FIELD: pharmacology.
SUBSTANCE: invention relates to the extraction of cannabinoids from plant material. A method for producing cannabidiol (CBD) or a neutral cannabinoid, comprising: i) contacting a biomass containing CBD and/or cannabidiolic acid (CBDA), or a neutral cannabinoid, or a cannabinoid in the form of a carboxylic acid, with an extracting solvent for at least 10 minutes at temperature from 0° C to the boiling point of the solvent to obtain, after removal of the biomass, an extracted solution in which said extracting solvent is selected from the group consisting of pentane, hexane, heptane, octane, methylcyclohexane, acetone, propanol, ethanol, methanol, ethyl acetate, toluene, methylene chloride and their mixtures; proceeding according to process (A) comprising: ii-a) contacting the extracted solution with an aqueous-alcoholic solution and adjusting the pH to 7.5–12.5 with a suitable alkaline solution, obtaining, after phase separation, a first aqueous-alcoholic phase and the first organic phase; in the case where the extracting solvent is a water-miscible solvent, a first water-immiscible solvent selected from the group consisting of pentane, hexane, heptane, methylcyclohexane and mixtures thereof is also added; iii-a) contacting the first aqueous-alcoholic phase with a second water-immiscible solvent and an acidic solution suitable to adjust the pH to 2.0–6.5 to obtain a second organic phase and a second aqueous-alcoholic phase; said second water-immiscible solvent is selected from the group consisting of pentane, hexane, heptane, methylcyclohexane and mixtures thereof; iv-a) evaporating the second organic phase and heating the resulting oil at a temperature between 65°C and 180°C for at least 10 minutes to achieve decarboxylation of CBDA to CBD; or proceeding according to process (B) comprising: ii-b) evaporating the pro-extracted solution to obtain a pro-extracted oil and contacting the obtained pro-extracted oil with an alcohol at a temperature below 20°C for at least 10 minutes to obtain a suspension of extract and waxes, where the specified alcohol is selected from the group consisting of methanol, ethanol, propanol and mixtures thereof; iii-b) filtering and evaporating the slurry to obtain a dewaxed extracted oil and contacting the resulting dewaxed extracted oil with a water-immiscible organic solvent and an aqueous-alcoholic solution to obtain an organic phase containing the dewaxed and resinous extract and an aqueous -alcohol phase containing resins; iv-b) evaporation of the organic phase containing the dewaxed and resinous extract and chromatography of the resulting residue on silica gel using a suitable eluent to collect fractions containing CBD or other neutral cannabinoid; and further after iv-a) and iv-b) follows v) crystallization of CBD or neutral cannabinoid from a third water-immiscible solvent selected from the group consisting of pentane, hexane, heptane, octane, methylcyclohexane and mixtures thereof, or alternatively, in process A, the first organic phase obtained at the end of step (ii-a) is sent to steps (ii-b) to (iv-b) of process B and the CBD thus obtained is then also subjected to step (v) crystallization.
EFFECT: process described above makes it possible to obtain cannabinoids in a highly pure crystalline form.
9 cl, 1 dwg, 7 ex
