Hydrogen Bromide → 4-Fluorophenylglyoxal hydrate

4-Fluoroacetophenone (27.6 g, 0.2 moles) was dissolved in dimethylsulfoxide (140 ml). 48% Hydrobromic acid (101.1 g, 68.0 ml, 0.6 moles) was added over 20 minutes. The resulting solution was aged at 55-60° C. for 22 hours. The mixture was cooled to room temperature and partitioned between water (1.0 liters) and ethyl acetate (250 ml). The aqueous phase was extracted with ethyl acetate (2×250 ml). The combined ethyl acetate extracts were filtered and solvent switched to toluene at 60° C. under reduced pressure. The solution was diluted to 200 ml with toluene, and water (10 ml) was added. The resulting slurry was stirred at room temperature for 18 hours then at 0° C. for 1 hour. The product was collected by filtration and washed with cold toluene (50 ml). The solid was sucked down on the filter for 30 minutes and air dried to constant weight to afford 4-fluorophenylglyoxal hydrate (24.8 g) as a white solid in 73% yield.