Hydrochloric Acid → 2-Isocyanatoethyl methacrylate

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Reaction Steps

In a round bottom flask 35.7 g (156 mmole, 97.8%) 2-Methyl-acrylic acid 2-[(imidazole-1-carbonyl)-amino]-ethyl ester (Example 1) were dissolved in about 100 ml chloroform at room temperature (30 min). The clear yellow solution was diluted with about 100 ml toluene. To the resulting turbid dispersion 11.5 g (313 mmole=200% of theory) dry hydrogen chloride were added at about 23° C. within about 30 min, while cooling. A second liquid phase was formed. The reaction mixture was stirred for another hour. At ambient pressure 123 g of chloroform were distilled from the reaction mixture at about 69-74° C. Thereafter, the vessel was kept at about 91-92° C. for about 1 h. Meanwhile imidazolium hydrochloride began to crystallize giving a greenish suspension. After about 1 hour of stirring at room temperature the toluene phase was decanted, precipitated washed with more toluene. The clear yellow phase was evaporated at about 40° C. and about 25 mbar under exclusion of light. This raw product (according to NMR) consisted of MOI with about 18% residual toluene. It was distilled at about 48° C. and about 1.4 mbar. The clear product was stabilized with 200 ppm phenothiazine. A yield of 52% was obtained with the distilled product. Analytics showed 96.8% purity (GC) and 400 ppm residual chlorine.

Provenance & Evidence