Adamantane is an organic compound with a formula C10H16 or, more descriptively, (CH)4(CH2)6. Adamantane molecules can be described as the fusion of three cyclohexane rings. The molecule is both rigid and virtually stress-free. Adamantane is the most stable isomer of C10H16. The spatial arrangement of carbon atoms in the adamantane molecule is the same as in the diamond crystal. This similarity led to the name adamantane, which is derived from the Greek adamantinos (relating to steel or diamond). It is a white solid with a camphor-like odor. It is the simplest diamondoid. The discovery of adamantane in petroleum in 1933 launched a new field of chemistry dedicated to the synthesis and properties of polyhedral organic compounds. Adamantane derivatives have found practical application as drugs, polymeric materials, and thermally stable lubricants. History and synthesis In 1924, H. Decker suggested the existence of adamantane, which he called decaterpene. The first attempted laboratory synthesis was made in 1924 by German chemist Hans Meerwein using the reaction of formaldehyde with diethyl 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, later named Meerwein's ester, was used in the synthesis of adamantane and its derivatives. D. Bottger tried to obtain adamantane using Meerwein's ester as precursor. The product, tricyclo-[3.3.1.13,7], was not adamantane, but a derivative. Other researchers attempted to synthesize adamantane using phloroglucinol and derivatives of cyclohexanone, but also failed. Adamantane was first synthesized by Vladimir Prelog in 1941 from Meerwein's ester. With a yield of 0.16%, the five-stage process was impractical (simplified in the image below). The method is used to synthesize certain derivatives of adamantane. 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%. The process was still too complex, and a more convenient method was found in 1957 by Paul von Ragué Schleyer: dicyclopentadiene was first hydrogenated 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 laboratory practice. The adamantane synthesis yield was later increased to 60% and 98% by ultrasound and super acid catalysts. Today, adamantane is an affordable chemical compound with a cost