A diamine is an

amine In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

with two

amino group In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

s. Diamines are used as

monomers A monomer ( ; ''wikt:mono-, mono-'', "one" + ''wikt:-mer, -mer'', "part") is a molecule that can chemical reaction, react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called ...

to prepare

polyamide A polyamide is a polymer with repeating units linked by amide bonds. Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made throug ...

polyimide Polyimide (sometimes abbreviated PI) is a monomer containing imide groups belonging to the class of high-performance plastics. With their high heat-resistance, polyimides enjoy diverse applications in roles demanding rugged organic materials, suc ...

s, and

polyurea Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate component and an amine component. The isocyanate can be aromatic or aliphatic in nature. It can be monomer, polymer, or any variant reaction of isocyanate ...

s. The term ''diamine'' refers mostly to

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diamines, as those are the most reactive. In terms of quantities produced,

1,6-diaminohexane Hexamethylenediamine or hexane-1,6-diamine, is the organic compound with the formula H2N(CH2)6NH2. The molecule is a diamine, consisting of a hexamethylene hydrocarbon chain terminated with amine functional groups. The colorless solid (yellowish f ...

(a precursor to

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) is most important, followed by

ethylenediamine Ethylenediamine (abbreviated as en when a ligand) is the organic compound with the formula C2H4(NH2)2. This colorless liquid with an ammonia-like odor is a basic amine. It is a widely used building block in chemical synthesis, with approximately ...

. Vicinal diamines (1,2-diamines) are a structural motif in many biological compounds and are used as

ligands In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ...

coordination chemistry A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of chemical bond, bound molecules or ions, that are in turn known as ' ...

Aliphatic diamines

Linear

* 2 carbon backbone:

(1,2-diaminoethane). Related derivatives include the N-alkylated compounds, 1,1-dimethylethylenediamine,

1,2-dimethylethylenediamine N,N'-Dimethylethylenediamine (DMEDA) is the organic compound with the formula (CHNH)CH. It is a colorless liquid with a fishy odor. It features two secondary amine functional groups. Regarding its name, N and N' indicate that the methyl groups ...

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tetrakis(dimethylamino)ethylene Tetrakis(dimethylamino)ethylene (TDAE) is an organic compound with the formula , It is a colorless liquid. It is classified as an enamine. Primary and secondary enamines tend to isomerize, but tertiary enamines are kinetically stable. One unusual ...

TMEDA Tetramethylethylenediamine (TMEDA or TEMED) is a chemical compound with the formula (CH3)2NCH2CH2N(CH3)2. This species is derived from ethylenediamine by replacement of the four amine hydrogens with four methyl groups. It is a colorless liquid, ...

. Many 1,2-diamine derivatives are of practical interest such as

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. * 3 carbon backbone:

1,3-diaminopropane 1,3-Diaminopropane, also known as , is a simple diamine with the formula H2N(CH2)3NH2. A colourless liquid with a fishy odor, it is soluble in water and many polar organic solvents. It is isomeric with 1,2-diaminopropane. Both are building blocks ...

(propane-1,3-diamine) * 4 carbon backbone:

putrescine Putrescine is an organic compound with the formula (CH2)4(NH2)2. It is a colorless solid that melts near room temperature. It is classified as a diamine. Together with cadaverine, it is largely responsible for the foul odor of Putrefaction, putref ...

(butane-1,4-diamine) * 5 carbon backbone:

cadaverine Cadaverine is an organic compound with the formula (CH2)5(NH2)2. Classified as a diamine, it is a colorless liquid with an unpleasant odor. It is present in small quantities in living organisms but is often associated with the putrefaction of Tiss ...

(pentane-1,5-diamine) 120px,

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* 6 carbon backbone:

hexamethylenediamine Hexamethylenediamine or hexane-1,6-diamine, is the organic compound with the formula H2N(CH2)6NH2. The molecule is a diamine, consisting of a hexamethylene hydrocarbon chain terminated with amine functional groups. The colorless solid (yellowish f ...

(hexane-1,6-diamine, HMD). HMD and other long chain diamines can be prepared by

hydrocyanation In organic chemistry, hydrocyanation is a process for conversion of alkenes to nitriles. The reaction involves the addition of hydrogen cyanide and requires a catalyst if the substrate alkene is unactivated. This conversion is conducted on an in ...

to give di

nitrile In organic chemistry, a nitrile is any organic compound that has a functional group. The name of the compound is composed of a base, which includes the carbon of the , suffixed with "nitrile", so for example is called " propionitrile" (or pr ...

, which can be hydrogenated.

Branched

Derivatives of ethylenediamine are prominent: *

1,2-diaminopropane 1,2-Diaminopropane (propane-1,2-diamine) is organic compound with the formula CHCH(NH)CHNH. A colorless liquid, it is the simplest chiral diamine. Preparation Industrially, this compound is synthesized by the ammonolysis of 1,2-dichloropropane: ...

, which is chiral. *

2,3-Butanediamine 2,3-Butanediamine are organic compounds with the formula CH3CH(NH2)CH(NH2)CH3. Three stereoisomers exist, meso and a pair of enantiomers. These diamines form complexes with transition metals. Synthesis 2,3-Butanediamines can be prepared by hyd ...

, two diastereomers, one of which is C₂-symmetric. *

Diphenylethylenediamine 1,2-Diphenyl-1,2-ethylenediamine, DPEN, is an organic compound with the formula H2NCHPhCHPhNH2, where Ph is phenyl (C6H5). DPEN exists as three stereoisomers: meso and two enantiomers S,S- and R,R-. The chiral diastereomers are used in asymmetric ...

, two diastereomers, one of which is C₂-symmetric. * trimethylhexamethylenediamine, several isomers * 1,2-Diaminocyclohexane, two diastereomers, one of which is C₂-symmetric.

Cyclic

1,4-Diazacycloheptane, 120px, right *

piperazine Piperazine () is an organic compound with the formula . In term of its structure, it can be described as cyclohexane with the 1- and 4-CH2 groups replaced by NH. Piperazine exists as deliquescent solid with a saline taste. Piperazine is freely sol ...

() * 1,4-Diazacycloheptane

Xylylenediamines

Xylylenediamines are classified as alkylamines since the amine is not directly attached to an aromatic ring. *''o''-xylylenediamine or OXD * ''m''-xylylenediamine or MXD *''p''-xylylenediamine or PXD

Aromatic diamines

Three

phenylenediamine Phenylenediamine may refer to: * ''o''-Phenylenediamine or OPD, a chemical compound C6H4(NH2)2 * ''m''-Phenylenediamine or MPD, a chemical compound C6H4(NH2)2 * ''p''-Phenylenediamine or PPD, a chemical compound C6H4(NH2)2 Related compounds * ''N ...

s are known: * ''o''-phenylenediamine or OPD * ''m''-phenylenediamine or MPD * ''p''-phenylenediamine or PPD. 2,5-diaminotoluene is related to PPD but contains a methyl group on the ring. ''p''-phenylenediamine, 120px, thumb Various N-methylated derivatives of the phenylenediamines are known: * dimethyl-4-phenylenediamine, a reagent. * N,N'-di-2-butyl-1,4-phenylenediamine, an antioxidant. Examples with two aromatic rings include derivatives of

biphenyl Biphenyl (also known as diphenyl, phenylbenzene, 1,1′-biphenyl, lemonene or BP) is an organic compound that forms colorless crystals. Particularly in older literature, compounds containing the functional group consisting of biphenyl less one ...

and

naphthalene Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white Crystal, crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 Parts-per notation ...

: * 4,4'-diaminobiphenyl * 1,8-diaminonaphthalene

Geminal diamines

160px, Bis(dimethylamino)methane

Geminal In chemistry, the descriptor geminal () refers to the relationship between two atoms or functional groups that are attached to the same atom. A geminal diol, for example, is a diol (a molecule that has two alcohol functional groups) attached to ...

diamines (1,1-diamines) are an unusual class of diamines mainly of academic interest.

Bis(dimethylamino)methane Bis(dimethylamino)methane is the organic compound with the formula CH3)2Nsub>2CH2. It is classified as an aminal as well as a ditertiary amine, in fact the simplest. It is a colorless liquid that is widely available. It is prepared by the reac ...

( CH₃)₂Nsub>2CH₂) is a stable example. Geminal diamines with N-H bonds are particularly rare. They are invoked as intermediates in transimination reactions and the reduction of

amidines Amidines are organic compounds with the functional group RC(NR)NR2, where the R groups can be the same or different. They are the imine derivatives of amides (RC(O)NR2). The simplest amidine is formamidine, HC(=NH)NH2. Examples of amidines incl ...

. In aqueous conditions they preferentially eliminate the less basic amine to leave an iminium ion. Some stable geminal diamines have been isolated. The parent gem-diamine is

methylenediamine Methanediamine is the simplest geminal diamine. Its chemical formula is CH2(NH2)2, and its structure consists of two amino groups on a central carbon atom. Although methanediamine only exists transiently in solution, its hydrochloride salt has be ...

(diaminomethane), which again is mainly of theoretical interest.

References

External links

* {{MeshName, Diamines
Synthesis of diamines
Monomers