首页> 外文期刊>Polyhedron: The International Journal for Inorganic and Organometallic Chemistry >Kinetics of ligand exchange between 2-thenoyltrifluoroacetone and zirconium-lactate solution in weakly acidic lactate buffers
【24h】

Kinetics of ligand exchange between 2-thenoyltrifluoroacetone and zirconium-lactate solution in weakly acidic lactate buffers

机译:在弱酸性乳酸缓冲液中2-壬基三氟丙酮和乳酸锆溶液之间的配体交换动力学

获取原文
获取原文并翻译 | 示例
获取外文期刊封面目录资料

摘要

Zirconium(IV) (total Zr = T-Zr) in excess lactate (total lactate = T-L) buffer forms "zirconium-lactate", which reacts with 2-thenoyltrifluoroacetone (HT) resulting in UV spectral changes sufficient for monitoring the kinetics of the reaction. The ligand HT undergoes a very fast keto enolate equilibration: HK reversible arrow H+ + E-, for which the equilibrium constant was spectrophotometrically evaluated as K-T = 7.15 x 10(-7). In lactate buffers, under the conditions, T-HT T-Zr T-L, the reaction follows first-order kinetics with respect to both T-RT and T-Zr. The first-order rate constant, k(0) increases with decreasing T-L and increasing pH. These simple kinetic observations, and the associated spectral changes, can be interpreted by the sequence: (a) fast, reversible aquation of "zirconium-lactate" with concomitant loss of only one lactate (L) (eqm. const. K-A), (b) rapid hydrolysis (eqm. const. K-B) of the aquated product and loss of a proton followed by, (c) reversible, rate determining (k(1), k(-1)) entry of the enolate form (E-) of HT into the coordination sphere of Zr-IV. Kinetic studies yielded k(1)K(A)K(B) = 2.62 x 10(-6) mol(-2) dm(6) s(-1) and k(-1) = 4.9 x 10(-3) s(-1). The spectrally evaluated equilibrium constant for the overall reaction is K=3.2. These constants are related as: K(A)K(B)k(1)/k(1) = K(AB)k(1)/k(1) = KKa; and yielded pK(a) (3.8) in close agreement with the reported value (3.86).
机译:过量乳酸(总乳酸= TL)中的锆(IV)(总Zr = T-Zr)形成“乳酸锆”,与2-thenoyltrifluoroacetone(HT)反应,产生足以监测紫外光动力学的紫外光谱变化。反应。配体HT经历了非常快的酮-烯醇平衡:HK可逆箭头H + + E-,其平衡常数通过分光光度法评估为K-T = 7.15 x 10(-7)。在乳酸缓冲液中,在T-HT T-Zr T-L条件下,反应遵循相对于T-RT和T-Zr的一级动力学。一级速率常数k(0)随着T-L的降低和pH值的增加而增加。这些简单的动力学观察结果以及相关的光谱变化可以通过以下顺序解释:(a)快速,可逆的“乳酸锆”水化,伴随而来的只有一个乳酸(L)(eqm。const。KA)的损失,( b)水合产物的快速水解(eqm。const。KB),质子损失,然后(c)可逆的速率确定(k(1),k(-1))烯醇式(E- )进入Zr-IV的协调范围。动力学研究得出k(1)K(A)K(B)= 2.62 x 10(-6)mol(-2)dm(6)s(-1)和k(-1)= 4.9 x 10(-3) )s(-1)。整个反应的光谱评估平衡常数为K = 3.2。这些常数如下:K(A)K(B)k(1)/ k(1)= K(AB)k(1)/ k(1)= KKa;并产生pK(a)(3.8),与报告值(3.86)极为一致。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号