Tricyclo [22.214.171.124 3.7 ] decane
|Molecular formula||C 10 H 16|
colorless solid with a camphor smell
|External identifiers / databases|
|Molar mass||136.23 g mol −1|
1.07 g cm −3 (20 ° C)
266-268 ° C
almost insoluble in water
|As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .|
Adamantane is a bridged hydrocarbon and the simplest diamondoid . It forms colorless crystals that smell like camphor . Formally, the structure of adamantane consists of four cyclohexane molecules in a chair conformation . This highly symmetrical structure ( point group T d ) is also found in other chemical substances such as methenamine and phosphorus trioxide ; it is sometimes referred to as adamantane-like .
The tricyclic hydrocarbon is easily accessible by rearrangement of tetrahydrodicyclopentadiene , which is produced by hydrogenation of the Diels-Alder dimer of cyclopentadiene , using aluminum chloride . The production takes place at 160 ° C and approx. 3 MPa.
Over 10,000 tons of adamantane are produced annually.
Adamantane is a solid substance at room temperature that occurs in two polymorphic crystal forms. At room temperature, the crystal form I is present, which changes into the liquid phase at 270 ° C. A phase transition from crystal form II to form I is observed at −64.5 ° C. Here the transition from the crystalline to a plastic crystalline form takes place. This means that the compound is in a mesomorphic state above this temperature up to the melting point and thus also at room temperature . The behavior is analogous to similar "spherical" molecules such as cubane or tetramethylbutane , which form similar mesophases.
Adamantane is very stable and generally not very reactive. Eliminations are impossible, Bredt's rule applies to all carbon atoms. Substitution reactions mainly take place at the bridgehead C1. Adamantane is almost insoluble in water.
Adamantane is used in polymer compounds to improve resistance to solvents , chemicals and heat . It is used as a matrix for radicals and as a reference substance in solid-state NMR spectroscopy . Due to the high symmetry of the molecules, there is a molecular rotation in the solid that is particularly easy to measure.
It is also used to manufacture other adamantane derivatives :
- Adamantan-1-ylamine ( amantadine ) is used against Parkinson's disease and against the flu caused by the influenza A virus . It has a preventive effect against the influenza A virus H5N1 of the bird flu H5N1 48 hours after infection.
- 3,5-Dimethyl-adamantan-1-ylamine ( memantine ) is used as an anti- dementia agent in the treatment of moderate to severe dementia of the Alzheimer's type.
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