Ethyl 2-chloroacetoacetate → HCID 14500718, compound

Participants

Reaction Steps

A stirred solution of 25.8 g (0.16 mole) of 4-pentyl-3-thiosemicarbazide in 150 mL of tetrahydrofuran was treated with 26.4 g (0.16 mole) of ethyl 2-chloroacetoacetate, stirred at ambient temperature for 2 hr, heated at reflux for 4 hr, and stirred for ~16 hr at ambient temperature. The reaction mixture contained amorphous material and large yellow crystals, which dissolved on heating at reflux for 1 hr. Upon cooling, large yellow crystals separated and were removed by filtration (sulfur). The filtrate was diluted with ice water, made acidic with 6N sulfuric acid and filtered to remove additional sulfur. The filtrate was adjusted to pH 6 with sodium carbonate and a total of 32.2 g of precipitated product was collected in 3 fractions. All the material was chromatographed twice on silica gel without purification, first by eluting with methylene chloride and the second time by eluting with benzene. A third column of 800 g of silica gel was eluted with isopropyl ether to give an orange oil which was not the product, then eluted with 50/50 isopropyl ether/methylene chloride. The product crystallized from the second eluent to give 7.8 g of white crystalline product after washing with isopropyl ether to remove a yellow color, mp 117°-119° C.

Provenance & Evidence