SUBSTITUTION OF PYRAZINES BY ALDEHYDES IN MODEL SYSTEMS

The effect of long-chain aldehydes on the formation of long-chain alkyl-substituted pyrazines was investigated in model systems of acetol and ammonium acetate with and without the addition of pentanal or hexanal. When the systems were reacted at 100 °C for 4 h, 2, 5-dimethyl-3-pentylpyrazine and 2, 6-dimethyl-3-pentylpyrazine were formed in the model system with added pentanal, and the corresponding hexylpyrazines were formed in the hexanal system. Other pyrazines, including 2,3,5-trimethylpyrazine, 2-methyl-5(or 6)-ethylpyrazine, 2,5-dimethyl-3-ethylpyrazine, 2,6-dimethyl-3-ethylpyrazine, 2,5-dimethyl-3-allylpyrazine, 2,5-dimethyl-3-propenylpyrazine, 2,3,5-trimethyl-6-butylpyrazine, 2,3,5-trimethyl-3-pentylpyrazine, 2,3,5-trimethyl-3-hexylpyrazine, 2,5-dimethyl-3-propylpyrazine, and 2,6-dimethyl-3-propylpyrazine, were also obtained from the model systems. Formation pathways are proposed for some of these pyrazines. © 1990, American Chemical Society. All rights reserved.