Hydrogen Bromide → 5-Bromo-2,2-difluoropentanoic acid

HBr gas was introduced into 48% HBr in H2O (100 ml) with occasional cooling in an ice bath until the weight became 180 g. The HBr solution was then added to Part (5) compound (8.4 g, 36.3 mmole) at room temperature and the reaction was stirred for 5 hours at room temperature. The reaction was cooled to 0° C. and poured into Et2O (900 ml) in an ice bath. The products were extracted into the Et2O layer. The water layer was further extracted with Et2O (200 ml and 100 ml). The combined ether layers were washed with H2O (200 ml). The H2O wash was backwashed with Et2O (100 ml). The Et2O layers were combined and dried over MgSO4. Filtration and evaporation of solvent gave the title compound (7.8 g, quant.) as a colorless liquid.