Salbutamol → Salbutamol caprate

Participants

Reaction Steps

Salbutamol base (13.91 g; 58.13 mmol) was dissolved in ethanol (600 mL, 96%) with magnetic stirring to give a pale yellow liquid. Capric acid (10.01 g; 58.11 mmol) was added with vigorous stirring which was continued until all solid material had dissolved. The solvent was removed by rotary-evaporation to give a pale yellow tacky semi-solid. This was dissolved in warm ethyl acetate (300 mL), then stored at 5° C. for 36 hours, resulting in the precipitation of a fine white solid. The mother liquor was removed by vacuum filtration, and the precipitate washed with cold ethyl acetate. Any remaining solvent was removed by storing the precipitate at 35° C. and 0 bar pressure for 6 hours. Salbutamol caprate was obtained as a white solid (18.93 g; 79.13%). Moisture content K.F. 0.32%; melting point 99.4° C. (onset of endotherm in DCS thermogram). The theoretical percentage of salbutamol base in salbutamol caprate is 58.14%. Experimentally the percentage salbutamol base in salbutamol caprate was found to be 56.42%. The pH of a saturated aqueous solution is 7.24. The aqueous solubility is 4.76 mg/mL.

Provenance & Evidence