Phenobarbital sodium synthesis

Yield:-

Reaction Conditions:

with sodium hydroxide in acetone

Steps:

5
Preparation of phenobarbital sodium salt is achieved by dissolving phenobarbital and sodium hydroxide in acetone followed by removal of the acetone. The obtained material is analyzed by XRPD and is shown to have a different pattern than phenobarbital free form. The sodium salt exhibits a single endothermic event attributed to the melt at 297° C. by DSC and a continuous weight loss is observed by TGA. ¹H-NMR analysis is consistent with the chemical structure of phenobarbital. Moisture sorption analysis indicates the material is hygroscopic adsorbing approximately 34 wt % water at 90% RH. Between 10-60% RH the sample adsorbed approximately 2 wt % water indicating a sesqui or dihydate. Karl Fischer analysis of the starting material shows approximately 10 wt % water which is comparable to a sesquihydate (9.0 wt %). Upon desorption, the curve stabilizes at approximately 12 wt % water indicating a stable dihydrate from 40-5% RH. XRPD analysis of the material following the moisture sorption experiment affords a diffraction pattern which shows differences in comparison to the diffraction pattern of the initial material which may be due to a change in hydration state following drying. Following water slurry and amorphous XRPD pattern is observed and the aqueous solubility of the amorphous material is 86.5 mg/ml. The residual solid isolated from the seven day toluene slurry are analyzed by XRPD and is amorphous

References:

Sun, Tong;Watson, Shawn;Manchanda, Rajesh US2010/35904, 2010, A1 Location in patent:Page/Page column 5

FullText