The occurrence of 3-alkyl-2-methoxypyrazines in raw vegetables

A survey has been made of the occurrence and relative amounts of 3‐isopropyl‐, 3‐sec‐butyl‐ and 3‐isobutyl‐2‐methoxypyrazines in a broad selection of raw vegetables. At least one of these compounds was detected in all but four and all three were identified in 13 of the 27 vegetable tissues examined. The technique is described for their separation, identification and estimation. This involved headspace collection of total volatiles on porous polymer traps, separation by trapping and transfer between capillary columns and mass spectral identification. A general synthesis of 3‐substituted‐2‐methoxypyrazines giving high yields and single end products is described. A possible biogenesis of the named compounds is discussed.