David H. Giamalva

KINETICS OF OZONATION. 2. AMINO ACIDS AND MODEL COMPOUNDS IN WATER AND COMPARISONS TO RATES IN NONPOLAR SOLVENTS

Die absoluten Geschwindigkeiten der Reaktion (RG) verschiedener Aminosauren und Modellverbindungen (I)-(XIX) mit Ozon in wasrigen Pufferlosungen (verschiedene pH-Werte) werden gemessen.

Toxicity of polycyclic aromatic hydrocarbons. I. Effect of phenanthrene, pyrene, and their ozonized products on blood chemistry in rats

Male Sprague-Dawley rats were treated with a single ip injection of physiological saline (3.0 ml/kg), dimethyl sulfoxide (DMSO, 3.0 ml/kg), phenanthrene (150 mg/kg), ozonized products of phenanthrene (150 mg/kg), pyrene (150 mg/kg), or ozonized products of pyrene (150 mg/kg). Phenanthrene, pyrene, and their ozonized products were dissolved in DMSO (50 mg/ml). Serum aspartate aminotransferase (AST) activity was increased significantly 24 hr after ip administration of DMSO when compared with physiological saline. Phenanthrene produced a significant elevation of serum AST and gamma-glutamyl transpeptidase (GGTP) levels related to physiological saline and DMSO-injected rats 24 hr after injection. However, GGTP levels for groups treated with DMSO or phenanthrene were not significantly increased when compared with saline groups 72 hr after injection. Ozonized products of phenanthrene produced a significant elevation of serum AST, alanine aminotransferase (ALT), GGTP, and bilirubin levels when compared with groups treated with physiological saline, DMSO, and phenanthrene 24 or 72 hr after injections. The ozonized products of phenanthrene also produced significant elevation of serum creatinine levels compared with physiological saline, DMSO, and phenanthrene groups at 24 hr after treatment and of blood urea nitrogen (BUN) levels at 24 and 72 hr. Although pyrene caused a small but significant increase in the serum AST and bilirubin levels 24 hr after treatment, no significant change in the serum AST, ALT, GGTP, BUN, and creatine levels were observed with the ozonized products of pyrene at 24 or 72 hr. This study demonstrates significant alterations in serum chemistry induced by reaction products of ozone with phenanthrene. No such effect was observed when the products of pyrene ozonation were administered. Although the ozonation products of pyrene were not toxic under the conditions of this study, phenanthrene products were more hepatotoxic than was phenanthrene itself. Nephrotoxicity was also an apparent effect of ozonized phenanthrene. Since ozone-polycyclic aromatic hydrocarbon (PAH) reactions may occur in the atmosphere, these reactions might produce compounds that are more toxic than either ozone or the PAH alone.

Kinetics of ozonation. 5. Reactions of ozone with carbon-hydrogen bonds.

Rates of ozonation for 10 ethers, 2 aldehydes, and 2 saturated hydrocarbons are reported in carbon tetrachloride solvent, over a 36-60/sup 0/C temperature range. More limited data are reported in acetonitrile. The resulting activation parameters are inconsistent with a mechanism involving prior complexation of ozone with an ..cap alpha.. oxygen atom or with hydrogen-atom abstraction. Of the mechanisms previously proposed in the literature, a hydride abstraction and the concerted insertion of ozone into a C-H bond are most consistent with their kinetic data. A comparison of rate constants in carbon tetrachloride to rate constants measured in acetonitrile indicates that the effect of solvent polarity is small, so either an ionic mechanism must involve a high degree of ion pairing or an insertion mechanism involves a dipolar contribution.

Autoxidation of methyl linoleate initiated by the ozonide of allylbenzene

Allylbenzene ozonide (ABO), a model for polyunsaturated fatty acid (PUFA) ozonides, initiates the autoxidation of methyl linoleate (18∶2 ME) at 37°C under 760 torr of oxygen. This process is inhibited by d-α-tocopherol (α-T) and 2,6-di-ert-butyl-4-methylphenol (BHT). The autoxidation was followed by the appearance of conjugated diene (CD), as well as by oxygen-uptake. The rates of autoxidation are proportional to the square root of ABO concentration, implying that the usual free radical autoxidation rate law is obeyed. Activation parameters for the thermal decomposition of ABO were determined under N2 in the presence of radical scavengers and found to be Ea=28.2 ±0.3 kcal mol−1 and log A=13.6±0.2; kd (37°C) is calculated to be (5.1±0.3)×10−7 sec−1. Autoxidation data are also reported for ozonides of 18∶2 ME and methyl oleate (18∶1 ME).