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0 °C

A 200 mL round bottom flask was charged with 4,4,4-trifluorobutanal (5 g, 39.7 mmol) and diluted with diethyl ether (79 mL). The flask was placed in an ice bath and the reaction mixture was cooled to 0° C. Bromine (2.043 mL, 39.7 mmol) was then added drop wise over the course of 15 min. After which the reaction was stirred for 15 min and then let warm to rt. After 3.5 hours, NMR showed complete consumption of the starting material to desired product. The mixture was cooled in an ice bath and slowly quenched with sat'd sodium bicarbonate. The contents of the flask were transferred to a separatory funnel where the layers were separated and the organics were washed with bicarbonate, brine, and dried with magnesium sulfate. A short path distillation apparatus was equipped to the flask and the combination was placed in an oil bath set to 40° C. After 15 min, the flask was removed from the oil bath and the crude residue was distilled at moderate vacuum (˜50 torr) to remove any lower boiling point impurities as well as excess diethyl ether. The atmosphere was restored to normal once bubbling had subsided for 5 min. This process was repeated a few times to remove the majority of diethyl ether. 1H NMR consistent with desired. 2-bromo-4,4,4-trifluorobutanal (7.4 g, 91% yield). 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 9.54-9.36 (m, 1H), 4.52-4.46 (m, 1H), 3.21 (dqd, J=16.0, 10.1, 5.8 Hz, 1H), 2.73-2.62 (m, 1H).

1. customThe flask was placed in an ice bath
2. temperaturelet warm to rt
3. waitAfter 3.5 hours
4. customconsumption of the starting material to desired product
5. temperatureThe mixture was cooled in an ice bath
6. customslowly quenched with sat'd sodium bicarbonate
7. customThe contents of the flask were transferred to a separatory funnel
8. customwhere the layers were separated
9. washthe organics were washed with bicarbonate, brine
10. dry with materialdried with magnesium sulfate
11. distillationA short path distillation apparatus
12. customwas equipped to the flask
13. customthe combination was placed in an oil bath
14. customset to 40° C
15. waitAfter 15 min
16. customthe flask was removed from the oil bath
17. distillationthe crude residue was distilled at moderate vacuum (˜50 torr)
18. customto remove any lower boiling point impurities as well as excess diethyl ether
19. customonce bubbling
20. waithad subsided for 5 min
21. customto remove the majority of diethyl ether