2-Methylbenzoic acid → 2-(Bromomethyl)benzoic acid

Temperatur

-20 °C

In a 1 L round bottom flask fitted with a reflux condenser, a stirred suspension of 10.00 g of o-toluic acid and 19.56 g (1.5 eq.) N-bromosuccinimide in 735 mL chloroform was sparged for 0.5 h with nitrogen. The sparging was discontinued, and the suspension was stirred and irradiated under nitrogen atmosphere using a 500 W quartz halogen lamp at 75% power, causing the solids to dissolve and the chloroform to reflux. The red color of the reaction mixture disappeared after 1.5 h, and 6.52 g (0.5 eq.) of N-bromosuccinimide was added. The reaction mixture was stirred and irradiated under nitrogen atmosphere with a 500 W quartz halogen lamp at 75% power for another 1.5 h, at which time the solution became colorless. The solvent volume was reduced in vacuo to about 100 mL, and then cooled to −20° C. The resultant suspension was vacuum filtered through a 1 cm bed of dry silica in a 150 mL fritted funnel. The silica was washed with 2.5 L of chloroform. The chloroform filtrate was reduced in vacuo to about 1 L, washed in a separatory funnel with 3×1 L volumes of water followed by one 3×1 L volume of brine to remove traces of succinimide, then dried with magnesium sulfate and vacuum filtered. The chloroform was reduced by rotary evaporation at reflux at 1 atmosphere to 250 mL and cooled at −20° C. for 3 days. The resultant crystals were vacuum filtered, washed with 30 mL of chloroform followed by 50 mL of hexanes, then dried in a vacuum oven at room temperature overnight, providing 8.48 g (54%) 2-bromomethylbenzoic acid as a white crystalline power.

1. customIn a 1 L round bottom flask fitted with a reflux condenser
2. customwas sparged for 0.5 h with nitrogen
3. customirradiated under nitrogen atmosphere
4. dissolutionto dissolve
5. temperaturethe chloroform to reflux
6. stirringThe reaction mixture was stirred
7. filtrationfiltered through a 1 cm bed of dry silica in a 150 mL fritted funnel
8. washThe silica was washed with 2.5 L of chloroform
9. washwashed in a separatory funnel with 3×1 L volumes of water
10. customto remove traces of succinimide
11. dry with materialdried with magnesium sulfate and vacuum
12. filtrationfiltered
13. customThe chloroform was reduced by rotary evaporation
14. temperatureat reflux at 1 atmosphere to 250 mL
15. temperaturecooled at −20° C. for 3 days
16. filtrationfiltered
17. washwashed with 30 mL of chloroform
18. customdried in a vacuum oven at room temperature overnight

ORD-Eintrag

ord-a3a9b3a4d457478b94eb0b77a3d3fdfe

Quelldatensatz

uspto-grants-2008_10

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07432369B2