Dimerization of Linear Butenes and Pentenes in an Acidic Zeolite (H-MFI).
Dimerization of Linear Butenes and Pentenes in an Acidic Zeolite (H-MFI).
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DOI：
10.1002/anie.202013671
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发表时间：
2021-02-15
期刊：
影响因子：
--
通讯作者：
Sauer J
中科院分区：
文献类型：
--
作者：
Berger F;Sauer J
量子化学证据表明，直链丁烯和戊烯在 H-MFI 沸石布朗斯台德位点的二聚产生具有环己烷环的烷烃，而不是支链烯烃。形成的环烷烃中不存在任何 C=C 双键，这解释了低聚反应在二聚体处停止的现象。计算出的2-戊烯在气相中二聚的反应焓对于支链烯烃为-84 kJ mol-1，但对于烷基环戊烷和-己烷分别为-153和-154 kJ mol-1。与计算出的二聚体吸附焓分别为-111和-127 kJ mol−1一起，这意味着表面二聚体形成焓分别为-264和-281 kJ mol−1，与实验值-285 kJ mol−1非常一致。相反，预测的支化醇盐形成焓 -198 kJ mol−1，与实验偏差 87 kJ mol−1。计算出的 Brønsted OH 基团的红外光谱显示，观察到约 3000 cm−1 处的谱带（与烯烃形成氢键）转变为约 3450–3500 cm−1 处强度较低的谱带（与烷烃相互作用）。直链丁烯和戊烯在沸石布朗斯台德酸位点的二聚产生具有环己烷环的烷烃，而不是支链烯烃。后者中不存在任何 C=C 双键不仅解释了观察到的红外光谱的变化，而且还解释了低聚在二聚体处停止的观察结果。
Quantum chemical evidence is produced to show that dimerization of linear butenes and pentenes at zeolitic Brønsted sites in H‐MFI yields alkanes featuring cyclohexane rings rather than branched alkenes. The absence of any C=C double bond in the formed cyclic alkane explains the observations that oligomerization stops at the dimer. The calculated reaction enthalpies for the dimerization of 2‐pentene in the gas phase are −84 kJ mol−1 for branched alkenes, but −153 and −154 kJ mol−1 for alkyl‐cyclopentane and ‐hexane, respectively. Together with calculated adsorption enthalpies of the dimers, −111 and −127 kJ mol−1, respectively, this implies surface dimer formation enthalpies of −264 and −281 kJ mol−1, respectively, in close agreement with the experimental value of −285 kJ mol−1. In contrast, the predicted enthalpy for formation of branched alkoxides, −198 kJ mol−1, deviates by 87 kJ mol−1 from experiment. Calculated IR spectra for the Brønsted OH group show the observed conversion of the band at approximately 3000 cm−1 (hydrogen bond with alkene) to a less intense band at approximately 3450–3500 cm−1 (interaction with alkane). Dimerization of linear butenes and pentenes at zeolitic Brønsted acid sites yields, rather than branched alkenes, alkanes featuring a cyclohexane ring. The absence of any C=C double bond in the latter explains not only the observed change of the IR spectra, but also the observation that oligomerization stops at the dimer.
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影响因子：
3
作者：
Grimme, Stefan
通讯作者：
Grimme, Stefan
影响因子：
2.8
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
Iglesia, Enrique
DOI：
10.1002/anie.201601534
发表时间：
2016-04-18
期刊：
Angewandte Chemie (International ed. in English)
影响因子：
--
作者：
Piccini G;Alessio M;Sauer J
通讯作者：
Sauer J
影响因子：
4.4
作者：
Hättig, C;Weigend, F
通讯作者：
Weigend, F