孔 成,蔡志彬,金 梵
(浙江工業(yè)大學(xué)化學(xué)工程與材料學(xué)院,浙江杭州 310014)
三苯胺衍生物具有給電子性強(qiáng)、氧化電位低、玻璃化溫度和空穴遷移率高、溶解性、成膜性好的特點(diǎn)[1-3],可以作為有機(jī)發(fā)光二極管中的空穴傳輸材料和發(fā)光材料,用于制備有機(jī)電致發(fā)光器件[4-5]、有機(jī)太陽能電池[6-7]和有機(jī)效應(yīng)管[8-9]等有機(jī)光電器件。
4-(二苯氨基)苯甲醛(3)是重要的有機(jī)合成中間體,其合成方法通常是以DMF為溶劑,POCl3為催化劑,通過 Vilsmeier 反應(yīng)合成[10-14]。但Vilsmeier試劑中的重要原料POCl3具有高度腐蝕性,使用不慎,會(huì)引發(fā)爆炸等安全問題。
為此,本文對(duì)合成3的工藝進(jìn)行研究,以尋找一種簡(jiǎn)便的合成方法。以AlCl3為催化劑,苯為溶劑,三苯氨(1)和原甲酸三乙酯(2)為原料,合成了3(Scheme 1),其結(jié)構(gòu)經(jīng)1H NMR和FT-IR表征。合成3的較佳工藝條件為:1 40 mmol,n(1)∶n(2)∶n(AlCl3)=1 ∶5 ∶8,苯為溶劑,于30 ℃反應(yīng) 4 h,收率91%。
2作為一種便宜和高效的甲酰化試劑,已被用于溫和條件下芳香化合物的甲?;饕性诜宇惢衔铮?5-18],對(duì)其它芳環(huán)的甲酰法,文獻(xiàn)報(bào)道還非常少。
Scheme 1
該方法具有原料易得、反應(yīng)條件溫和,操作簡(jiǎn)單,收率較高等優(yōu)點(diǎn)。
X-4型數(shù)字顯示顯微熔點(diǎn)儀(溫度未校正);Bruker AVANCEⅢ500 MHz型核磁共振儀(DMSO-d6為溶劑,TMS為內(nèi)標(biāo));Thermo Nicolet 6700型傅立葉變換紅外光譜儀(KBr壓片)。
1,工業(yè)品;其余所用試劑均為分析純。
在配帶干燥管的反應(yīng)瓶中加入1 9.80 g(40 mmol),2 29.64 g(200 mmol)和苯70 mL,冰水浴冷卻,攪拌反應(yīng)30 min。邊快速攪拌邊緩慢加入無水AlCl348 g(320 mmol),加畢,撤去冰浴,于30℃反應(yīng)4 h。緩慢傾入Na2S2O4冰水溶液中,用CH2Cl2(3×100 mL)萃取,合并有機(jī)層,用水(2×100 mL)洗滌,無水MgSO4干燥,旋蒸脫溶后經(jīng)硅膠柱層析[洗脫劑:V(石油醚)∶V(乙酸乙酯)=10 ∶1]純化得淡黃色晶體 3 9.95 g,收率91%,m.p.127 ℃ ~128 ℃(126 ℃ ~126.5 ℃[19]);1H NMR δ:9.77(s,1H,CHO),7.73(d,J=8.85 Hz,2H),7.41 ~ 7.45(m,4H),7.20 ~7.26(m,6H),6.89(d,J=8.75 Hz,2H);FT-IR ν:3 100,1 690,1 600,1 490,1 320,1 300,1 210,1 150,800,750,700 cm-1。
(1)溶劑
1 40 mmol,r=n(1):n(2)∶n(AlCl3)=1 ∶5∶8,于30 ℃反應(yīng)4 h,其余反應(yīng)條件同 1.2,考察溶劑對(duì)3收率的影響,結(jié)果見表1。由表1可見,收率隨溶劑極性減小而增大;苯類溶劑使收率明顯提高,不同取代基的苯類溶劑的收率差別不大。最佳溶劑為苯。
表1 溶劑對(duì)3收率的影響*Table 1 Effect of solvent on yield of 3
表2 反應(yīng)溫度對(duì)3收率的影響*Table 2 Effect of reaction temperature on yield of 3
表3 反應(yīng)時(shí)間對(duì)3收率的影響*Table 3 Effect of reaction time on yield of 3
(2)反應(yīng)溫度
以苯為溶劑,其余反應(yīng)條件同2.1(1),考察反應(yīng)溫度對(duì)3收率的影響,結(jié)果見表2。由表2可見,反應(yīng)溫度為10℃時(shí),收率較低;隨著溫度的升高,收率不斷提高;在30℃左右時(shí),收率最高(91%);超過50℃致部分二取代副產(chǎn)物生成,致使收率降低。較佳的反應(yīng)溫度為30℃。
(3)反應(yīng)時(shí)間
以苯為溶劑,于30℃反應(yīng),其余反應(yīng)條件同2.1(1),考察反應(yīng)時(shí)間對(duì)3收率的影響,結(jié)果見表3。由表3可見,隨著反應(yīng)時(shí)間的增加,收率逐漸上升;4 h后收率幾乎不再變化。較佳的反應(yīng)時(shí)間為4 h。
(4)r
以苯為溶劑,于30℃反應(yīng)4 h,其余反應(yīng)條件同2.1(1),考察r對(duì)3收率的影響,結(jié)果見表4。由表4可見,r=1∶2∶4時(shí),收率較低;r=1 ∶5∶8時(shí),收率達(dá)91%;超過此比例后收率增加不明顯。較佳的r=1∶5∶8。由于AlCl3在反應(yīng)過程中會(huì)與羰基和乙氧基絡(luò)合,2則容易被AlCl3分解。故該反應(yīng)中2和AlCl3必須大量過量。
綜上所述,合成3的較佳工藝條件為:1 40 mmol,n(1)∶n(2)∶n(AlCl3)=1 ∶5 ∶8,苯為溶劑,于30℃反應(yīng)4 h,收率91%。
表4 r對(duì)3收率的影響*Table 4 Effect of r on yield of 3
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