Adamantane is a colorless, crystalline chemical compound with the formula C10H16. It consists of four fused cyclohexane rings in a rigid chair conformation. Adamantane was first isolated from petroleum in 1932 and first synthesized in 1941, though the synthesis method was inefficient. It has since been synthesized through efficient methods such as hydrogenation of dicyclopentadiene. Adamantane derivatives have applications as drugs, polymers, and lubricants.

1. PPT OF ALBUISSA MUHAMMED
HAMED
887B 3RD COURSE

2. Adamantane is a colorless, crystalline chemical compound with a camphor-
like odor. With a formula C10H16, it is a cycloalkane and also the
simplest diamondoid. Adamantane molecules consist of four
connected cyclohexane rings arranged in the "armchair" configuration. It is
unique in that it is both rigid and virtually stress-free. A boat-shaped
configuration can also exist. Adamantane is the most stable among all the
isomers with formula C10H16, which include the somewhat similar twistane.
The spatial arrangement ofcarbon atoms in adamantane molecule is the same
as in the diamond crystal. This motivates the name adamantane, which is
derived from the Greek adamantinos (relating to steel or diamond).[4]
The discovery of adamantane in petroleum in 1933 launched a new field of
chemistry dedicated to studying the synthesis and properties of polyhedral
organic compounds. Adamantane derivatives have found practical application
as drugs, polymeric materials and thermally stable lubricants.

4. Properties
Chemical formula C10H16
Molar mass 136.24 g·mol
−1
Appearance White to off-white powder
Density 1.08 g/cm
3
(20 °C),
[2]
solid
Melting point 270 °C (518 °F; 543 K)
Boiling point Sublimes
Solubility in water Poorly soluble
Solubility in other solvents Soluble in hydrocarbons
Refractive index(nD) 1.568
[3]
Structure
Crystal structure cubic, space group Fm3m
Coordination geometry 4
Dipole moment 0 D
Hazards
Main hazards Flammable
S-phrases 24/25/28/37/45

5. The possibility of the existence of a hydrocarbon with the C10H16 formula and diamond-like structure
of the molecule was suggested by H. Decker at a conference in 1924. Decker called this
molecule decaterpene and was surprised that it had not been synthesized yet.[5]
The first attempt of laboratory synthesis was made by German chemist Hans Meerwein in 1924
using reaction of formaldehyde withdiethyl malonate in the presence of piperidine. Instead of
adamantane, Meerwein obtained 1,3,5,7-tetracarbomethoxybicyclo[3.3.1]nonane-2,6-dione. This
compound was later named Meerwein's ester and used in the syntheses of adamantane and its
derivatives.[6] Later, another German chemist D. Bottger tried to obtain adamantane using
Meerwein's ester as precursor. However, the product, tricyclo-[3.3.1.13,7] decane ring system, was
again an adamantane derivative.[7]
Other researchers attempted to synthesize adamantane using phloroglucinol and derivatives
of cyclohexanone but also without success.[8]
Meerwein's ester
Adamantane was first synthesized by Vladimir Prelog in 1941 from Meerwein's ester.[9][10] The
process was impractical as it contained five stages (simplified in the image below) and had a yield
of about 0.16%. However, it was sometimes used to synthesize certain derivatives of adamantane.[

7. Prelog's method was refined in 1956. The decarboxylation yield was increased by the
addition of the Heinsdecker pathway (11%), and the Hoffman reaction (24%) that raised
the total yield to 6.5%.[11][12] The process was still too complex, and a more convenient
method was found by Paul von Ragué Schleyer in 1957: dicyclopentadiene was
firsthydrogenated in the presence of a catalyst (e.g. platinum dioxide) and then
transformed into adamantane using a Lewis acid (e.g. aluminium chloride) as another
catalyst. This method increased the yield to 30–40% and provided an affordable source
of adamantane; it therefore stimulated characterization of adamantane and is still used
in the laboratory practice.[13][14] The adamantane synthesis yield was later increased to
60%[15] and nowadays, adamantane is an affordable chemical compound with a cost of
the order $1/gram.

8. All the above methods yield adamantane in the form of polycrystalline powder.
Using this powder, single crystals can be grown from the melt, solution or
vapor phase (e.g. with the Bridgman–Stockbarger technique). Melt growth
result in the worst crystalline quality with a mosaic spread in the X-ray
reflection of about 1°. Best crystals are obtained from the liquid phase, but the
growth is inpracticably slow – several months for a 5–10 mm crystal. Growth
from the vapor phase is a reasonable compromise in terms of speed and
quality.[2] Adamantane is sublimated in a quartz tube placed in a furnace,
which is equipped with several heaters maintaining a certain temperature
gradient (about 10 °C/cm for adamantane) along the tube. Crystallization starts
at one end of the tube which is kept near the freezing point of adamantane.
Slow cooling of the tube, while maintaining the temperature gradient,
gradually shifts the melting zone (rate ~2 mm/hour) producing a single-
crystal boule.[16]
Natural occurrence
Before adamantane was synthesized, it was isolated from petroleum by the
Czech chemists S. Landa, V. Machacek and M. Mzourek in 1932[17] .[18] They
used fractional distillation, which separates the organic molecule components
of petroleum based on their boiling points. Landa et al. could produce only a
few milligrams of adamantane, but noticed its high boiling and melting points.
Because of the (assumed) similarity of its structure to that of diamond, the new
compound was named adamantane.[8]
Petroleum remains the only natural source of adamantane; the content varies
between 0.0001 and 0.03% depending on the oil field and is too low for

9. Physical properties[edit]
Pure adamantane is a colorless crystalline solid with a characteristic camphor smell. It is practically
insoluble in water, but readily soluble in nonpolar organic solvents.[21]Adamantane has an unusually
high melting point for a hydrocarbon. At 270 °C, its melting point is much higher than other
hydrocarbons with the same molecular weight, such
ascamphene (45 °C), limonene (−74 °C), ocimene (50 °C), terpinene (60 °C) or twistane (164 °C), or
than a linear C10H22 hydrocarbon decane (−28 °C). However, adamantane slowly sublimates even at
room temperature.[22] Adamantane can distill with water vapor.[20]
Structure[edit]
Adamantane molecule consists of three condensed cyclohexane rings fused in the
chair conformation. The molecular parameters were deduced by electron diffraction and X-ray
crystallography. The carbon–carbon bond length is 1.54 Å and is almost identical to that of diamond,
and the carbon–hydrogen distance is 1.112 Å.[3]
At ambient conditions, adamantane crystallizes in a face-centered cubic structure (space
group Fm3m, a = 9.426 ± 0.008 Å, four molecules in the unit cell) containing orientationally
disordered adamantane molecules. This structure transforms into an ordered body-
centered tetragonal phase (a = 6.641 Å, c = 8.875 Å) with two molecules per cell either upon cooling
to 208 K or pressurizing to above 0.5 GPa.[8][22]

10. Hardness[edit]
Elastic constants of adamantane were measured using large (centimeter-sized) single
crystals and the ultrasonic echo technique. The principal value of the elasticity tensor,
C11, was deduced as 7.52, 8.20 and 6.17 GPa for the <110>, <111> and <100> crystalline
directions.[16] For comparison, the corresponding values for crystalline diamond are
1161, 1174 and 1123 GPa.[23] The arrangement of carbon atoms is the same in
adamantane and diamond.[24] However, in the adamantane solid, molecules do not form
a covalent lattice as in diamond, but interact through weak Van der Waals forces. As a
result, adamantane crystals are very soft and plastic.[2][16][25]
Spectroscopy[edit]
The nuclear magnetic resonance (NMR) spectrum of adamantane consists of two poorly
resolved signals, which correspond to the inequivalent sites 1 and 2 (see picture below).
Their positions are 1.873 ppm and 1.756 ppm for adamantane in CDCl3 and 1H NMR,
and are 28.46 ppm and 37.85 ppm for 13C NMR.[26] The simplicity of the NMR spectrum
is a good monitor of the purity of adamantane – most derivatives have lower molecular
symmetry and therefore more complex spectra.
Mass spectra of adamantane and its derivatives are rather characteristic. The main peak
at m/z = 136 corresponds to the C
10H+
16 ion. Its fragmentation results in weaker signals as m/z = 93, 80, 79, 67, 41 and 39.[3][26]
The infrared absorption spectrum of adamantane is relatively simple because of the high
symmetry of the molecule. The main absorption bands and their assignment are given
in the table:[3]

11. Nomenclature[edit]
According to the rules of systematic nomenclature, adamantane should be called
tricyclo[3.3.1.13,7]decane. However, IUPAC recommends using the name
"adamantane".[1]
The adamantane molecule is composed of only carbon and hydrogen and has
high Td symmetry. Therefore, its 16 hydrogen and 10 carbon atoms can be
described by only two sites, which are labeled in the figure as 1 (4 equivalent
sites) and 2 (6 equivalent sites).
The closest structural analogs of adamantane
are noradamantane and homoadamantane, which respectively contain one less
and one more CH2 link than the adamantane.

12. Chemical properties[edit]
Usually, hydrocarbons which contain only σ-bonds are relatively inert
chemically. However, adamantane and its derivatives are highly reactive.
This property is particularly evident in the ionic reactions
where carbocations are formed as intermediates.
Adamantane cations[edit]
The adamantane cation can be produced by reacting 1-fluoro-adamantane
with SbF5 and it has high stability compared with other carbocations, even
tertiary ones.[30][31]
The dication of adamantane was obtained in solutions of superacids. It also
has elevated stability due to the phenomenon called "three-dimensional
aromaticity"[32] orhomoaromaticity,[33] This four-center two-electron
bond involves one pair of electrons delocalized among the four bridgehead
atoms.

14. Reactions[edit]
Most reactions of adamantane occur via the 3-coordinated carbon sites and are
described in the subsections below. The 2-coordinated, bridging carbon sites are much
less reactive. They are involved in the reaction of adamantane with
concentrated sulfuric acid which produces adamantanone.[34]
The carbonyl group of adamantanone allows further reactions via the bridging site.
For example, adamantanone is the starting compound for obtaining such derivatives
of adamantane as 2-adamantanecarbonitrile[35] and 2-methyl-adamantane.[36]

15. Bromination[edit]
Adamantane readily reacts with various brominating agents, including
molecular bromine. The composition and the ratio of the reaction products depend on
the reaction conditions and especially the presence and type of catalysts.[19]
Boiling of adamantane with bromine results in a monosubstituted adamantane, 1-
bromadamantane. Multiple substitution with bromine is achieved by adding a Lewis
acidcatalyst.[37]
The rate of bromination is accelerated upon addition of Lewis acids and is unchanged
by irradiation or addition of free radicals. This indicates that the reaction occurs via an
ionic mechanism.[8]

16. Fluorination[edit]
The first fluorinations of adamantane were conducted using 1-
hydroxyadamantane[38] and 1-aminoadamantane as initial compounds. Later,
fluorination was achieved starting from adamantane itself.[39] In all these cases, reaction
proceeded via formation of adamantane cation which then interacted with fluorinated
nucleophiles. Fluorination of adamantane with gaseous fluorine has also been
reported.[40]
Carboxylation[edit]
Carboxylation of adamantane was first reported in 1960, using formic acid as a
carboxylating agent and carbon tetrachloride as a solvent.[41]
tert-butanol (t-BuOH) and sulfuric acid were added to generate adamantane cation; the
cation was then carboxylated by carbon monoxide generated in situ in the interaction
between the formic and sulfuric acids.[8] The fraction of carboxylated adamantane was
55-60%.[42]

17. Hydroxylation[edit]
The simplest adamantane alcohol, 1-hydroxyadamantane, is readily formed by
hydrolysis of 1-bromadamantane in aqueous solution of acetone. It can also be
produced byozonation of the adamantane:[43]

18. Others[edit]
Adamantane interacts with benzene in the presence of Lewis acids, resulting in
a Friedel–Crafts reaction.[44] Aromatically substituted adamantane derivatives can be
easily obtained starting from 1-hydroxyadamantane. In particular, the reaction
with anisole proceeds under normal conditions and does not require a catalyst.[37]
Nitration of adamantane is a difficult reaction characterized by moderate yields.[45] An
important nitrogen-substituted drug amantadine can be prepared by reacting
adamantane with bromine or nitric acid to give the bromide or nitroester at the 1-
position. Reaction of either compound with acetonitrile affords the acetamide, which is
hydrolyzed to give 1-adamantylamine:[46]

19. Uses[edit]
Adamantane itself enjoys few applications since it is merely an
unfunctionalized hydrocarbon. It is used in some dry
etching masks[47] and polymer formulations.
In solid-state NMR spectroscopy, adamantane is a common standard for chemical
shift referencing.[48]
In dye lasers, adamantane may be used to extend the life of the gain medium; it cannot
be photoionized under atmosphere because its absorption bands lie in the vacuum-
ultraviolet region of the spectrum. Photoionization energies have been determined for
adamantane as well as for several bigger diamondoids.
In medicine[edit]
All medical applications known so far involve not pure adamantane, but its derivatives.
The first adamantane derivative used as a drug was amantadine – first (1967) as
anantiviral drug against various strains of flu[50] and then to treat Parkinson's
disease.[51][52] Other drugs among adamantane derivatives
include adapalene, adapromine,amantadine, bromantane, carmantadine, chlodantane, d
opamantine, memantine, rimantadine, saxagliptin, tromantadine,
and vildagliptin. Polymers of adamantane have been patented as antiviral agents
against HIV.[53]

27. In designer drugs[edit]
Adamantane was recently identified as a key structural subunit in several
synthetic cannabinoid designer drugs, namely AB-001 and SDB-001.[54]
Potential technological applications[edit]
Some alkyl derivatives of adamantane have been used as a working fluid in hydraulic
systems.[55] Adamantane-based polymers might find application for coatings
oftouchscreens,[56] and there are prospects for using adamantane and its homologues
in nanotechnology. For example, the soft cage-like structure of adamantane solid allow
incorporation of guest molecules, which can be released inside the human body upon
breaking the matrix.[15][57] Adamantane could be used as molecular building blocks for
self-assembly of molecular crystals.[58][59]

28. Adamantane analogues[edit]
Many molecules adopt adamantane-like cage structures. Those include phosphorus
trioxide P4O6, arsenic trioxide As4O6, phosphorus pentoxide P4O10 =
(PO)4O6, phosphorus pentasulfide P4S10 = (PS)4S6,
and hexamethylenetetramine C6N4H12 = N4(CH2)6.[60] Particularly notorious
is tetramethylenedisulfotetramine, often shortened to "tetramine", arodenticide banned
in most countries for extreme toxicity to humans. The silicon analogue of adamantane,
sila-adamantane, was synthesized in 2005.Adamantane cages can be stacked together to produce higher diamondoids, such as
diamantane (C14H20 – two fused adamantane cages), triamantane (C18H24), tetramantane
(C22H28), pentamantane (C26H32), hexamantane (C26H30), etc. Their synthesis is similar to
that of adamantane and like adamantane, they can also be extracted from petroleum,
though at even much smaller yields.

30. 463px-Adamantane_acsv.svg