离子选择电极法测定N,N—二甲基膦酸基甘氨酸与钙的络合物组成和稳定常数

WITH ION SELECTIVE ELECTRODES DETERMINATING THE COMPOSITION AND STABILITY CONSTANTS OF Ca-N,N-BIS(PHOSPHONOMETHYL)GLYCINE COMPLEXES

N,N—二甲基膦酸基甘氨酸[N,N—Bis(pheosphonomethyl)glycine,以下简称NBPG]结构式为在农业上作为植物生长调节剂,有明显的增糖增产作用。从化学结构上看,又是很好的络合剂。B.BynozkuHa等人曾研究过与Fe^(3+)、Mn^(2+)、Pb^(2+)的络合反应。本文用钙离子选择电极法测定了NBPG与Ca^(2+)生成络合物的组成和稳定常数;同时测定了NBPG的各级电离常数,为NBPG的开发应用奠定基础。

The electric dissociation constants of N,N-Bis(phosphonomethyl)glycine (NBPG,H_5L) were determined as pK_(a1) 1. 75 ± 0. 02, pK_(a2) 2. 04 ± 0. 01, pK^(a3) 5. 08 ± 0. 02, pK_(a4) 6. 38 ± 0. 01, pK_(a5) 10. 76±0. 03,determination being carried cut by pH-potentiometry descibed in the paper. The composition and stability constants of Ca-NBPG were CaL 6. 41±0. 01, CaHL 3. 06±0. 01 (NaNO_3 0. 1mol·l^(-1), 18℃, as determined with ion selective electrodes.