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Nitrobenzoic Acid (nitrobenzoic + acid)
Selected AbstractsDispersive Effects in Chemomechanical Reactions with Polyallylamine-Derived HydrogelsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2008Kazuaki Kato Abstract Volume changes of polyallylamine-derived hydrogels crosslinked with glutaraldehyde are determined with a large variety of effector compounds. Monocarboxylic effectors lead to smaller contractions, in contrast to dicarboxylate structures, which allow more effective non-covalent crosslinking between the positively charged nitrogen centers of the polymer backbone. Electroneutral compounds lead to negligible changes, whereas effectors with either a large p -moiety like in naphthoic acid or phenyl derivatives with polarizable substituents induce large contractions. This finding is in line with significant contributions of van der Waals interactions between the effectors within the hydrogel. Chemomechanical differences between regioisomeric effectors such as p - and o -nitrobenzoic acid are in agreement with independent results of dispersive interactions in related complexes. The volume decrease corresponds almost entirely to the gravimetrically determined water content of the gels. The acidity profile shows a strong contraction above pH 10, which is consistent with the known pK value of such polyamines. NMR spectra of the gels indicate strong binding of the effectors by line broadening, which is significant only for the chemomechanically active compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] HPLC separation of fullerenes on two charge-transfer stationary phasesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2006Qiong-Wei Yu Abstract Two charge-transfer stationary phases were prepared by immobilizing p -nitrobenzoic acid and naphthyl acetic acid onto silica. The nitrophenyl moiety and the naphthyl moiety were grafted to silica gel through the spacer of aminoalkyl silanes. The HPLC separation of C60, C70, and higher fullerenes on the new stationary phases was also studied. The influence of mobile phase and column temperature on the separation of C60 and C70 was examined, respectively. The retentions of C60 and C70 on the two stationary phases increased with decreasing toluene content in the mobile phase or with increasing column temperature. Higher fullerenes can be separated well using toluene as the mobile phase on the stationary phase of p -nitrobenzoic acid-bonded silica. [source] Genotoxicity of nitrosulfonic acids, nitrobenzoic acids, and nitrobenzylalcohols, pollutants commonly found in ground water near ammunition facilitiesENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2006Tamara Grummt Abstract 2-Amino-4,6-dinitrobenzoic acid (2-A-4,6-DNBA), 4-amino-2,6-dinitrobenzoic acid (4-A-2,6-DNBA), 2,4,6-trinitrobenzoic acid (2,4,6-TNBA), 2-amino-4, 6-dinitrobenzylalcohol (2-A-4,6-DNBAlc), 4-amino-2,6-dinitrobenzylalcohol (4-A-2,6-DNBAlc), 2,4-dinitrotoluol-5-sulfonic acid (2,4-DNT-5-SA), 2,4-dinitrotoluol-3-sulfonic acid (2,4-DNT-3-SA), and 2, 4-dinitrobenzoic acid (2,4-DNBA) are derivatives of nitro-explosives that have been detected in groundwater close to munitions facilities. In the present study, the genotoxicity of these compounds was evaluated in Salmonella/microsome assays (in strains TA100 and TA98, with and without S9 and in TA98NR without S9), in chromosomal aberration (CA) tests with Chinese hamster fibroblasts (V79), and in micronucleus (MN) assays with human hepatoma (HepG2) cells. All compounds except the sulfonic acids were positive in the bacterial mutagenicity tests, with 2,4,6-TNBA producing the strongest response (8023 revertants/,mol in TA98 without S9 activation). 2-A-4,6-DNBA was a direct acting mutagen in TA98, but negative in TA100. The other positive compounds were ,1,3 orders of magnitude less mutagenic than 2,4,6-TNBA in TA98 and in TA100; relatively strong effects (,50,400 revertants/,mol) were produced by the benzylacohols in the two indicator strains. With the exception of 2,4-DNBA, the mutagenic responses were lower in the nitroreductase-deficient strain TA98NR than in the parental strain. 2,4-DNBA produced a marginally positive response in the V79-cell CA assay; the other substances were devoid of activity. Only the benzoic acids were tested for MN induction in HepG2 cells, and all produced positive responses. As in the bacterial assays, the strongest effect was seen with 2,4,6-TNBA (significant induction at ,1.9 ,M). 4-A-2,6-DNBA was positive at 432 ,M; the weakest effect was observed with 2,4,-DNBA (positive at ,920 ,M). The differences in the sensitivity of the indicator cells to these agents can be explained by differences in the activities of enzymes involved in the activation of the compounds. The strong responses produced by some of the compounds in the human-derived cells suggest that environmental exposure to these breakdown products of nitro-explosives may pose a cancer risk in man. Environ. Mol. Mutagen., 2006. © 2005 Wiley-Liss, Inc. [source] Nitrobenzene toxicity: QSAR correlations and mechanistic interpretations,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 10 2003Alan R. Katritzky Abstract The overall five-parameter QSAR correlation [ in terms of log(IGC50,1)] based on CODESSA-PRO methodology for the aquatic toxicity of 97 substituted nitrobenzenes to the ciliate Tetrahymena pyriformis supports previous conclusions that hydrophobicity and electrophilic reactivity control nitrobenzene toxicity. Correcting for the ionization of acidic species (picric and nitrobenzoic acids) improves the results: . Consideration of the total set of 97 compounds suggests two mechanisms of toxic action. A subset containing 43 compounds favorably disposed to reversible reduction of nitro group with respect to the single occupied molecular orbital energy, ESOMO correlated well with just four theoretically derived descriptors: . Another set of 49 substances predisposed to aromatic nucleophilic substitution modeled well () with five descriptors. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||