SU883018A1 - Cis-1,3-diminocyclohexane-n,n'-dimalonic acid as complexing agent - Google Patents

Description

The invention relates to a novel chemical compound based on cis-1/3-diaminocyclohexane, namely cis-1, 3-diaminocyclohexane-NI N-dimshonovoy acid, which can be used as complexone in chemistry and chemical technology. In analytical chemistry and other areas, ethylenediami-N, N, N, N tetraacetic acid (EDTA) is widely used. It is used for the separation and analysis of mixtures of rare earth elements, and is also widely used in complexometric analysis of many metals ll. When conducting complexometric analysis of mixtures of metals using EDTA, it is often necessary to take additional measures to conceal the interfering metals, since EDTA forms stable complexes with most metals and does not show sufficient selectivity with respect to certain of them. There are also data on the analysis of complexones, malonic acid derivatives, in particular, ethylene diamine N, N-diphenoic acid (EDCA) 12 However, EDCA does not form sufficiently strong complexes with a number of metals, which reduces the possibilities of its use in analytical chemistry. The aim of the invention is to expand the range of compounds used as chelating agents with improved properties. This goal is achieved by cis1, 3-diaminocyclohexane-N, N-dimalonic acid (cis-1,3-DCHGMK) of the structural formula 3-diai “1-inocyclohexane with monobromomalonic acid in fir-tree in aqueous solution at elevated temperature. After graduation

the reaction solution is evaporated, cooled, acidified with concentrated HBr and poured into methanol. Obtained: The complexone sodium salt is purified and dried under vacuum. Pure cis-1, 3-DTSGMK is obtained using cation exchanger KU-2.

; Example. 3.0 g of (1,6-) cis-1,3-diaminocyclohexane dihydrrichloride are dissolved in a minimal amount of water and mixed with 50 ml of an aqueous solution of 7.3 g (4, O-10 mol) of monobromomalonic acid. The reaction is carried out at 75 C in a water bath for b h at pH 8.5 - 9, O, which is maintained by means of MaOK. After completion of the reaction, the solution is evaporated, cooled to 5 ° C and acidified with conc. .HBr to pH 5. The precipitated small by-product precipitate is filtered off and the filtrate is poured with vigorous stirring into a 10-fold volume of methanol. The precipitated flaky white precipitate of the sodium salt of cis-1, 3-VDGMK washed with acetone and dried in a vacuum Cabinet at room temperature. The product is purified by reprecipitation in a water-methanol mixture of 1:10. The free acid is obtained by passing a solution of sodium cis-1,3-DCCMC through a column filled with cation exchanger KU-2 in the H-form by evaporation of the resulting solution under vacuum and precipitating in methanol, followed by drying. 1.1 g of cis-1,3-DCGMK are obtained. Yield 22% (counting on). The complex is a white substance, well soluble in water, difficultly soluble in alcohols and practically insoluble in acetone and diethyl ether. Melting point is 130 ° C.

Found,%: C 45.31; H 5.67; K 8.85. For CftH eOeNj.

Calculated,%: C 45.28; H 5.70; N 8.80

The acid dissociation constants of cis-1,3-DCCMC were determined by pH-potentiometric titration of a complexone solution of 0.1N NaOH free of COj at 25 ° C, (, 1 (KNO,).

Cys-1,3-DCHMC forms stable complexes with metal ions. (Table 1). Comparative data of the logarithms of the stability constants of the complexes cis-1,3-DTSGMK and, EDCMC with some metals are presented in Table 1.

As can be seen from Table 1, cis-1,3-DCHMC forms more durable complexes with lead, cadmium and rare-earth elements than EHMPs by about 3-4 times, which is important for the use of complexone in analytical chemistry.

It is also possible to use cis-1, 3-DCGMK for the complexonomic determination of lead. When using EDTA for the complexometric determination of lead with eriochrome black T, alkaline earth metals are simultaneously titrated as an indicator. The use of cis-1,3-DCHMC for this purpose allows the direct determination of lead in the presence of an excess of alkaline earth metals, since this complex forms complexes (low stability with alkaline earth metals and magnesium.

The logarithms of the stability constants of the complexes formed by the EDTA and cis-1,3-DCGMK complexes are presented in Table. 2

The results of direct complexometric titration (indicator of eriochrome black t) (ammonia buffer) of lead in the presence of alkaline earth metals and magnesium using EDTA and cis-1,3-DCHMC are presented in Table. 3

As can be seen from the table. 3, EDTA does not allow direct complexometric determination of lead in the presence of alkaline earth metals and magnesium.

Using cis-1,3-DCCMC, it is possible to accurately determine the lead in the mixture.

Thus, the proposed compound has good complexone properties.

Table 1

17.78

13.87

14,13

18.74

11.31

9.91

4.93

3.67

Claims (2)

Claims Cis-1, 3-diaminocyclohexane-8, —Ν ’-dimalonic acid ^ formulas_ SI, - SI — NN— 4 \ ^{C0 (>} x C0OYA Xf / j SI --- neither — SIS 'shit as a complexon. '' Sources of information taken into account in the examination 1. Dyatlova N.M., Temkina V.Ya. and 50 Kolpakova I.D. Complexons. M., Chemistry, 1970, p.335, 293. 2. USSR copyright certificate __ No. 316685, cl. C 07 C 87/16, 1971.