Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907-2084, USA.
Chemistry. 2012 Jul 9;18(28):8692-8. doi: 10.1002/chem.201103628. Epub 2012 Jun 12.
The chemical properties of a 1,8-didehydronaphthalene derivative, the 4,5-didehydroisoquinolinium cation, were examined in the gas phase in a dual-cell Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer. This is an interesting biradical because it has two radical sites in close proximity, yet their coupling is very weak. In fact, the biradical is calculated to have approximately degenerate singlet and triplet states. This biradical was found to exclusively undergo radical reactions, as opposed to other related biradicals with nearby radical sites. The first bond formation occurs at the radical site in the 4-position, followed by that in the 5-position. The proximity of the radical sites leads to reactions that have not been observed for related mono- or biradicals. Interestingly, some ortho-benzynes have been found to yield similar products. Since ortho-benzynes do not react via radical mechanisms, these products must be especially favorable thermodynamically.
研究了 1,8-二脱氢萘衍生物，即 4,5-二脱氢异喹啉鎓阳离子，在双池傅里叶变换离子回旋共振（FT-ICR）质谱仪中的气相化学性质。这是一个有趣的双自由基，因为它有两个靠近的自由基部位，但它们的耦合非常弱。事实上，双自由基被计算为具有近似简并的单重态和三重态。与具有附近自由基部位的其他相关双自由基相反，该双自由基被发现仅经历自由基反应。第一个键形成发生在 4-位的自由基部位，然后是在 5-位。自由基部位的接近导致了尚未观察到的与相关单核或双自由基的反应。有趣的是，一些邻苯炔已被发现产生类似的产物。由于邻苯炔不通过自由基机制反应，这些产物在热力学上一定是特别有利的。
