Adamantane

Adamantane
IUPAC name	Adamantane[1]
Other names	Tricyclo[3.3.1.13,7]decane
Identifiers
CAS number	281-23-2 Y
PubChem	9238
SMILES	C1C3CC2CC(CC1C2)C3
InChI	1/C10H16/c1-7-2-9-4-8(1)5-10(3-7)6-9/h7-10H,1-6H2
InChI key	ORILYTVJVMAKLC-UHFFFAOYAG
ChemSpider ID	8883
Properties
Molecular formula	C10H16
Molar mass	136.23 g mol−1
Appearance	White to off-white powder
Density	1.07 g/cm³ (20 °C), solid
Melting point	270 °C (543 K)
Boiling point	Sublimes
Solubility in water	Poorly soluble
Solubility in other solvents	Soluble in hydrocarbons
Structure
Crystal structure	cubic Space group Fm3m
Coordination geometry	4
Dipole moment	0 D
Hazards
S-phrases	24/25/28/37/45
Related compounds
Related compounds:	Memantine Rimantadine Amantadine
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Adamantane (tricyclo[3.3.1.1^3,7]decane) is a colourless, crystalline compound with a camphor-like odour.^[2] With a formula C₁₀H₁₆, it is a cycloalkane and also the simplest diamondoid. Adamantane was discovered in petroleum in 1933.^[3] Its name derived from the Greek adamantinos (relating to steel or diamond), due to its diamond-like structure.^[4] Adamantane is the most stable isomer of C₁₀H₁₆.

Synthesis

Adamantane was first synthesised by Prelog in 1941.^[5][6] A more convenient method was found by Schleyer in 1957, from dicyclopentadiene by hydrogenation followed by acid-catalysed skeletal rearrangement.^[7][8]

Properties

At ambient conditions, admanatane crystallizes in a cubic structure containing orientationally disordered adamantane molecules. This structure transforms into an ordered tetragonal phase with two molecules per cell either by cooling to 208 K or by pressurizing above 0.5 GPa. In both phases, the adamantane molecules are not cubic, but ellipsoidally distorted. However, the carbon-carbon distances 1.53 A are close to that in diamond (1.54 A). Adamantane is volatile and sublimates even at room temperature.^[9]

Uses

Adamantane itself enjoys few applications since it is merely an unfunctionalised hydrocarbon. It is used in some dry etching masks.^[10] It is also used in some polymer formulations.

In solid-state NMR spectroscopy, adamantane is a common standard for chemical shift referencing.^[11]

In dye lasers, adamantane may be used to extend the life of the gain medium; it cannot be photoionised under atmosphere because its absorption bands lie in the vacuum-ultraviolet region of the spectrum. Photoionization energies have been determined recently for adamantane as well as for several bigger diamondoids.^[12]

Adamantane derivatives

Adamantane derivatives are useful in medicine, e.g. amantadine, memantine and rimantadine. Condensed adamantanes or diamondoids have been isolated from petroleum fractions, where they occur in small amounts. These species are of interest as molecular approximations of the cubic diamond framework, terminated with C-H bonds. 1,3-dehydroadamantane is a member of the propellane family.

Due to its stability, specific steric properties and conformational rigidity, the 1-adamantyl group is a substituent in organic and organometallic chemistry. Some of the first persistent carbenes featured adamantyl substituents.

Adamantane analogues

Many molecules adopt cage structures with adamantanoid structures. Particularly useful compounds with this motif include phosphorus trioxide P₄O₆, arsenic trioxide As₄O₆, phosphorus pentoxide P₄O₁₀ = (PO)₄O₆, phosphorus pentasulfide P₄S₁₀ = (PS)₄S₆, and hexamethylenetetramine C₆N₄H₁₂ = N₄(CH₂)₆.^[13] Particularly notorious is Tetramethylenedisulfotetramine, often shortened to "tetramine", a rodenticide banned in most countries for extreme toxicity to humans.

References