Hydrogen Bromide → 2,5-Dibromo-4-methylpyridine

Temperature

2 °C

2-Amino-5-bromo-4-methylpyridine (2.0 g, 10.7 mmol) was dissolved in 48% aqueous HBr (14 mL, 123 mmol) and cooled to 2° C. in a salt/ice bath. Bromine (1.65 mL, 32.1 mmol) was added dropwise keeping the internal temperature below 2° C. A solution of sodium nitrite (3.69 g, 53.5 mmol) in water (5 mL) was added keeping the internal temperature below 5° C. and stirred for 1 h between 0° C. and 5° C. The pH was adjusted to ˜13 by slow addition with cooling of 50% NaOH (aq). After warming to r.t. the reaction was extracted with ether, the organics were dried over MgSO4 and concentrated to give a brown oil. Flash chromatography on silica gel eluting with 5% ether/hexane gave the product as a white solid (1.83 g, 7.29 mmol, 68%). MS [M+H]+: 251.9; tR=2.3 min. (method 1)

1. customthe internal temperature below 2° C
2. customthe internal temperature below 5° C.
3. additionThe pH was adjusted to ˜13 by slow addition
4. temperatureAfter warming to r.t. the reaction
5. extractionwas extracted with ether
6. dry with materialthe organics were dried over MgSO4
7. concentrationconcentrated
8. customto give a brown oil

ORD record

ord-238ee90e5be9455faff1967b03e285a4

Source dataset

uspto-grants-2013_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08481738B2