The Gas-Chromatographic Behaviour of the Phosphoric Acid n-Alkyl Esters on Silicon Stationary Phases. Reactions on Columns

Abstract

Instability of the trialkylphosphates (RO)₃P(O), with R ? C₂H₁₁ - C₈H₁₇ has been observed when pairs of these esters were analysed on gas-chromatographic columns with silicone stationary phases, e.g., OV-17. New peaks were identified between those corresponding to the initial esters analysed separately. The Kovats retention indices were calculated for these peaks, with n-alkanes, as standards and phosphorus indices with tri-n-alkyl-phosphates as standards. The relationships between the retention indices and the number of the total carbon atoms in the molecules of the alkyl-phosphates was represented for the identification of the new peaks. The new peaks were identified as mixed phosphates with general structure (RO)z(RO)P(O), where R and R are alkyl radicals C₅H₁₁-C₆H₁₇. These phosphates are the results of interchange of alkoxy groups from the esters in the conditions of high temperature (240°C) of the chromatographic colums. The retention data of the esters examined are shown in the table.