| Ethylenediamine is a colourless to yellowish, strongly alkaline liquid, melting
at 8.5 C, boiling at 116 C; completely soluble in water and soluble alcohol. It
is a manufactured chemical that does not occur naturally. It has two primary
amine groups. There are homologous odd number amine (on even number linear
carbon chain) series of ethylenediamines; diethylenetriamine (linear C-4
diamine), triethylenetetramine (linear C-6 triamine), tetraethylenepentamine
(linear C-8 pentamine), and pentaethylenehexamine (linear C-10 hexamine).
Diethylenediamine is the simplest cyclic ethyleneamine (C-4), called piperazine.
It has two secondary amine groups in cyclic system. It is a deliquescent
crystalline compound melting at 105 C; soluble in water, alcohol, glycerol, and
glycols. It is used as a main ingredient of anthelmintics and psychoactive
drugs. Aminoethylpiperazine is also a member of C- 6 cyclic ethyleneamine which
has aminoethyl attached to a nitrogen in piperazine. Accordingly, it has one
primary, one secondary, and one tertiary nitrogen atom. It is used in the
synthesis of catalysts, epoxy curing agent, and corrosion inhibitors.
Aminoethylethanolamine (AEEA) is an analogue of diethylenetriamine. A hydroxyl
group replace for an primary amine group. AEEA has one primary amine, one
secondary amine, and one primary hydroxyl group. AEEA is a useful intermediate
in the production of surfactants, chelating agents, and curing agents. Other
branched or cyclic ethylenediamines include N,N'-Bis-(2-aminoethyl)piperazine)
[CAS #: 6531-38-0], N-[(2-aminoethyl)2-aminoethyl]piperazine) [CAS #: 24028-46-4], tris(2-aminoethyl)amine)
[CAS #: 4097-89-6].
Ethylenediamines are produced by the reaction of aqueous ammonia with
1,2-dichloroethane. This process yields the mixture of polyamines in the form of
hydrochloride salts. The next step is neutralisation of the salts with aqueous caustic soda
to separate free amines. The individual free amines are isolated by fractional
distillation. Ethylenediamines are capable of entering into a variety of
reactions because of their combination of reactivity, basicity, and surface
activity and of the basic functionality of the nitrogen atom. They are therefore
important intermediates for a wide variety of chemical syntheses. Examples of
products obtained by reacting amines are as follows:
- with carboxylic acid
dericatives (acids, esters, anhydrides, or acyl halides): amides and
amidoamines
- with fatty acid: imidazoline
- with cyanides or nitriles:
amidoamines, polyamides, imidazolines
- with urea: substituted urea and
ammonia
- with ethyleneimines: hydroxyalkyl amine derivatives
- with aliphatic
alcohols and glycols: alkylated ethyleneamines or cyclic ethyleneamines
- with
alkyl or aryl halides: substituted amines
- with aliphatic aldehydes:
substituted imidazolidines
- with carbon disulfide: thiocarbamates
- with
carbon dioxide: carbamate
- with inorganic acids: water soluble
salts
Ethylenediamine is used as a very important bidentate ligand
forming chelate agents. The main application is to produce chelating agents
such as ethylenediaminetetraacetic acid (EDTA). It is used in the manufacture of
carbamate fungicides, surfactant and dyes. It is useful also in manufacturing
accelerator or curing agent in epoxy industry. Additional applications include
manufacturing photography development chemicals and cutting oils, bleaching
activators for washing powders especially at low temperature, lubricant for
plastics and polyamide process, and fuel additives.
Diethylenetriamine is
a yellow, hygroscopic liquid; boiling point of 206 C; soluble in water and
hydrocarbons. It is used as a solvent for sulfur, acidic gas, resin and as a
fuel and oil field component. It is used as an Intermediate for organic
synthesis (modified polyamides, corrosion inhibitors, fuel additives, epoxy
curing agents, fabric softeners and adhesion promoters) and saponification agent
for acidic materials.
Triethylenetetramine is a clear to yellowish oily
liquid; melting point 12 C, boiling point 280 C. It is miscible with water and
the solution is alkaline ( (pH 10 at 10% solution). It reacts with ketones,
halogenated hydrocarbons, nitriles, epoxides, and with strong oxidants.
Commercial triethylenetetramine is a mixture of linear TETA (typically 60%) and
branched or cyclic TETA such as N,N'-Bis(2-aminoethyl)piperazine,
N-[1-(2-piperazin-1-yl-ethyl)]ethane -1,2-diamine, tris-(2-aminoethyl)-amine.
TETA and its derivatives are used as an epoxy curing agent. Their applications
are similar to those of ethylenediamine and diethylenetriamine.
End uses
of ethylenediamine family products include:
- Dispersant-detergent
- Modified
Polyamides
- Fabric Softeners
- Ore Flotation
Agents
- Emulsifiers
- Corrosion Inhibitors
- Adhesives
- Binding
Agents
- Chelating Agents
- Bleach Activators
- Epoxy Curing Agent
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Chelation is a chemical combination with a metal in complexes in which the
metal is part of a ring. Organic ligand is called chelator or chelating agent,
the chelate is a metal complex. The larger number of ring closures to a metal
atom is the more stable the compound. This phenomenon is called the chelate
effect; it is generally attributed to an increase in the thermodynamic quantity
called entropy that accompanies chelation. The stability of a chelate is also
related to the number of atoms in the chelate ring. Monodentate ligands which
have one coordinating atom like H2O or NH3 are easily broken apart by other
chemical processes, whereas polydentate chelators, donating multiple binds to
metal ion, provide more stable complexes. Chlorophyll, green plant pigment, is a
chelate that consists of a central magnesium atom joined with four complex
chelating agent (pyrrole ring). The molecular structure of the chlorophyll is
similar to that of the heme bound to proteins to form hemoglobin, except that
the latter contains iron(II) ion in the center of the porphyrin. Heme is an iron
chelate. Chelation is applied in metal complex chemistry, organic and inorganic
chemistry, biochemistry, and environment protection. It is used in
chemotherapeutic treatments for metal poisoning. Chelating agents offers a wide
range of sequestrants to control metal ions in aqueous systems. By forming
stable water soluble complexes with multivalent metal ions, chelating agents
prevent undesired interaction by blocking normal reactivity of metal ions. EDTA,
ethylenediaminetetraacetate (hexadentating), is a good example of common
chelating agent which have nitrogen atoms and short chain carboxylic groups. The
sodium salt of EDTA is used as an antidote for metal poisoning, an
anticoagulant, and an ingredient in a variety of detergents. Chelating agents
are important in the field of soap, detergents, textile dyeing, water softening,
metal finishing and plating, pulp and paper, enzyme deactivation, photo
chemistry, and bacteriocides.
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