Tetrafluoroboric acid → 5-Bromo-2,4-difluoro-3-methylbenzenediazonium tetrafluoroborate
Reaction equation
[Br:1][C:2]1[C:3]([F:11])=[C:4]([CH3:10])[C:5]([F:9])=[C:6]([CH:8]=1)[NH2:7].[N:12]([O-])=O.[Na+].[F:16][B-:17]([F:20])([F:19])[F:18].[H+]>O>[F:16][B-:17]([F:20])([F:19])[F:18].[Br:1][C:2]1[C:3]([F:11])=[C:4]([CH3:10])[C:5]([F:9])=[C:6]([N+:7]#[N:12])[CH:8]=1Participants
5
Procedure
To a suspension of 5-bromo-2,4-difluoro-3-methylaniline (24.60 g) in 42% fluoroboric acid (150 ml) with stirring vigorously at -3° to 0° C. was added sodium nitrite (11.47 g) in water (20 ml) dropwise during 40 minutes. After stirring for 1.5 hours at 0° to 5° C., the reacting mixture was cooled with ice bath sufficiently and the resulting precipitate was collected by filtration. This precipitate was washed with small portion of water and ether and dried under reduced pressure to give the title compound (28.83 g) as pale brown prisms, mp 147°-150° C. (decompd.).