Ethylenediaminetetraacetic acid (EDTA) is aOrganic compound, the chemical formula is CtenHsixteenNtwoOeight, white powder under normal temperature and pressure.It is a kind of2+、Ca2+、Mn2+、Fe2+Divalent metal ion boundChelating agent。Because most nucleases and some proteases need Mg2+, so it is often used asNuclease、proteaseOfinhibitor；It can also be used to remove heavy metal ion pairsenzymeInhibition of.
White odorless, tasteless, colorless crystalline powder, melting point 250 ℃ (decomposition).Insoluble in ethanol and general organic solvents, slightly soluble in cold water, soluble in sodium hydroxidesodium carbonateAnd ammonia.It is soluble in more than 5% inorganic acid, ammonia water and 160 phr boiling water.Its alkali metal salt is soluble in water.[1]
purpose
Announce
edit
EDTA is an important complexing agent.EDTA is widely used asColor sensitive materialBleaching fixative, dyeing auxiliaries, fiber treatment auxiliaries, cosmetics additives, blood anticoagulants, detergents,stabilizer，synthetic rubberPolymerization initiator, EDTA is the representative material of chelating agent.And alkaline earth metalsrare earth elementAnd transition metals to form stable water solubilitycomplex compound。In addition to sodium salt, there are ammonium salt, iron, magnesium, calcium, copper, manganese, zinc, cobalt, aluminum and other salts, which have different uses.EDTA can also be used to makeRadioactive metalIt can be quickly excreted from the human body to detoxify.It is also a water treatment agent.EDTA is also an important indicator, but it is used to titrate metal nickel, copper, etcammoniaOnly when used together can it act as an indicator.
Incompatibility
Announce
edit
EDTA and its salts are incompatible with strong oxidants, strong bases and high valence metal ions such as copper, nickel and copper alloys.
EDTA or its disodium salt is weakly acidic and can react with carbonate to release carbon dioxide and metal to generate hydrogen.
Other incompatibilities, such as EDTA andDisodium EDTAChelating with zinc caninsulininvalid;Using disodium EDTA as stabilizerCalcium gluconateWhen the injection is mixed with parenteral nutrition solution, the trace metals in parenteral nutrition solution will be chelated;In the infusion, disodium EDTA is incompatible with amphotericin and hydralazine hydrochloride.
[If sulfuric acid is used instead of hydrochloric acid, sulfuric acid (98%) 1200kg shall be used]
major equipment
Salt forming pot;Condensation reaction tank;Acidification pot;Water washing pan;Centrifuge;Storage tank;Drying box
Operation process
Add 100kg into 800L stainless steel condensation reaction tankChloroacetic acid100kg ice and 135kg 30%sodium hydroxideSolution, add 18kg 83% - 84%ethylenediamine 。After holding at 15 ℃ for 1h, add 30% sodium hydroxide solution in batches of 10L each timePhenolphthalein indicatorAdd the next batch after it is not alkaline, and the final reactant is alkaline.After 12h at room temperature, heat to 90 ℃, add activated carbon, filter, wash the filter residue with water, and finally the total volume of solution is about 600L.Add concentrated hydrochloric acid to pH=3 to precipitate crystals.Filter and wash with water until there is no chloride reaction.Drying, EDTA 64kg.The yield was 95%.It can also be carried out at higher temperatures.For example, the following molar ratio is used: ethylenediamine: chloroacetic acid: sodium hydroxide=1:4.8:4.8, reaction temperature is 50 ℃, reaction time is 6h, and then boiling time is 2h. The reaction product is acidified with hydrochloric acid to obtain EDTA crystal in 82%~90% yield.
quality index
Content ≥ 90% Fe ≤ 0.01%
Burning residue ≤ 0.15% heavy metal (Pb2+） ≤0.001%
In NatwoCOthreeMedium solubility qualified
quality testing
(1) Content determination
useComplexometric titration。First, prepare EDTA with KOH into a sample solution with pH of 12.0~13.0.withAcid chrome blue KAnd naphthol green as mixed indicator, titrate analytically pure CaCO dried at 120 ℃ with sample solutionthreeThe end point is when the solution changes from purplish red to blue-green.
(2) Determination of burning residue
Follow the conventional method.
Safety measures
(1) If toxic or corrosive substances such as chloroacetic acid and ethylenediamine are used in production, the production equipment should be sealed, operators should wear labor protection appliances, and the workshop should be kept in good ventilation.
(2) The product shall be sealed and packed, and stored in a ventilated and dry place. Attention shall be paid to moisture-proof and sunscreen. It shall not be mixed with alkaline chemicals.
Laboratory method
Announce
edit
Weigh 94.5g (1.0mol) of monochloroacetic acid to 1000mLRound bottom flaskMedium, slowly add 50%sodium carbonateSolution untilcarbon dioxideUntil bubbles occur.Add 15.6g (0.2mol) ethylenediamine, shake well, place for a while, add 100mL of 40% NaOH solution, add water to the total volume of about 600mL, install an air cooling reflux device, heat preservation on a 50 ℃ water bath for 2h, and then heat preservation and reflux on a boiling water bath for 4h.Remove the flask, cool it, pour it into the beaker, adjust the pH to 1.2 with concentrated HCl, then white precipitate is generated, filter it, and obtain crude EDTA product.The refined product is pure.
