One-step Synthesis of Acetic Acid from Methanol Alone Using Dual Functional Complex Catalysis

甲醇是由天然气经济地生产出来的，用途广泛。基于以甲醇为唯一原料合成乙酸的独特思路，研究了具有该功能的催化剂，取代了传统的再乙醇羰基化反应。发现[Ru(SnCl_3)_5L]^<n->(L=MeCN, PPh_3, n=3; SnCl_3^-, n=4)形式的杂核混合团簇对该新反应有效。催化活性的依赖于岛的种类（PPh_3 > MeCN >> SnCl_3^-, 65 C）表明，中性配体的存在是重要的。在反应过程中检测到少量甲酸甲酯，在某些情况下检测到微量甲醛缩二甲基（乙醛）。从这些结果可以看出，该反应是按照(1)甲醇->甲醛（脱氢）、(2)甲醛->甲酸甲酯（tischenko型二聚化）和(3)甲酸甲酯->乙酸的顺序进行的。事实上，当甲醛（多聚甲醛）或甲酸甲酯作为反应物时，会产生更多的乙酸（醋酸甲酯）。在CO气氛下进行反应时，。反应速率降至1/4，这可能是由于CO与催化活性物质（配位不饱和配合物）的配位作用；这一事实否定了甲醇与一氧化碳反应生成乙酸的可能性，甲醇分解后可能产生少量乙酸。游离Cl^-离子的加入使乙酸的主要产物变为甲酸甲酯，游离PPh_3的加入抑制了[Ru(SnCl_3)_5(PPh_3)]^<3->催化剂对甲酸甲酯的异构化反应。这些事实表明，甲酸甲酯的活化是由RU（II）与C-H键-（软Lewis酸和碱）和SN（II）与氧原子（硬Lewis酸和碱）的多中心相互作用组成的。少

Methanol, produced economically from natural gas, has versatile utilty. Based on the unique idea of synthesizing acetic acid with methanol used as the sole source(instead of conventional carbonylation of reethanol with CO), catalysts possessing this function were investigated. It was found that heteronuclear mixed cluster conlexes of the forms [Ru(SnCl_3)_5L]^<n->(L=MeCN, PPh_3, n=3 ; SnCl_3^-, n=4) were effective for this new reaction. Dependence of the catalytic activity on the kind of lisand (PPh_3 > MeCN >> SnCl_3^-, 65ﾟC) suggests that the presence of neutral ligand is important. During the reaction a small amount of methyl formate was detected, and in a certain case a trace amount of formaldehyde dimethyl acetal(sethylal)was detected. From these results, it is concluded that the reaction proceeds with the sequentialprocesses of (1) methanol -> formaldehyde (dehydrogenation), (2) formaldehyde -> methyl formate (Tischenko-type dimerization), and (3) methyl formate -> acetic acid. I … More n fact acetic acid (methyl acetate) was produced, when either formaldehyde (paraformaldehyde) or methyl formate was given as the reactant. When the reaction was performed under CO atmosphere, . the reaction was retarded considerably(the rate becoming to 1/4), which may be due to the coordination of CO to the catalytically active species(coordinatively unsaturated complex) ; this fact is against the'possibility of acetic acid formation by the reaction of methanol with CO which might be present in a small amount by the decomposition of methanol. Addition of free Cl^- ion changed the main product from acetic acid into methyl formate, and the isomerization of methyl formate to acetic acid with [Ru(SnCl_3)_5(PPh_3)]^<3-> catalyst was inhibited by the addition of free PPh_3. These facts indicate that-the activation of methyl formate occurs with a multi-center interaction consisting of the interactions between RU(II)and C-H bond-(soft Lewis acid and base), and between SN(II)and oxygen atom(hard Lewis acid and base). Less