View source for N-(2-Carboxyethyl)iminodiacetic acid

{{DISPLAYTITLE:''N''-(2-Carboxyethyl)iminodiacetic acid}}
{{Chembox
| Name = ''N''-(2-Carboxyethyl)iminodiacetic acid
<!-- Images -->
| ImageFile = Β-Alanindiessigsäure Struktur.svg
| ImageSize = 185px
| ImageAlt =
<!-- Names -->
| IUPACName = ''N'',''N''-Bis(carboxymethyl)-β-alanine
| SystematicName = 3-[Bis(carboxymethyl)amino]propanoic acid
| OtherNames =
<!-- Sections -->
| Section1 = {{Chembox Identifiers
| CASNo = 6245-75-6
| PubChem = 535795
| ChemSpiderID = 466712
| EC_number = 228-360-6
| UNII = KOU355F9Z2
| StdInChI = 1S/C7H11NO6/c9-5(10)1-2-8(3-6(11)12)4-7(13)14/h1-4H2,(H,9,10)(H,11,12)(H,13,14)
| StdInChIKey = UWRBFYBQPCJRRL-UHFFFAOYSA-N
| SMILES = C(CN(CC(=O)O)CC(=O)O)C(=O)O
}}
| Section2 = {{Chembox Properties
| C=7|H=11|N=1|O=6
| Appearance = White solid<ref name="saapedia" />
| Density =
| MeltingPtC = 190–200
| MeltingPt_notes = (decomposition)<ref name="TCI">{{TCI Europe|N0408|Name=N-(2-Carboxyethyl)iminodiacetic Acid|Datum=5. Juni 2017}}</ref>
| BoilingPt =
| Solubility = Soluble <ref name="saapedia">SAA Pedia: [http://www.saapedia.org/en/saa/?type=detail&id=197 N,N-Bis(carboxymethyl)-beta-alanine]</ref>
}}
| Section3 = {{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
}}
'''''N''-(2-Carboxyethyl)iminodiacetic acid''' or '''β-ADA''' '''(β-alanine diacetate)''' is an [[organic compound]] with the formula {{chem2|HO2CCH2CH2N(CH2CO2H)2}}.  It is a white solid.  The compound is classified as an aminocarboxylic acid, formally a derivative of [[glycine]].
==Ligand properties==
The conjugate base is  [[tetradentate complexing agent]] that forms 1:1 complexes with cations having a charge number of at least +2, e.g. the "[[Hard water|hard water forming]]" [[cations]] [[Calcium|Ca<sup>2+</sup>]] or [[Magnesium|Mg<sup>2+</sup>]]. ''N''-(2-Carboxyethyl)iminodiacetic acid should not be confused with α-alaninediacetic acid, also known as methylglycinediacetic acid (MGDA) or α-ADA. Alkaline earth and heavy metal complexes of both, α-ADA and β-ADA are biodegradable (in contrast to chelate complexes with conventional complexing agents such as [[Ethylenediaminetetraacetic acid|EDTA]]).
== Production ==
''N''-(2-carboxyethyl)iminodiacetic acid was first prepared from [[Β-Alanine|β-alanine]] and [[Monochloroacetic Acid|monochloroacetic acid]] as reported by [[Gerold Schwarzenbach]] in 1949.<ref>{{cite journal|doi=10.1002/hlca.19490320403 |title=Komplexone XV. Neue Derivate der Imino-diessigsäure und ihre Erdalkalikomplexe. Beziehungen zwischen Acidität und Komplexbildung |date=1949 |last1=Schwarzenbach |first1=G. |last2=Ackermann |first2=H. |last3=Ruckstuhl |first3=P. |journal=Helvetica Chimica Acta |volume=32 |issue=4 |pages=1175–1186 }}</ref>
:{{chem2|HO2CCH2CH2N(CH2CO2H)2  +  2 ClCH2CO2H  ->  HO2CCH2CH2N(CH2CO2H)2  +  2 HCl}}
The double cyanomethylation of β-alanine as starting material provides with [[methanal]] and alkali cyanides and subsequent hydrolysis of the intermediately formed bis-methyl cyanides followed by acidification with mineral acids β-ADA (N-(2-carboxyethyl)iminodiacetic acid) in yields of only 80%, but very high purity of 99.8%.<ref>{{Cite patent|country = EP|number = 490228|title = Verfahren zur Herstellung von beta-Alanindiessigsäure und ihren Alkalimetallsalzen|gdate =1990-12-14 |A-Datum = |invent1 = M. Zipplies et al.|assign1= BASF AG}}</ref>
[[File:Alanindiessigsäure Synthese 2 V3.svg|rahmenlos|907x907px]]
The [[cyanoethylation]] of [[iminodiacetic acid]] with [[2-propenenitrile]] by a [[Michael addition]] provides the ethyl cyano compound, which produces after alkaline hydrolysis and acidification β-ADA with  a total yield of 93.6% and purity of 99.9% .<ref name="Kneip">{{Cite patent|country = EP|number = 641310|title = Verfahren zur Herstellung von β-Alanindiessigsäure oder ihren Alkalimetall- oder Ammoniumsalzen|gdate =1997-01-15 |A-Datum = |invent1 = M. Kneip et al.|assign1= BASF AG}}</ref>
[[File:Alanindiessigsäure Synthese 3 V3.svg|rahmenlos|748x748px]]
In the analogue reaction with [[acrylic acid ester]]s, 99.9% β-ADA are obtained after acidification in a total yield of 97.6%.<ref name="Kneip" />
A more direct route is via the Michael addition of [[acrylic acid]] to iminodiacetic acid, which produces the trisodium salt of β-ADA in 97% yield and 99.2% purity.<ref>{{Cite patent|country = EP |number = 0356972 |title =Verfahren zur Herstellung von beta-Alanindiessigsäure oder ihren Alkalimetall- oder Ammoniumsalzen |gdate = 1997-04-02.|A-Datum = |invent1 = R. Baur et al. |assign1= BASF AG}}</ref> The conversion to β-ADA itself is not described in this patent specification.
The most economical synthesis route is based on iminodiacetic acid, which is easily accessible by oxidizing diethanolamine and serves as a key raw material for the [[herbicide]] [[glyphosate]].
== Properties ==
''N''-(2-Carboxyethyl)iminodiacetic acid is very well degradable in [[sewage plant]] simulations (98% after eight weeks).  It is low in toxicity.<ref>{{citation|surname1=L. Nitschke, A. Wilk, C. Cammerer, G. Lind, G. Metzner|periodical=Chemosphere |title=Biodegradation and aquatic toxicity of β-alaninediacetic acid (β-ADA)|volume=34|issue=4 |at=pp.&nbsp;807–815|date=February 1997 |doi=10.1016/S0045-6535(97)00009-X
|pmid=9569945 |bibcode=1997Chmsp..34..807N }}</ref> Elsewhere, the poor microbial degradability and adsorbability of β-ADA is pointed out.<ref>Hessisches Landesamt für Umwelt und Geologie, ''[http://www.hlug.de/fileadmin/dokumente/wasser/fliessgewaesser/gewaesserbelastung/orientierende_messungen/6.12Komplexbildner.pdf 6.12 Komplexbildner]'', S. 12/3, 2003.</ref> The contradictory assessment of the degradability of β-ADA, the weaker complex formation compared to the (rapidly biodegradable) [[methylglycine diacetic acid]] (MGDA, Trilon M) and the lower stability in wide temperature and pH ranges have substantially contributed to the breakthrough of MGDA as the most suitable substitute for EDTA.<ref>Environmental Protection Agency, [http://www.epa.gov/dfe/saferingredients.htm#about ''DfE's Safer Chemical Ingredients List, Chelating Agents''], [http://www.epa.gov/dfe/saferingredients-cas.htm#164462162 Alanine, N,N-bis(carboxymethyl)-, sodium salt (1:3)].</ref>
== Use ==
Like other complexing agents from the class of aminopolycarboxylic acids, ''N''-(2-carboxyethyl)iminodiacetic acid is used in water softening, in detergents and cleaning agents, in electroplating, [[cosmetics]], paper and textile production. This is based on  its ability to form stable [[chelate complex]]es with [[polyvalent ions]], in particular the water hardness formers Ca<sup>2+</sup> and Mg<sup>2+</sup>, as well as transition and heavy metal ions, such as Fe<sup>3+</sup>, Mn<sup>2+</sup>, and Cu<sup>2+</sup>, etc.
== References ==
<references />
{{DEFAULTSORT:Carboxyethyliminodiacetic acid, N-2-}}
[[Category:Alpha-Amino acids]]
[[Category:Beta-Amino acids]]
[[Category:Tricarboxylic acids]]