Knüpfer Christian, Färber Christian, Langer Jens, Harder Sjoerd
Inorganic and Organometallic Chemistry, Universität Erlangen-Nürnberg, Egerlandstrasse 1, 91058, Erlangen, Germany.
Angew Chem Int Ed Engl. 2023 Apr 24;62(18):e202219016. doi: 10.1002/anie.202219016. Epub 2023 Mar 28.
Alkenes that normally do not react with LiAlH (3-hexene, cyclohexene, 1-Me-cyclohexene), can be reduced to the corresponding alkanes by a mixture of LiAlH and Fe (the iron was activated by Metal-Vapour-Synthesis). This alkene-to-alkane conversion with a stoichiometric quantity of LiAlH /Fe does not need quenching with water or acids, implying that both H's originate from LiAlH . The LiAlH /Fe combination is also a remarkably potent cooperative catalyst for hydrogenation of multi-substituted alkenes and benzene or toluene. An induction period of circa two hours and the minimally required temperature of 120 °C, suggests that the actual catalyst is a combination of Fe and the decomposition product of LiAlH (LiH and Al ). A thermally pre-activated LiAlH /Fe catalyst did not need an induction time and is also active at room temperature and 1 bar H . A combination of AliBu and Fe is an even more active hydrogenation catalyst. Without pre-activation, tetra-substituted alkenes like Me C=CMe and toluene could be fully hydrogenated.
通常不与氢化铝锂反应的烯烃（3-己烯、环己烯、1-甲基环己烯），可通过氢化铝锂和铁的混合物（铁通过金属气相合成法活化）还原为相应的烷烃。用化学计量的氢化铝锂/铁将烯烃转化为烷烃无需用水或酸淬灭，这意味着两个氢原子均来自氢化铝锂。氢化铝锂/铁组合对于多取代烯烃以及苯或甲苯的氢化也是一种非常有效的协同催化剂。约两小时的诱导期和最低所需温度120°C表明，实际催化剂是铁与氢化铝锂的分解产物（氢化锂和铝）的组合。热预活化的氢化铝锂/铁催化剂无需诱导时间，在室温及1巴氢气压力下也具有活性。三异丁基铝和铁的组合是一种活性更高的氢化催化剂。无需预活化，像四甲基乙烯和甲苯这样的四取代烯烃就能完全氢化。
