SU854926A1 - Heptamethylenediamine n,n,n'-,n'-tetraacetic acid as complexing agent - Google Patents

Description

(54) HEPTAMBTHYLENEDIAMIN-N, N, N, N-TETER ACOXY ACID AS A COMPLEX

one

The invention relates to polymethylenediamine-based chelating agents.

Known use as complexone ethylenediamine-M, N, N, N-thete of acetic acid EDTA. W and 2J.

The disadvantage of this complexone is the high stability of its complexes with calcium, therefore, when used in practice for the removal of toxic metals from living organisms, there is a danger of calcium removal.

The purpose of the invention is to expand the range of compounds used as chelating agents.

Heptamethylenediamine-N, N, N, N -tetraacetic acid (HMDTA) has the structural formula

. (JHzCjOOH

(JOOHKlHz

I /

M- (YNg) 7-1

X

ci-HzCJoo-H.

dOOH-CH /

The synthesized complexone forms stable complexes with metal ions and can be used in analytical chemistry, as well as in medicine and agriculture. Heptamethylenediamine-N, N, N, N-tatraacetic acid is synthesized by reacting heptamethylene diamine dichlorohydrate with chloroacetic acid in an alkaline sequence in an aqueous solution at elevated temperature. After completion of the reaction, the solution is evaporated and

Acidify with concentrated PVG to pH 2-ii. 5. The precipitated complexone is separated, dried and purified by recrystallization from an ox.

Example. In 200 ml of water is dissolved with stirring. 10.2 g

5 (0.05 mol) of heptameti dichlorohydrate, lendiamine and 22.0, g (0.23 mol) of chloroacetic acid. Then LiOH-H, 0 is added to pH 8-9. The resulting solution is heated in a water bath for 4 hours, maintaining a pH of 8-9 by adding LiOH-H O and the amount of solution by adding WATER. At the end of the reaction, the solution is evaporated in a water bath, cooled to room temperature, and acidified with concentrated HBr to a pH of 2-2.5. For a more complete loss of complexone, pacTiJOp is placed in the refrigerator. The precipitated heptamethylenediamine-N, N, N, M -this 30 raacetic acid is filtered,

washed with cold water and then with acetone. Dried for 2-3 hours. If necessary, the complex is purified by recrystallization from water. The output of 13.6 g (75%). The complex is a white, crystalline substance, poorly soluble in water and readily soluble in alkali solutions.

Found,%: C 49.90; H 7.18; N 7.81

C H.

Calculated,%: C 49, 69; H 7, 24;

N 7.73.

Acid dissociation constants of heptamethylenediamine-S, K, S, s-tetraacetic acid are determined by the method of pH-potentiometric titration of solution of complexone 0.1 n KOH free from CO at 25 ° C ,, 1 (KNOi).

Below are the values of the negative decimal logarithms of the acid dissociation constants of GMDTA: pK. 1.94 + 0.05; , 98 + 0.03; pK., -9.79 + 0.01; , 58 + 0.01.

The logarithms of the stability constants of the middle complexes of HMDTA and EDTA with a number of metals are presented in Table 1.

Table 1

Known methods for the complexonometric determination of mercury (P), calculated for the absence of interfering metals or the determination of mercury, are carried out by indirect methods, including two titrations 2.

As an example, the results of the complexometric determination of mercury in complex mixtures containing mercury (P) and copper (U), carried out with the help of three different complexones. Titrations were carried out at pH 6 (urotropin buffer), indicator xylene orange. The complexometric titration of mercury in the presence of copper using EDTA, NTA and GMDTA is given in Table 2.

Table 2

Claims (1)

Claim Heptamethylenediamine-N, N, N ', N ^f -tetra · acetic acid of the formula soone-sn ₂ sn ₂ soon N - (. CH ₂ ) ₇ -N ^z • COOH-CI / CHN1COOH as a complexon.