Camphorquinone vs Naphthalene

Camphorquinone also known as 2,3-camphoranedione, is an organic compound extracted from camphor.A yellow solid used as a photoinitiator for curing dental composites.Camphorquinone is produced by oxidation of camphor with selenium dioxide.

Light curing details

Polymerization initiated by camphorquinone is very slow, so amines such as N,N-dimethyl-p-toluidine, 2-ethyl-dimethylbenzoate, N-phenylglycine are usually added to increase the curing speed.It absorbs very weakly at 468 nm (extinction coefficient of 40 M−1 cm−1) and appears yellowish.Photoexcitation leads to almost quantitative formation of its triplet state via intersystem crossing and very weak fluorescence.

Naphthalene

Naphthalene is an organic compound,It is the simplest PAH, a white crystalline solid with a characteristic odor that can be detected at concentrations as low as 0.08 ppm.As an aromatic hydrocarbon, the structure of naphthalene consists of a pair of fused benzene rings.It is the main ingredient in traditional moth balls.

Physical properties

The naphthalene molecule can be viewed as a fusion of a pair of benzene rings.(In organic chemistry, rings are fused if they share two or more atoms.) Therefore, naphthalene is classified as a benzene-type polycyclic aromatic hydrocarbon (PAH).Each of the eight carbon atoms not shared by the two rings bears a hydrogen atom.For the purposes of standard IUPAC nomenclature for derived compounds, these eight atoms are numbered 1 through 8 around the perimeter of the molecule, starting with the carbon atom adjacent to the shared atom. Shared carbon atoms are labeled 4a (between 4 and 5) and 8a (between 8 and 1).

Electrical conductivity

Pure crystalline naphthalene is a moderate insulator at room temperature with a resistivity of about 1012Ω·m.The resistivity drops more than 1000-fold upon melting to about 4 × 108 Ω m. In both liquids and solids, resistivity depends on temperature as ρ = ρ0 exp(E/(k T)), where ρ0 (Ω m) and E (eV) are constant parameters and k is Boltzmann’s constant ( 8.617× 10−5 eV/K), where T is the absolute temperature (K).The parameter E in the solid is 0.73.However, solids exhibit semiconducting properties below 100 K.