal yield, but this often leads to increased processing time. As will be described, the methodology disclosed herein utilizes a solventless approach along with microwave treatment under atmospheric pressure or under vacuum in order to provide rapid decarboxylation with high yield.

[0025] Figure 1 schematically illustrates an example method for decarboxylation of cannabinolic acids. Cannabis plants include a variety of cannabinolic acids. The primary cannabinolic acids of interest are tetrahydrocannabinolic acid and cannabidiolic acid, but the methodology herein is not limited to these. Initially, the cannabinolic acids are in cannabis plant material. Such plant material can be subjected to known extraction processes to produce what is known as crude resin. The crude resin is the relatively unpurified extraction product from the cannabis plant material and often contains, in addition to cannabinolic acids, undesired compounds of lipids and waxes. The lipids and waxes may be substantially removed after decarboxylation.

[0026] In the example method, the crude resin is provided as a solventless cannabis crude resin 20 (hereafter "crude resin 20"). In this example, the crude resin 20 is held in a container 22. The crude resin 20 is introduced into a microwave reactor 24 at ambient pressure or under vacuum. That is, no pressurization is required and the pressure may vary as the ambient pressure varies. In this regard, no sealing of the crude resin 20 in the container 22 or reactor 24 are necessarily required, although if sub-ambient pressures are used then sealing may be provided.

[0027] The reactor 24 is operable to generate microwave energy 26 and thereby subject the crude resin 20 to the microwave energy. In examples, the reactor has a power of 100W to 10 kW and the microwave energy has a frequency of 700 MHz to 5 GHz. The crude resin 20 is subjected to the microwave energy. The microwave energy heats the crude resin 20 to a temperature of about 90°C to 240°C and causes the decarboxylation of the cannabinolic acids to produce decarboxylated cannabinoid crude resin. The reaction chemistry of such decarboxylation is well-known and thus not described further herein.

[0028] The crude resin 20 is subjected to the microwave energy for an amount of time at which there is substantially full decarboxylation of the cannabinolic acids, which will typically be from about 0.5 minutes to 15 minutes. For example, substantially full decarboxylation is conversion of more than 90% of cannabinolic acids to their conjugate cannabinoids, but more desirably is conversion of at least 92%. After decarboxylation, the decarboxylated cannabinoid crude resin can be collected from the microwave reactor for use or further processing.

[0029] Figure 2 illustrates further examples of the method and an apparatus 50 for decarboxylation of cannabinolic acids in the crude resin 20. As shown, the apparatus 50 includes a chamber 52 having an interior in which a microwave reactor 54 is disposed. The microwave reactor 54 is operable as discussed above to generate microwave energy. The apparatus 50 has an inlet 56 into the microwave reactor 54 that configured to receive the crude resin 20. For example, the inlet 56 includes one or more tubes through which the crude resin 20 can flow into the microwave reactor 54. There is an outlet 58 from the microwave reactor 54 that is configured to discharge the decarboxylated cannabinoid crude resin. For example, the outlet 58 includes one or more tubes through which the crude resin 20 can flow from the microwave reactor 54. Optionally, there is a vacuum port 60 connected with the microwave reactor 54 and a vacuum pump 62 connected with the vacuum port 60. The vacuum pump 62 is operable via the vacuum port 60 to decrease pressure in the microwave reactor 54.

[0030] Figure 3 illustrates another example apparatus 150 for decarboxylation of cannabinolic acids in the crude resin 20. The apparatus 150 is similar to the apparatus 50 except that rather than a vertical as in the apparatus 50, the apparatus 150 has a horizontal configuration. Here, the inlet 156 is on the side of the microwave reactor 54 and the outlet 158 is on the other side of the microwave reactor 54. For example, the inlet 156 is vertically above the outlet 158 such that the crude resin 20 can be gravity-fed into and through the microwave reactor 54, such as for continuous processing of a crude resin feed stream. Here, the vacuum port 160 is connected through the inlet 156 to the microwave reactor 54.

[0031] The disclosed method and apparatuses, facilitate short reaction time which is heretofore unknown for decarboxylation, power reductions, high yields, and high purity (low level terpenoids condensation). The following examples demonstrate additional, non-limiting aspects of the present disclosure.

[0032] Example 1

[0033] Starting material: Crude hemp extract resin - 10 g, CBDA - 62%, THCA - 8%

[0034] Apparatus: microwave reactor, 2.54 GHz, 700 W

[0035] Protocol: 10 g of the crude hemp extract resin was placed in a 100 mL long neck glass flask. The flask was placed in the microwave reactor and treated for 4 min without a stopper, after which the flask was removed from the microwave reactor and the reaction mixture was analyzed by TLC, UV-Vis, HPLC with the following results.

[0036] Reaction mixture weight - 9.6 g, CBDA - 0.2%, THCA - 0, CBD - 64%, THC

- 8%

[0037] Example 2

[0038] Starting material: Crude hemp extract resin - 10 g, CBDA - 62%, THCA - 8%

[0039] Apparatus: microwave reactor, 2.54 GHz, 700 W

[0040] Protocol: 10 g of the crude hemp extract resin was placed in a 100 mL long neck glass flask. The flask was placed in the microwave reactor and microwaved for 4 minutes under vacuum (40 mm), after which the flask was removed from the microwave reactor and analyzed by TLC, UV-Vis, HPLC with the following results.

[0041] Reaction mixture weight - 9.2 g, CBDA - 0%, THCA - 0, CBD - 64%, THC -

8%

[0042] Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.

[0043] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.

Claims

CLAIMS What is claimed is:

1. A method of decarboxylating cannabinoid acids, comprising: providing a solventless cannabis crude resin that contains cannabinolic acids; introducing the solventless cannabis crude resin into an inlet of a microwave reactor; at a pressure of 1 atm or less, subjecting the solventless cannabis crude resin to microwave energy in the microwave reactor, the microwave energy causing decarboxylation of the cannabinolic acids to produce decarboxylated cannabinoid crude resin; and collecting the decarboxylated cannabinoid crude resin from an outlet of the microwave reactor.

2. The method as recited in claim 1, wherein the solventless cannabis crude resin resides in the microwave reactor for 0.5 minutes to 15 minutes.

3. The method as recited in claim 1, wherein the solventless cannabis crude resin flows through the microwave reactor while being subjected to the microwave energy.

4. The method as recited in claim 1, wherein the decarboxylated cannabinoid crude resin has a yield of at least 92% conversion of the cannabinolic acids to decarboxylated cannabinoids.

5. The method as recited in claim 1, wherein the microwave energy has a frequency of 700 MHz to 5 GHz, and the microwave reactor has a power 100W to lOkW.

6. The method as recited in claim 1, wherein the solventless cannabis crude resin is heated to a temperature of 90°C to 240°C in the microwave reactor.

7. The method as recited in claim 1, including generating a vacuum in the microwave reactor.

8. A method of decarboxylating cannabinoid acids, comprising: providing a solventless cannabis crude resin that contains cannabinolic acids; at a pressure of 1 atm or less, subjecting the solventless cannabis crude resin to microwave energy in a microwave reactor, the microwave energy causing decarboxylation of the cannabinolic acids to produce decarboxylated cannabinoid crude resin; and collecting the decarboxylated cannabinoid crude resin from the microwave reactor.

9. The method as recited in claim 8, wherein the solventless cannabis crude resin resides in the microwave reactor for 0.5 minutes to 15 minutes.

10. The method as recited in claim 8, wherein the solventless cannabis crude resin is static in the microwave reactor while being subjected to the microwave energy.

11. The method as recited in claim 8, wherein the decarboxylated cannabinoid crude resin has a yield of at least 92% conversion of the cannabinolic acids to decarboxylated cannabinoids.

12. The method as recited in claim 8, wherein the microwave energy has a frequency of 700 MHz to 5 GHz, and the microwave reactor has a power 100W to lOkW.

13. The method as recited in claim 8, wherein the solventless cannabis crude resin is heated to a temperature of 90°C to 240°C in the microwave reactor.

14. The method as recited in claim 8, including generating a vacuum in the microwave reactor.

15. An apparatus for decarboxylation of cannabinolic acids, the apparatus comprising: a microwave reactor operable to generate microwave energy; an inlet into the microwave reactor and configured to receive a solventless cannabis crude resin that contains cannabinoid acids; and an outlet from the microwave reactor and configured to discharge decarboxylated cannabinoid crude resin.

16. The apparatus as recited in claim 15, wherein the microwave reactor has a power 100W to lOkW and is operable to generate the microwave energy with a frequency of 700 MHz to 5 GHz.

17. The apparatus as recited in claim 15, further comprising a vacuum port connected with the microwave reactor and a vacuum pump connected with the vacuum port, the vacuum pump operable via the vacuum port to decrease pressure in the microwave reactor.