Diamond

The unique nature of diamond is heavily dependent upon its composition, crystal
structure, and mechanical, thermal, and electromagnetic properties.1 Of those
dependencies, composition exacts the most influence over the characteristics.

Crystal structure is the repeating pattern of diamondís composition, and each
of the properties are the result of molecular interaction which is determined by
composition. Therefore, composition is paramount in the determination of the
qualities of diamond. Before its discovery, adamantane was known as decaterpene,
the name applied by Decker to his tricyclic hydrocarbon. Decker believed that
his decaterpene was similar in structure as the diamond lattice. Decaterpene, as
in diamond, was proposed by Decker to be highly structured and strain free.2

Decker proposed decaterpene in 1924, but that was all it was until 1933 when the
structure was proven to exist. Isolated in the petroleum of Hodinin,

Czechoslovakia by Landa and Machachaeck, decaterpene became incarnate.3 However,
the fact that they found the structure Decker predicted did not mean that his
nomenclature would be used to identify the compound. That honor was bestowed
upon its discoverers Landa and Machcahcaeck who used the Greek translation of
diamond, adamantane, to identify the compound.2 Crude petroleum is separated
into its component compounds by fractional distillation. The procedure involves
a sample of the petroleum to be heated until the sample is vaporized leaving
behind any solid impurities. The resulting steam enters a fractional
distillation column in which a temperature gradient had been instilled. The
temperature of the column decreases as the steam rises through the column. The
idea is that, as the temperature of the column decreases, the vapor temperature
will decrease. When the boiling point of a compound is passed, the compound will
condense on the sides of the column and be collected in the fraction well at
that point. Thus the mixture is separated into fractions of compounds with
similar boiling points in a mixture.4 Adamantaneís high boiling point caused
it to be one of the initial compounds to condense with the kerosene fraction in
the 190o C cut.5 The only problem with the fractional distillation method is
that adamantane cannot be extracted in large quantities because it exists in
only a small quantity in petrol. The presence of adamantane was found to be only

0.0004% of the composition of petroleum by the fractional distillation method.2

Adamantane is not alone in the petroleum distillate in which it is present.

Alkylated adamantane derivatives also show up in adamantane containing
distillate. (II, III, IV) The output of adamantane is capable of being increased
if the thiourea adduct method is employed on the petroleum. Landa and Hale were
able to isolate complexes of adamantane from crude petroleum that had bonded to
thiourea.5 Now that the natural product has been discovered, the next logical
step would be to formulate the natural process in which the compound was made.

As of 1964, the natural method that creates the adamantane compound had not been
found. The natural process that was attempted was to bombard adamantane-free
petroleum with catalysts in an attempt to initiate the formation of adamantane.

The resulting mixture was fractioned and analyzed to see if any extra adamantane
was created. In most cases, the catalyst failed to produce any adamantane.

However, many of the catalysts produced derivatives that had the ring structure
but with extra components attached.5 The only catalyst shown to make a
significant amount was AlCl3, but not enough was created for the catalyst to be
considered for mass production of adamantane. Catalysts that failed were:
oil-bearing stone from Hodin with and without HF, aluminum silicate, aluminum
oxide, concentrated sulfuric acid, zinc chloride, iron(III) chloride, tin(IV)
chloride, antimony(V) chloride.5 It is believed that the reason many of the
catalysts did not work, even though they are present in natural petroleum, is
that the conditions that they were subjected to were experimental in nature. The
creation of adamantane is thought to be a biogenesis of petroleum under a set of
conditions that is not able to be recreated in the lab.2 With the natural
mechanism a mystery, a synthetic method to create the compound was sought after
to allow the study of adamantane to proceed. After all, with Landa in complete
control of the slim supply of adamantane, the cost of adamantane skyrocketed.6

Two methods were investigated to be able to create the natural adamantane
structure: ring closure and isomerization. Before adamantane was known to the
world, the starting material commonly used to synthesize adamantane and its
derivatives through ring closure was being developed. In 1922, Meerwein was
investigating a way to remove the bridgehead carboxymethoxy group of ring
compounds, and reseal the ring structure