2,2,5-Trimethyl-1,3-dioxane-4,6-dione → 5-(2-Bromo-4-fluoro-phenylazo)-2,2,5-trimethyl-[1,3]dioxane-4,6-dione

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Reaction Steps

130 g 2-Bromo-4-fluoro-aniline was dissolved in 700 ml ice and 600 ml 3M hydrochloric acid. The resulting suspension was maintained at ca. 5° C. during the addition of a solution of 47.3 g sodium nitrite in 45 ml water. When the addition was complete, the mixture was stirred 45 min at ca 5° C. The resulting brown suspension was added slowly to a cooled mixture of 108.3 g 2,2,5-trimethyl-1,3-dioxan-4,6-dione and 932 g sodium acetate in 400 ml water and 700 ml ethanol, maintaining the temperature between 3 and 8° C. A yellow precipitate formed. The mixture was stirred a further 2 h at 3-8° C., filtered and the precipitate washed with water and dried under vacuum to afford the title compound as a yellow solid. ISP-MS: m/e 359 ([M+H]+). Yield 231 g, mp 92-93° C.

Provenance & Evidence