and the Failure To Detect N - Acetylation of 2 - Aminofluorene in the Dog *

N-Hydroxy-2-acetylaminofluorene (N-hydroxy-AAF), in conjugated form, was identified as a urinary metabolite of 2-acetylaminofluorene (AM') in male mongrel dogs. This metabolite was isolated and characterized in crystalline form. 7-Hydnoxy AM', in conjugated form, and AM? were also found in the urine of dogs fed AAF; no 1-, 3-, or 5-hydroxy-AAF was detected. The ingestion of N-hydroxy-AAF led to the urinary excretion of the same metabolites; however, none of these acetylated metabo lites was detected in the urine of dogs fed 2-aminofluorene, N-hydroxy-2-aminofluorene, 1-hydroxy-AAF, or 3-hydroxy-AAF. Dietary supplementation with calcium pantoth enate and riboflavin and an attempt to induce acetylase activity by feeding 2-amino fluonene for several days did not lead to the urinary excretion of any recognizable acetylated urinary metabolites of 2-aminofluorene. Furthermore, under similar condi tions the specific activities of the acetylated urinary metabolites of 2-(acetyl-1'-C'4) aminofluonene fed in mixtures with unlabeled 2-aminofluorene were not appreciably different from the specific activity of the ingested acetyl-labeled AAF. In a dog fed a single dose of AAF-9-C'4 63 pen cent of the C'4 was excreted in the feces, and 19 per cent of the C'4 was found in the urine during the next 5 days. Approximately 3 per cent of an oral dose of AAF was found as 7-hydnoxy-AAF in the feces collected during the 1st day. No N-hydroxy amides were detected in the urine of dogs after ingestion of the fol lowing amides: acetanilide and its p-vinyl, p-fluoro, and p-ethoxy derivatives; trans 4-acetylaminostilbene; 2-propionylaminofluonene; and 2-n-butyrylaminofluorene. Ad ministration of 2-acetylaminonaphthalene to a dog led to the urinary excretion of very small amounts of this amide and its N-hydroxy metabolite. The synthesis of N-hydroxy-2-aminofluorene, a new compound, is described.