Relation between the Structure of Molecules of Nitrogen-Containing Heterocyclic Compounds and Their Adsorption on Graphitized Carbon Black

Abstract

The retention volumes for small (zero) sample size (Henry constants) of hydrogen-treated graphitized thermal carbon black (HTGTCB) in five- or six-membered mono- and bicyclic nitrogen-containing compounds have been determined. Comparison of Henry constants K₁ and initial heats of adsorption q̄₁ of nitrogen-containing heterocyclic compounds with those of hydrocarbons of a similar structure has shown that adsorption of the studied heterocyclic compounds on HTGTCB depends on the number and position of nitrogen atoms in their molecules. An increase in the number of nitrogen atoms in flat molecules of azoles (pyrrole, pyrazole, 1,2,4-triazole) brings about the growth of K₁ and q̄₁. In six-membered cycles the growth of K₁ and q̄₁ is observed only during the transition from pyridine to 1,2-diazine (pyridazine), whereas in transition to 1,3- and 1,4-diazines (pyrimidine and pyrazine), and further on to s-triazine, the retention greatly reduces. In azanaphthalenes (quinoline, cinnoline, quinoxaline) and benzazoles (indole, indazole) the growing number of nitrogen atoms also results in weaker retention.