Adamantane chemical structure

Diamondoids show unique properties due to their exceptional atomic arrangements. Adamantane consists of cyclohexane rings in chair conformation. The name adamantine is derived from the Greek word for diamond since its chemical structure is like the three-dimensional diamond subunit, as shown in Fig. 5. 

Tetrodotoxin, an extremely poisonous heterocycle present in Japanese puffer fish (various species of Spheroides), exerts its action by blocking the sodium ion channels in the peripheral nervous system. Chemically it has an adamantane-like structure, namely octahydro-12 - (hydroxymethyl) - 2 - imino-5,7,9,1 Oa-dimethano- 10aH-[ 1,3] -dioxo-cino-[6,5-d]pyrimidine-4,7,10,11,12-pentol. When chemically dehydrated, it rehydrates in dilute acid.73 Methanol, and ammonia, can add similarly. Because 2-amino-1,6-dihydropyrimidine forms the central part... 

A mixture of 8.0 g (4.2 mmol) methoxynoria, 8.2 g (60 mmol) K2CO3, and 0.064 g (0.2 mmol) tetrabutylammonium bromide in 95 ml NMP (1-methyl-2-pyrrolidone) is stirred at 60°C for 3 h. After that, a solution of 4.3 g (1.5 mmol) BMA (2-bromoacetyloxy-2-methyladamantane) in 5 ml NMP is added slowly to the resultant mixture, poured into chloroform, and washed with 0.1 M oxalic acid aqueous solution and water. The organic layer is dried over MgS04, and the solution is concentrated by rotary evaporator. The concentrated solution is added to methanol to obtain the white solid. The resulting precipitate is collected by vacuum filtration and dried at 60°C in vacuo for 12 hr. Thus, adamantylester of noria is finally obtained. The chemical structure of noria profecfed by adamantane is shown in Figure 3.18. 

Chemical Structure see Figure 79.3 Chemical Name adamantan-1-amine Chemical Formula Cj Hj N molecular wt 159... 

Figure 1, Molecular structures of adamantane, diamantane, and triamantane, the smaller diamondoids, with chemical formulas C10H16, C14H20, and CigH24, respectively.

Figure 34 Chemical formula of y-cyclodextrin consisting of eight glucose molecules with adamantane as the guest entrapped within its hydrophobic cavity. Structures of a- and P-cyclodextrins will be similar but made up of six and seven (n = 6, 7) glucoses,...

The chemistry of adamantane and related cage-like hydrocarbons has developed rapidly in recent years. These developments, encompassing a broad spectrum of the chemical world, have not been stimulated by any unique properties associated with the cage strutures of these molecules the chemistry of such systems is typically hydrocarbon in nature. The particular utility of cage-like substrates in a variety of chemical investigations arises, for the most part, from their conformational rigidity variables (e.g. those associated with structure) appropriate to more mobile compounds are often eliminated by the use of cage-like systems. The availability, ease of functionalization, and the near ideal structure of adamantane make it extremely useful for this purpose. 

A. Together with methane, the hydrocarbon adamantane (75), the parent structure of 74, has a tetrahedral skeleton. Therefore derivatives of adamantane that have four different substituents at the bridgehead positions should be chiral this has been demonstrated for 76 (see Hamill and McKervey31). It follows that in 74, Ha and Hb are enantiotopic, and indeed 74 has a plane of symmetry through C(l) and C(3). A parallel situation exists in ethanol, which has a plane of symmetry through two carbon atoms and oxygen. Although H and Hb in 74 are enantiotopic, the chemical shift difference between these protons is likely to be very small. 

Figure 6 Adamantane-Uke cage structure of [M4 (SPh) 10] (phenyl groups omitted) determined with the Cd , Zn , and Co ions. (Reprinted with permission from Ref. 41. 1982 American Chemical Society)...

The structures, stabilities, and Si NMR chemical shifts for a series of neutral and cationic sila-adamantanes, for example... 

The structures and NMR chemical shift properties of a series of 1,3-dehydro-sila-adamantane dications, 118-121, have been calculated by DFT methods <2003JA15507, 2002JOC8721>. The cations are found to exhibit three-dimensional heteroaromaticity and indicate that there is significant positive charge at the Si centers. Related results have been obtained for the germanium analogue of 121 <2003JA15507>. 

Figure 15.7 The face-centered cubic structure of adamantane that is a chemical compound with a formula CioHie. The carbon atoms are located in the adamantane crystal like in dia-...

The postulate of a diamondoid (adamantane-type) system in coal (but not necessarily as the main building block of coal) was first advocated in the late 1950s on the basis of the spectroscopic properties (especially x-ray diffraction profiles) of coal but only required that a small part of the carbon exist in such structures. This postulate was truly novel insofar as it offered the attractive option of a three-dimensional structure for coal, an option that has only been acknowledged once in the chemical formulae of that era. 

The continuous reduction in size of a solid finally leads to a situation where the original solid state properties can be only partially observed or may be even completely lost, as these properties are exclusively the result of the cooperation between an infinite number of building blocks. Further reduction of size finally leads to typical molecular behavior. On the other hand, even here are structural relations to the bulk occasionally detectable. For instance, the arrangements of the sp hybridized carbon atoms in cyclohexane or in adamantane can easily be traced back to the diamond lattice, whereas benzene or phenanthrene represent derivatives of the graphite lattice. However, neither cyclohexane, benzene, nor phenanthrene have chemical properties which are comparable with those of the carbon modifications they originate from. The existence of the above mentioned Q, C]o or Ci4 units is otUy made possible by the saturation of the free valencies by hydrogen atoms. Comparable well known examples for other elements are numerous, for instance the elements boron, silicon, and phosphorous. Figure 1-1 illustrates some of the relations between elementary and molecular structures. 

Wiswesser line notation [46-48] is another important historical development in chemical notation that offered useful service in early searches for chemical compounds. More recent developments were more mathematical, based on suitable modifications of graph theoretical concepts. In the case of structurally related molecules, simple nomenclatures have been developed for benzenoid hydrocarbons by Balaban based on the concept of inner duals. In this approach, benzene rings are represented by single vertices that are connected if benzene rings have a common CC bond [26,49], Balaban and Schleyer extended the dualist graph principle to polymantane, which is bnilt from adamantane units superimposed on a diamond lattice [50,51]. 

Hyperflorin, an antibiotic isolated from St. John s wort Hypericum perforatum L.), has been found on the basis of chemical and spectroscopic evidence to possess structure (639). ° A review on the conformational analysis of bicyclo[3,3,l]nonanes has appeared,and the conformations of l,5-disubstituted-3,7-dimethyIenebicyclo-[3,3,l]nonane derivatives have been shown, on the basis of lanthanide-induced n.m.r. shifts, to be predominantly in the double-chair form. In a notable paper that contains a wealth of information pertinent to adamantane synthesis, it has been reported that bicyclo[3,3,l]nonane-3,7-dicarboxylic acid, its dimethyl ester, and various derivatives exist mainly in the chair-boat conformation. The synthetic entry to these systems is illustrated for the above diester (643) in which the starting point is adamantanone (640) thus, ring expansion with diazomethane followed by SeOj oxidation gave the a-diketone (641) which was cleaved with periodate to give the diacid (642). Esterification using diazomethane gave (643) which exists, as does the diacid, as... 

Figure 4 (a) Perspective views of the structure of a single adamantane cage with TUBA connections between cadmium ions, (b) View of the structure of 4d2DMF, showing the fourfold interpenetration of diamondoid networks. (Reprinted with permission from Ref 24. Copyright (2009) American Chemical Society.)... 

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