Surface area of reversed-phase HPLC columns.

Six reversed-phase columns from different manufacturers were characterized in terms of adsorbent geometry (e.g., pore volume, surface area, column void volume, and interparticle volume). Measurement of the surface area of chemically modified silica-based adsorbents is discussed together with the methods for the determination of the amount of adsorbent in the column. The behavior of nearly ideal chromatographic systems was studied. Retention factors of alkylbenzenes in acetonitrile/water and methanol/water systems were compared with surface-specific retention factors. The distribution of conventional retention factor values for the same analyte among the six columns using identical chromatographic conditions exceeded 35%, while the relative standard deviation of surface-specific retention factors was on the level of 3%.

Dual nucleophilic catalysis with DABCO for the N-methylation of indoles.

DABCO is an extremely active catalyst for the methylation of indoles in conjunction with dimethyl carbonate (DMC). This green chemistry is highly effective and produces N-methylindoles in nearly quantitative yields. The reaction sequence consists of competing alkylation and acylation pathways and involves 1,4-diazabicyclo[2.2.2]octane (DABCO) dually as a nucleophilic catalyst, ultimately resulting in a single product: the N-methylated indole.