Naphthalene, Structure and Reactivity & Other Names Of Naphthalen
Naphthalene
Naphthalene is an organic compound with formula【C10H8】
It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass.As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings. It is best known as the main ingredient of traditional mothballs.
Other Names Of Naphthalen
white tar, camphor tar, tar camphor, naphthalin, naphthaline, antimite, albocarbon, hexalene, mothballs, moth flakes
Structure and Reactivity
A naphthalene molecule can be viewed as the fusion of a pair of benzene rings. (In organic chemistry, rings are fused if they share two or more atoms.) As such, naphthalene is classified as a benzenoid polycyclic aromatic hydrocarbon(PAH). There are two sets of equivalent hydrogen atoms: the alpha positions are numbered 1, 4, 5, and 8 (per diagram in right margin), and the betapositions, 2, 3, 6, and 7.
Unlike benzene, the carbon–carbon bonds in naphthalene are not of the same length. The bonds C1−C2, C3−C4, C5−C6 and C7−C8 are about 1.37 Å (137 pm) in length, whereas the other carbon–carbon bonds are about 1.42 Å (142 pm) long. This difference, established by X-ray diffraction,[17] is consistent with the valence bondmodel in naphthalene and in particular, with the theorem of cross-conjugation. This theorem would describe naphthalene as an aromatic benzene unit bonded to a diene but not extensively conjugatedto it (at least in the ground state). As such, naphthalene possesses several resonancestructures.
Two isomers are possible for mono-substituted naphthalenes, corresponding to substitution at an alpha or beta position. Bicyclo[6.2.0]decapentaeneis a structural isomer with a fused 4–8 ring system.
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