N,N-二甲基苯胺类化合物的合成

Synthesis of N,N-Dimethylaniline Derivatives

以卤代芳烃为底物、N,N-二甲基甲酰胺(DMF)为二甲胺源,在氢氧化钾碱性条件下,经芳香亲核取代反应得到一系列N,N-二甲基苯胺类化合物(Ⅰa~Ⅰh),通过~1HNMR、CNMR、ESI-MS对目标化合物结构进行了表征,并通过X-射线单晶衍射对目标化合物2-二甲氨基-5-硝基苯甲酸(Ⅰh)的结构进行进一步确证。以目标化合物N,N-二甲基-4-硝基苯胺(Ⅰa)的合成为模型反应,确定最佳合成条件如下:氢氧化钾用量n(KOH)∶n(4-氟硝基苯)为3∶1、DMF用量n(DMF)∶n(4-氟硝基苯)为15∶1、反应温度为100℃、反应时间为14 h,在此条件下,目标化合物Ⅰa收率达到88%。不同卤(氟、氯、溴、碘)取代的4-卤硝基苯与DMF反应均能得到目标化合物Ⅰa,其中,4-氟硝基苯的反应活性最高,而4-氯硝基苯的反应活性最低。

Taking halogenated aromatic compounds as substrates, and N,N-dimethylformamide(DMF) as an amine source, we synthesized a series of N,N-dimethylaniline derivatives(Ⅰa-Ⅰh) by aromatic nucleophilic substitution reaction under potassium hydroxide alkaline condition.Moreover, we characterized the structures of the target compounds by ~1HNMR,CNMR,and ESI-MS,and further confirmed the structure of 2-dimethylamino-5-nitrobenzoic acid(Ⅰh) by X-ray single crystal diffraction.The synthesis of the target compound N,N-dimethyl-4-nitroaniline(Ⅰa) is taken as the model reaction, therefore, the optimum synthesis conditions are determined as follows: the dosage of KOH is n(KOH)∶n(4-fluoronitrobenzene) of 3∶1,the dosage of DMF is n(DMF)∶n(4-fluoronitrobenzene) of 15∶1,the reaction temperature is 100 ℃,and the reaction time is 14 h.Under above conditions, the yield of the target compound Ⅰa can reach 88%.The target compound Ⅰa can be obtained by the reaction of 4-halogenated nitrobenzene with different halosubstituted group(fluorine, chlorine, bromine, and iodine) and DMF.Among them, 4-fluoronitrobenzene has the highest reactivity, while 4-chloronitrobenzene has the lowest reactivity.