钯催化1,3-丁二烯羧酯化合成3-戊烯酸甲酯

Palladium Catalyzed Carboxylation of 1,3-Butadiene to Methyl 3-Pentenoate

以1,3-丁二烯、CO和甲醇为原料,进行羧酯化反应合成3-戊烯酸甲酯是Altam路线生产己内酰胺绿色工艺的关键步骤.将Pd与三齿N-杂环配体或双膦配体组成的催化体系用于1,3-丁二烯的羧酯化反应中,其中乙酸钯/2,6-二(3,5-二甲基吡唑基)吡啶催化剂表现出中等的催化活性,在150oC,p(CO)=6.0MPa的优化条件下反应6h,1,3-丁二烯转化率为78.8%,3-戊烯酸甲酯选择性达92.2%(TON=226);而乙酸钯/2,2′-二(二苯基膦基)苯醚催化体系的活性更高,在优化反应条件下,1,3-丁二烯转化率达90.4%,3-戊烯酸甲酯选择性为91.6%(TON=181).在200oC及类似的羧酯化反应条件下,1,3-丁二烯发生二聚反应,其转化率为99%以上,二聚产物4-乙烯基-1-环己烯选择性高于96%.

Palladium salts with N-heterocyclic ligand or biphosphine ligand were used as the catalysts for the carboxylation of 1,3-butadiene with carbon monoxide in methanol to methyl 3-pentenoate,which is one of the key reactions in Altam process for production of ε-caprolactam.The combination of Pd（OAc）2 with 2,6-bis（3,5-dimethylpyrazol-1-yl）pyridine exhibited moderate catalytic activity under the optimized conditions （150 oC,p（CO）=6.0 MPa,6 h）,reaching 78.8% conversion of 1,3-butadiene and 92.2% selectivity for the target product （TON=226）.Using Pd（OAc）2/（oxydi-2,1-phenylene）bis（diphenylphosphine） as the catalyst remarkably increased the reaction efficiency,achieving 90.4% conversion of 1,3-butadiene and 91.6% selectivity for the product （TON=181）.At temperature above 200 oC,1,3-butadiene underwent dimerization to form 4-vinyl-1-cyclohexene in 96% yield.