Author(s)

Pavel Straka^1*, Miroslava Novotná², Petr Buryan², Olga Bičáková¹

¹Institute of Rock Structure and Mechanics, v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic.
²Institute of Chemical Technology, Prague, Czech Republic.

Gas chromatographic measurements of the retention times of alkyl naphthalenes on packed columns with polar and non-polar stationary phases have proven that the logarithm of the relative retention time increases bi-linearly (not linearly) with the number of carbon atoms in a molecule. This is caused by a strong inclination of alkyl side chains toward intramolecular cyclization. A FTIR spectral analysis has shown that longer alkyl side chains of alkyl naphthalenes are cyclized through an interaction between the terminal CH₃ group and the aromatic ring. Conventional aromatic-aliphatic molecules thus become new molecules with quasi-alicyclic rings. This, however, alters the effect of non-covalent van der Waals attractive forces both inside and outside the molecules, which is reflected in an exponential increase of the retention times of alkyl naphthalenes with a side chain longer than propyl and in the bi-linearity of the logarithmic dependence of the relative retention times on the number of carbons in the molecule.

Alkyl Naphtalenes, Retention Times, Molecular Mechanics, van der Waals Forces

Straka, P. , Novotná, M. , Buryan, P. and Bičáková, O. (2014) The Cyclization of Alkyl Side Chains of Naphthalenes: The GC/Potential Energies/FTIR Approach. American Journal of Analytical Chemistry, 5, 957-968. doi: 10.4236/ajac.2014.514103.