Collisionally activated dissociation of 1-benzyloxypyridinium cations
Collisionally activated dissociation of 1-benzyloxypyridinium cations
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1-苄氧基吡啶鎓阳离子的碰撞激活解离
DOI：
10.1039/p29900001051
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
J. Eyler
中科院分区：
文献类型：
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作者：
A. Katritzky;Z. Dega‐Szafran;C. Watson;J. Eyler
18个吡啶环取代的N-苄氧基吡啶鎓阳离子都通过两种交替的途径解离，得到（A）阳离子C7 H7+和取代的吡啶1-氧化物，和（B）阳离子C7 H7 O+和取代的吡啶。测量了两种途径的出现势（Eapp）;它们对于主导途径（A）比（B）高3-17 kcal mol-1。将Eapp值与通过AM 1方法计算的反应物和产物的ΔHf值进行比较，证明了在产物样过渡态（TS）中，途径（A）而不是（B）的广泛重排。对于吡啶环取代基，两组Eapp都与π σ大致相关;对于4-二甲氨基衍生物，发现两个额外的均裂途径，得到（C）α，阳离子Me 2NC 5 H4 NO + stec和（D）4-二甲氨基吡啶自由基阳离子。
Eighteen pyridine-ring substituted N-benzyloxypyridinium cations all dissociate by two alternative pathways to give (A) a cation C7H7+ and the substituted pyridine 1-oxide, and (B) a cation C7H7O+ and the substituted pyridine. Appearance potentials (Eapp) have been measured for both pathways; they are higher by 3–17 kcal mol–1 for the dominant pathway (A) than for (B).The Eapp values are compared with the ΔHf values calculated by the AM1 method for reactants and products demonstrating extensive rearrangement in a product-like transition state (TS) for pathway (A) but not for (B). Both sets of Eapp correlate roughly with Σσ for the pyridine ring substituents.For the 4-dimethylamino derivatives, two additional homolytic pathways are found to give (C) a, cation Me2NC5H4NO+˙ and (D) the 4-dimethylaminopyridine radical cation.