La morphine s'obtient par extraction à partir de la sève du pavot à opium. La sève est récupérée grâce à des saignées dans le bulbe de la plante
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Mode opératoire de l'extraction :
| Triturate the sample (8 g) with water (30 mL) and calcium hydroxide (2 g) in a mortar. This liberates the alkaloids from their salts, and convert morphine and narcotine into their water soluble calcium salts. Transfer the mixture (grease the lip of the mortar) to a tared flask and make up to exactly 90 g with water. Shake occasionally during half an hour and filtered through a dry Buchner funnel into a dry Buchner flask. Transfer exactly 52 mL of the filtrate to a clean dry conical flask, and add ammonium chloride (2 g)n, ether (25 mL) and 90% ethanol (5 mL). The function of ammonium chloride is to decompose the calcium salts of the alkaloids. |
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(RO2)Ca + 2NH4Cl --> 2ROH + 2NH3 + CaCl2 |
| Ether acts as a solvent for narcotine and the ethanol facilitates the crystallisation of the morphine which separates from the solution. Cork the flask, shake for 5 minutes and occasionally during half an hour, so that total shaking time is about 15 minutes. Allow to stand overnight. Decant the ethereal solution as completely as possible with a tight plug of cotton wool retaining the crystals in the flask as far as possible. Wash the contents of the flask with a further quantity of ether (10 mL) and decant through the filter. Wash the filter with solvent ether (5 mL) added slowly and in a small quantities. Displace the air in the flask gently with air from a bellows to ensure removal of ammonia fumes. Transfer the contents of the funnel back to the flask with water from a wash bottle. Add N/10 [0.1 M] HCl (25 mL), boil gently to remove CO2, and back titrate the excess acid with N/10 [0.1 M] NaOH using methyl red as indicator. |