Polymerization of methyl methacrylate by trialkylborane-pyridine system
Polymerization of methyl methacrylate by trialkylborane-pyridine system
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三烷基硼烷-吡啶体系甲基丙烯酸甲酯聚合
DOI：
10.1002/pol.1970.110080804
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发表时间：
1970
期刊：
影响因子：
--
通讯作者：
S. Iwabuchi
中科院分区：
文献类型：
--
作者：
K. Kojima;Y. Iwata;M. Nagayama;S. Iwabuchi
已经表明，三烷基硼烷可以在氧或含氧化合物存在下引发乙烯基单体的聚合（1-8）。Borsini和Cipolla首次报道了电子给体（如乙醚和吡啶）对氯乙烯与三烷基硼烷聚合的影响（9）。三烷基硼烷引发剂的几个缺点之一是三烷基硼烷在空气中不稳定。我们已经研究了通过添加胺来稳定三烷基硼烷引发剂，并且发现吡啶（Py）及其衍生物在氧气存在下加速由三正丁基硼烷（Bu 3B）引发的甲基丙烯酸甲酯（MMA）的聚合（图1）。其他环胺，如甲基吡啶、二甲基吡啶、喹啉和吖啶，也显示出良好的催化效果，而三乙胺和二甲基对甲苯胺的效果较差（图1和2）。聚合速率通过电化学计量法测量。在Bu 3B-Q系统中，发现初始速率与Bu 3的初始浓度的平方根（[BqB]，图3）以及MMA的初始浓度（[MMA];图4）成比例，其可以表示为：Bu 3B和Py（1：3，在inole中）的反应研究如下。在红外光谱中，1580 cm ~（-1）处的CN伸缩特征吸收向1620 cm ~（-1）处的下侧移动，1000-1200 cm ~（-1）处的芳香族吸收峰减弱。可见光光谱在405 mp处出现一个新的吸收带，它既不属于Bu_3B也不属于Py。这些光谱数据表明形成了Bu 3B-Py络合物。因此，初始速率可以用Bu 3B-b络合物更好地表示为：
It has been shown that trialkylboranes can initiate the polymerization of vinyl monomers in the presence of oxygen or oxygencontaining compounds (1-8). Borsini and Cipolla were the first to report some effects of electron donors, such as diethyl ether and pyridine, on the polymerization of vinyl chloride with trialkylborane (9). One of a few disadvantages of trialkylborane initiators is that trialkylboranes are unstable in air. We have studied the stabilization of trialkylborane initiators by the addition of amines and found that pyridine (Py) and its derivatives accelerate the polymerization of methyl methacrylate (MMA) initiated by tri-n-butylborane (Bu3B) in the presence of oxygen (Fig. 1). Also other cyclic amines, such as picoline, lutidine, quinoline and acridine, showed good catalytic effects, while triethylamine and dimethyl-p-toluidine were less effective (Fig. 1 and 2). Polymerization rates were measured dilatometrically. In the Bu3B-Q system, the initial rate was found to be proportional to the square root of the initial concentration of Bu3 ([BqB], Fig. 3) and also to the initial concentration of MMA [MMA]; Fig. 4), which could be expressed by:The reaction of Bu3B and Py (1: 3 in inole) was studied as follows. In the IR-spectrum, a characteristic absorption of CN stretch of Py at 1580 cm-'was shifted to the lower side at 1620 cm-'and aromatic bands at 1000-1200 cm-I were diminished. The visible light spectrum showed a new absorption band at 405 mp, which belongs neither to Bu3B nor to Py. These spectral data would suggest the formation of a Bu3B-Py complex. Therefore, the initial rate could be better expressed in the term of the Bu3B-b complex by: