Bazanov Boris, Geiger Uzi, Grinstein Dan, Welner Shmuel, Haas Yehuda
Institute of Chemistry, Safra Campus, The Hebrew University of Jerusalem , 9190401 Jerusalem, Israel.
J Phys Chem A. 2017 Sep 14;121(36):6727-6731. doi: 10.1021/acs.jpca.7b04222. Epub 2017 Aug 31.
The cyclopentazolate anion, N, has been researched extensively over the years and detected in the gas phase more than a decade ago, but was only recently measured in solution. The process whereby aryl pentazole reduction leads to the production of N is still not fully understood. Here, the production of N in solution was investigated using isotopic labeling techniques while implementing changes to the synthesis methodologies. N labeled phenyl pentazole produced appropriately labeled phenyl pentazole radical anions and N which, upon collision induced dissociation, produced the expected N signals. Changing to higher purity solvent and less coated Na metal allowed for a much more rapid pace, with experiments taking less time. However, the best yields were obtained with heavily coated metal and much longer reaction times. Utilization of a vacuum line and ultrapure solvents led to no products being detected, indicating the importance of a sodium passivation layer in this reaction and the possibility that sodium is too strong a reducer. These findings can lead to better production methods of N and also explain past failures in implementing aryl pentazole reduction techniques.
多年来，环戊唑酸根阴离子N一直受到广泛研究，十多年前就在气相中被检测到，但直到最近才在溶液中被测定。芳基五唑还原生成N的过程仍未完全明了。在此，利用同位素标记技术对溶液中N的生成进行了研究，同时对合成方法进行了改进。用N标记的苯基五唑产生了经适当标记的苯基五唑自由基阴离子和N，后者在碰撞诱导解离时产生了预期的N信号。改用更高纯度的溶剂和涂层较少的钠金属可使反应速度大大加快，实验所需时间缩短。然而，使用涂层厚重的金属和更长的反应时间可获得最佳产率。使用真空管路和超纯溶剂未检测到产物，这表明钠钝化层在该反应中的重要性，以及钠作为还原剂可能太强的可能性。这些发现有助于改进N的生产方法，并解释过去实施芳基五唑还原技术失败的原因。
