2(3)-benzoxazolinone (I) has been isolated from rye (Virtanen and Hietala, 19557, corn, and wheat (Virtanen, et al., 1956). It was later found that this compound is stored in the plant as the glucoside of 1,4-~enzoxzinone and is formed when the plant is injured. Kl~p and Robinson (1969) found concentrations as high as 1.4 mg/g in inbred strains of corn and had shown that the presenee of the compound was associated with the resistanee of the plant to attack by fungi and corn borer. A wide variety of N-nitroso amines, amides, ureas, and carbamates have been shown tobe extremely potent earcinogens and their presence in food products has been of considerable public health eoncern (Magee and Barnes, 1967; Low, 1974). Since these compounds are readily formed by the action of nitrite ton on the appropriate precursor under acidic conditions, it was felt that N-nitrosobenzoxazolinone (I=~l) might be formed in corn, wheat, or rye that had been heavily fertilized with nitrite-nitrate or that the nitroso compound may be formed through the action of dietary nitrite. In an attempt to form I_~_I, 0.01 mole of ~, 0.02 mole NaN02, and 0.02 mole HCI were stirred at 0o for 12 hr. in an aqueous medium. However, the starting material was recovered nearly quantitatively. The procedure was repeated using glacial acetic acid as the solvent and proton source (i0 ~ 26 hr.), and again only starting material was found. In a third attempt, trifluoroacetic acid was used as the solvent and proton source (0 ~ , 22 hr.), and the reaetion mixture was found to contain a small quantity of _I and a nearly quantitative yield of 6-nitrobenzoxazolinone (III). The identity of fil was confirmed by TLC, IR, and mass spectral data of an authentic standard. Activated aromatie systems, such as with phenols, usually yield C-nitroso eompounds with nitrous acid which are then oxidized to C-nitro compounds. Since Ill is easily formed from ~ by the action of nitric acid at room temperature (Clark and Pessolona, 1958), the formation of the N-nitroso derivative in this case probably oecurs in a similar manner.