2,6-二氯吡啶-4-甲醛的合成及副产物研究

Study on the Synthesis of 2,6-Dichloropyridine-4-carboxaldehyde and Its By-product

摘要:

以2,6-二羟基异烟酸为原料，经过氯代、胺解、脱水和还原反应制得2,6-二氯吡啶-4-甲醛(1)，及另一个应用较广的化工中间体2,6-二氯吡啶-4-甲胺，结构经ESI-MS、1H-NMR确证，目标产物总收率达到26.2 %。结果表明：当n(2,6-二氯-4-氰基吡啶): n(二异丁基氢化铝)=1:1.6，温度为-15 ℃，反应时间12 h，还原反应目标产物收率达到最佳为45 %，副产物2,6-二氯吡啶-4-甲胺收率12 %。

Abstract:

2,6-Dichloropyridine-4-carboxaldehyde was prepared from 2,6-dihydroxy isonicotinic acid with overall yield of 26.2 % via chlorination, amidation, dehydration and reduction. Its structure was confirmed by 1H-NMR and ESI-MS. Meanwhile, another useful intermediate 2,6-dichloro-pyridine-4-methylamine was obtained. The procedure of reduction reaction was optimized and when the molar ratio of 2,6-dichloro-4-cyanopyridine/Diisobutyl aluminum hydride was 1:1.6, the reaction temperature was -15℃ and the reaction time was 12h, the yields of 2,6-dichloropyridine-4-carboxaldehyde and (2,6-dichloropyridin-4-yl)methanamine were 45.4 % and 12.0 % respectively.