3,5-二羟基苯甲酸转移加氢制备-3,5-二氧代环己烷羧酸

Preparation of 3,5-Dioxocyclohexanecarboxylic Acid from 3,5-Dihydroxybenzoic Acid by Transfer Hydrogenation

以3,5 二羟基苯甲酸为原料,采用Pd/C〔w(Pd)=5%〕催化剂,通过转移加氢法合成了3,5 二氧代环己烷羧酸。考察了适宜的催化剂制备及反应条件:浸渍制备的PdCl2/C经氢气还原,以甲酸钠为氢供体,水作溶剂,在90℃下反应2h,经HPLC分析得3,5 二氧代环己烷羧酸的收率为95%。得到的3,5 二氧代环己烷羧酸粗产物经柱层析分离得到纯品,并以1HNMR和元素分析法进行确证。催化剂经过XRD表征,确认了活性组分是原子态的Pd。并对催化剂失活原因做了初步分析。

3,5-Dioxocyclohexanecarboxylic acid was prepared from 3,5-dihydroxybenzoic acid through transfer hydrogenation with Pd/C 〔w(Pd)=5%〕 as catalyst.The catalyst was prepared through impregnation method and reduced by pure hydrogen.Using water as solvent and sodium formate as hydrogen source,the transfer hydrogenation reaction was carried out for 2 h to produce 3,5-dioxocyclohexanecarboxylic acid(Ⅰ) in 95% yield as monitored by HPLC.Pure Ⅰ was separated from the crude product with column chromatography and was identified by ~1HNMR and elementary analysis.The catalyst was characterized by XRD and BET techniques.Palladium is considered as the active substance of the catalyst,and the main reason of catalyst deactivation arises from the loss of palladium.