含吸电子基团的芳香醛的合成

Synthesis of Aromatic Aldehyde Containing Electronwithdrawing Groups

芳香醛化合物是重要的有机中间体,广泛应用于医药、农药等领域。研究介绍了一种合成苯环的邻、对位含有吸电子基团的芳香醛的改进工艺。分别以4-氯-2-硝基甲苯,4-硝基甲苯,4-氰基甲苯为原料,以N,N-二甲基甲酰胺(DMF)为溶剂,在140℃回流条件下与N,N-二甲基甲酰胺二甲缩醛(DMFDMA)合成相应的苯乙烯胺化合物,苯乙烯胺化合物再在过氧化氢的作用下氧化得到相应的芳香醛。论文主要是从溶剂、反应温度、H2O2的用量对产品收率的影响进行了研究,并确定了适宜的反应条件,在该反应条件下,不同醛的收率(4-氯-2-硝基苯甲醛,4-硝基苯甲醛,4-氰基苯甲醛)分别是:75.6%;58.3%;68.2%。该路线具有工艺简单,原料价廉且环境友好等优点。主要中间体和目标产物经高效液相色谱和1H-NMR核磁鉴定。

Aromatic aldehydes are very important organic intermediates, which are widely used in pharmaceuticals, pesticides and other areas. In this paper, an improved synthetic method of aromatic aldehydes containing electrowithdrawing groups in ortho or para （or both） position of the aromatic ring was introduced. 4-choloro-2-nitrotoluene, 4-nitrotoluene and 4-cyanotoluene were used as raw materials, respectively, via enamination with N,N-dimethylformamide dimethyl acetal （DMFDMA） in the present of N,N-dimethylformamide （DMF） as solvent and under reflux, the corresponding styrylarnine compounds were produced; then the intermediates were further oxidized by H2O2 under different reaction conditions. The effects of solvent species, reaction temperature and the used amount of H2O2 on the product yield were studied, and the optimal reaction conditions were determined. Under those optimal conditions, the best yields of different aldehydes are 75.6% （4-chloro-2-nitrobenzaldehyde）, 58.3% （4-nitrobenzaldehyde） and 68.2% （4-cyanobenzaldehyde）, respectively with the advantages of simple process, low cost and being environment-friendly.. The main intermediates and objective products were confirmed by HPLC and 1H-NMR.