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5 c. 2,5-Dimethyl-3,6-dipropyl-pyrazine was prepared by first forming 3-oximino-2-hexanone by reacting 2 -hexanone with nitrosyl chloride according to the method of BOUVEAULT, Bull. [3] 31, 1163 (1904). The autocondensation of two molecules of the imino-ketone in the presence of zinc and acetic acid [according to the method described in Chimia 11, 310 (1957)] yielded 2,5-dimethyl-3,6-dipropyl-pyrazine which had a b.p. of 109°-110°C./10 mm. Hg. 5 d. 2,5-Dimethyl-3,6-diisopropyl-pyrazine was prepared by first forming 4-methyl-3-oximino-2-pentanone by reacting 4-methyl-2-pentanone with nitrosyl chloride according to the method of BOUVEAULT, Bull. [3] 31, 1163 (1904). The autocondensation of two moles of the imino-ketone in the presence of zinc and acetic acid [according to the method described in Chimia 11, 310 (1957)] yielded 2,5-Dimethyl-3,6-diisopropyl-pyrazine which had a b.p. of 91°C./8 mm. Hg.