Isomer differentiation by charge inversion tandem mass spectrometry: an investigation into the structure of the ionic products from an SN(ANRORC) eeaction.
Negative ion fast atom bombardment and negative ion chemical ionization tandem mass spectrometry combined with charge inversion reactions are used to confirm that 2-chloro-5nitropyridine reacts with the hydroxide ion by an SN(ANRORC) mechanism in solution to form a ring-opened C5H3N2O 3 (-) anion that has the structure of the (M-H)(-) anion of 2-nitro-4-cyano-2-butenal. The addition of excess hydroxide ion forms the expected 2-oxy5-nitropyridine anion. In the gas phase the same reaction forms only the 2-oxy-5-nitropyridine anion. High energy charge inversion is shown to be an excellent means of differentiating between these isomeric negative ions.
USDA Human Nutrition Research Center at Tufts University, 711 Washington Street, 02111, Boston,, MA, USA.
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Dolnikowski