Acetic Acid → 2,2-Dimethyl-5-(1-methylethylidene)-1,3-dioxane-4,6-dione

Meldrum's acid (100.0 g) was charged to a dry, nitrogen flushed reactor. Acetone (632.1 mL) was then charged to the reactor and the mixture was agitated for about 5 minutes at 20° C.-25° C. until a solution was obtained. Acetic acid (0.791 mL) was then charged to the reactor, followed by 1.215 mL of morpholine, and the solution was agitated at 20° C.-25° C. for about 48 hours. An aliquot (˜0.2 mL) was withdrawn for analysis of the conversion, which may be monitored by either GC or 1H-NMR. If the ratio of the area % of 2,2-dimethyl-5-(propan-2-ylidene)-1,3-dioxane-4,6-dione to Meldrum's acid is ≧80:20, proceed to the next step; if it is not, the batch should be aged for an additional 3 hours before repeating the check. The acetone was distilled at about 40° C. and 150-200 mmHg. After approximately two-thirds of the reaction volume was distilled out, 563 mL of methylcyclohexane was charged and the distillation continued until the acetone stopped distilling over. A total of 645 mL (508 g) of distillate was collected for this run. MTBE (500 mL) was charged to the batch at 40° C. and the batch was cooled to 20° C.-25° C. The solution was observed to make sure a cloudy solution was obtained (no solids). If there is solid present, additional MTBE may be charged to effect dissolution. The batch was quickly washed with two 50 g portions of 5 wt. % NaOH solution (prepared from 5 g of NaOH and 95 mL of water). The MTBE was distilled out at 40° C.-45° C. and 150-200 mmHg. A total of 400 mL (300 g) distillate was collected for this run. As distillation proceeds, a white slurry formed. The internal temperature was ramped to 0° C.-5° C. over 1 hour and then held at this temperature for at least 1 hour. The slurry was filtered, the cake was washed with two 100 mL portions of cold (˜0° C.-5° C.) methylcyclohexane, and the solid was dried at 20° C.-35° C. and 25-50 mmHg for no less than 4 hours. 2,2-Dimethyl-5-(propan-2-ylidene)-1,3-dioxane-4,6-dione was obtained as a white solid (93.7 g, 70.4% yield, 96.0 wt. % purity by assay).

1. customwas obtained
2. stirringthe solution was agitated at 20° C.-25° C. for about 48 hours
3. customAn aliquot (˜0.2 mL) was withdrawn for analysis of the conversion, which
4. waitthe batch should be aged for an additional 3 hours
5. distillationThe acetone was distilled at about 40° C.
6. distillationAfter approximately two-thirds of the reaction volume was distilled out
7. addition563 mL of methylcyclohexane was charged
8. distillationthe distillation
9. distillationstopped distilling over
10. distillationA total of 645 mL (508 g) of distillate was collected for this run
11. additionMTBE (500 mL) was charged to the batch at 40° C.
12. temperaturethe batch was cooled to 20° C.-25° C
13. customwas obtained (no solids)
14. additionmay be charged
15. dissolutiondissolution
16. washThe batch was quickly washed with two 50 g portions of 5 wt. % NaOH solution (prepared from 5 g of NaOH and 95 mL of water)
17. distillationThe MTBE was distilled out at 40° C.-45° C.
18. distillationA total of 400 mL (300 g) distillate was collected for this run
19. distillationAs distillation proceeds
20. customa white slurry formed
21. waitThe internal temperature was ramped to 0° C.-5° C. over 1 hour
22. waitheld at this temperature for at least 1 hour
23. filtrationThe slurry was filtered
24. washthe cake was washed with two 100 mL portions of cold (˜0° C.-5° C.) methylcyclohexane
25. customthe solid was dried at 20° C.-35° C.
26. wait25-50 mmHg for no less than 4 hours

ORD record

ord-9742a83afd594ccbb1f269d2be7a8f7e

Source dataset

uspto-grants-2012_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08268859B2