BASE STRENGTHS OF SOME SATURATED CYCLIC ETHERS IN AQUEOUS SULFURIC ACID
BASE STRENGTHS OF SOME SATURATED CYCLIC ETHERS IN AQUEOUS SULFURIC ACID
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DOI：
10.1021/ja00868a038
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发表时间：
1962-01-01
影响因子：
15
通讯作者：
WU, CY
中科院分区：
文献类型：
--
作者：
ARNETT, EM;WU, CY
八种环醚的氧鎓离子的 pKP 已通过溶剂萃取-气相色谱技术测定，并发现其碱度顺序与之前针对其他六种酸性体系对相同醚测定的碱度顺序相同。饱和环醚比它们的开链类似物更具碱性，并且溶剂化的空间位阻比无环化合物重要得多。在该系列中发现了相反的 I 应变顺序：六亚甲基氧化物>四氢呋喃>四氢吡喃，并且似乎也适用于类似的地雷。这不能用通常的极性或空间因素来解释。根据游离碱中的电子相关力提出了一种解释，这导致质子化时非键相互作用的减轻。当与吗啉在饱和胺的碱度等级上的位置相比时，二恶烷是令人惊讶的碱性。对此异常现象给出了解释。
The pKPs of the oxonium ions of eight cyclic ethers have been determined by the solvent extraction-glc technique and found to follow the same order of basicity as was previously determined for the same ethers against six other acidic systems. The saturated cyclic ethers are more basic than their open chain analogs and steric hindrance to solvation is of much less importance than in acyclic compounds. A reverse I-strain order is found in the series: hexamethylene oxide> tetrahydro-furan> tetrahydropyran, and also appears to obtain for the analogous¡ mines. This cannot be explained by the usual polar or steric factors. An interpretation is advanced in terms of electron-correlation forces in the free base which lead to relief of non-bonded interactions upon protonation. When compared to the position of morpholine on the scale of basicities of saturated amines, dioxane is surprisingly basic. An explanation for this anomaly is presented.