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

Participants

Reaction Steps

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.

Provenance & Evidence