(+/-)-trans-1,2-Diaminocyclohexane
[CAS# 1121-22-8]

Identification

• Classification: Chemical reagent >> Organic reagent >> Polyamine
• Name: (+/-)-trans-1,2-Diaminocyclohexane
• Synonyms: (+/-)-trans-1,2-Cyclohexanediamine
• Molecular Formula: C₆H₁₄N₂
• Molecular Weight: 114.19
• CAS Registry Number: 1121-22-8
• EC Number: 601-163-6
• SMILES: C1CC[C@H]([C@@H](C1)N)N

Properties

• Density: 0.951 g/mL
• Melting point: 14-15 °C
• Boiling point: 79-81 °C (15 mmHg)
• Refractive index: 1.4885-1.4905
• Flash point: 68 °C
• Water solubility: Soluble

Safety Data

• Hazard Symbols: GHS05;GHS07 Danger
• Risk Statements: H314-H317
• Safety Statements: P260-P261-P264-P272-P280-P301+P330+P331-P302+P352-P302+P361+P354-P304+P340-P305+P354+P338-P316-P321-P333+P317-P362+P364-P363-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1B	H314
Serious eye damage	Eye Dam.	1	H318
Skin sensitization	Skin Sens.	1	H317
Eye irritation	Eye Irrit.	2	H319
Skin corrosion	Skin Corr.	1C	H314
Flammable liquids	Flam. Liq.	4	H227
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315

• Transport Information: UN 2735

Discovery and Applications

(+/-)-trans-1,2-Diaminocyclohexane is an organic compound consisting of a cyclohexane ring substituted with two amino (-NH₂) groups at the 1 and 2 positions in a trans configuration. The term "(+/-)" indicates that the compound is a racemic mixture, containing equal amounts of both enantiomers (the (1R,2R) and (1S,2S) forms). Its molecular formula is C₆H₁₄N₂.

This compound is a key chiral diamine and has found broad utility as a ligand, intermediate, and building block in both academic research and industrial applications. The trans stereochemistry refers to the spatial arrangement of the two amino groups being on opposite sides of the cyclohexane ring, resulting in distinct chemical and physical properties compared to the cis isomer.

The synthesis of racemic trans-1,2-diaminocyclohexane is typically achieved through hydrogenation of o-phenylenediamine or nitrocyclohexane derivatives, or via reductive amination processes involving cyclohexanedione intermediates. Alternatively, it can be derived from resolution of the cis isomer under specific catalytic or crystallization conditions. Commercially, the racemic trans form is widely available and cost-effective.

One of the most important applications of (+/-)-trans-1,2-diaminocyclohexane is in coordination chemistry. It serves as a bidentate ligand, coordinating metal ions through both nitrogen atoms. Complexes formed with transition metals, such as platinum, ruthenium, and rhodium, are extensively used in catalysis, including asymmetric hydrogenation, oxidation, and C-C bond-forming reactions. Metal complexes of the enantiopure forms of this diamine are also used as chiral auxiliaries or catalysts in enantioselective synthesis.

Another critical application is in the field of pharmaceuticals. While the racemate itself is not typically used as a drug, its derivatives and metal complexes have shown significant biological activity. For example, certain platinum complexes containing trans-1,2-diaminocyclohexane ligands exhibit antitumor activity and are structurally related to oxaliplatin, a clinically used anticancer drug.

In polymer and material science, (+/-)-trans-1,2-diaminocyclohexane is used as a monomer or curing agent in the production of polyureas and polyimides, where its rigidity and stereochemistry contribute to thermal and mechanical stability of the resulting materials.

Physically, the compound is a colorless to pale yellow solid at room temperature. It is soluble in water, alcohols, and many organic solvents. The two amino groups contribute to its basicity and reactivity, allowing it to participate in condensation, alkylation, acylation, and other transformations. As a primary diamine, it can also undergo reactions with aldehydes and ketones to form Schiff bases or with carboxylic acids and acid chlorides to form diamides.

In handling, it should be noted that the compound is corrosive and may cause irritation to skin, eyes, and respiratory system. Proper protective equipment and ventilation are necessary during use.

In summary, (+/-)-trans-1,2-diaminocyclohexane is a versatile, racemic chiral diamine widely employed in coordination chemistry, asymmetric catalysis, and materials synthesis. Its structural rigidity, trans stereochemistry, and dual amine functionality make it a valuable intermediate and ligand across diverse chemical disciplines.

References

2018. Recent Developments in the Synthesis of Pyrido[1,2-a]benzimidazoles. Synthesis, 50(8).
DOI: 10.1055/s-0036-1589533

2018. Asymmetric Synthesis of Adamantyl GABA Analogues. Synthesis, 50(19).
DOI: 10.1055/s-0037-1610824

2024. Rational design of dual Chemo- and Thermo-responsive phase separation of Poly(4-hydroxystyrene) in non-aqueous media. Polymer Journal, 56(10).
DOI: 10.1038/s41428-024-00968-9