1,3-Cyclohexanedicarboxylic acid → 3-Oxabicyclo[3.3.1]nonane-2,4-dione

Temperatur

140 °C

A suspension of 1,3-cyclohexanedicarboxylic acid (490 g, 2.88 mol) in acetic anhydride (1500 ml) was heated to 140° C., refluxing for 2 hours. Acetic anhydride was then removed with distillation (oil bath 180° C). To the residue was added acetic anhydride (1000 ml) and refluxed at 140° C. for 1 hour. The acetic anhydride was removed again with distillation (under house vacuum, about 50° C.). After crystals appeared, the mixture was cooled to room temperature and MTBE (400 ml) was added. The mixture was then cooled to 0-5° C. The crystals were filtered, washed with MTBE (250 ml), and dried under house vacuum to give the title compound (382 g). The filtrate was concentrated to a residue and suspended in MTBE (100 ml) to give the second crop of the title compound (14.0 g). The total yield was 396 g (90.5%). Mp 138-140° C.

1. temperaturerefluxing for 2 hours
2. customAcetic anhydride was then removed with distillation (oil bath 180° C)
3. additionTo the residue was added acetic anhydride (1000 ml)
4. temperaturerefluxed at 140° C. for 1 hour
5. customThe acetic anhydride was removed again with distillation (under house vacuum, about 50° C.)
6. temperaturethe mixture was cooled to room temperature
7. additionMTBE (400 ml) was added
8. temperatureThe mixture was then cooled to 0-5° C
9. filtrationThe crystals were filtered
10. washwashed with MTBE (250 ml)
11. customdried under house vacuum

ORD-Eintrag

ord-1a22a9b284944989b8ea87f7105a94c8

Quelldatensatz

uspto-grants-2004_06

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06743794B2