Naphthalene is aromatic:a look at spectra. easeanaaoag他eaeemeeasesaneghan --0 e8e2e10pobasreutenaayemd 的 aeaghTenpas2 2 nnd22eee出aene,139人 osenmoeitanneheneehthat noid hydr ocarbon matic RPe 00-00-C00-00l o9-o9-o9-c8-c9 66 Naphthalene is aromatic: a look at spectra. Naphthalene is a colorless crystalline material with a melting point of 80o C. The UV spectrum of naphthalene indicates an extended, conjugated system with peaks at wavelengths as long as 320 nm. The electrons in naphthalene are more delocalized than in benzene and several resonance structures can be drawn: The overlap of the 10 p orbitals results in a fairly even distribution of electron density. X-ray crystallographic measurements have determined the exact bond distances and angles in naphthalene. The C-C bond distances deviate slightly from those in benzene, 1.39 Å, C-C single bonds, 1.54Å and C=C double bonds, 1.33 Å. The 1H NMR spectrum of naphthalene shows two symmetric multiples at δ = 7.49 and 786 ppm. Coupling constants in the naphthalene nucleus are similar to those in substituted benzenes: •Jortho = 7.5 Hz •Jmeta = 1.4 Hz •Jpara = 0.7 Hz These peak positions are characteristic of ring￾current deshielded aromatic hydrogens. The 13C NMR spectrum shows three lines with chemical shifts in the range of other benzene derivatives: Most fused benzenoid hydrocarbons are aromatic. Linear and angular fusion of a third benzene ring onto naphthalene result in anthracene and phenanthrene. Anthracene is about 6 kcal mol-1 less stable than phenanthrene due to differences in resonance stabilization