Adamantane

Tricyclo [ 3.3.1.13,7 ] decane

Camphor- smelling colorless solid

Fixed

1.07 g · cm -3 ( 20 ° C)

266-268 ° C Sublimation from 20 ° C

Insoluble in water

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Adamantane is a cycloalkane and the simplest diamondoid. The structure of the adamantane formally consists of four Cyclohexanmolekülen in chair conformation. This highly symmetric structure ( point group Td) is also found in other chemical substances such as hexamine and phosphorus trioxide; such substances are sometimes referred to as adamantane -like. The analogy is limited to the structure.

The colorless, camphor- smelling crystals sublimate, despite their high melting point even at room temperature, which is due to the spherical shape of the molecule.

Occurrence

Adamantane occurs in nature only in trace amounts in some mountain crystals before. It is also found in small quantities in petroleum, from which it was first isolated.

Synthesis

The tricyclic hydrocarbon is easily accessible by rearrangement of tetrahydrodicyclopentadiene, which is prepared by hydrogenation of the Diels -Alder dimer of cyclopentadiene by means of aluminum chloride. The preparation takes place at 160 ° C and about 3 MPa.

With an improved synthesis of superacid as catalyst via the detour of a synthesis of 1,3 -dialkyl- adamantane can be installed in the adamantane polymers by a process of Sun Oil.

Over 10,000 tons of adamantane are produced annually.

Properties

Adamantane is very stable and generally less reactive. Eliminations are impossible, the Bredt rule applies to all carbon atoms. Substitution reactions mainly take place at the bridgehead C1. In water adamantane is almost insoluble.

Use

Adamantane used in polymer compounds in order to improve the resistance to solvents, chemicals and heat. It is used as a matrix for radicals and as a reference substance in the solid-state NMR spectroscopy. Due to the high symmetry of the molecules, a molecular rotation in the solid state exists, which is particularly easy to measure.

It is also for the production of other adamantane derivatives use:

• Adamantane -1 -ylamine ( Amantadine ) is used for Parkinson's disease and against triggered by influenza A virus influenza. It has a preventive effect against the influenza A virus H5N1 strain of avian influenza H5N1 48 hours after infection.

• 3,5-dimethyl- adamantane -1 -ylamine ( Memantine ) is used as an anti-dementia drug in the treatment of moderate to severe dementia of the Alzheimer type.