Ethylenediamine

Synthesis

Ethylenediamine is produced industrially by treating 1,2-dichloroethane with ammonia under pressure at 180 °C in an aqueous medium (EDC process):

:[[File:Ethylendiamin Darstellung.svg|400px]]

In this reaction hydrogen chloride is generated, which forms a salt with the amine. The amine is liberated by addition of sodium hydroxide and can then be recovered by fractional distillation. Diethylenetriamine (DETA) and triethylenetetramine (TETA) are formed as by-products.

Another industrial route to ethylenediamine involves the reaction of ethanolamine and ammonia: :[[File:EDA synthesis from MEOA.svg|400px]] This process involves passing the gaseous reactants over a bed of nickel heterogeneous catalysts.

It can be prepared in the lab by the reaction of either ethylene glycol or ethanolamine and urea, followed by decarboxylation of the ethyleneurea intermediate.

Ethylenediamine can be purified by treatment with sodium hydroxide to remove water followed by distillation.

Applications

Ethylenediamine is used in large quantities for production of many industrial chemicals. It forms derivatives with carboxylic acids (including fatty acids), nitriles, alcohols (at elevated temperatures), alkylating agents, carbon disulfide, and aldehydes and ketones. Because of its bifunctional nature, having two amino groups, it readily forms heterocycles such as imidazolidines.

Precursor to chelation agents, drugs, and agrochemicals

A most prominent derivative of ethylenediamine is the chelating agent EDTA, which is derived from ethylenediamine via a Strecker synthesis involving cyanide and formaldehyde. Hydroxyethylethylenediamine is another commercially significant chelating agent. Salts of ethylenebisdithiocarbamate are commercially significant fungicides under the brand names Maneb, Mancozeb, Zineb, and Metiram. Some imidazoline-containing fungicides are derived from ethylenediamine.

Pharmaceutical ingredient

Ethylenediamine is an ingredient in the common bronchodilator drug aminophylline, where it serves to solubilize the active ingredient theophylline. Ethylenediamine has also been used in dermatologic preparations, but has been removed from some because of causing contact dermatitis. When used as a pharmaceutical excipient, after oral administration its bioavailability is about 0.34, due to a substantial first-pass effect. Less than 20% is eliminated by renal excretion.

Ethylenediamine-derived antihistamines are the oldest of the five classes of first-generation antihistamines, beginning with piperoxan aka benodain, discovered in 1933 at the Pasteur Institute in France, and also including mepyramine, tripelennamine, and antazoline. The other classes are derivatives of ethanolamine, alkylamine, piperazine, and others (primarily tricyclic and tetracyclic compounds related to phenothiazines, tricyclic antidepressants, as well as the cyproheptadine-phenindamine family)

Role in polymers

Ethylenediamine, because it contains two amine groups, is a widely used precursor to various polymers. Condensates derived from formaldehyde are plasticizers. It is widely used in the production of polyurethane fibers. The PAMAM class of dendrimers are derived from ethylenediamine.

Tetraacetylethylenediamine

The bleaching activator tetraacetylethylenediamine is generated from ethylenediamine. The derivative N,N-ethylenebis(stearamide) (EBS) is a commercially significant mold-release agent and a surfactant in gasoline and motor oil.

Other applications

• as a solvent, it is miscible with polar solvents and is used to solubilize proteins such as albumins and casein. It is also used in certain electroplating baths.
• as a corrosion inhibitor in paints and coolants.
• ethylenediamine dihydroiodide (EDDI) is added to animal feeds as a source of iodide.
• chemicals for color photography developing, binders, adhesives, fabric softeners, curing agents for epoxies, and dyes.
• as a compound to sensitize nitromethane into an explosive. This mixture was used at Picatinny Arsenal during World War II, giving the nitromethane and ethylenediamine mixture the nickname PLX, or Picatinny Liquid Explosive.

Coordination chemistry

Ethylenediamine is a well-known bidentate chelating ligand for coordination compounds, with the two nitrogen atoms donating their lone pairs of electrons when ethylenediamine acts as a ligand. It is often abbreviated "en" in inorganic chemistry. The complex [Co(en)3]3+ is a well studied example. Schiff base ligands easily form from ethylenediamine. For example, the diamine condenses with 4-Trifluoromethylbenzaldehyde to give to the diimine. The salen ligands, some of which are used in catalysis, are derived from the condensation of salicylaldehydes and ethylenediamine.

Related ligands

Related derivatives of ethylenediamine include ethylenediaminetetraacetic acid (EDTA), tetramethylethylenediamine (TMEDA), and tetraethylethylenediamine (TEEDA). Chiral analogs of ethylenediamine include 1,2-diaminopropane and trans-diaminocyclohexane.

Safety

Ethylenediamine, like ammonia and other low-molecular weight amines, is a skin and respiratory irritant. Unless tightly contained, liquid ethylenediamine will release toxic and irritating vapors into its surroundings, especially on heating. The vapors absorb moisture from humid air to form a characteristic white mist, which is extremely irritating to skin, eyes, lungs and mucous membranes.

References

References

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