Chemistry:2,2',2''-Nitrilotriacetonitrile

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2,2',2''-Nitrilotriacetonitrile
Nitrilotriacetonitril Strukturformel.svg
Names
Preferred IUPAC name
2,2′,2′′-Nitrilotriacetonitrile
Identifiers
3D model (JSmol)
ChemSpider
UNII
Properties
C6H6N4
Molar mass 134.142 g·mol−1
Structure[1]
Pnma
orthorhombic
a = 7.1085, b = 9.9320, c = 9.3869
Hazards
GHS pictograms GHS06: ToxicGHS07: HarmfulGHS08: Health hazard
GHS Signal word Danger
H301, H302, H312, H315, H319, H335, H373
P260, P261, P264, P270, P271, P280, P301+310, P301+312, P302+352, P304+340, P305+351+338, P312, P314, P321, P322, P330, P332+313, P337+313, P362, P363, P403+233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Nitrilotriacetonitrile (NTAN) is a precursor for nitrilotriacetic acid (NTA, a biodegradable complexing agent and building block for detergents), for tris(2-aminoethyl)amine (a tripodal tetradentate chelating agent known under the abbreviation tren) and for the epoxy resin crosslinker aminoethylpiperazine.

Production

The synthesis of nitrilotriacetonitrile is based on the basic building blocks ammonia, formaldehyde and hydrogen cyanide, which are reacted (via the triple cyanomethylation of the ammonia) in acidic aqueous medium in discontinuous or continuous processes.[2][3]

Synthesis of nitrilotriacetonitrile NTAN

Ammonia is introduced as a gas, in form of hexamethylenetetramine[4] or as ammonium sulfate together with formaldehyde as aqueous solution (usually 37% by weight) at pH values <2 and treated with aqueous prussic acid solution or liquid hydrogen cyanide at temperatures around 100 °C. Prussic acid is used directly from the Andrussow process or the BMA process of Evonik Degussa[5] without pre-purification if necessary. When the mother liquors are returned, yields of more than 90% are achieved.

Problematic, particularly in the case of a continuous process, is the tendency of NTAN to precipitate at temperatures below 90 °C which can lead to clogging of tube reactors and conduits and thermal runaway of the reaction.[6]

Properties

Nitrilotriacetonitrile is a colorless and odorless solid which dissolves hardly in water but dissolves well in nitromethane and acetone.[7]

Use

Nitrilotriacetonitrile can be homopolymerized or copolymerized with iminodiacetonitrile in the melt in the presence of basic catalysts such as sodium methoxide to form dark-colored solid polymers which can be carbonized to form nitrogen-containing and electrically conductive polymers at temperatures above 1000 °C.[8] The products obtained have not found application as conductive polymers.

The hydrogenation of NTAN first converts a cyano group into an imino group which attacks a cyano group (which are adjacent and sterically suitable for forming a six-membered ring) rather than being further hydrogenated to the primary amino group. The end product of the catalytic hydrogenation of nitrilotriacetonitrile is therefore 1-(2-aminoethyl)piperazine.

Synthesis of aminoethylpiperazine by hydrogenation of NTAN

If the catalytic hydrogenation of NTAN is carried out with e. g. Raney nickel in the presence of a large excess of ammonia, it gives tris(2-aminoethyl)amine.[9]

Synthesis of tris (2-aminoethyl) amine(tren)

Tris(2-aminoethyl)amine is used as a tetrazident complexing agent (abbreviated as "tren"), which forms stable chelates, particularly with divalent and trivalent transition metal ions.[10]

Nitrilotriacetonitrile reacts with methanal at pH 9.5 to give 2,2-dihydroxymethyl-nitrilotriacetonitrile, which is hydrolyzed with sodium hydroxide solution at 100 °C to give the trisodium salt of 2-hydroxymethylserine-N,N-diacetic acid, from which the free acid can be obtained by acidification in 51% yield.[11]

Synthesis of 2-hydroxymethylserine-N, N-diacetic acid trisodium salt from NTAN

The compound is suitable as a complexing agent for heavy metal ions or alkaline earth metal ions, as a stabilizer for bleaching agents (e.g. for sodium perborate, in solid detergent preparations) and as a builder in detergents for inhibiting the formation of incrustations in textiles during laundering.

The hydrolysis of nitrilotriacetonitrile with water in concentrated sulfuric acid yields under gentle conditions practically quantitatively nitrilotriacetamide, which has been investigated as a neutral tetradentate ligand for metal complexation.[12] At elevated temperature, 3,5-dioxopiperazine-1-acetamide is formed by ring closure, which can be quantitatively converted into the nitrilotriacetamide after neutralization and heating with excess aqueous ammonia.[13][14]

Synthesis of nitrilotracetamide (and 3,5-dioxopiperazine-1-acetamide)

Nitrilotriacetonitrile serves mainly as a raw material for the production of the biodegradable, but carcinogen suspected complexing agent nitrilotriacetic acid by acid or base-catalyzed[15][2] hydrolysis of the cyano groups.

Alkaline hydrolysis of NTAN to NTA trisodium salt

Undesirable residual contents of cyanide ions in the hydrolyzate can be removed by post-treatment with oxidizing agents such as sodium hypochlorite at pH 8.[16]

References

  1. ↑ CSD Entry: CIRWOR 2,2',2-Nitrilotriacetonitrile
  2. ↑ 2.0 2.1 "Process for preparation of an amine nitrile" US patent 3337607, published 1967-08-22
  3. ↑ H. Neumaier, W. Vogt, K. Sennewald, R. Schuller, G. Lenz, "Process for the manufacture of nitrilotriacetonitrile", US patent 3840581, published 1974-10-08
  4. ↑ "Process and preparation of amino nitriles and acetic acids" US patent 3061628, published 1962-10-30
  5. ↑ "Process for producing nitrilotriacetonitrile" EP patent 0102343, published 1986-02-26
  6. ↑ E. Fiedler (2016), "Emergency Runaway Reaction – What Precedes? What Follows?", Chem. Engineer. Transactions (CET) 48: 361–366, doi:10.3303/CET1648061, ISBN 978-88-95608-39-6 
  7. ↑ "Product Stewardship Summary, Chelates: NTAN" (PDF; 45.7 KB). Akzo Nobel Functional Chemicals. https://www.akzonobel.com/dissolvine/system/images/AkzoNobel_NTAN_08-2011_tcm108-76620.pdf. 
  8. ↑ "New polymers from nitrilotriacetonitrile and iminodiacetonitrile" US patent 3578643, published 1971-05-11
  9. ↑ "Hydrogenation of nitrilotriacetonitrile" US patent 3565957, published 1971-02-23
  10. ↑ G. Anderegg; V. Gramlich (1994), "1:1 Metal Complexes of Bivalent Cobalt, Nickel, Copper, Zink, and Cadmium with the Tripodal Ligand tris[2-(dimethylamino)ethyl]amine: Their stabilities and the X-ray crystal structure of its copper(II) complex sulfate", Helv. Chim. Acta 77 (3): 685–690, doi:10.1002/hlca.19940770312 
  11. ↑ "2-Methyl- und 2-Hydroxymethyl-serin-N,N-diessigsäure und ihre Derivate" EP patent 0396999, published 1990-11-14
  12. ↑ D.A. Smith; S. Sucheck; S. Cramer; D. Baker (1995), "Nitrilotriacetamide: Synthesis in concentrated sulfuric acid and stability in water", Synth. Commun. 25 (24): 4123–4132, doi:10.1080/00397919508011491 
  13. ↑ "A process for preparing 3,5-dioxo-1-piperazineacetamide and nitrilotriacetic acid triamide" GB patent 1170399, published 1969-11-12
  14. ↑ D.A. Smith; S. Cramer; S. Sucheck; E. Skrzypzak-Jankun (1992), "Facile synthesis of substituted nitrilotriacetamides", Tetrahedron Lett. 33 (50): 7765–7768, doi:10.1016/0040-4039(93)88040-P 
  15. ↑ "Hydrolysis of nitrilotriacetonitrile" US patent 4547589, published 1985-10-15
  16. ↑ "Hydrolyzed nitrilotriacetonitrile compositions, nitrilotriacetonitrile hydrolysis formulations and methods for making and using same" US patent 8362298, published 2013-01-29



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