Synthesis
3,4,6-Trichloropyridazine (12 g, 65.4 mmol) was used as a raw material, which was dissolved in acetic acid (45 mL) and the reaction was heated at 130 °C for 2 hours. Upon completion of the reaction, the mixture was cooled to room temperature and subsequently slowly poured into ice water (200 mL). The precipitated solid was collected by filtration to finally obtain 5,6-dichloropyridazin-3(2H)-one (3.7 g).
References
[1] Monatshefte fuer Chemie, 1968, vol. 99, p. 15 - 81
[2] Pharmaceutical Bulletin, 1957, vol. 5, p. 376,377
[3] Pharmaceutical Bulletin, 1958, vol. 6, p. 641
[4] Patent: WO2013/185284, 2013, A1. Location in patent: Page/Page column 70
[5] Patent: US2013/331382, 2013, A1. Location in patent: Paragraph 0749
