反应详情

温度

60 °C

This method describes an improved method for the synthesis of D,L-2-isobutyl-3-(methoxycarbonyl)-propionic acid (3). Maleic anhydride (750 g, 7.65 moles) was dissolved in hot toluene (500 mL), filtered, and allowed to cool thus producing a finely divided crystalline precipitate. The resulting mixture was further cooled in a refrigerator. 2-Methylpropene was condensed into cold toluene (1 L). The cold maleic anhydride suspension was transferred, with the aid of additional toluene (300 mL), to the glass liner of a Parr 2 gallon stirred autoclave. The 2-methylpropene solution was then added followed by 4-tert-butyl catechol (2 g). The autoclave was sealed and heated, with stirring, to 170° C. over 45 minutes and maintained at that temperature for an additional 9.5 hours. The reaction was then allowed to cool to 60° C. over 7 hours after which, the autoclave was vented. After an additional 1.5 hours, the internal temperature had reached 45° C. and the autoclave was opened. The solvent was removed and the residue was distilled under aspirator pressure through a 10 inch vacuum jacketed Vigreux column fitted with a partial take off head to give unreacted maleic anhydride (139.4 g, 18.6% yield) and β-methallylsuccinic anhydride (765.3 g, 79.8% yield).

1. filtrationfiltered
2. temperatureto cool thus
3. customproducing a finely divided crystalline precipitate
4. temperatureThe resulting mixture was further cooled in a refrigerator
5. customThe autoclave was sealed
6. temperatureheated
7. stirringwith stirring, to 170° C. over 45 minutes
8. temperaturemaintained at that temperature for an additional 9.5 hours
9. customhad reached 45° C.
10. customThe solvent was removed
11. distillationthe residue was distilled under aspirator pressure through a 10 inch vacuum
12. customfitted with a partial take off head