Hydrogen Bromide → HCID 14646171, compound

Participants

Reaction Steps

In a 2 liter, three-necked flask equipped with a reflux condenser and an addition funnel are placed 200 g pentaerythritol (1.47 mole) and 16 ml 48% hydrobromic acid in about 500 ml glacial acetic acid. The mixture is refluxed for about one-half hour until all pentaerythritol is dissolved. Then, 170 ml 48% hydrobromic acid are added, followed by 310 ml acetic anhydride and the mixture is refluxed for 3 hours. Then, 94 ml 48% hydrobromic acid followed by 150 ml acetic anhydride are added and the mixture is refluxed for an additional 3 hours. The acetic acid is then removed as completely as possible on a rotary evaporator. Ethanol (95%, 750 ml) and 17 ml 48% hydrobromic acid are then added to the residue. The flask is equipped with 1 m Vigreux column and the azeotrope ethyl acetate/ethanol is slowly distilled off. When 500 ml distillate has been collected, an additional 750 ml 95% ethanol is added and the distillation is continued until about 400 ml is left over. After cooling, the precipitated pentaerythritol is filtered off. The solvent is evaporated and the residue is dissolved in water. The aqueous phase is extracted twice with carbon tetrachloride and twice with ether. The water is evaporated on the rotary evaporator and the last traces of water are removed by azeotropic distillation with toluene using a Dean-Stark trap. The solid is recrystallized from chloroform containing 10% acetonitrile. The first crop yielded 190 g monobromopentaerythritol. The total yield is 70%.

Provenance & Evidence