Propanal → (Z)-Methyl 3-methyl-4-oxobut-2-enoate

18 g (0.2 mol) of sarcosine were suspended by stirring in 500 ml of cyclohexane in a flask and, starting at 20° C., a mixture of 1809 g (20.6 mol) of methyl glyoxylate and 1194 g (20.6 mol) of propionaldehyde was added within 90 min. During the dropwise addition the temperature rose slowly to the boiling point (75° C.). After the addition was complete, initially a small amount of water was removed as azeotrope, and then the mixture was distilled until the bottom temperature was 100° C. to remove cyclohexane. Then 2220 g (21.8 mol) of acetic anhydride were added to the residue, and the reaction mixture was distilled to a bottom temperature of 150° C. to remove acetic acid. Fractional distillation of the bottom product yielded 1822 g (14.2 mol) of methyl 3-formylcrotonate, corresponding to a yield of 69% of theory, with a trans/cis isomer ratio of 93/7.

1. customstarting at 20° C.
2. additionwas added within 90 min
3. additionDuring the dropwise addition the temperature
4. customrose slowly to the boiling point (75° C.)
5. additionAfter the addition
6. custominitially a small amount of water was removed as azeotrope
7. distillationthe mixture was distilled until the bottom temperature
8. customwas 100° C.
9. customto remove cyclohexane
10. distillationthe reaction mixture was distilled to a bottom temperature of 150° C.
11. customto remove acetic acid
12. distillationFractional distillation of the bottom product

ORD record

ord-f9396432881741cdb0f2d624b5add410

Source dataset

uspto-grants-1993_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05202461