COPPER-QUINOLINE DECARBOXYLATION
COPPER-QUINOLINE DECARBOXYLATION
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DOI：
10.1021/ja00713a047
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发表时间：
1970-01-01
影响因子：
15
通讯作者：
SCHAMBACH, RA
中科院分区：
文献类型：
--
作者：
COHEN, T;SCHAMBACH, RA
先生：据我们所知，在广泛使用的铜喹啉脱羧2中二氧化碳损失的机制从未被提出过。该反应通常通过将喹啉溶液中的芳香族羧酸与铜粉一起加热来进行，但有时也使用铜盐。我们发现，铜金属过程比涉及羧酸的铜盐或亚铜（酸加氧化亚铜）盐（180-200）的过程慢得多，并且只要维持氮气气氛，产率就非常好。尼尔森最近在研究中使用了亚铜盐，他提供了有机铜化合物是反应中间体的证据。 4* 我们自己的结果证实了这一结论，此外，还提供了各种新的观察结果和提出二氧化碳损失机制的基础。相关结果如下。(1)二氧化碳的损失在亚铜或羧酸铜中是一级的。(2)铜和亚铜盐的脱羧速率几乎相同。(3)任一类型的盐都充当过量羧酸分解的催化剂，并且反应在金属离子中是准一级的。(4)某些螯合剂，例如1、 10-菲咯啉和2, 2'-联吡啶显着提高了两种盐的脱羧速率。后一种试剂虽然效果较差，但价格便宜得多，当过量使用 10 摩尔时，速率会增加 17 倍。(5) 而亚铜和铜都不是
Sir: To our knowledge, a mechanism for the loss of carbon dioxide in the widely used copper-quinoline decar-boxylation2 has never been suggested. The reaction is usually performed by heating an aromatic carboxylic acid in quinoline solution with copper powder, al-though copper salts are sometimes used. We have found that the copper metal procedure is much slower than that involving the cupric3 or cuprous (acid plus cuprous oxide) salt of the carboxylic acid (180-200) and that the yields are excellent provided that a nitrogen atmosphere is maintained. Cuprous salts have re-cently been utilized in studies by Nilsson, who has provided evidence that organocopper compounds are intermediates in the reaction. 4* Our own results con-firm this conclusion and, inaddition, provide a variety of new observations and a basis for suggesting a mechanism for the loss of carbon dioxide. Pertinent results are as follows.(1) The loss of carbon dioxide is first order in cuprous or cupric carboxylate.(2) Cupric and cuprous salts decarboxylate at nearly the same rate.(3) Either type of salt behaves as a catalyst for the decomposition of excess carboxylic acid and the reactions are pseudo-first-order in the metal ions.(4) Certain chelating agents such as 1, 10-phenanthroline and 2, 2'-bipyridyl considerably increase the rate of decarboxylation of both types of salt. The latter re-agent, which is less effective but far less expensive, increases the rate by a factor of 17 when used in a ten-molar excess.(5) Whereas neither cuprous nor cupric