| 铝离子对α-酮戊二酸的催化脱羧作用 |
| Effect of Aluminum Ion on the α-Ketoglutarate Decarboxylation in Acidic Aqueous Solution |
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| 摘要: 为了研究铝(Ⅲ)与生命体中重要的有机分子α-酮戊二酸的作用机制,我们采用了电位滴定、核磁共振、拉曼光谱和分子力学计算对酸性溶液中的反应体系的配位作用和互变异构进行了分析, 并采用电喷雾质谱以及固体和溶液核磁共振谱表征了浓溶液反应体系中的沉淀,来说明铝(Ⅲ)对α-酮戊二酸的催化脱羧反应过程。得到如下实验结论:(1)配位作用:铝(Ⅲ)与α-酮戊二酸在酸性溶液中配位形成1∶1[AlLH2+,AlL+,AlLH-1]和1∶2[AlL2]-,AlL2]H-2]3-]的单核形态以及2∶1[Al2]L4+]的双核形态。(2)互变异构:在酸性溶液中Al3+通过配位作用促进α-酮戊二酸烯醇化,生成易于脱羧的β、γ-不饱和酸的结构。(3)催化脱羧:由于铝(Ⅲ)的电子沉降作用,使β、γ-不饱和酸更易脱羧,如果是1∶2的形态,则脱羧生成沉淀。 |
| 关键词: 铝 α-酮戊二酸 配位作用 互变异构 脱羧作用 |
| 基金项目: |
| Abstract: The complexation and decarboxylation of α-ketoglutaric acid with Al in acidic aqueous solution and solid state were studied with various analytical techniques. In a dilute aqueous acidic solution (< 10-3mol·L-1), α-KG binds Al in a bidentate manner (L∶Al=1∶1) [AlLH2+, AlL+, AlLH-1] at the carboxyl and carbonyl moieties while the decarboxylation tendency is very weak. However, in a high dose reactant solution ( >10-2mol·L-1), Al ion coordinates with α-ketoglutarate in a bidentate manner (L∶Al=2∶1) [AlL2-,AlL2H-23-] at pH 4～6. Then, it promotes α-ketoglutarate tautomerization to β,γ-unsaturated acid enolic structure, which is readily to decarboxylate in the presence of Al’s electron-withdrawing effect. Finally, the decarboxylation product is also formed. These results may help to further understand metal ions-catalyzed decarboxylation mechanism and Al in-fluences on enzyme reactions in biological system. |
| Keywords: aluminum α-ketoglutarate complexation tautomerization decarboxylation |
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| 杨小弟,白志平,毕树平,李百秦.铝离子对α-酮戊二酸的催化脱羧作用[J].无机化学学报,2002,18(10):981-986. |
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