Oxygen reactive ion reactions with methane

Catechols likewise undergo 0-alkylation under phase transfer conditions, yielding methylenedioxy derivatives on reaction with methylene bromide [8]. This reaction constitutes a useful route to this commonly occurring oxygen heterocycle as well as providing a facile protection method for 1,2-dihydroxyarenes. Dibromo-methane rather than the more reactive diiodomethane was used in this reaction because the latter is a source of iodide ion which poisons the phase transfer catalyst by selectively ion-pairing with the quaternary ammonium cation. Phenoxide ion can apparently compete successfully with bromide but not iodide in the formation of an extractable ion pair under these conditions. 

The first commercial instrument to use this approach was called dynamic reaction cell (DRC) technology Similar in appearance to the hexapole and octapole collision/reaction cells, the DRC is a pressurized multipole positioned prior to the analyzer quadrupole. However, this is where the similarity ends. In DRC technology, a quadrupole is used instead of a hexapole or octapole. A highly reactive gas such as ammonia, oxygen, or methane is bled into the cell, which is a catalyst for ion-molecule chemistry to take place. By a number of different reaction mechanisms, the gaseous molecules react with the interfering ions to convert than into either an innocuous species different from the analyte mass or a harmless neutral species. The analyte mass then emerges from the DRC free of its interference and is steered into the analyza quadrupole for conventional mass separation. 

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