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

从天然气中经济地生产甲醇，具有多方面的用途。基于以甲醇为唯一原料合成乙酸的独特思路（而不是传统的乙醇与CO羰基化），研究了具有这一功能的催化剂。发现[Ru（SnCl_3）_5L]^（L = MeCN，PPh_3，n = 3; SnCl_3 ^-，n = 4）的杂原子混合簇合物对该反应是有效的。<n->催化活性与配体种类（PPh_3&gt; MeCN&gt;&gt; SnCl_3 ^-，65 ℃）的关系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，检测到痕量的甲醛二甲缩醛（乙缩醛）。结果表明，该反应按甲醇→甲醛（脱氢），甲醛→甲酸甲酯（Tischenko型二聚），甲酸甲酯→乙酸的顺序进行。我 ...更多信息 事实上，当甲醛（多聚甲醛）或甲酸甲酯作为反应物时，产生乙酸（乙酸甲酯）。当反应在CO气氛下进行时，反应被显著地延迟（速率变为1/4），这可能是由于CO与催化活性物质（配位不饱和络合物）的配位;这一事实与通过甲醇与CO反应形成乙酸的可能性相反，所述CO可能通过甲醇的分解以少量存在。游离Cl~-的加入使乙酸转化为甲酸甲酯，而游离PPh_3的加入抑制了[Ru（SnCl_3）_5（PPh_3）]_4催化甲酸甲酯异构化反应。<3->这些事实表明，甲酸甲酯的活化是由Ru（II）与C-H键（软刘易斯酸和碱）和SN（II）与氧原子（硬刘易斯酸和碱）的相互作用组成的多中心相互作用。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