In
chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...
, melem is a
compound
Compound may refer to:
Architecture and built environments
* Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall
** Compound (fortification), a version of the above fortified with defensive struc ...
with formula ; specifically, 2,5,8-triamino-heptazine or 2,5,8-triamino-tri-''s''-triazine, whose molecule can be described as that of
heptazine
Heptazine, or tri-''s''-triazine or cyamelurine, is a chemical compound with formula , that consist of a planar triangular core group or three fused triazine rings, with three hydrogen atoms at the corners. It is a yellow, weakly fluorescent soli ...
with the three hydrogen atoms replaced by
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. It is a white crystalline solid.
[
]
Preparation
Melem can be prepared by thermal decomposition of various C−N−H compounds, such as melamine
Melamine is an organic compound with the formula C3H6N6. This white solid is a trimer (chemistry), trimer of cyanamide, with a 1,3,5-Triazine, 1,3,5-triazine skeleton. Like cyanamide, it contains 66% nitrogen by mass, and its derivatives ha ...
C3N3(NH2)3, dicyandiamide H4C2N4, ammonium dicyanamide NH4 (CN)2 cyanamide
Cyanamide is an organic compound with the formula C N2 H2. This white solid is widely used in agriculture and the production of pharmaceuticals and other organic compounds. It is also used as an alcohol-deterrent drug. The molecule features a ...
H2CN2, at 400 to 450 °C.[
]
Structure and properties
Crystal structure
Melem crystallizes in the group
A group is a number of persons or things that are located, gathered, or classed together.
Groups of people
* Cultural group, a group whose members share the same cultural identity
* Ethnic group, a group whose members share the same ethnic iden ...
P21/c (No. 14), with parameters a = 739.92(1) pm, b = 865.28(3) pm, c = 1338.16(4) pm, β = 99.912(2)°, and Z = 4. The almost-planar molecules are arranged in parallel layers spaced 327 pm apart. The molecule is in the triamino form, rather than one of the possible tautomers.[
]
Thermal decomposition
When heated above 560°, melem transforms into a graphite-like C−N material.[
]
Melemium cations
Melem accepts up to three protons yielding cations called melemium . Some salts described in the literature are melemium sulfate, • 2, melemium perchlorate, • , melemium hydrogensulfate and two melemium methylsulfonates • and • . The protons can be inserted in any of the six outer nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
atoms of the heptazine core, yielding many tautomers of apparently similar energies.[
]
See also
* Triazine
Triazines are a class of nitrogen-containing heterocycles. The parent molecules' molecular formula is . They exist in three isomeric forms, 1,3,5-triazines being common.
Structure
The triazines have planar six-membered benzene-like ring but ...
, with a single C-N ring
* Melamine
Melamine is an organic compound with the formula C3H6N6. This white solid is a trimer (chemistry), trimer of cyanamide, with a 1,3,5-Triazine, 1,3,5-triazine skeleton. Like cyanamide, it contains 66% nitrogen by mass, and its derivatives ha ...
, triamino triazine
* Melaminium , a cation derived from melamine
* Melam
The term "melam" means "ensemble," as in a "musical ensemble." In Kerala, "melam" refers to a group of Maddalam (drums) and similar percussion instruments (such as a Chenda) in a rhythmic performance. Those who play in melams are called 'Melakaa ...
, a condensation dimer of melamine
* Melamium , a cation derived from melam
* Melon
A melon is any of various plants of the family Cucurbitaceae with sweet, edible, and fleshy fruit. It can also specifically refer to ''Cucumis melo'', commonly known as the "true melon" or simply "melon". The term "melon" can apply to both the p ...
, a condensation oligomer of melem
References
[Tamikuni Komatsu (2001)> {{Cite journal , last=Komatsu , first=Tamikuni , date=2001-01-01 , title=The First Synthesis and Characterization of Cyameluric High Polymers , url=https://onlinelibrary.wiley.com/doi/10.1002/1521-3935(20010101)202:13.0.CO;2-G , journal=Macromolecular Chemistry and Physics , language=en , volume=202 , issue=1 , pages=19–25 , doi=10.1002/1521-3935(20010101)202:1<19::AID-MACP19>3.0.CO;2-G , issn=1022-1352, url-access=subscription ]
[Fabian Karl Keßler (2019), ]
Structure and Reactivity of s-Triazine-Based Compounds in C/N/H Chemistry
'. Doctoral thesis, Fakultät für Chemie und Pharmazie, Ludwig-Maximilians-Universität München
The Ludwig Maximilian University of Munich (simply University of Munich, LMU or LMU Munich; ) is a public university, public research university in Munich, Bavaria, Germany. Originally established as the University of Ingolstadt in 1472 by Duke ...
Heterocyclic compounds with 3 rings
Nitrogen heterocycles
Tricyclic compounds
Amines