颜料N-(2-甲氧苯基)-3-氧代-2-[4-(2,4,6-三氧代四氢嘧啶-5-亚乙基)-苯偶氮]丁酰胺的合成

Synthesis and properties of pigment N-(2-methoxy-phenyl)-3-oxo-2-[4-(2,4,6-trioxo-tetrahydro-pyrimidin-5-ylidenemethyl)-phenylazo]-butyramide

以4-氨基苯甲醛和巴比妥酸为原料、无水乙醇为溶剂,通过Knoevenagel缩合反应合成5-[(4-氨基苯基)亚甲基]-2,4,6(1H,3H,5H)-嘧啶三酮(1),其经过重氮化后,偶合邻甲氧基乙酰乙酰苯胺,制得颜料N-(2-甲氧苯基)-3-氧代-2-[4-(2,4,6-三氧代四氢嘧啶-5-亚乙基)-苯偶氮]丁酰胺(P.Y.X).利用1H NMR、FT-IR和元素分析对其结构进行了表征.考察了重氮化反应无机酸及用量、偶合反应时间、反应温度及pH对反应效率的影响,研究发现当重氮化反应选用硫酸且n(硫酸)∶n(1)=30∶1,在偶合反应时间为1.5 h、反应温度为20℃、pH为5.5时,效果最佳,产物收率为84.3%.通过UV-Vis、热重分析(TGA)及SEM测定了颜料的光吸收性能、热稳定性及固体粉末颗粒形貌特征.结果表明:紫外光谱的λmax为392 nm(1.5×10^(-5) mol/L氯仿溶液),εmax为3.0×10^(4) L·mol^(-1)·cm^(-1);其热分解温度高于210℃,在254℃时失重速率达到最大;通过溶剂DMF改性处理6 h后,所得颜料颗粒形貌规整,颜色鲜亮,可作为一类重要的着色剂,应用于油墨、涂料、橡胶及塑料着色方面.

Using 4-aminobenzaldehyde and barbituric acid as raw materials,anhydrous ethanol as solvent through knoevenagel condensation reaction to synthesize 5-[(4-aminophenyl)methylene]-2,4,6(1H,3H,5H)-pyrimidinetrione(1).After diazotization,coupling with 2-methoxy-N-acetoacetanilide to produce pigment N-(2-methoxy-phenyl)-3-oxo-2-[4-(2,4,6-trioxo-tetrahydro-pyrimidin-5-ylidene-methyl)-phenylazo]-butyramide(P.Y.X).It was confirmed by 1H NMR,FT-IR and elemental analysis.The effects of the mineral acid type and dosage for diazo reaction,the coupling reaction time,temperature and pH value on the reaction efficiency were investigated.And it was found that when sulfuric acid was selected for the diazo reaction,and the molar ratio n(sulfuric acid)∶n(1)was 30∶1,the coupling reaction time was 1.5 h,the temperature was 20℃and the pH was 5.5,the yield was 84.3%.Light absorption,thermal stability and solid powder morphology of the pigment were determined.The results showed that theλmax of UV spectra was 392 nm(1.5×10^(-5 )mol/L chloroform solution),εmax was 3.0×10^(4) L·mol^(-1)·cm^(-1),and the thermal decomposition temperature was higher than 210℃,the weightlessness rate reached the maximum at 254℃.The pigment modificationed in DMF has the advantages of regular morphology and bright color after 6 h.It can be used as an important colorant in ink,paint,rubber and plastic coloring.