trans-1,2-Cyclohexanediamine-N,N,N',N'-tetraacetic acid monohydrate
[CAS# 125572-95-4]

Identification

• Classification: Analytical chemistry >> Analytical reagent >> Common analytical reagents
• Name: trans-1,2-Cyclohexanediamine-N,N,N',N'-tetraacetic acid monohydrate
• Synonyms: trans-(±)-N,N'-1,2-Cyclohexanediylbis[N-(carboxymethyl)glycine monohydrate
• Molecular Formula: C₁₄H₂₂N₂O₈.H₂O
• Molecular Weight: 364.35
• CAS Registry Number: 125572-95-4
• EC Number: 681-197-6
• SMILES: C1CC[C@H]([C@@H](C1)N(CC(=O)O)CC(=O)O)N(CC(=O)O)CC(=O)O.O

Properties

• Melting point: 213 - 216 °C (Expl.)

Safety Data

• Hazard Symbols: GHS07;GHS09 Warning
• Risk Statements: H315-H319-H332-H335-H411
• Safety Statements: P261-P264-P264+P265-P271-P273-P280-P302+P352-P304+P340-P305+P351+P338-P317-P319-P321-P332+P317-P337+P317-P362+P364-P391-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H332
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335

Discovery and Applications

trans-1,2-Cyclohexanediamine-N,N,N',N'-tetraacetic acid monohydrate is a derivative of ethylenediaminetetraacetic acid (EDTA) modified by incorporating a cyclohexane ring in place of the ethylene bridge. The compound was developed during investigations into new chelating agents with enhanced stability and selectivity for metal ions. The incorporation of the cyclohexane moiety was intended to introduce conformational rigidity, which influences the binding characteristics of the ligand compared to more flexible analogues like EDTA.

This chelating agent binds strongly to a variety of metal ions, forming stable complexes through its four carboxylate groups and two amine groups. The trans-configuration of the cyclohexane ring orients the two nitrogen donor atoms on opposite sides, favoring the formation of octahedral complexes with metal ions. The monohydrate form refers to the inclusion of one molecule of water per formula unit, which can influence the physical properties such as solubility and crystalline structure but does not significantly alter the chelation behavior.

The primary application of trans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid monohydrate lies in coordination chemistry and analytical chemistry. It is employed in metal ion sequestration, particularly for transition metals such as copper, nickel, and zinc. Its enhanced rigidity compared to EDTA often results in higher thermodynamic stability constants for certain metal complexes, making it useful in contexts where stronger or more selective binding is desired.

In biochemical and biomedical research, this compound has been used to study the structure and function of metalloproteins by chelating metal ions that are critical to enzyme activity. Additionally, it has found application in environmental chemistry, notably in processes involving the removal or stabilization of heavy metals from wastewater and contaminated soils. The stability and specificity of its metal complexes are advantageous for minimizing the unintended release of metals into the environment.

The design and use of trans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid monohydrate reflect the broader scientific interest in modifying classic chelators to tune their chemical and physical properties for specialized applications. Its introduction provided researchers and industrial users with a more rigid and sometimes more selective alternative to EDTA, contributing to advancements in metal coordination chemistry, environmental remediation, and biochemistry.

References

1975. The reversible reduction of horse metmyoglobin by the iron(II) complex of trans-1,2-diaminocyclohexane-N,N,N,n-tetraacetate. Biochemistry, 14(24).
DOI: 10.1021/bi00696a014

2023. Determination of Calcium in Meat Products by Automatic Titration with 1,2-Diaminocyclohexane-N,N,N’,N’-tetraacetic Acid. Molecules (Basel, Switzerland), 28(18).
DOI: 10.3390/molecules28186592