nitrogen-dioxide and methylaniline

Skin lipids of mice exposed to NO2 contain lipid-soluble nitrosating agent(s) (NSA) that react in vitro with amines to produce nitrosamines. To test whether this reaction occurs in skin, we exposed mice to 50 ppm NO2 for 4 h and, 20 h later, applied 25 mg morpholine or N-methylaniline to the skin, which was then analyzed for the corresponding nitrosamine. When morpholine was applied, mean N-nitrosomorpholine yield was only 0.3 nmol/mouse (not significant). When N-methylaniline was applied and mice were killed after 10-40 min, N-nitroso-N-methylaniline yield in the skin was 13-21 nmol/mouse of which 87% occurred in the hair. NSA formation when mice were exposed to 6.5 ppm NO2 was only 0.15% of that for exposure to 50 ppm NO2. NSA occurred mostly in surface lipids of the skin and its in vitro reaction to give nitrosamines was not inhibited by alpha-tocopherol. When morpholine was painted and mice were then exposed to 55 ppm NO2 for 30 min, the skins contained 19 nmol N-nitrosomorpholine/mouse, attributed to a direct reaction between NO2 and the amine. We concluded that nitrosamine formation in skin by this direct reaction may be more important than the reaction of amines with NO2-derived NSA.

Topics: Aniline Compounds; Animals; Male; Mice; Morpholines; Nitrogen Dioxide; Nitrosamines; Skin

Reaction of N-methylaniline in solution with ca. 100,000 ppm gaseous NO2 leads to significant amounts of ring- and N-nitro products, in addition to N-methyl-N-nitrosoaniline. Reaction of heterocyclic amines in solution with 5-1000 ppm gaseous NO2 gives significant amounts of N-nitrosamines and much higher amounts of N-nitramines than those obtained from concentrated gaseous NO2. The results are interpreted as evidence that N-nitrosation proceeds via an unsymmetrical ON-ONO2 dimer, whereas N-nitration may involve a free-radical process involving NO2, itself.

Topics: Amines; Aniline Compounds; Chemical Phenomena; Chemistry; Nitrogen Dioxide; Nitrosamines