Formaldehyde → Ethylenediaminetetraacetic Acid

Participants

Reaction Conditions

Reaction Steps

1-mol of ethylenediamine (60.0-g) is mixed with 0.18-mol sodium hydroxide (14.7-g of 50% NaOH) and raised to 70° C. 4.47-mol of sodium cyanide (729.6-g of 30% aq sln) and 4.55-mol of formaldehyde (273.2-g of 50% aq sln) are added at a constant rate over 4.5-hrs and the reaction is allowed to quickly reach boiling temperature (materials can be obtained at Sigma-Aldrich). Any vapors escaping from the reaction are refluxed back to the reactor for the first half of the addition. After the first half of the addition, vapors are no longer refluxed, but distilled away from the reactor. Upon completion of the addition, the reaction is boiled for 2-hrs to remove any excess ammonia. 222.2-mol of water (151.3-g) are added back to the reaction and the reaction is cooled to room temperature. The resulting product contains 39.90-wt % tetrasodium ethylenediaminetetraacetate (Na4EDTA) and 2.5-wt % trisodium nitrilotriacetate (Na3NTA), as determined by HPLC analysis (see method below).

Provenance & Evidence