Diazabenzenes. II. Synthesis, Photolysis and Mass Spectra of Some Tetraalkylpyrazines

Abstract

2,3,5,6-Tetramethyl-, tetraethyl- and tetraisopropyl-pyrazines were obtained by fusion of ammonium acetate with the appropriate acyloin or reduction of the α,α'-diketone dioxime with zinc dust and alkali. Photolysis of a cyclohexane solution of tetraisopropylpyrazine led inter alia to formation of bicyclohexyl. Photolysis of an aqueous solution of tetramethylpyrazine containing sodium borohydride caused complete reduction of the pyrazine ring to the hexahydro stage.

The high-resolution mass spectra of these pyrazines are discussed and explained in the light of deuterium labelling and metastable defocusing information.