SYNTHETIC APPLICATIONS OF ACTIVATED METAL CATALYSTS .2. THE FORMATION OF HETEROCYCLIC DIARYLS
SYNTHETIC APPLICATIONS OF ACTIVATED METAL CATALYSTS .2. THE FORMATION OF HETEROCYCLIC DIARYLS
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DOI：
10.1039/jr9560000616
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发表时间：
1956-01-01
期刊：
影响因子：
--
通讯作者：
SASSE, WHF
中科院分区：
文献类型：
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作者：
BADGER, GM;SASSE, WHF
据报道，雷尼镍是制备杂环二芳基的有用催化剂。例如，当吡啶与催化剂回流时，以蒸发(和回收)不变碱的有效产率提供2：2‘-联吡啶。由于2：2‘-联吡啶和许多相关的杂环二芳基类化合物形成了具有特征的金属络合物，该方法对制备这些有价值的试剂具有一定的价值。在使用W7 Raney镍的吡啶的初步实验中，粗品呈深棕色，产量很小。因此，为了目前的目的，人们试图通过对催化剂进行各种处理来修改和改进催化剂，以减少吸附的氢量。最令人满意的催化剂(见实验部分)是通过在真空中的蒸汽浴中加热W7 Raney镍获得的。然后将吡啶添加到基本干燥(和自燃)的催化剂中，小心地排除空气，直到镍完全被覆盖。在反应混合物中加入氢受体(如丙酮和环己酮)对产率没有影响，用过氧化氢水溶液失活的催化剂效果较差。在目前发现的最佳条件下，得到的粗品2：2‘-联吡啶为淡黄色晶体，提纯容易。在一些运行中，得到了少量的不溶性有机镍化合物。在常压下热解得到少量挥发性物质，经鉴定为2：2‘-联吡啶。这也是当有机镍化合物在温浓盐酸中溶解并使溶液碱化时获得的。值得注意的是，
RANEY nickel is here reported as a useful catalyst for the preparation of heterocyclic diaryls. For example, pyridine, when refluxed with the catalyst, affords 2: 2'-dipyridyl in useful yield on evaporation (and recovery) of the unchanged base. As 2: 2'-dipyridyl and many related heterocyclic diaryls form characteristic metallic chelate compounds, the method should prove of value for the preparation of these valuable reagents. In the preliminary experiments with pyridine, in which W7 Raney nickel was used, the crude product was dark brown and was obtained only in small yield. Attempts were therefore made to modify and improve the catalyst for the present purpose, by treating it in various ways to reduce the amount of adsorbed hydrogen. The most satisfactory catalyst (see Experimental section) was obtained by heating W7 Raney nickel on a steambath in a vacuum. Pyridine was then added to the essentially dry (and pyrophoric) catalyst, with care to exclude air until the nickel had been completely covered. The addition of hydrogen acceptors (such as acetone and cyclohexanone) to the reaction mixture was without influence on the yield, and a catalyst which had been deactivated with aqueous hydrogen peroxide was much less effective. Under the best conditions so far found, the crude 2: 2'-dipyridyl was obtained as pale yellow crystals which could be purified without difficulty. In some runs a small amount of an insoluble organonickel compound was obtained. Pyrolysis of this material at atmospheric pressure gave a little volatile material which was identified as 2: 2'-dipyridyl. This was also obtained when the organonickel compound was dissolved in warm concentrated hydrochloric acid, and the solution basified. It may be noted that