Naphthalene numbering system

Here again the high reactivity is due to the gain of aromatic stabilization in the adduct. Polycyclic aromatics are moderately reactive as the diene component in Diels-Alder reactions. Anthracene forms adducts with a number of dienophiles. The addition occurs at the centre ring. The naphthalene ring system is much less reactive. 

The accepted numbering system for these hydrocarbons is as shown in the structures. The 1- and 2-positions of the naphthalene ring sometimes are designated as a and /3, but we prefer not to use these designations. Some illustrative substitution products are ... 

Thus, 87 gives a satisfactory picture for a ten w-electron naphthalene-like system, but the localization of charges is unsatisfactory because abundant chemical evidence shows that carbon atoms numbered 2 and 5 are more positive than carbon atoms 3 and 4, and according to 87, mesomeric displacement of the negative charge on atom 3a would lead to the opposite conclusion. 

Naphthalene. Since Z = 2, the molecule occupies a site of symmetry I in other words, there is an inversion center in the middle of the C4a-C8a bond. With reference to the atom numbering system shown below, the asymmetric unit can be taken as one of the right (1 1,4a), left (5-8,8a), upper (1,2,7,8,8a) or lower (3,4,4a, 5,6) half of the molecule. Note that the idealized molecular symmetry P>2h of naphthalene is not fully utilized in the solid state, and some of the chemically identical bond distances and bond angles have different measured values. 

Fig. 3. Structure of various ansamycins. (Numbers in brackets indicate molecular weights. For all naphthalenic ansamycins the numbering system as proposed by Prelog7 8) has been used.)...

Appendix II presents the structures of organic compounds. Structure 1 provides the number, names, and adiabatic electron affinities of the Bergman Dewar set. Structure 2 gives the adiabatic electron affinities, gas phase acidities, and names of the DNA and RNA bases. Structure 3 shows the charge transfer complex acceptors. Structure 4 gives the numbering system of naphthalene and biphenyl and compares the structures of acenaphthylene and biphenylene. 

Two isomeric monosubstituted naphthalenes are differentiated by the prefixes 1- and 2-, or a- and 3 For more highly substituted naphthalenes, the arrangement of the substituents is indicated by numbers. Since there are three substituent groups on the naphthalene ring of cadalene, we must use the number system ... 

Solvent, temperature, and excitation wavelength significantly affected the photochemical outcomes of a naphthalene — dicyanoethene system tethered by different number ( ) of methylene groups (1-3). The temperature dependence and theoretical calculations indicated the diversity of exciplex conformations, an ensemble of which can he effectively altered by changing excitation wavelength to eventually switch the regioselectivity of photoreactions (Scheme 11). ... 

Naphthalene, anthracene, and phenanthrene are the three simplest members of this class. They are all present in coal tar, a mixture of organic substances formed by heating coal at about 1000°C in the absence of air. Naphthalene is bicyclic and its two benzene rings share a common side. Anthracene and phenanthrene are both tricyclic aromatic hydrocarbons. Anthracene has three rings fused in a linear fashion an angular fusion characterizes phenanthrene. The structural formulas of naphthalene, anthracene, and phenanthrene are shown along with the numbering system used to name their substituted derivatives ... 

The binding behaviour of benzene can be extrapolated to many other aromatic compounds such as naphthalene and benzene derivativesInterestingly, a large number of probe molecules contain aromatic rings and many of them will prefer the outer regions of micelles, whereas in bilayer systems, the same molecules prefer the interior of the aggregate ". Qearly these probes cannot be used to determine polarity of the micellar interior or the extent of water penetration therein . 

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