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Results and discussion Polymer synthesis Optically active aromatic PA5a–PA5h containing bulky pendent group were synthesized from the reaction of optically active dicarboxylic diacid 1 with aromatic diamines 2a–2h by the direct polycondensation procedure using two different methods (Scheme 1). From a technological viewpoint, the use of an organic solvent in large-scale production is not very affable. So we carried out the polymerization reaction in imidazolium types ILs in order to description a safe, straightforward and efficient method for polymerization reaction. At first, in order to choose the best IL for the preparation of PAs, the reaction of monomer 1 with 2h was carried out in different synthetic ILs such as: 1,3-dipropylimidazolium bromide, 1,3-diisopropylimidazolium bromide, 1,3dibenzylimidazolium chloride, 1,3-dibenzylimidazolium bromide, 1,3-dibutylimidazolium bromide, 1,3-dipentylimidazolium bromide, 1,3- diheptylimidazolium bromide, 1,3-dialylimidazolium chloride and 1,3-dialylimidazolium bromide and in the absence of any IL under oil bath (Scheme 2) and the results are shown in Table 1. According to Table 1 the best inherent viscosity and yield was obtained when [1,3-(isopr)2im]Br was used as IL for direct polycondensation. So [1,3-(isopr)2im]Br was selected for other polymerization. It is interesting to mention that, the polymers were not obtained in the absence of either of ILs or TPP, so the presence of both components are necessary for polyamidation reactions, and consequently ILs play as a catalyst as well as solvent for these reactions. Since the amounts of ILs were used for each reaction is very low, we did not recycle them. Otherwise, these ILs could be easily separate from resulting polymers and reused Thus, an efficient, simplified and benign procedure for the preparation of PAs was carried out via direct polyamidation reaction of chiral diacid 1 with different aromatic diamines 2a–2h. The polymerization reaction was performed using oil bath heating by TPP and 1,3-(isopr)2im]Br as a condensing agent (Method I) and also was carried out under same conditions via Yamazaki phosphorylation reaction, using TPP/Py/NMP/CaCl2 as a condensing agent (Method II) and the results are shown in Tables 2 and 3. |
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jiangguofeng
金虫 (著名写手)
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- 专业: 合成药物化学
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大四写论文: 金币+50, 翻译EPI+1, ★★★很有帮助 2015-04-09 00:03:33
大四写论文: 金币+50, 翻译EPI+1, ★★★很有帮助 2015-04-09 00:03:33
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结果与讨论 聚合物的合成 用两种不同的方法（图1）经过直接的过程由光学活性的二羧基的二酸1与芳族二胺2a-2h的反应合成了带有大侧基的光学活性的芳族PA5a-PA5h。 从技术观点来看在大规模生产中使用有机溶剂不是很友善的。所以我们在咪唑盐型IL中进行的这种聚合反应以说明一个安全、简单并有效的方法用于聚合反应。首先,为了选择最好的IL用于制备PA,单体1与2h的反应是在不同的合成的IL中进行的：1,3 -二丙基咪唑溴、1,3 -二异丙基咪唑溴、1,3 -二苄基咪唑氯、1,3 - 二苄基咪唑溴、1,3 -二丁基咪唑溴、1,3 -二苯基咪唑溴1,3 -二庚基咪唑溴、1,3 -二烯丙基咪唑氯和1,3 -二烯丙基咪唑溴，在没有任何IL的情况下，油浴加热（图２），结果列于表1。根据表1，当使用[ 1,3 - ( isopr) 2im] Br作为用于直接缩聚反应的IL时得到最好的特性粘度和收率。 所以选择[ 1,3 - isopr) 2im] Br用于另外的聚合反应。令人感兴趣的是提到这种聚合物不是在既没有IL也没有TPP的情况下得到的,所以两种成分的存在对聚酰胺化反应是必需的,因此IL担当了这些反应的催化剂和溶剂。因为用于各反应的IL量非常低,所以我们不进行回收。不然,这些IL也很容易从生成的聚合物中分离出并再次使用 因此,通过手性二酸1与不同的芳族二胺2a-2h的直接的聚酰胺化反应进行了一种有效的、简化的并温和的方法用于PA的制备。 用油浴加热通过TPP和1,3 - ( isopr) 2im] Br作为冷凝剂（方法I）并且还进行了相同条件下通过山崎磷酰化反应,使用TPP/Py/NMP/CaCl2作冷凝剂（方法II）完成了这种聚合反应，结果列于表2和表3。 |
2楼2015-04-08 10:50:28
