Disodium ethylenediamine tetracetic

Preparation of 0.05 M Disodium Ethylenediamine Tetracetate Solution (Disodium Edetate 0.05 M)... 

Procedure Weigh accurately about 0.15 g of calcium chloride dihydrate and dissolve it in 50 ml of DW. Titrate with 0.05 M disodium ethylenediamine tetracetate to within a few ml of the expected end point, add 8.0 ml of sodium hydroxide solution and 0.1 g of calcon mixture and continue the titration until the colour of the solution changes from pink to a full blue colour. Each ml of 0.05 M disodium ethylene disodium tetracetate is equivalent to 0.007351 g of CaCl2.2H20. 

Ethylenediamine tetracetic acid is found to be sparingly soluble in water ( 0.2% w/v) whereas its corresponding disodium salt is almost 50 times more soluble than the parent compound (solubility 10% w/v). Therefore, it is the disodium salt of EDTA which is normally used in complexometric titrations. 

The schematic of the process is shown in Fig. 28.29. The manufacturing procedure is divided into five major steps the synthesis of azine, the removal of low boilers, high boilers separation, hydrolysis of azine, and the dehydration of hydrazine. The synthesis of azine requires a residence time of 7 hours. Ammonia, hydrogen peroxide, and methyl ethyl ketone (MEK) are fed into the reactors along with methanol and acetonitrile at about 50°C. Small amounts of the disodium salt of ethylenediamine tetracetic acid are added to the reactants. In the low-boilers removal step, the unreacted ammonia, MeOH, MEK, and acetonitrile are separated and recycled to the reactors. The high-boilers solution contains water, MEK-azine, and acetamide. The acetamide is formed in the following reaction ... 

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