Hydrochloric Acid → 4-Methylbenzene-1,3-dicarboxylic acid

Temperatur

-78 °C

To THF (130 ml) solution of 3-bromo-4-methyl-benzoic acid (5.0 g, 23.25 mmol) under nitrogen and cooled to −78° C. (dryice/methanol) was added MeMgBr in ether (3.0 M, 8.5 ml, 25.57 mmol) at such a rate that the temperature did not exceed −75° C. The temperature was then allowed to rise to −60° C. and after gas evolution had ceased, the solution was cooled again to −78° C. BuLi in hexane (1.6 M, 29.06 ml, 46.50 mmol) was then added dropwise such that the temperature did not rise above −75° C. The mixture was then stirred at this temperature for 15 minutes before crushed dryice (4.4 g, 100 mmol) was added. The precipitate was vigorously stirred as the temperature was allowed to freely rise to ambient temperature. The mixture was made acidic using 6 N HCl and the solid material collected filteration, washed with diethyl ether and dried. Recrystallisation from water afforded off-white pure compound (81%) m.p. 296-298° C. (sublimed). NMR conforms to expected structure.

1. customdid not exceed −75° C
2. customto rise to −60° C.
3. customdid not rise above −75° C
4. custombefore crushed dryice (4.4 g, 100 mmol)
5. additionwas added
6. stirringThe precipitate was vigorously stirred as the temperature
7. customto freely rise to ambient temperature
8. customthe solid material collected filteration
9. washwashed with diethyl ether
10. customdried
11. customRecrystallisation from water afforded off-white pure compound (81%) m.p. 296-298° C. (sublimed)

ORD-Eintrag

ord-3886f99cec384555968b3816e10cb5c9

Quelldatensatz

uspto-grants-2008_08

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07413727B2