反应详情

A solution of 88.5 g methylhydrazine (1.92 moles) in 340 ml THF is added at +25° C. to a solution of 250 g maleic acid monomethyl ester (1.92 moles) and 194.5 g triethylamine (1.92 moles) in 1850 ml THF. During the addition a precipitation of the triethylamine salt of the intermediate methyl 3-carboxy-3-(1-methyl-hydrazino)-propionate is formed. After stirring for 2 hours at +25° C., a solution of 101.6 g acetaldehyde (2.3 moles) in 370 ml THF is added at +25° C. The precipitation dissolves during the addition. After stirring for 1 hour at +25° C. the solution is evaporated completely. To remove traces of water or methanol, the residue is mixed with 750 ml toluene and evaporated again completely (10 mbar, 60° C.). Yield: 429.6 g of methyl 3-carboxy-3-(2-ethylidene-1-methylhydrazine)-propionate triethylamine salt as viscous yellow oil (83%).

1. additionDuring the addition
2. customa precipitation of the triethylamine salt of the intermediate methyl 3-carboxy-3-(1-methyl-hydrazino)-propionate
3. customis formed
4. customThe precipitation
5. dissolutiondissolves during the addition
6. stirringAfter stirring for 1 hour at +25° C. the solution
7. customis evaporated completely
8. customTo remove traces of water or methanol
9. additionthe residue is mixed with 750 ml toluene
10. customevaporated again completely (10 mbar, 60° C.)