Examples single ring

Thomson based h(s configurations on the work of fin American physicist, Alfred Mayer, who had experimented wilh magnets attached to corks and floated In a circular basin of water. When five magnets were placed in the water, for example, they formed a single ring The ad-... 

With regard to the results obtained by means of X-ray diffraction, the most interesting observation is the first example of ring-chain tautomers 7A 7B, which exist as a remarkable 7A 7B = 1 1 mixture in a single... 

As can be observed, the group of thyroid hormone receptors (1 A) is represented by molecular scaffolds of low structural complexity, with at most a single ring in the core ring system. In this respect, the scaffold simplicity of the molecules annotated to this group contrasts with the wide diversity of scaffolds found in the other two nuclear receptor groups. For example. 

In addition to the monocyclo >cnt dicnyl compounds just described, there are many compounds which contain a single ring per metal atom with a variety of additional ligands, such as carbon monoxide, to complete the coordination sphere. These include monomers and dimers, with and without melal-metal bonds as necessary to obey the 18-clcctron rule. Some examples are shown in Fig 15.38. 

Not until 1967 was covalent hydration found in a single-ring aromatic nucleus, but several examples are now known. The cation of 5-nitro-pyrimidine (also its 2-methyl and 2-benzyl derivatives) adds a molecule... 

In 1931, Erich Htickel postulated that monocyclic (single ring) planar compounds that contained carbon atoms with unhybridized atomic p orbitals would possess a closed bond shell of delocalized n electrons if the number of n electrons in the molecule fit a value of 4 + 2 where n equaled any whole number. Because a closed bond shell of n electrons defines an aromatic system, you can use Hiickel s Rule to predict the aromaticity of a compound. For example, the benzene molecule, which has 3 n bonds or 6 n electrons, is aromatic. 

Cyclic (or ringed) hydrocarbons are simply named with the prefix cyc/o- followed by an ending that is determined by how many carbon atoms are in the molecule. For example, a ringed hydrocarbon molecule containing five carbon atoms and only single bonds would be named cyclopentane. If the same molecule had a double bond between two carbon atoms in the ring, the name would be cyclopentene. 

Huckel s rule applies only to compounds with a single ring, such as benzene and cyclobutadiene. However, it can be used with multiple-ring compounds if the resonance structure with all of the double bonds on the periphery of the ring is considered. For example, using such a structure for naphthalene shows 10 electrons in the cycle, so it is predicted to be aromatic. 

Aromatic hydrocarbons occur to a varying extent and have a higher ratio of carbon to hydrogen than any of the commonly occurring paraffins or naphthenes. They correspond to a molecular formula of CnH2n-6 if they are mononuclear (single ring only). Benzene, toluene, and cumene are mononuclear examples of this series, and naphthalene is a dinuclear example (Eq. 18.5). 

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