Oxidation of Quinoline to Quinolinic Acid by High-Valenced Ruthenium Catalyst

吡啶-2，3-二羧酸（喹啉酸）是一种重要的中间体，用于生产农用化学品、医药品和特种表面涂料。已知四氧化钌是在环境温度下裂解芳环的强氧化剂。在CCl_4-H_2O两相体系中，ClO与RuO_2或RuCl_3催化剂的组合用于萘氧化裂解制邻苯二甲酸。在钌催化剂（Qu/Ru=200-4000）存在下，喹啉被ClO定量氧化为喹啉酸。用光谱法讨论了钌在水溶液中的活性物种。在水溶液中，只有当OH^-浓度达到一定程度时，钌催化剂与ClO协同作用才能将喹啉快速、定量地氧化为喹啉酸 关于我们 （喹啉酸的分离产率：84%）。在反应的喹啉分子中ClO的消耗接近8，这对应于化学计量值。随着反应的进行，OH的浓度随着喹啉酸的形成而沿着降低。当OH浓度达到0.20- 0.24M时，观察到喹啉的急剧消耗，伴随着在较高OH浓度下定量形成的喹啉酸的分解。分光光度法研究表明，喹啉选择氧化为喹啉酸的活性物种可能是（Ru（VII）O_4）（最大吸收波长：385 nm）。OH-浓度在0.20- 0.24M时，吸收消失。在3.3-4.5 M的较高OH浓度下，形成草酸作为主要反应产物。以喹啉计，草酸的分离收率可达168%。选择性生成草酸的活性物种为（Ru（VI）_4^<-->Less

Pyridine-2,3-dicarboxylic acid (quinolinic acid) is an important intermediate reagent for making agrochemicals, pharmaseuticals and specialized surface coatings. Ruthenium tetraoxide is known as a strong oxidant to cleave aromatic rings at ambient temperatures. The combination of ClO with a catalytic ampunt of RuO_2 or RuCl_3 has been used for the oxidative cleavage of naphthalene to phtalic acid in two-phase system of CCl_4-H_2O. In the present study, quinoline is oxidized to quinolinic acid quantitatively by ClO in the presence of ruthenium catalyst (Qu/Ru=200-4000) at ambient temperatures in alkaline aqueous solution. The active species of ruthenium involved in aqueous solution is discussed by spectrometry. The effect of substituents as well as the oxidation of isoquinoline is also examined.Quinoline was oxidized to quinolinic acid rapidly and quantitatively by ruthenium catalyst in conjunction with ClO in aqueous solution only in the case that appropriate concentration of OH^- was … More involved in the solution (isolated yield of quinolinic acid: 84%). The consumption of ClO over a molecule of quinoline reacted was close to 8, which corresponds to a stoichiometric value. As the reaction proceeded, the concentration of OH decreased along with the formation of quinolinic acid. When the concentration of OH reached to 0.20-0.24 M, drastic consumption of quinoline was observed, accompanied with the decomposition of quinolinic acid which had been formed quantitatively in the higher OH concentration. The spectrophotometric study indicates that the active species for selective oxidation of quinoline to quinolinic acid may be (Ru(VII)O_4) (absorption maximum:385nm). The absorption was found to be disappeared below OH_- concentration of 0.20-0.24 M. In the higher OH concentration of 3.3-4.5 M, oxalic acid was formed as a major reaction product. The isolated yield of oxalic acid reached to 168% based on quinoline reacted. The active species for the selective formation to oxalic acid is found to be (Ru(VI)_4^<--> Less