Citric Acid → 648-93-1

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Reaction Steps

Citric acid powder, 2.1 grams, was dissolved in 1 liter of bidistilled water and the resulting pH of this dilute solution was approximately 3.0 units. To 100 ml of this citric acid solution hydrated morphine base powder (Mb ·H2O) was added in 100 mg amounts, following each of which additions the mixture was stirred until morphine was completely dissolved and the pH was measured. Following addition of the 10th aliquot (1 gram total) there remained in suspension a small cloud of precipitate and the pH had risen to 6.5-7.0 units. After one hour at room temperature, with the small cloud of precipitate remaining settled at the bottom of the flask, it was resuspended evenly by stirring and shaking and 2.0 ml was withdrawn. To this small 2.0 ml aliquot was added 0.5 ml of 95% ethanol (20% v/v), the precipitate disappeared and pH remained at 6.5-7.0 units. To the 98 ml of pure aqueous solution remaining, HCl, N/2, was added in 0.2 ml aliquots with stirring to a total of 1.8 ml, at which point the precipitate disappeared and pH levels measured 6.0-6.3 units. Thus, there was formulated 100 ml of aqueous trimorphine citrate at a concentration of 9.4 mg/ml (morphine base powder was in the monohydrate form).

Provenance & Evidence