反应详情

温度

-2 °C

Methyl hydrogen (2Z)-2-butendioate (also known as the monomethyl ester of maleic acid) (50 g, 0.385 mol) was added dropwise to a solution of hydrogen bromide in acetic acid (141.43 g, 33%, 0.577 mol) at 0° C. over 1 h. The reaction mixture was stored at about 5° C. overnight. The solvent was then removed under reduced pressure. Toluene (100 mL) was added, and the mixture was evaporated under reduced pressure. The process was repeated three times using more toluene (3×100 mL). Then toluene (50 mL) was added, and the mixture was cooled to −2° C. Hexanes (50 mL) was added dropwise to the mixture. When the addition was complete the mixture was stirred about 30 minutes while the product crystallized. The product was then isolated by filtration and dried in vacuo to provide the title compound as a white solid (63.37 g, 81.8% yield). A sample recrystallized from toluene/hexanes melted at 38-40° C.

1. customThe solvent was then removed under reduced pressure
2. additionToluene (100 mL) was added
3. customthe mixture was evaporated under reduced pressure
4. additionThen toluene (50 mL) was added
5. additionHexanes (50 mL) was added dropwise to the mixture
6. additionWhen the addition
7. customcrystallized
8. customThe product was then isolated by filtration
9. customdried in vacuo