Hydrochloric Acid → Furaneol

To a suspension of 113.4 g of sodium methylate in 750 g of methyl t-butyl ether was added at 5° C. in one hour 146 g of diethyl oxalate followed by a stirring period of one hour at 5° C. Then 204 g of diethyl 2-methyldiglycolate in two hours was added at 5° C. and the mixture was stirred for four hours at that temperature followed by a reflux period of three hours. The reaction mixture was added to 797 g of 8.9% hydrochloric acid solution at 20° C. and the pH of the resulting mixture was adjusted to 5 with 33% sodium hydroxide solution. To the separated upper layer was added with stirring 903 g of 17.8% sodium hydroxide solution at 20° C. The layers were allowed to settle and the separated lower layer was kept at 20° C. for 20 hours. Then, 200 g of water was added, 104 g of methyl bromide was introduced at 20° C. in one hour, and the mixture was stirred for another hour; and the pH of the solution was adjusted to 6.5 by the addition of concentrated hydrochloric acid solution. Extraction with methyl t-butyl ether yielded 95 g of 2,5-dimethyl-4-hydroxy-3[2H] furanone of 97.3% purity (molar overall yield 72.2%).

1. waitfollowed by a reflux period of three hours
2. additionTo the separated upper layer was added
3. customthe separated lower layer
4. waitwas kept at 20° C. for 20 hours
5. additionThen, 200 g of water was added
6. addition104 g of methyl bromide was introduced at 20° C. in one hour
7. stirringthe mixture was stirred for another hour
8. additionand the pH of the solution was adjusted to 6.5 by the addition of concentrated hydrochloric acid solution
9. extractionExtraction with methyl t-butyl ether

ORD record

ord-58efa3bdb6a3488f8c51b19354e7aa37

Source dataset

uspto-grants-1995_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05412121