Process to extract and purify delta-9-tetrahydrocannabinol

Abstract

Δ9-THC carboxylic acid is extracted from cannabis flowers using a first organic solvent, then separated using a second aqueous solvent. Δ9-THC carboxylic acid is converted to Δ9-THC carboxylic salt before being extracted by a third organic solvent and converted back to Δ9-THC carboxylic acid. Using a solvent swap, Δ9-THC carboxylic acid is decarboxylated and extracted again with an organic solvent prior to purification to give Δ9-THC.

What is claimed is: 
     
         1 . A method of producing Δ 9 -THC consisting essentially of:
 extracting Δ 9 -THC carboxylic acid from  cannabis  flowers using heptane to obtain a heptane extract; 
 filtering the heptane extract to remove solid plant matter; 
 separating the Δ 9 -THC carboxylic acid from the heptane extract by contacting the heptane extract with sodium chloride water adjusted to a pH range of 13.2 to 13.4 using an inorganic base to form a liquid mixture; 
 stirring the liquid mixture; and 
 leaving the liquid mixture to settle; 
 wherein the liquid mixture forms three layers consisting of a first organic layer, a second oily layer, and third aqueous layer; and 
 separating out the oily layer from the other two layers by a separatory funnel. 
 
     
     
         2 . The method of  claim 1 , further consisting essentially of suspending the oily layer in an aqueous solvent containing sodium chloride and an inorganic base to adjust the aqueous solvent to a pH of 13.2 to 13.4 to convert Δ 9 -THC carboxylic acid to Δ 9 -THC carboxylic salt. 
     
     
         3 . The method of  claim 2 , further consisting essentially of extracting Δ 9 -THC carboxylic salt with an organic solvent. 
     
     
         4 . The method of  claim 3 , wherein the organic solvent is tert-butyl methyl ether. 
     
     
         5 . The method of  claim 3 , further consisting essentially of converting the Δ 9 -THC carboxylic acid salt in the organic solvent back to Δ 9 -THC carboxylic acid by adding an aqueous solvent containing sodium chloride and an inorganic base to adjust the aqueous solvent to a pH of 13.2 to 13.4 and a strong inorganic acid into the Δ 9 -THC carboxylic salt in organic solvent mixture. 
     
     
         6 . The method of  claim 5 , further consisting essentially of:
 washing the resulting mixture with a sodium chloride water solution to form an organic solvent layer and an aqueous layer; and   separating the organic solvent layer from the aqueous layer,   wherein the organic solvent layer comprises Δ 9 -THC carboxylic acid in water and organic solvent.   
     
     
         7 . The method of  claim 6 , further consisting essentially of:
 removing water from the Δ 9 -THC carboxylic acid in water and organic solvent mixture using Na 2 SO 4 ;   removing the organic solvent using vacuum to give a crude solid containing Δ 9 -THC carboxylic acid;   dissolving the solid in pentane;   treating the crude solid containing Δ 9 -THC carboxylic acid dissolved in pentane with active carbon to remove non-THC cannabinoids;   removing the pentane using vacuum; and   filtering to obtain Δ 9 -THC carboxylic acid solid.   
     
     
         8 . The method of  claim 7 , further consisting essentially of:
 dissolving Δ 9 -THC carboxylic acid solid into an alcohol and adding the mixture into boiling water;   heating the mixture to between 80° C. and 100° C. for at least 40 minutes; and   cooling the mixture to room temperature and adding a sodium chloride solution into the mixture;   wherein the Δ 9 -THC carboxylic acid is decarboxylated to convert Δ 9 -THC carboxylic acid to Δ 9 -THC.   
     
     
         9 . The method of  claim 8 , wherein the alcohol is ethanol, isopropyl alcohol, propyl alcohol, or butyl alcohol. 
     
     
         10 . The method of  claim 8 , further consisting essentially of extracting Δ 9 -THC using n-pentane 1 to 3 times. 
     
     
         11 . The method of  claim 10 , further consisting essentially of purifying Δ 9 -THC by removing water using Na 2 SO 4  and removing n-pentane by vacuum. 
     
     
         12 . The method of  claim 11 , further consisting essentially of combining purified Δ 9 -THC with a pharmaceutically acceptable carrier.