Synthesis
General procedure for the synthesis of 4-chloroquinoline-7-carboxylic acid from 4-chloro-7-trifluoromethylquinoline: 10.0 g (43.2 mmol) of 4-chloro-7-trifluoromethylquinoline was dissolved in 200 mL of concentrated hydrochloric acid. The reaction was heated in a microwave reactor with radiation at 550 W power for 2 hours. Upon completion of the reaction, the reaction mixture was slowly poured into ice water and the pH was adjusted to 3-4 with sodium hydroxide solution.The precipitated product was collected by diafiltration, washed several times with deionized water and subsequently dried. Finally 8.9 g of 4-chloroquinoline-7-carboxylic acid was obtained in 99% yield of the theoretical value. Thin layer chromatography (TLC) analysis showed an Rf value of 0.45 (silica gel plate, unfolding agent was toluene/ethanol = 4:1). The molecular formula of the product was C10H6ClNO2 (molecular weight 207.62), and the mass spectrometry analysis showed that the molecular ion peak (M+H)+ was 208/210 (chlorine isotope peak).
References
[1] Patent: WO2004/58743, 2004, A1. Location in patent: Page/Page column 116-117
[2] Patent: WO2004/80970, 2004, A1. Location in patent: Page 34; 35
[3] Patent: WO2016/118565, 2016, A1. Location in patent: Paragraph 00320
[4] Patent: US2004/102450, 2004, A1. Location in patent: Page/Page column 72
[5] Patent: US5773449, 1998, A
