2-Phenylisobutyric acid → 2-(4-Bromophenyl)-2-methylpropanoic acid

Temperature

35 °C

Dry dimethylphenylacetic acid, 152 g, 0.926 mole, was added to a flask equipped with a reflux condenser, magnetic stirrer and oil bath. A solution of bromine, 50 mL, 0.97 mole, in dry carbon tetrachloride (172 mL) was then added along with iron metal "filings," 0.23 g. The mixture was gently refluxed for 16 hours and cooled to ca. 35° C. whereupon material began to crystallize out of solution. Enough carbon tetrachloride (ca. 300 mL) was then added to redissolve the crystals and the solution was washed with ca. 500 mL of dilute aqueous H2SO4, followed by 500 mL of water. The washed CCl4 solution was extracted with 10% aqueous NaOH. The combined basic extracts were washed with petroleum ether or pentane to remove CCl4 and then neutralized at 0° C. with aqueous H2SO4 (50%). The precipitated crude acid was collected on a filtering funnel, washed with cold water and vacuum dried at 40° C. The crude yield was 220 g (98%), mp=106°-116° C. Four recrystallizations from methanol-water (50/50 vol) gave a final mp of 122°-124° C.

1. customequipped with a reflux condenser, magnetic stirrer and oil bath
2. temperatureThe mixture was gently refluxed for 16 hours
3. customto crystallize out of solution
4. additionEnough carbon tetrachloride (ca. 300 mL) was then added
5. dissolutionto redissolve the crystals
6. washthe solution was washed with ca. 500 mL of dilute aqueous H2SO4
7. extractionThe washed CCl4 solution was extracted with 10% aqueous NaOH
8. washThe combined basic extracts were washed with petroleum ether or pentane
9. customto remove CCl4
10. customneutralized at 0° C. with aqueous H2SO4 (50%)
11. customThe precipitated crude acid
12. customwas collected on a filtering funnel
13. washwashed with cold water and vacuum
14. customdried at 40° C
15. customFour recrystallizations from methanol-water (50/50 vol)
16. customgave a final mp of 122°-124° C.

ORD record

ord-242a3c2964054b57981fb70d7290cfd3

Source dataset

uspto-grants-1982_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04310655