Oxidation of Hydrocarbons Catalyzed by mu-Oxopolynuclear Mixed Metal Complexes

(1)在O_2气氛下，用mu-氧三核羧酸铁[Fe_3O(O_2CR)_6(H_2O)_3]^+对苯乙烯进行了氧化反应。溶解在苯乙烯中的配合物的氧化速率差异不大。羧酸盐配合物具有较高的环氧化物选择性，其酸强度（pKa）接近4。苯甲酸酯配体的哈米特值从很小的负值到零，具有最大的环氧化物选择性（28%）。(2) Fe^< III>、Fe^<II>和Co_2^<III>、Co^<II>的氧化速率和环氧化物选择性均优于其同价配合物。它的同系物V_2^<IV>V^<III>也是有效的。然而，Mn_2^<III>Mn^<II>没有任何效果。在混合金属（Fe_2^<III>M^<II>, M = Mn, Co, Ni, Zn, Mg）配合物中，锌对环氧化物的选择性最高，在85℃时达到35%。Fe_2^<III>Mn^<II>复合物无活性。结果表明，Cr_2>IIIFe^<II>配合物具有比Fe_2III^<Zn> ^<更强的活性。(3)室温氧化较慢，要求高于70℃。氧化速率随温度的升高而升高，在95℃时达到最大值。配合物的活性和环氧化物选择性在低温条件下存在差异，但在95℃以上基本稳定。在85-95℃时，环氧化物选择性最高。氧压的降低降低了氧化速率，但提高了环氧化物的选择性。在低于13kpa的O_2压力下，环氧化物含量高于50%。(4)将Fe_2^<III>M^<II>O(OAc)_6(H_2O)_3 （M = Fe, Mg, Zn, Mn, Co, Ni）浸渍在SiO_2上煅烧，制备了3种金属的簇状金属氧化物催化剂（Fe负载率为7.8 wt%）。在573K下进行了1-丁烷脱氢制丁二烯反应；M = Mn和Zn的活性高于M = Fe, M = Co和Ni的活性几乎相同，而M = Mg的活性则没有。对丁二烯的选择性分别为71%（Zn）、68%（Fe）、67%（Co）和53%（Ni）。少

(1) The oxidation of styrene has been carried out in O_2 atmosphere with mu-oxotrinuclear ironcarboxylates, [Fe_3O(O_2CR)_6(H_2O)_3]^+. Small differences were found for oxidation rates among complexes which were dissolved in styrene. Relatively high epoxide selectivity was obtained for complexes with carboxylates, their acid strength(pKa) of nearly 4. Benzoate ligands whose Hammett values are from small negative figures to zero gave maximum epoxide selectivity(28%). (2) In the oxidation with mu-oxotrinuclear mixed valence metal carboxylates Fe_2^<III>Fe^<II> and Co_2^<III>Co^<II> are superior in the oxidation rates and epoxide selectivity to their homovalence complexes. Its homologue, V_2^<IV>V^<III> is also effective. However, Mn_2^<III>Mn^<II> has none of effectiveness. Among mixed metal (Fe_2^<III>M^<II>, M = Mn, Co, Ni, Zn, Mg) acetate complexes zinc exerted highest epoxide selectivity(35% at 85ﾟC). No activity was observed for Fe_2^<III>Mn^<II> complex. Almost the same epoxide sel … More ectivity with that for Fe_2III^<Zn>II^< was found for Cr_2>IIIFe^<II> complex. (3) The oxidation was slow at room temperature and requires higher than 70ﾟC. The oxidation rate increases with the increase of temperature and reaches maximum at 95ﾟC. Differences of activity and epoxide selectivity are observed among complexes at low temperatures but were leveled off above 95ﾟC. Highest epoxide selectivity was found at 85-95ﾟC. The decrease of oxygen pressure decreased oxidation rate, but increased epoxide selectivity. Higher than 50% of epoxide was obtained at less than 13 kPa of O_2 pressure. (4) Clustered metal oxide catalysts(Fe loading 7.8 wt%) with 3 metals were prepared by impregnating Fe_2^<III>M^<II>O(OAc)_6(H_2O)_3 (M = Fe, Mg, Zn, Mn, Co, Ni) on SiO_2 followed by calcination. Dehydrogenation of 1-butane to butadiene at 573K were carried out with those catalysts; higher activities than that for M = Fe were obtained for M = Mn and Zn, almost the same for M = Co and Ni, and no activity was observed for M = Mg. Selectivities to butadiene are 71%(Zn), 68%(Fe), 67%(Co) and 53%(Ni). Less