反应详情

A round-bottom flask equipped with a PTFE-coated magnetic stir bar was charged with N-methyliminodiacetic acid (25.0 g, 170 mmol, 1.0 equiv), acetic anhydride (85 mL, ˜850 mmol, ˜5 equiv.), and pyridine (274.9 μL, 3.4 mmol, 0.02 equiv). The flask was capped with a rubber septum which was pierced with an 18 gauge needle (alternatively a reflux condensor could be used). The reaction was lowered into a preheated 70° C. oil bath and stirred until the mixture became clear and dark orange (about 1.5 h). The acetic acid, pyridine, and remaining acetic anhydride were then removed by vacuum distillation (37° C. to 42° C. at 30 Torr). The resulting brown-black liquid was azeotroped three times with toluene (50 mL) to remove residual acetic acid and then transferred to an Erlenmeyer flask. To this flask was added enough diethyl ether to dissolve the crude N-methyl morpholine dione product (˜400 mL). The resulting mixture was filtered to remove a black-brown precipitate, and the filtrate was concentrated in vacuo. The resulting pale yellow solid was then recrystallized from a minimum amount of hot diethyl ether to yield N-methyl morpholine dione (MIDA anhydride; 16.9 g, 131 mmol, 77%) as an off-white crystalline solid.

1. customA round-bottom flask equipped with a PTFE-coated magnetic stir bar
2. customThe flask was capped with a rubber septum which
3. customwas lowered into a preheated 70° C.
4. customdark orange (about 1.5 h)
5. customwere then removed by vacuum distillation (37° C. to 42° C. at 30 Torr)
6. customThe resulting brown-black liquid was azeotroped three times with toluene (50 mL)
7. customto remove residual acetic acid
8. additionTo this flask was added enough diethyl ether
9. dissolutionto dissolve the crude N-methyl morpholine dione product (˜400 mL)
10. filtrationThe resulting mixture was filtered
11. customto remove a black-brown precipitate
12. concentrationthe filtrate was concentrated in vacuo
13. customThe resulting pale yellow solid was then recrystallized from a minimum amount of hot diethyl ether