2-甲基-8-羟基喹啉-5-甲醛的制备工艺

STUDY ON PREPARATION OF 2-METHYL-8-HYDROXYLQUINOLINE-5-CARBALDEHYDE

以2-甲基-8-羟基喹啉为原料,在酸性条件下与水合氯醛发生缩合反应生成2-甲基-5-(α-羟基-β-三氯)-8-羟基喹啉(Ⅰ)和2-甲基-8-羟基喹啉-5-磺酸(Ⅱ),Ⅰ在碱性条件下水解生成2-甲基-8-羟基喹啉-5-甲醛(Ⅲ)。合成Ⅰ的最佳反应条件为:n(2-甲基-8-羟基喹啉)∶n(水合氯醛)∶n(硫酸)=1∶1.2∶4.6,反应温度为80℃,反应时间为10h,产物收率为54.8%;合成Ⅲ的最佳反应条件为:n(Ⅰ)∶n(KOH)=1∶5.1,回流反应7h,收率为26.9%。产物经熔点仪、元素分析仪、液-质联用仪、红外光谱仪及核磁共振氢谱等进行表征。

2-Methyl-5-（a-hydroxy-β-trichloroethyl）-8-hydroxyquinoline （Ⅰ） and 2-methyl-8-hydroxy-lquinoline-5-sulfonic acid （Ⅱ） was synthesized by reaction of 2-methyl-8-hydroxyl quinoline and chloral hydrate with sulfuric acid as solvent.2-Methyl-8-hydroxyl quinoline-5-carbaldehyde was synthesized by reaction of （Ⅰ） with KOH in methanol.The optimum conditions of （Ⅰ） were found as follows：n（2-methyl-8-hydroxyquinoline） ∶ n（chloral hydrate） ∶ n （H2SO4） =1 ∶ 1.2 ∶ 4.6,reaction temperature was 80 ℃,reaction time was 10 h and the yield of （Ⅰ） was 54.8％.The optimum conditions of（Ⅲ）were found as follows：n（Ⅰ） ∶ n（KOH）=1 ∶ 5.1,reaction time was 7 h under reflow and the yield of （m） was 26.9％.The structure of resultant was characterized with melting point detector,elemental analyzer,LC-MS,IR and 1H NMR.