NUCLEAR MAGNETIC RESONANCE STUDY OF THERMAL DECOMPOSITION OF ETHYLENEDINITRILOTETRAACETIC ACID AND ITS SALTS IN AQUEOUS SOLUTIONS

被引:24
作者
VENEZKY, DL
MONIZ, WB
机构
[1] Chemistry Division, Naval Research Laboratory, Washington
关键词
D O I
10.1021/ac60270a005
中图分类号
O65 [分析化学];
学科分类号
070302 ; 081704 ;
摘要
Aqueous and deuterium oxide solutions of ethylenedinitrilotetraacetic acid (H4EDTA), disodium ethylenedinitrilotetraacetate (Na2H2EDTA), and tetralithium ethylenedinitrilotetraacetate (Li4EDTA) were degassed to remove dissolved oxygen and then heated at 200 °C in sealed NMR tubes for periods ranging from one hour to over 300 hours. Periodic examination of the contents using proton NMR showed that decomposition occurred rapidly in the order H4EDTA > Na2H2EDTA > Li4EDTA. Approximate rates for the degradation processes have been determined. The longest half-life, that for O.1M Li4EDTA solution, is approximately 13 hours at 200 °C. The NMR results suggest a primary, pH dependent, stepwise loss of (–CH2CO2-) groups from EDTA4- to form (-O2CCH2)NHCH2CH2N(CH2CO2-)2, NH2CH2CH2N(CH2CO-2)2, and (CH2NHCH2CO-2)2. A slower, secondary decomposition produced products not yet identified. © 1969, American Chemical Society. All rights reserved.
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页码:11 / &
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