Methanol → Methyl (E)-4-Chloro-3-methoxy-2-butenoate

206.6 g (0.47 mol) of a 35 percent mixture of 4-chloroacetoacetyl chloride in methylene chloride was cooled to -10° C. Under nitrogen, 102.4 g (3.2 mol) of methanol was added in 30 minutes and then 83.3 g (0.7 mol) of thionyl chloride was added in 30 minutes (formation of dimethyl sulfite). The temperature was raised to room temperature and the solution was stirred for 3 hours at 20° to 25° C. The excess methanol and methylene chloride were then distilled off at reduced pressure. The residue (raw 4-chloro-3,3-dimethoxybutanoic acid methyl ester) was mixed with 0.21 g of methanesulfonic acid and warmed to 125° to 130° C. at a pressure of 100 mbars. Thus, the formed methanol and the excess dimethyl sulfite was distilled off. The residue (raw 4-chloro-3-methoxy-but-2E-enoic acid methyl ester) was taken up in 110.2 g (120 ml) of toluene and the organic phase was washed with 69.8 g of aqueous 16 percent HCl for 30 minutes, with 32.1 g of an aqueous 10 percent sodium chloride solution for 10 minutes, with 134 g of aqueous 10 percent NaOH for 75 minutes and finally with 32.1 g of an aqueous 10 percent sodium chloride solution for 10 minutes. The toluene was then evaporated off and the residue was distilled at a pressure of 20 mbars and a temperature of 95° to 97° C. 4-chloro-3-methoxybut-2E-enoic acid methyl ester was obtained in a yield of 61.7 g (80 percent) in a purity of 99.5 percent (GC).

1. distillationThe excess methanol and methylene chloride were then distilled off at reduced pressure
2. additionThe residue (raw 4-chloro-3,3-dimethoxybutanoic acid methyl ester) was mixed with 0.21 g of methanesulfonic acid
3. temperaturewarmed to 125° to 130° C. at a pressure of 100 mbars
4. distillationThus, the formed methanol and the excess dimethyl sulfite was distilled off
5. washthe organic phase was washed with 69.8 g of aqueous 16 percent HCl for 30 minutes, with 32.1 g of an aqueous 10 percent sodium chloride solution for 10 minutes, with 134 g of aqueous 10 percent NaOH for 75 minutes and finally with 32.1 g of an aqueous 10 percent sodium chloride solution for 10 minutes
6. customThe toluene was then evaporated off
7. distillationthe residue was distilled at a pressure of 20 mbars
8. customa temperature of 95° to 97° C

ORD-Eintrag

ord-6e000af733c14051a930cff8a460def2

Quelldatensatz

uspto-grants-1990_10

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US04966989